6 Most Common Mercruiser Problems

If you own a late model Mercruiser engine in your boat, you're almost guaranteed to run into one of these common problems. WE ARE IN NO WAY AFFILIATED OR SPONSORED BY MERCRUISER

[@DIGITALCANADA]

Really love the way you explained 6 key issues in just about 30 seconds each, with zero fluff. This is quality content! Thank you sir! You won my subscription!

[@BoatBuy]

DIGITAL CANADA PRODUCTIONS Thank you!

[@joeangelmartinez4712]

Completely aggree

[@karlknudson1264]

Me to. Can't stand bloke the about everything except what you won't to no for 30 min

[@goutvols103]

Thanks for the info. I am seeing more and more multiple engine outboards instead of Inboard/Outboard and inboard engines. The efficiency and horsepower of outboards have increased over the years.

[@crisprtalk6963]

All killer no filler. Love this guy!

[@briantorpey3746]

Excellent commentary , very accurate about the IAC motor/valve

[@Bertsblurts]

Thank you for the info. Stalling at idle is my problem and you nailed it. Thanks.

[@BoatBuy]

Bertsblurts You’re welcome! Glad it was useful.

[@clintonr4211]

Great having u guys around.

[@BoatBuy]

Thanks Clinton.

[@stevetompsett5102]

Yep my steering arm had the rusted issue you describe..wish the previous owner had been more vigilant

[@joshuagosine9540]

this video definitely deserves a like. awesome info.i guess time is limited for you in creating these but longer vids please. lol

[@BoatBuy]

Joshua Gosine Thanks Josh!

[@godszenith4920]

That was great guy! Good video..i m a decent mechanic but new to boat motor realities...so much appreciated.

[@BoatBuy]

No worries - glad it was helpful!

[@randyscott3386]

Great Video !

[@Compass18]

Same here! I couldn't figure out why I kept stalling at idle and now, after a year, you gave me the clear answer! Thanks a ton

[@BoatBuy]

You're welcome Spencer.

[@juhavehnia7862]

You need to add IAC muffler to the video. Sometimes IAC motor is working fine but if the muffler gets blocked or blocked by oil / other residue things don't work as they should!

[@kyletodd6133]

This guy knows his stuff!

[@BoatBuy]

Thanks for the kind words Kyle!

[@yachtwork]

Awesome. Super good info.

[@BoatBuy]

Thanks Scott!

[@1951RKP]

I don’t work on salt water boats so I’ve not seen a few of the problems you spoke about. IAC is a problem I’ve seen frequently enough I try to get my customers to keep a spare on board th each them symptom and how to change them. One thing I see frequently on Mercs is the slave solenoid going bad. Easy fix and at least you can start the engine if you know how to jump across the top. That to I recommend my frequent boating customers to keep a spare and many know how to change and I’ve showed them how to jump across for emergency start if they get stranded. One other problem I’ve encountered is new parts that are defective. New parts bad I’ve seen is distributor caps on Mercs with flat caps. The slave solenoid. Went through new ones the other day before I found a good one.

[@BoatBuy]

Yep, they’re all common problems too.

[@pap91rt50]

What year did the new manifiolds start?

[@TheBeingReal]

Salt water is just abusive to everything. Regardless if Merc, Volvo or any other recreational brand. That steering pin issue: shops by me won’t touch the half-baked repair kit where you cut through the transom assy. Put in the SeaCore unit and problem solved.

[@brendenwoolums7474]

What's your opinion on the Vazer?

[@aflong2005]

Where's this water px sensor kit?

[@andybub45]

We had a 1989 regal with a mercruiser 350 (GM 350) V8, alpha one outdrive. Never had any issues with the engine, but the sterndrive had issues when it got older. We fixed it and got rid of it. We bought a 2007 Sea Ray 230 select, Mercruiser 5.0 MPI (GM 305). No issues so far, although there is a hissing noise, probably the IAC. Hasnt failed yet. We love our mercruisers with GM V8s.

[@BoatBuy]

Hissing noise is likely the IAC filter. Pop your flame arrestor off and you should see a space for a small sponge looking filter.

[@intheshell35ify]

IAC can also cause a hum/whistle/moan just as you come off idle.

[@mikedodd9294]

there is a little fiber filter you can buy that can help with this. Many boats run without it and the engine has a noticeable hiss. I prefer to have it installed. But you can also get an odd whistle here or there, nothing to worry about. I suggest STANDARD BRAND IACs on the Merc MPI's available at O'Reily Auto Parts after trying all the ebay specials and even the official Quicksilver ones. Standard ones made in Mexico, with lifetime warranty, last the longest in my experience.

[@willytv275]

Nice video - the steering pin you mentioned, to replace it, do you have to A) pull the engine or B) use the kit that requires drilling holes in either side of the transom plate?

[@BoatBuy]

Yes, either is possible although depending on the access available to the back of the transom.

[@willytv275]

OK, thank you for the reply. I replaced the gimbal ring in my older boat which has an Alpha one GEN one drive. I used the drill-through kit with hole saw that I mentioned in my previous comment. I recently purchased a Cobalt 252 with Merc 496 and Bravo 3 drive. The pin that I mentioned earlier, is getting very rusty and probably eating out the seal around it.. Why they would not include a stainless pin from the factory is beyond me. Anyway, I am wondering how difficult it will be to take out the carbon steel pin and replace it with a stainless one and new seal. I know it is a big job, and at present I am just squirting grease up in there trying to slow the rusting process.

[@spinedoc893]

Aside from the IAC valve these are pretty much salt water only issues. Another common issue is the ignition module which gives basically the opposite to the IAC valve. The engine starts and idles but stalls as you give it throttle.

[@BoatBuy]

Yeah, fair point. We rarely see freshwater boats over here in Australia...

[@sheshucksshells-rachaelcon543]

We have a 2005 Bayliner mercruiser 5.0. It doesn’t have an IAC. The carb was just replaced last month. Now we’re having issues with stalling when the engine is hot and we’re at idle speed. Once the engine is hot and it stalls, we struggle to get it started. Help!!!!

[@carlossolda1546]

Hi. Very useful explanation. Thanks. I'd like to ask you about Exhaust Manifolds (muffles) replacement. Can you tell me if a Mercury 4.5L/250HP engine manufactured in 2015 is considered an old or new model to present the kind of issue you mentioned on the video ? Is that possible to perform an inspection to check whether a replacement is necessary ? Thank You.

[@BoatBuy]

Hey Carlos, Those newer manifolds still need to be removed and inspected now they're coming on to 7 years old. There is a gasket near where the catalytic converter mounts, and a water cooled passage around it. You split it there and inspect the internal condition. They're very expensive to purchase if you need to replace them.

[@markmckenzie5981]

@boatbuy what are we meant to do to extend the life of the transom/steering assembly? Mine's wet during use but I don't know what to do about it.

[@BoatBuy]

Hey Mark, You can change the steering pin shaft/seal but you will need to assess the condition of the housing when it’s apart as it’s common the seal mounting surfaces corrodes and even if you put a new seal it will leak again. It’s a lot of work to “maybe” fix it, that’s why most people replace the whole transom assembly. I’ve also seen people fix the seal, only to have the trim lines/rams fail or other areas and it ends up costing them the same as if they had of replaced the whole transom assembly by the time they slip the boat again, strip it down etc.

[@SC-yx6wr]

Good list. I might add the beltdriven seawater-fuelpump system on older motors is a terrible design, and I have three fail from leaks, and one seize on me while under way leaving me dead in the water. Not fun. They need to have the tiny oil sump that the fuel pump arm and cam run in properly serviced on a regular basis, which is NOT indicated in the manual. There are companies makine OEM and upgraded performance replacement seawater-fuel pumps, but they are costly. I have had two big block and one small block v8's and all of them had bad grounding connections to the engine block which make for fun times debugging wonky electrics and no-starts. On earlier engines, the starter +ve terminal is also used as a junction post for multiple wires, and its very hard to access under the motor and also tends to work loose causing intermittent electrical glitches. Also, need to inspect bellows often, including the tiny one on the shift lineage shaft, or they will sink your boat at the dock. Speaking of which, you can actually damage the linkage and transmission if the gear selector is engaged when the motor is not running. THE worst are those blue plastic wing screws that plug the drains for the coolant pump and manifolds. They are hollow plastic, and our tech once broken one off in the bottom of the manifold with his boot, which caused a syphon and filled the boat with water, almost sank at the dock. They can be replaced with stainless steel cap bolts with "O" rings. I could go on all day...

[@BoatBuy]

Great info, thanks for adding!

[@vinnylima7571]

I'm looking at a 2018 sea ray sundancer 320 inboard with twin 350. Salt water use year round. Wonder if I should rethink. How often will these problems occur ?

[@daniels2761]

Get an outboard boat instead.

[@easemailboxes]

Your not entertaining buddy...... but you are really useful! Great stuff! Thanks a load! and thanks for reading your comments section!

[@BoatBuy]

😂😂 Thanks mate. Wife tells me vids are boring… I get it!!

[@michaelking42]

@@BoatBuy Thanks mate, I really appreciate this boring video. I'd love to see you do an explanation of how the IAC works.

[@dior1992]

What a smile! Could have convinced to sell me about anything

[@BoatBuy]

Thanks Dior!

[@heavydssutton9083]

Can you talk about - a boat that once is heated up, stalls out when you try to punch it again ,like pulling a skier - PLEASE

[@matthewpillay]

It seems to me that if this #1 problem of a leaking seapump causes so much subsequent issues due to the resulting salt spray, someone should look into fabricating a cowl of some sort that fits over the spinning pulley to contain the spray. This will perhaps concentrate the spray directly downwards into the bilge. We can get a bit more fancy with the solution by including a water sensor that lights up an led on the dash when it sensors the spray

[@D_and_L]

Flushing the engine more will help with corrosion.

[@BoatBuy]

That's an excellent idea Matt.

[@malthelarsen9784]

If you cycle it with fresh (not salt Water) would that help with some of the problems

[@BoatBuy]

Nah it's a little bit more complicated than just running fresh water through it....

[@falconeaterf15]

Had a 4.3 mercruiser and a frost plug popped out the engine while underway in the middle of summer. Shop replaced it, boat ran poorly with low power. Shop said engine seemed fine , compression etc. Eventually found the exhaust baffle had overheated and distorted and stuck half closed, blocking exhaust flow. Ah, the joys of boating......

[@BoatBuy]

It's not always obvious, it's unfortunate when you've gotta spend extra time finding these things. If only we had x-ray vision..

[@andybub45]

Bust out another thousand!

[@direstrait5418]

They said it was fine.. as they always say..

[@STLT]

Mostly salt issues, fresh is the transom assemblyx6

[@rodsnyder979]

How do you install a mercruiser 1.7 DTI turbo diesel interupter switch

[@BoatBuy]

Generally you would install a Bravo X drive sterndrive behind a diesel which has a cone clutch as opposed to a dog clutch. This means no need for an interruptor switch.

[@stevewenzel391]

How are the bravo 3 5.0 mpi looking to buy a sea ray with that engine

[@BoatBuy]

Not a bad option. Carry all the usual common things but generally speaking Bravo 3 is the more heavy duty unit with duo-propellers. Find out when manifolds and risers were done. Budget for a sea pump if it’s 5+ years old. Check transom assembly Replace bellows on sterndrive if it’s due

[@errolseager1292]

I purchased a 5.0 MPI mercruiser package with Bravo 2X stern leg and smart craft controls and instrumentation, it also has a closed cooling system in the crate, the thing is it was built and crated in 2005 and has never been taken out of the crate or been run, I took the plugs out recently and borescoped it and it looks new inside, I had to remove the serpentine belt to turn the engine over by hand as the raw water pump is jammed, some questions for you. 1) what are the chances of a successful start up, 2) will it have the newer dry joint risers and how can I tell without removing them, 3) would it be worth making and fitting some form of drip tray between the heat exchanger and alternator, 4) I am in New Zealand and paid $15,000 for the package which includes a 19 3/4 x 19 prop, does this sound like a good deal, I will be fitting the unit to an 8.2 metre Frank Pelin Topaz gullwing planing hull trailer launch

[@BoatBuy]

Hey Errol, 1. I'd try turning the engine over by means of hooking up to the crankshaft with the belt disconnected. If the engine spins freely and it's just the sea pump seized, then you'll likely have a successful startup if it's a brand new engine thats been stored in a crate. 2. It may, but you can tell from the outside. Here is a link to photo of the differences: boatbuy.com.au/wp-content/uploads/2021/06/Wet-Joint-vs-Dry-Joint-Exhaust-Manifold-1.png 3. I wouldn't worry, I'd just make sure you service your heat exchanger regularly and don't let it leak 4. That sounds like a bargain. The bravo 2 X sterndrive alone is around 11k. Just check the ratios are suitable for your application, you might need to try a few propellors.

[@errolseager1292]

@@BoatBuy Thanks for the prompt reply, yes it's a brand new engine and stern drive, it is a turnkey package with all the factory documentation etc and includes all the parts and cables for a dual helm setup. As I said, I have had the belt off and turned it and it rotates freely so I guess I will need to fit a new impeller in the pump, I didn't realise the stern drive was worth that much, I am pleased I picked the package up for what I paid, I don't recall what the ratio is but I have a feeling I will need a different prop and am prepared for that scenario, the prop supplied is alloy so I thought if I had to replace it I would get a stainless one.

[@BoatBuy]

Sounds good! See if you can get a few to try before you spend up on a stainless one.

[@velisercanbahtiyar2579]

Hello, I am about to purchase a Mariah 216 Talari with a GM350 5.7 engine. According to the seller, while the engine is working properly, it suddenly starts vibrating and not exceeding 2000-3000 rpm. When they check, they notice that one of the spark plugs is loose and they tighten it, but the engine still does not run properly. The problem continues. After doing some research, I learned that such a problem can cause great damage to the non-ignition cylinder and therefore to the piston. The cylinder and the faulty piston had to be replaced completely. I was wondering your opinion. Thank you very much in advance.

[@BoatBuy]

Yes, it is definitely possible. You need to organise a mechanic to do a compression test to verify if any damage has been done.

[@arthurmomo4406]

So my boat originally had the new style Dry Joint Exhaust manifolds. But they had cracked and I bought a pair of the older style exhaust manifolds. Does anybody know if the old style manifold will still work?

[@BoatBuy]

Old style (wet joint) will definitely work, but I would highly recommend staying with dry joint. If the wet joint fails it's more likely to damage your engine internally.

[@Discoworx]

Nice, quick video thanks. I've just bought a boat with a 3.0 tks. It runs on for say 5 seconds. Only 20 hours of use. 91 octane fuel with 1ml/l fuel doctor stabiliser in it. Idles ok. Could start better. Where's the first place to look? Thanks

[@lh98]

@Robert Miller more info would be helpful, year of boat/engine, if it’s carb or fuel injected etc. it sounds brand new if only 20 hours but if that was the case i’d think your dealer would cover that issue. more input and details if you want ppl to help

[@Discoworx]

@@lh98 oops, sorry, quite right. MerCruiser, carb, 2013. Previous owner says she ran premium (higher octane) fuel and it didn't run on. I haven't used enough of my regular fuel yet so haven't tried but I'm not really believing her. Mate had a boat which he could never stop from running on, he sold it and the new owner put on a new distributor cap which solved it. Obvs could be a timing issue and it could be the tks module (not that I know what that is yet). Was hoping to put the call out and somebody says "yeah that's a common issue on those, you need to do XYZ..." Rather than go through a lengthy problem solving process. Cheers

[@winstons1806]

Robert, try running at idle for a minute or two before turning off.

[@godwinapap1683]

The tacho on my 3.o mpi mercriuser stopped working after been touched by a marine mechanic, who's no longer answering my calls and messages. I run some tests myself and the tacho works on an other engine. The gray wire on the hull wiring loom gives continuity. There is continuity between the service tacho plug and the gray wire on the 10 pin engine loom. When I disconnected the coil plug and temporary rewired the coil to the service tacho plug, the tacho works fine. Is there a plug between the coil and the obdm plug that can be a potential fault please?

[@BoatBuy]

I'd always thought the tacho ran off the alternator - but it depends on the model. I'd suggest looking up a service manual, as it will have a detailed wiring diagram and you'll be able to chase the wiring back to the source.

[@billl3936]

taking on water with my 1988 wellcraft 210 classic. 5.7 motor with Alpha one o/I. water is cold so do not think it is from exhaust. not getting pulleys of fan belts wet. any thoughts on what to check?

[@BoatBuy]

Get a torch and look right up the back of the boat and see if there is anything dripping from the transom. Otherwise get the engine running (if there is access) and look around the inlet cooling side for a leak from a hose.

[@paulhartman7144]

Check the bellows ( they r the waffle looking rubber tubes on the out drive ) tilt motor up and see if they are starting to dry rot also check the little bellows around shift cable . Look behind motor against the stern If you see water dripping your bellows is probably bad

[@Andrico77]

Add the the cool fuel 3 module.

[@BoatBuy]

Yes, that’s a popular issue. Could be time to update this video…

[@hildablanco1591]

The vaper lock flushing system can rust and put water in your fuel system

[@BoatBuy]

Yes, another common one. This video is due for an update!

[@pheonix5823]

Great info,I'm looking at a boat at the moment its a 07 Rai-line 186 has a 3lt Mercruiser with 320hrs,, dealer says its all good, located Cleveland Brisbane anyone recommend a marine mech I could get to go over the motor

[@BoatBuy]

Call Leighton on 0411 126 287 and he will sort it out for you!

[@pheonix5823]

@@BoatBuy thanks very much..

[@markgardner8892]

With all these potential issues from a end user perspective seems these engines are bound to fail… how often would you need to service to prevent issues if the boat lives in the water

[@BoatBuy]

Yeah, you will find some people outlay for a re-power every 10-15 years instead of all the constant repairs. Generally every year should be fine for servicing.

[@clintonr4211]

My 350 mag engine runs well for 4 to 6 minutes at 4000 rpm and then starts hunting or jerking. Pls can it be the fuel pumps as i changed the plugs and the fuel filters. Pls helo.

[@BoatBuy]

Sounds like you need to take it to a Marine Mechanic to diagnose.

[@1LETrackPerformance]

Can anyone diagnose this? I have a mercruiser 5.7 that Boggs out at the high rpm range and popping back out of the intake manifold

[@BoatBuy]

Have a look under the distributor cap for some corrosion or wear.

[@troydimsdale2331]

I’ve got MerCruiser 350 mags and I’m getting the message engine misfire “service engine soon”. What could cause that?

[@BoatBuy]

I'd take a look at spark plugs, ignition leads, distributor cap and rotor button. Could also be coil - but need to test it.

[@palbaustad6420]

Hey, I have a MerCruiser 2.8 QSD. It`s hard to start. Runs fine when started. I have checked all injectors and replaced the return valve. Any ideas?

[@BoatBuy]

Not too familiar with this particular model but is there glow plugs?

[@palbaustad6420]

@@BoatBuy No i don`t think it is. If the engine sits for 30 minutes(warm engine) it gets hard to start again.... fuel filters are changed...

[@David-hu3mf]

What do you generally do with the ever common problem of the carb mercruiser 454 taking ages to fire up? Everything has been rebuilt and serviced. Runs perfect when started but takes ages to fire up when cold. Is this just the mechanical fuel pump taking a long time to get fuel to the fuel bowl in the carburettor? Or something else that I’m missing? Any help much appreciated.

[@BoatBuy]

David Russell are you pumping the throttle when you crank the engine? What sort of choke setup do you have? Shouldn’t really take ages to start. What are your compression readings?

[@David-hu3mf]

@@BoatBuyThanks for your reply. Yes I give it two to three pumps before cranking. Lso tried pumping it wjile cranking. Seems to flood engine if i do that. It's got a new carburetor with electric choke which is adjusted and operating normally. Engine is only freshly rebuilt approximately 100hrs ago, so I assume compression should be in spec. Not sure what's happening with it.

[@BoatBuy]

David Russell I would still check compression. It’s really a process of elimination, as an engine needs spark, compression and fuel to start. A well maintained engine should start pretty easily.

[@rethink333]

BoatBuy I had almost the same identical problem. Mercruser 5.O 2bl carb. It was my fuel pump. The fuel filter that is next to the carb had some gunk in it too. Take the cover off and pump. Disconnect the throttle cable hand to see if the fuel is squirting into the carb. Might help.

[@hjmmuller6720]

after 1/2 year of a brand new bravo z-drive 2x4,5l i had to replace both shafts due to corrosion. Only used in brackish water. No warranty was granted by mercury, no help from authorized dealer due to missing anode measuerement equipment. Mercathode system is blinking….

[@BoatBuy]

Need to figure out why the Mercathode is blinking. You can get a corrosion assessor (usually an electrician) to come and test your boat in it's berth and comment accordingly.

[@stevetompsett5102]

I've a issue with no water being pumped through the motor.could Thisbe thermostat or leg water pump ?

[@BoatBuy]

Depends what model. Is it an alpha or a bravo? Is the boat moored or on a trailer? Are you running it on a flusher or in the river?

[@lopezreinier22]

That could be the seawater impeller. Check that first.

[@stevetompsett5102]

@@lopezreinier22 hi mate . Yes water the sea water impeller cheers

[@mojotrinity4927]

What year did they go to the dry joint?

[@BoatBuy]

Mojo Trinity 2002

[@mojotrinity4927]

BoatBuy cool thanks for the reply.

[@DFSixe]

5 out of 6

[@sevendyseven4090]

2005+ mercruiser 350 MAG MPI 300hp with a BRAVO III drive that just started knocking, is this a confirmed rebuild or could it be simple timing/exhaust valve flapper type type stuff?

[@BoatBuy]

Does it continue to knock when you increase the throttle/revs? If it goes away - maybe a lifter. If it stays - likely a rebuild.

[@sevendyseven4090]

@@BoatBuy Thx, Ya, the Knock was 100% consistent.. my friend ordered the last available new motor, $16,000 (in Canada), today.

[@BoatBuy]

Ouch!

[@sevendyseven4090]

@@BoatBuy I know right!.. He is selling a good few things in his yard now, lol.

[@aronalbright6923]

I have a 2001 mercruiser 3.0 that runs fine but after about 3 hrs it doesn’t want to idle, I do have to keep the rpms up a bit .. if it goes dead it is very hard to crank back up, actually the last time I never could crank it back up on the water. Does that sound like iac motor or something else ? I just had carb rebuilt, filters changed out and new spark plugs installed. Thanks

[@BoatBuy]

Hey Aron, The 3.0L Mercruiser doesn't have an IAC motor because it's not fuel injected. I would be checking the compression, and looking for any leaks in fuel lines etc. Sounds fuel related.

[@sheshucksshells-rachaelcon543]

@@BoatBuy we have a 5.0 mercruiser, 2005 Bayliner. We are having similar issues to Aron. Our carb was just replaced last month. Once the engine is warmed up, we seem to have issues with stalling at idle. We’ve changed the TKS module, fuel filters, and the fuel water separator. We have been using 87/89 octane fuel so we’re thinking of adding a fuel treatment and going with 91 octane. Like I said, all issues seem to be when the engine is warm. Any advice? We have a buyer lined up and we’re moving so time is crucial.

[@BoatBuy]

@@sheshucksshells-rachaelcon543 Has the carby been cleaned?

[@kevinclarisey1509]

My 2001 5.0 has been doing the double alarm beeps every couple of minutes. Can't figure out why. Tried disconnecting sensor wires at the hydraulic reservoir tank but the beeps keep coming. Any thoughts to diagnose it?

[@BoatBuy]

Is it an MPI engine or carby?

[@kevinclarisey1509]

@@BoatBuy It's MPI

[@BoatBuy]

I’d be taking a look at the water pressure sensor. Without plugging in a computer I can’t tell you 100%, but water pressure sensor is located on the power steering cooler up the back of the engine.

[@kevinclarisey1509]

@@BoatBuy How about the engine temperature sensor? Wondering about that since it doesn't start the alarm beeps until the engine is fully warmed up. Also, FYI, all gauges read normal.

[@gerardjames2196]

Guys im having a headache with my 5.0 mpi. Doesn't rev past 2000 rpm

[@BoatBuy]

Sure. Have you done a compression test first?

[@troyaitken1145]

Thx for that info. Do you have an idea as to why my merc will not go over 4000 rpm. Will drop to 3500 then 3200. Then come back up to 4000 and even went up to full rpm for a short bit only to go back down. No alarm all sensors changed plugs and distributor cap change. Could it be the ECM, Colin wire or fuel flow problem. Please, please help. Graceful

[@BoatBuy]

Troy Aitken Hey Troy, I’d be putting a fuel pressure gauge on provided its an MPI. If the pressure is fluctuating while you have the issues you know where to look. If it holds good pressure you can rule out fuel and go to the next step.

[@molleymillard6766]

In addition to his reply about the fuel pump, I was astounded to find out how much water I had in the gas tank. Faulty o-ring on the gas cap and dried out o-ring on the tank access panel on top of a missing gasket on the fuel sender unit (won't be using that mechanic anymore) - all combined to allow water into the gas tank. Unscrew your water/gas separator and pour into a gatorade bottle and see if you have water - I had to drain my tank entirely and start over.

[@spektrum426]

Hi, I’m considering a used boat that has a low hour Mercruiser 4.3 MPI. It’s been used in salt water without a fresh water kit installed - Anything I should look out for? Would it be worth installing a fresh water kit for use in salt water?

[@BoatBuy]

Take a look at when manifolds and risers were last done, depending on if they're dry joint or wet joint. I don't see much advantage in installing a freshwater kit at a later stage in life, as any corrosion already in the engine block will still be there, and the expense of it will have zero gain. I'd say you're better of saving that money for maintenance / incidentals that will pop up along the way.

[@andybub45]

If your boat is large, dont buy it, because it will be very slow. We test drove one on our not-busy lake and it was very slow, could barely get out of its own wake. We bought a Sea Ray 230 select with a 5.0

[@ibrahimhoblos4573]

Would anyone know why I’d hear a rattling sound on a 2007 4.3mpi mercruiser only on idle and very low rev . Cheers

[@billyreidpath303]

Torce converter bolts loose

[@BoatBuy]

There is plenty of reasons. Have you removed the sterndrive for a look?

[@michaelmurphy3113]

I have a problem 2005 sea ray sundancer mercruiser 8.1 v drives. Port motor starts fine, will then stall out at idle. Doesn’t seem to do it when the motor is warm. I replaced iac valve still have the problem. What u think? Thanks!

[@BoatBuy]

Make sure IAC filter isn’t blocked. If still stalling, do a compression test?

[@michaelmurphy3113]

@@BoatBuy where would it get blocked from. Only stalls once and then it’s fine. So weird

[@BoatBuy]

There is a small filter, you should see it when you remove the IAC motor. They block with dirt and oil from the intake

[@BoatBuy]

@@michaelmurphy3113 they usually block at the inlet

[@getthinwithken2489]

I have a 1997 sea ray with the 4.3 mercruiser and it has the alpha 1 LX drive..the problem I'm having it the boat will run fine then shut off like I turned the key off..then I start it right back up and drive again for a few minutes at any speed and then it shuts off again....any idea why this would be happening?

[@BoatBuy]

Hey Ken, Is this a carburettor motor? It sounds like some sort of issue relating to fuel. I'd check you've got no fuel blockages or issues with water in the fuel (check the filter) and if that's OK you might need to look at pulling the carby off and getting it checked?

[@getthinwithken2489]

@@BoatBuy thanks I will do and comment back

[@getthinwithken2489]

@@BoatBuy ok so I found dirty fuel in the water separater so I pulled the tank and cleaned it out as well as pulled the carb and cleaned it and replaced with fresh gas..I also replaced the distributor cap and button cause they were both corroded...I'm still having the same issue with the boat dying and random points at even lower RPMS 1200 all the way up..any other suggestions as to where to go next

[@getthinwithken2489]

Ok it was the distributor sensor it still had the old style 2 wire changed over to 3 wire runs great

[@tykettlewell595]

I just bought a 1983 four winns with a mercruiser 120. It ran amazing then filled it up with regular u leader and now constantly stalling when hitting the throttle. I put premium in after running most of the regular out and let it run. It was fine for 25 minutes but when I hit the throttle it stalled every timed after about 10 seconds. Can anyone help

[@BoatBuy]

Check to see if you're supposed to run leaded only fuel in that engine. Otherwise you need to look at your compression readings, and then if they're fine I'd look at fuel (as in, carby, fuel blockage, filter, etc)

[@lh98]

@Ty Kettlewell have you checked simple things like fuel filter? btw i don’t think there is leaded gas anymore i believe that’s a typo and he’s saying he put regular unleaded in 🤓

[@mikedodd9294]

I had the raw water intake pump leak on my boat, salt water, what a NIGHTMARE that caused me. It was basically dripping salt water on the belt, which would spray a light mist of salt water up and over the front of the engine. A few months of this and I've had to remove every front brakcet and pully on the engine to grind and paint the rust off. All the pulley wheels that are plastic with bearing... right in the trash. They sieze up after a month of this salt water belt, self destruct actually while out on the water necessitating a tow. You have no idea what a PITA salt water can do to the outside of the engine. Also this takes out the CPS - Crank Shaft Position sensor, but the Standard Brand sold at O'Reily in the USA works well as a replacement. Boat is all fixed \ my mechanic said the Hardin Marine dual ball bearing and dual sealed STAINLESS STEEL pumps are lifetime parts that do not leak like the Mercury pumps and equielent in cost.

[@BoatBuy]

Mike this is awesome! Had no idea these pumps existed I will check them out.

[@devilgtp]

I love aussies!

[@BoatBuy]

Thanks Dakota Vanspronsen! Where you from?

[@johnjeunesse739]

I have a 2000 l29mpi engine in my boat everything runs exactly as it should.Rpm,s temp,oil pressure,voltage. The issue i have is when i run at around 1to1300 rpm Occaisionally the engine will loose 300 or so rpm then come back never stalls. Cant figuire this out any ideas

[@BoatBuy]

I would start with the fuel system. Can you run the boat on a different fuel supply? (Portable tank, with new line and primer?)

[@johnjeunesse739]

@@BoatBuy Have not tried this,here is some additional information, It never does it when its cold,it wont happen untill the engine has been running for an hour or so,some days it does not do it at all,it never happens above 1500rpm???any more ideas

[@joshuahumanes8468]

Where can I find the kit to move the water pressure sensor

[@BoatBuy]

They’re on Amazon, otherwise any Mercury dealer.

[@joshuahumanes8468]

@@BoatBuy is it for an outboard that you just convert over?

[@joshuahumanes8468]

@@BoatBuy could you send a link please?

[@BoatBuy]

Yep. It’s just a few fittings, a small piece of hose and a bracket.

[@BoatBuy]

@@joshuahumanes8468 Currently unavailable but this is what you need. Speak to local Mercury dealer. www.amazon.com/Mercury-Mercruiser-Quicksilver-8M0056795-Parts/dp/B00N9HQHTO

[@verasworld2016]

Mine keeps idling high over 2000rpms and kicks hard into drive and reverse

[@BoatBuy]

You need to get that looked at, it will likely damage the gearbox.

[@mitchellphillips3583]

Look out for blocked cooling galleries in the cool fuel system on Mercruiser - happened to me and was a bitch to find the cause . Your engine will run fine for maybe an hour then splutter and stop - if you wait an hour you can start it again - I’ve got a 5.0 mpi

[@BoatBuy]

Yep, see this one regularly too! Most people change the whole cool fuel module over here.

[@mitchellphillips3583]

@@BoatBuy once you know the problem not too hard to fix we blew mine out with an air compressor - bits of dry dirt or mud blew out been fine ever since

[@bryanreynolds2055]

👏🏼

[@donniesteel21]

Glossing on a mer cruiser?

[@BoatBuy]

Glossing?

[@andychips6923]

So it’s pretty obvious to say that salt water is way harder on a boat than lake water?

[@lewiswilliams1452]

I have a Mercruiser Alpha 1 - Gen 2; Not long after starting engine and increasing speed to about 5 knots the engine alarm beeps (constant beep-usually 'low oil pressure' or 'overheating'). If I try to increase the speed beyond about 5 knots the engine dies. But I can slowly drift along around 3-4 knots without the alarm coming on. Temperature guage is fine, oil levels for engine and leg seem fine. Any suggestions?

[@BoatBuy]

Lewis Williams What sort of Mercruiser? Injected? MPI?

[@lewiswilliams1452]

@@BoatBuy 5.0L MPI

[@BoatBuy]

Lewis Williams Only way forward would be to plug in a computer to see which alarm is sounding, then go from there. Look up the Rinda scan tool, although probably cheaper to take it to your local dealership.

[@rogerboeing]

maintenance !!!!!!!!!

[@BoatBuy]

It sure helps!

[@cheapme1850]

This really should have been titled “Saltwater Problems”. Most of these issues aren’t a problem for freshwater boaters.

[@user-cv8bl7pp1n]

We should not be fixing these problems Mercruiser should be all over it !

[@rifhanrazak8253]

If cod 602-5 what the problems

[@BoatBuy]

Sorry what do you mean?

[@paulhartman7144]

I have a problem boat runs flawless. Starting ideal and up to 4K rpms if I go (wot) wide open throttle it’s like I ran out of gas boat just dies , then when stops runs on a little knocking . I shut off boat and boat starts right up with no hesitation and again I can run 45mph at 4K rpms all day long open it up and it dies . I have ran all gas out of boat and the last 5 gallons I added water treatment to remove any moisture in tank then added 14 gallons of 91 octane and seafoam I have changed cap and rotor. Checked screen in carb spotless. And disconnected fuel line from carb and powered up fuel pump off battery directly pumping 5 gallons of fuel into a bucket to see if fuel pump would pump well . Flow was steady and good

[@paulhartman7144]

With no signed of water in system . Has anyone had this problem ? Or give me a idea on how to fix

[@gigsterc9971]

0:35

[@levelupmaintenance6297]

Mercruiser problems. Yes.

[@BoatBuy]

Thanks!

[@ralphdecesare5822]

Yup, he is dead on. I've had mercruiser engines for years and have had 5 of these issues go wrong. often multiple times. Especially when it comes to IAC valves. Seems they are built to fail. If you have a merc engine and your IAC lasts more than 3 years, you won the lottery!!

[@BoatBuy]

Thanks Ralph!

[@wilsont1010]

Built to fail when you're 500 miles on the salt water out in the ocean? What are they thinking?

[@greensphinx]

3:12

[@A.Matt7]

How about just spray grease and you wont have that issue of rust

[@BoatBuy]

Yes, but if your sea pump is leaking and you don’t know about it, you’re probably not meticulous enough to spray grease your engine every year!

[@craigmcphail931]

I have a 4.3 inboard ( 2200 Mustang ClubSport) that has a beeeeeep- stop - beeeeep - stop - beeeeeep etc immediately on start up and keeps gong in this pattern - it’s not constant but long and broken - It’s not over heating - idling and running fine - any ideas please to [e-mail]

[@stunnasam21]

Mine did this but ended up just being some water on the high water sensor, dried it off and it went away, kinda strange

[@martingoransson6711]

Great video, but here's a tip... When showing pictures like at kzbin.info/www/bejne/gHmolISCrs1pfdE (3 Exhaust Manifolds), then include an arrow pointing to the holes in the pictures you're talking about. Makes it easier for beginners to understand. Have a great day! :)

[@BoatBuy]

Thanks Martin! Will do

[@jmag6096]

If you have to have a Stern drive boat get a valvo Stern drive mer cruisers have 2/3 Male parts and are junk

[@TheBeingReal]

John Morgan Ask a Volvo owner who had the XPD outdrives. lol

[@dancindavey1515]

Sounds like every sentence is a question.

[@BoatBuy]

What do you mean? ;-) Only kidding.

[@falconeaterf15]

I found this content.......terrifying.

[@BoatBuy]

What's more terrifying, this content or finding out via your wallet? ;-)

[@The_Brew_Dog]

These are all saltwater issues. 6 most common wouldn’t be any of these in fresh water.

[@dsciarrino3663]

Junk.

[@markdimaio8396]

Total junk

[@BoatBuy]

mark dimaio Your not a fan of Mercruiser engines Mark?

[@markdimaio8396]

@@BoatBuy unfortunately for most boats produced for the masses Mercruiser is the only game in town .

[@mike64646]

i had to watch the entire thing only to discover it did not cover my issue....for me it was a waste of time. Give a quick verbal list at the beginning of what you are going to cover.

[@BoatBuy]

Sorry I couldn’t help you Mike. What issue are you experiencing maybe I can help you?