REVIEW: Everything Wrong With A Mercury Mercruiser

[@DEBOSSGARAGE]

What engine should we review next?

[@jasonandrew5707]

6.7 cummins, id be interested in learning more about that engine

[@01AceAlpha]

The lotus designed , mercury marine built LT5 from the C4 ZR-1!

[@Stahodad]

Anything Ford Ecoboosted...😮

[@Wreckerboy]

13B

[@ryanreining4310]

2uzfe out of the toyotas

[@NoSocial1984]

I was a boat mechanic for 8 years and worked on every brand. I did lots of those JB weld block repairs and never saw one come back leaking.

[@jacksgarageworkshop]

Will never own one of these, this will never affect me, yet here I am.

[@numlockkilla]

You say this and yet your looking to buy a boat.

[@Dean-zx6nx]

I’m here with you lol

[@karlmckinnell2635]

Bask in the glory 😅 and grimace in the agony 😢. Either way we enjoy 😊.

[@moo3993]

Same

[@braap802]

The best way to have a boat, is to have a buddy with a boat....i know better than to own the boat...but ill probably end up with one 😂

[@corey6393]

Back in the 90's I worked at a local marina. We did hundreds of winter/summerizations on boats and had large storage buildings for winter. I think I still have fiberglass shards in my forearms from reaching around the larger engines stuffed into the fiberglass boats. We (the young mechanics and helpers) always preferred to work on the Mercruiser stuff, and specifically the Cobalts. They were simply a better built and better engineered pleasure boat than any of the others at the time. Bayliner and Maxim were always the worst. We called them the "Kraco" of the boating world.

[@newjerseybill3521]

Maxims, an engineering disaster from 12v power distribution to engine space ventilation.

[@treuteln]

My 1994 Cobalt 220 with the 5.7L still running strong. Everything original minus plugs. Great boats, excellent quality even by todays standards.

[@matd3150]

My current boat has a $75 junkyard 4.3 from a blazer. I put it in 4 years ago and it's been phenomenal 😂

[@brandonlarry1645]

Did you switch oil pans? I'm doing the same things now.

[@matd3150]

@brandonlarry1645 nope I left the Blazer oil pan on it. I did switch dipsticks, so you need to fill your engine up with the correct amount of oil, then calibrate the boat dipstick to read correctly with the new pan.

[@tonydiesel3444]

Ho or reg 4.3?

[@matd3150]

@@tonydiesel3444 I'm not sure

[@thediplomasta5891]

For that price, you can do no wrong. Any win, even for a day, is worth it.

[@SilverFlint247]

You did an excellent explanation of the mechanical differences between automotive and marine engines. But you forgot an crucial difference, the electrical system. The electrical systems for marine application, not only the engine, is different than automotive. The engine bay of a car is very well ventilated, you can see the ground when you open the hood. For a boat, when you open the engine bay of an inboard like yours, you see a solid sealed (hopefully) hull. There is nowhere for the gas fumes to go. This is the main reason for activating the venting fans before starting your engine. The electrical system of a marine engine is specially designed to avoid the electrical arcs of the various form of switches to be in direct contact with the surrounding air. Even the wires are different, each braid is individually tinned to prevent corrosion. Never use a car alternator, marine grade alternator will have double insulation to prevent shock and sparks. Rich, be careful with the LS swap, use marine grade electrical system.

[@1Longranger]

Running in saltwater it is a glycol based coolant with heat exchanger. More complex with raw water pumps and heat exchangers but when maintained, more reliable to my mind.

[@UQRXD]

I agree former USCG.

[@jimsutch5461]

I had a 165 hp, 6 cylinder that I changed out the block. That boat and engine ran from 1988 through 2009. At that point the engine was tired and the hull was tired so I scrapped it. I would drain the block including the intake and exhaust. Drain and replace the grease in the lower unit and add stabilizer to the fuel. Never had any issues when starting in the spring.

[@cageordie]

Go and have a look at B is for Build. He swapped from twin v8 Cummins to twin high performance LS motors. It's like a slow motion train wreck. The original engines weren't Cummins best effort, but he killed one by not checking the oil, which it was burning fast.

[@mz22wa]

Why that hack didn’t just put in a pair of Cummins 6BTs or QSB 5.9/6.7s is beyond me. He doesn’t even get his hands dirty

[@cageordie]

@@mz22wa The original engines were 14 liter 419hp Cummins VT903Ms. He could have got another for around $10k. There are QSB6.7s that would beat the 903 power for a time. The 'government' rating on the 6.7s will go to 550hp. But continuous rating is 305hp. CAT C12 ACERT 12l diesels will run about 700hp for $40k. 500hp Yanmar diesels are about $25k each. Yanmar 6LT640 640hp marine diesels are $35k and would probably have worked too.

[@JayneCobbsBunk]

I think B (Chris?) has said he doesn't have much experience with diesels but lots with LS. I would have stuck with diesels too but the converrsion is more challenging & prob makes for better content. To be honest, i would have sold the boat instead of dealing with the blown engine!

[@mz22wa]

@@JayneCobbsBunk he doesn’t have experience with anything. Absolute hack job

[@ajherman]

Intake manifold gaskets are another one. If converting a truck engine to a marine application you have to swap the intake gaskets as well.

[@V8Power5300]

LS intakes are dry

[@05milmachine90]

Having built a truck engine for a boat that cracked. I noted the intake gaskets were different and a side by side comparison showed the head gaskets had way smaller passages for coolant flow on the boat motor. I would guess due to them running colder in a boat.

[@ajherman]

@@V8Power5300 only within the last few years have LS based Mercruisers really become a thing. The vast majority are still SBCs.

[@ajherman]

@@05milmachine90 I forgot about the head gaskets as well

[@shanecutbirth1835]

Best advice i ever got from an experienced gentleman was, if it floats flies or fornicates, rent don't buy!

[@stolenbmxr1]

As a 10 year mercruiser tech and a long time follower of your channel i thought for sure I’d see this video and see something you may not have, but your good! That being said if you need a random part we’ve got a hoard of mercruiser parts at our Maryland shop! Awesome video

[@lukeromanoski4404]

In stead of draining the engine we just had a big tub of antifreeze, ran the outboard in and pumped it in, did that for 5 winters never froze. No issues also stopped the rusting.

[@joedirt9600]

I have a couple 5.7's in my 30' Sea Ray Sundancer, never gave me any issues..but it takes some maintenance.

[@ronl2463]

Had on in a Crist-Craft with a merc-cruiser (5.7) for over 10 years and never had a single problem with it at the Lake of the Ozarks.

[@L8nightride1]

hi guys, new to the boating world here. I take pride in learning how to do my own work but a little behind in the learning process. I bought a boat from an old engineer in Detroit, Michigan who said the merc had a cracked head but that it was properly repaired (sleeved) when he bought it. I have only owned it a couple weeks now. I am starting out with purchasing all safety equipment before I go out and bought the shop manual for mercruiser. It is an 1986 tiara 5.7L. I would love any input you guys could pass along. I maintain all my own vehicles but it has been a long time since I worked with non fuel injected motors. I was in the Navy when distributor caps were still being used. I found a few spots that were soft on the top deck so I am going to get my first experience doing some fiberglass work. I have thought about using coosa board to replace soft spots which to my understanding is balsa. Loved the video by the way. I think you converting to diesel would be an excellent video.

[@jaimesan2609]

I don't think I have ever seen a more informative video. Kudos.

[@tujuprojects]

You should do a review of bigger marine diesels. Cat, Cummings, Scania, etc there is a lot of them.

[@EarlG-r4r]

Put the ladder up on the swim platform next time so it’s not bouncing in the water behind you. 😉

[@joesilverbliss1721]

I have done that😅

[@SkypowerwithKarl]

All the newer models(not just MerCruiser) that have catalyst are to be avoided at all costs . They run in “closed loop” and use an O2 sensor. Those sensors go out regularly and will cost you a pleasant weekend and expensive repair. They typically cost more than the automotive equivalent. This might be the best time to get an older boat with fuel injection but not so new as to have a catalysts.

[@kevinmosser5969]

I don’t drain my boat engine, I use RV antifreeze after warmed up. Also kept in heated storage just in case.

[@thisisyourcaptainspeaking2259]

A common Mercruiser block for many years was the 880 roller cam block. Most 880 blocks were 2-bolt mains.

[@imtheonevanhalen1557]

Yeah, the 4 bolt mains BS came from endurance race engines.......zero need

[@garywelker8398]

I to will never own one of these boats, but the information and knowledge of this guy is AWSOME, and I thank you. I saw a 1969 Dodge Charger being built up a while ago, you car guys might have saw it on the show circuit or mags, it had a mercury motor in it, kinda looked like a cross between a flathead and hemi, the guy told me Mercury wants to get in the automotive end of motors, IDK. Anyways, thanks for the lesson.

[@Samuel_el_toro]

Those 96-2002 mercruiser intakes with injectors on the outside of the plenum are worth their weight in gold.

[@Jesse-lu7bt]

Mercrusers were manufacturing in stillwater Oklahoma good jobs back then

[@robertdinicola9225]

On floridas gulf coast we do manifolds and elbows every three years.

[@dogwithlaserpointer]

Something to note, JB Weld will in fact hold for 4 seasons anyway. If done properly. Remember that these aren't pressurized systems, I have personally put that stuff on a pressurized system and it held for the entire length of time that I owned the car, and the time that the next owner had it, don't know about after that. It ain't pro, but what does Derek say? If it works, is it really a dumb idea?

[@toddbarrett6799]

Great video. Glad to see I’m not the only one that forgets to put the ladder up. LOL

[@thepostman69]

You left out the 3.0 merc.... because there are no flaws! Just don't mind the vibration 😂

[@Dankcatvacs]

bring boat stereo

[@RoymanHernandez-fw7bi]

Do you have a video on how to winterize a mercruser 5.0?

[@JasonGarber-n9y]

On my 2452 bayliner , i would run my v8 mercruiser inboard until the thermostat opened , take off the hose and then switch to marine antifreeze and would run until only pink antifreeze comes out, let it run for a couple more min the. I would fog the carburetors until it stalled the engine and that was it , thats how i did it for the inboard gas motors and i never had any prob, the only time i used the drain plugs was if i couldnt start the motor for whatever reason. I may b wrong but thats how i always winterized it .

[@mikedye5812]

Very few Mercruisers are 2 bolt main.

[@johnathancrotzer5491]

what about the 7.4 mercruiser. grandpa has one and want to know if there's anything we should watch out for

[@UQRXD]

I always go with heat exchanger fresh water cooling systems.

[@Islandwaterjet]

470 fan here.

[@kuzz7919]

Good video you touched on some good points.

[@samfrank2401]

the diesel swap talk reminds me of b is for build's series 😬

[@jeremyah78]

Great info for the people into boating!

[@theconfused_fisherman]

A diesel swapped bowrider would be badass

[@airman6822]

Great video, great information.

[@johnycash9214]

i have a 2006 Murcruiser mag 350 mpi out of a crownline.. it has a ( two bolt main ).. Never seen 4 bolt main in any factory boat vortec. There is nothing about the motor besides the camshaft and different head gasket. They come with *Exact same factory with a ramjet 350 automotive cam. Same exact cast pistons, same block casting#.. The #1 problem with them is the merc sea pump are absolutely garbage. The glue the shaft in the bearing, The glue fails and the shaft walks out. They are disposable and good for about 20 hours. Korea makes a brass replacement that is so far so good.. The next issue with that engine is the plastic water distribution manifold on the bottom left of the engine. If the plastic plug is over tightened just slightly the plastic housing cracks.

[@jerrellkull5347]

IMHO a splayed cap 4 bolt main, is superior to a straight 4 bolt due to the 2 extra holes in each main web.

[@patricksproule6709]

A lot of Mercruisers are 2 bolt mains.

[@AB-bg1or]

I just helped my brother in law change out a fuel pump on a 5.0 TBI. Did the engineers at Mercruiser put that thing down there on purpose to make people's lives miserable? This is why I own a Yamaha outboard.

[@dontdiecurious]

What are the 2 VS 4 bolt you are talking about?

[@wbwb8459]

Put the Duramax in a Woodridge Classic..

[@stevesandstrom987]

Im pretty sure mercury built plenty of 350 engines with 2 bolt main bearings, i own one.

[@noid500cid4]

In the other video on this engine you took the pan off and showed the world its a 2 bolt block 👌☠️

[@rcdad2]

Back before we had kids and I could afford to put gas in a boat I pulled the perfectly fine 350 small block and put a 383 stoker kit in. My wife was not pleased, I was very pleased with the end result.

[@victorbitter583]

I used to go skiing in a 18ft with destroked 400 383. was lots of fun and bloody scary coming off @50knts.

[@gavinkeller183]

HUGE NOTE TO ADD. The starter, alternator, carb overflows were different than a truck or cars. They are supposed to be marine grade so there’s no open spark risk. The carb needs to have the jhook on the overflow in the event your floats stick open. Insurance used to cancel claims due to inspection’s showing non marine parts were used

[@johneckert1365]

Well, when someone puts a truck/car engine into thier boat, the generally always use the accessories from the boat engine, so no need to panic 😬

[@youdontknowmyname6956]

I dont mean to be rude, but if you're stupid enough to put a non marine part on a boat, you deserve what happens. Ngl, they actually recommend using marine plywood over treated osb in a lot of scenarios.

[@MikeCarlson-c8x]

As these engines get older internal scale will form that often plugs up the block drains and manifold drains. Use a small screw driver to poke into the opened petcocks to ensure all the water comes out. On the later models with connected hoses to a single drain remove the quick connect hose connection on each side of the block and insert a small screw driver to move the scale and allow the water to fully drain. I learned this the hard way and was told how by seasoned marina mechanic what I needed to do in the future.

[@matd3150]

This! I bought my boat with a bad engine and found this exact situation when I pulled it apart.

[@workingcountry1776]

What about using green coolant for storage? It has rust blocker? That's what friends do with race cars.

[@alexandermckay8594]

@@workingcountry1776 You can't. Boat engines are open loop.

[@bostemaly1348]

@@alexandermckay8594you can remove hoses an add coolant to them and it will either flush out water by replacing it or dilute the water enough to not freeze.

[@madmattthehatter]

​@@workingcountry1776 run muffs from a Rubbermaid container full of the coolant. Put another Rubbermaid under the prop and run the engine until the water turns the color of the coolant. There are videos on KZbin here but I've never done it yet.

[@Masterkill45588]

I work on alot of these and 100% agree with you the biggest issue they have is poor winterization and maintenance

[@deansapp4635]

30 plus years ago i did enjoy being on my friends boat powered by the GM 4 cyl Iron duke. It could pull 2 skiers and would run all day on 20 gals of fuel and was quiet

[@denjhill]

Had that little engine in a boat back then and it was great. Especially on fuel consumption.

[@dwaynepenner2788]

I had an old wakasha/ford 302 in a boat. I put a thermostat in it. Got a little better efficiency, but more importantly I got hot water to put in the wetsuit before jumping into the 5 degree Celsius lake.

[@mikevee9145]

I used to build the 3.0L I4 mercruiser engines for sprint cars, good engines.

[@drifter5682]

Ive had mine for 14 years in my bayliner never had a issue great engine

[@HookedOnTuna]

I work on boats on the coast I/O boats have fallen out of style to much headache. Outboards are taking over for the smaller sized boats. They were designed to be on a boat right from the start. They hold up well and in my opinion much easier and enjoyable to work on.

[@mz22wa]

And so much cheaper to own!! Compared to diesel boats, the annual running costs of OBs are so much cheaper even if they use twice the amount of fuel!

[@EarlG-r4r]

That’s funny the cost to have it serviced and replace it is 10 times the cost of a small block Chevy@@mz22wa

[@rannyacernese6627]

Inboards take up too much room on smaller boats.

[@conrasm]

Agreed. And the new 4 stroke OB’s are so quiet now. You can barely hear them idle except for bubbles from the exhaust. I have ‘06 Merc 150 EFI 2 stroke that’s fuel/oil injected and it’s loud. Sounds cool when you run it in the driveway with water muffs on it though.

[@madmattthehatter]

My Volvo Penta 305 required very little maintenance for 15 years (oil and filter changes and draining the block every winter) until sand blocked one of the drains and cracked the block. Still ran great but a bit of a leak problem. I bought a 380 hp 350 for $3500 and swapped computers for the fuel injection. Runs great, a 380 hp outboard would probably run 30k! I'm glad I got a inboard. I'm sure your "small" boat is much bigger than my boat LoL I wouldn't take mine on the ocean.

[@brianp6965]

Mercury usually specified forged components in their rotating assemblies, so engines with freeze damage like the one you pulled still have usable, USA-forged steel cranks, rods and pistons inside them. I'm not aware of any aftermarket companies who are forging new crankshafts in the US, so if you're building a small block/big block Chevy, a neglected, low-hour boat engine is a cheap source for high-quality parts. I'll take a forged GM crankshaft from the 90s over a new Chinese one any day.

[@dozerfarms]

Been on the same 350 Merc for 30 years... Thousands of hours, all original right down to the plugs and wires for over 25 years. The only problem we ever had was the raw water pump and finally a hairline crack in one of the cylinder heads. Just goes to show if you take care of it it'll take care of you.

[@windward2818]

Is your boat a fresh water or salt water application?

[@dozerfarms]

@windward2818 Both. Port is brackish, about 5 miles inland, occasional trips upriver, but most weekends are spent in the salt. Don't ask me why or how it's been so tough, but never would I trade for another boat or motor. The Bravo III, on the other hand... Number 3 was rebuilt, the lower unit was replaced the following season, and this will be the third season on number 4. If they don't pit themselves to death, they just self-destruct.

[@jamess3532]

@@dozerfarms My boat is 24 years old and like yours I'm still on the original engine, original starter, carb, alternator, everything. Thousands of hours and she still runs strong! I replace the water pump every other year, and all the fluids get changed yearly. 100% salt water use and the boat gets winterized every year by me. Sounds like you know how to take care of a boat and its engine. These are great motors. She'll still hit 50 mph on plane...

[@dozerfarms]

@jamess3532 Haha yessir! I do everything myself that doesn't require a special tool to do. Last weekend was waxing and waterproofing the canvas, the week before was the bottompaint, anodes, and outdrive oil, all I have left is to throw the rest of my stuff on board, hook up my instruments, and drop her in. Here's to a great 2024 season! 🍻

[@jamess3532]

@@dozerfarms I'm prepping mine for the season too. It will be a few weeks before she gets in the water though since I decided to replace the flooring in the cockpit. She was getting a little soft around the engine shroud. Just my opinion here, but learning how to maintain your own boat is paramount to getting the most out of it. I think a lot of folks purchase boats without learning what it takes to properly maintain them. If you do everything yourself you know it was done right. Happy boating.

[@JohnDoe-iz2pz]

That was awesome! Im a retired disabled MERCRUISER mechanic, you brought me back to the shop! You covered basically everything! The one thing I'd brought up is the "CORROSION SPAYS?" And fuel stabilers, thank you for the journey back to the best years of my life. Nice shop! I'd bet alot of dreams came threw there. Keep up the keeping up!!

[@hahaha12345678993]

i dont think the quote for boat ownership (the two best days in a boat owner's life are the day you buy a boat and the day you sell it) will stand true for rich, he will have lots of best days in between those two day

[@kstricl]

I can second that. I am in the process of getting a new to me boat "lake worthy", and even though the neighbor that gave it to me is a naysayer, I really haven't found any of the stuff they were freaking out over all that hard.

[@fishin11]

Retired marine tech here. Let’s add more fuel to the fire and why I’d NEVER own an I/O. Starting at the rear, two sets of gears, more mess to change water impeller, drive bellow, shift cable bellow, exhaust bellow, two u-joints, extra shift cable, trim limit and trim sender under water at all times, gimbal bearing, engine coupler, transom assembly, more weight, gimbal ring, upper swivel pin rusting, lower lube hose break and leak lube out, transom seal, exhaust shutters, exposed hydraulic lines for rams, $1500 minimum for bellow job, engine coupler job minimum $2500, on a same size boat outboard vs I/O, outboard faster hp being the same, lower unit pull every three years or sooner for inspection, plus everything you mentioned in video. And there are more reasons.

[@bobd9868]

I agree, you can’t beat a straight drive inboard setup if no outboards

[@travisboulton4312]

Another common issue with these engines is the oil pan will rust away and pour oil out, requiring an engine out job in most cases! Awesome video!

[@thediplomasta5891]

Usually, it's the oil pressure sensor that will rust away, allowing all the oil to leave the engine. I seen some really bad oil pans on these mercs, but never rusted thru. If the engine were that bad, it wouldn't be in running condition anyway. A starter will rust solid, long before an oil pan will. 😂 plus, the 4.3 oil pans are cast alum, instead of tin. And have plastic timing covers that are embossed with: replace if removed.

[@jimmalloy7279]

What's wrong with winterizing by running your engine with the outdrive in a barrel of 50% antifreeze? You won't worry about drain plugs.

[@aarontuerk7829]

Brings a smile to my face to see some marine content on the channel! Mercuiser didn't continue on with the LS line of engines but volvo penta did. Took a long time but all modern gasoline I/O's are running catalysts as well now. Albeit they are falling by the wayside of the simplicity, servicability and reliability of modern outboard engines . Im sure youve got a good marine contact near by you but if you ever have any questions dont hesitate to reach out - northern ontario based marine tech of 14 years 👍

[@conrasm]

What is the current 6.2L merc cruiser based on?

[@carlthor91]

Yep, had a Volvo Penta in my Bayliner. Long gone now.

[@NoNonsenseKnowHow]

Great video with lots of useful information. However I would have to disagree with your statement about "repaired" block crack not lasting more than a season. I've personally patched a couple with permatex the right stuff and they are still going strong. Totally acceptable quick fix imo. It's not a structural crack and the cooling system is not under any substantial pressure. Replacing the block for a hairline crack on the cooling system side is silly. That being said, it should definitely be disclosed if the boats being sold.

[@NoNonsenseKnowHow]

And actually yeah J-B weld might only last a season because it doesn't flex or grab like permatex the right stuff

[@albertbordelon2342]

I worked on these for over 10 years and was certified on Mercury outboards and Mercrusiers . Went to merc school in Dallas. In school we were told the only internal parts that were changed from the GM engine was the camshaft that made its power mainly in low to midrange around 4200 rpm’s. And installed Stainless steel valves.

[@erinfredrisk9840]

Do you plan of mating the LS to your current merc Alpha one drive or plan on upgrading to a Bravo?

[@DEBOSSGARAGE]

First Alpha, then when it blows, Bravo lol

[@richardluce775]

Not a “drop in” proposition. Alpha and Bravo transom plates and gimbal housings are different. IE can’t just slip a Bravo drive into Alpha unit.

[@stevenmccord3503]

I live in Fond du Lac right where they build Mercruisers. I was told by a retired tech that the Alpha is at its upper limit @ the 400hp or 400ft./lbs. I was told as long as you aren't doing full throttle holeshots with it and it's not a problem.

[@ratherbeboating10]

​@stevenmccord3503 even gen 1s lasted behind big blocks for a little while. What used to kill them was surfacing. Load and unload on the drive would absolutely rip it apart. With the LS the problem will more likely be rpm...

[@GIGABACHI]

One of the few perks of living in S.Florida: NO FREEZE worries. 👌😁

[@DEBOSSGARAGE]

That's what Texan's said... And then I got a cheap boat

[@nathan40307]

The secret is to live in a part of the world that doesn't stay frozen for 9 months out of the year. If it never freezes you dont have to winterize! Only fun about the cold is snowmobiling and that gets old quick.

[@DEBOSSGARAGE]

Tell the Texan's that, because I got a nice cheap boat. It only takes once

[@nathan40307]

@@DEBOSSGARAGE I am a Texan. You realize I was just kidding and ragging on Y'all Canadians? Every few years we have a freeze and have to actually winterize our boats. The ones that sit outside anyway. It never, ever, gets cold enough to worry about something in a garage.

[@BurchellAtTheWharf]

Hey, you want a cape boat fer your Duramax swap? 😉 Be a nice pleasure boat. But it needs some fiberglass work

[@JohnnyAnderson1]

wish someone would make a LS swap kit for these that didnt cost more than the boat...

[@scottmason3515]

4 bolt main GM blocks have not been used in the production marine world since the early 80s. Brass freeze (core) plugs and different camshaft are main differences between automotive & marine blocks sourced from GM. I look forward to your LS swap series. Keep up the good work.

[@stycchoas5514]

right on scott

[@malcolmhammond2135]

I believe the late model 350 magnums were all 4 bolt mains.

[@meatloafhgr11n12]

My 2011 350 mag mpi is a 2 bolt

[@petersouthernboy6327]

My 2000 Mercruiser 7.4L is a four bolt main.

[@newcombscc3674]

thank you!!!

[@MikeCarlson-c8x]

As these engines get older internal scale will form that often plugs up the block drains and manifold drains. Use a small screw driver to poke into the opened petcocks to ensure all the water comes out. On the later models with connected hoses to a single drain remove the quick connect hose connection on each side of the block and insert a small screw driver to move the scale and allow the water to fully drain. I learned this the hard way and was told how by seasoned marina mechanic what I needed to do in the future.

[@kennyspry5189]

Brother you didn't get anything wrong except for one thing Duramax Motors are JUNK!!! I have owned two of them and both gave me problems and I take care of my stuff. Say whatever you want about the FORD the New Motors are better than the Duramax Motors and that's just FACTS!!!! PERIOD!!!!!!

[@gamerwrecchris344]

Yeah because ford has a amazing track record designing their own diesel engines I mean the new Duramax engines are eh but a 2004-2006 Duramax is a solid motor if maintained properly (which is a shit ton).

[@JamesHarrell-m4j]

I think he had the cylinder head info backwards between the two engines. I would definitely use the 305 heads on the carb’d 350 engine. A 305 head usually has a much smaller combustion chamber and would raise the comp. ratio a great deal. I would transfer all the top end from the FI engine and stick on the carb’d 350 block. Run premium gas and hit the lake. 0:03

[@Ddabsolve]

305 heads on a vortec 350 will make it a dog.

[@temueralagaluga8279]

⁠@@DdabsolveRich’s isn’t a vortec

[@JamesHarrell-m4j]

@@Ddabsolve if you go back and look, his 350 carb’d engine is an ‘87 model. 305 Vortec heads would not make that engine a dog, plus he could use all the stock EFI from the original boat engine. 305 Vortec heads do not flow as well as the 350 Vortecs but they flow fairly decent, and prolly better than the ones that are on the carb’d 350.

[@Texassince1836]

The Vortec 350 head outflow Vortec 305 heads. The Vortec 350 is already over 9:1 compression with the 64cc heads.

[@rscottreynolds]

Nice! Good to hear positive comments towards mercury engineers, as my GF was Mercury's original chief engineer.

[@stevem3021]

He mentioned draining the blocks for the winter layup. Don't forget to run pink biodegradable Antifreeze through the engine via the raw water pickup. Either do it while the engine is hot or remove the thermostat and run. Run until you get solid pink coming out the exhaust. You will not crack a block that way. 4.3s love to crack behind the exhaust manifold.

[@joesilverbliss1721]

I was using the cheap pink stuff from Walmart then I realized you need the more expensive stuff rated for engines. The cheap stuff is alcohol based and not good. The expensive stuff has propylene glycol.

[@jamess3532]

@@joesilverbliss1721 You want to keep using the cheap stuff and drain it out after you run 5 gallons through the engine. The procedure is simple: Use a 5 gallon bucket with a spigot on the bottom that you can connect a short garden hose to and run it to your muffs. Run the engine until the thermostat is open using water and then switch to the coolant and run it until your 5 gallon bucket is empty. I collect most of it and store it back in the jugs for the following year. Pull your blue drain plugs and your done. Do not use radiator coolant rated for automobiles. Lots of youtube videos showing various methods....

[@thediplomasta5891]

We mainly use the pink for the water systems in the cabin. It's much cheaper to just drain out the water from the engine. Draining all the water from the water system is much more difficult.

[@jamess3532]

@@thediplomasta5891 As long as you can guarantee that there is absolutely no water left in your engine cooling system than you can get away with not running the antifreeze through it. Peace of mind and extra assurance is why the majority of us flush with RV antifreeze. Especially for those of us who live in extremely cold places where temps will stay below zero for a week straight, or longer. That way there if any residual water is trapped it's at least displaced with the antifreeze and won't crack your engine block. Like I said, I collect it all in a bin placed under the stern drive and put it back in the jugs for the following year. It hardly costs anything doing it this way and it's a lot cheaper than having to replace an engine block! I know some people use JB weld to fix cracks but that's not a real fix.

[@Sense_Per_Mile]

I took out my cracked 5.7 and completely built a 383 stroker along with Corsa 4” side exhaust. What a monster!!!

[@NoWr2Run]

FREAKIN BEAUTIFUL !

[@drizler]

I used Devcon epoxy on an exterior head crack in 2005. I’m still using it today around 1000 hours later. It’s sure worth a try. 1990 4.3👍🏻.

[@UQRXD]

I know one thing the Stern drives are a bitch to rebuild.

[@chevyjennings3404]

Great video. Mine is a 1999 Crown Line 23 ft 5.7 carbed. Bravo 3 (I think, 2 props) out drive, Fast boat and I have it professionally serviced twice a year, fall and spring. I think I am doing it right as I have no time to work on my boat myself but love it. Not a lot of hours but 100% good and reliable. Always kept inside and a great boat for lake Pend Oreille, 1600 ft deep!!!

[@Copesthetic-Aesthetic]

Finnegan towed his boat with no motor to a boat launch. Then pulled the motor out of the truck. Put it in the boat. Then went for a boat ride. Then put the motor back in the truck.

[@DEBOSSGARAGE]

I remember that episode. That was LS jet boat though

[@Copesthetic-Aesthetic]

@@DEBOSSGARAGE I can't remember what motor it was. Some I/O's do have closed cooling systems. Usually when they're used in salt or brackish water. I had Rinker a few years back that had radiator, and the feller that I bought it off used it Florida. Makes sence I guess. I imagine salt water, and cast iron would not get along. ☺ Anyways, yet another fantastic upload from you sir, and I can't wait for the next one. "You do good work"

[@tomcren59]

Having not one idea about boats a thought occurred to me. Why not use a heat exchanger to cool the engine? Use regular antifreeze then use the raw water to cool the coolant? I know weight and cost are a problem but I don't see a valad reason not to do it.

[@strokervolvo383]

That is common and considered a premium option. Referee to as closed cooling as opposed to raw water as he described. Also works better on EFI engines as it keeps them water temp more consistent

[@DEBOSSGARAGE]

That's what we are doing with the LS swap. Already have the heat exchanger

[@fahrvergnuugen]

Look out for sand/silt build up in your engine block. This affects the cooling, but it also can trap water that won’t drain when you open the plugs to winterize (ask me how I know). Pull the drain plugs completely and use a piece of stiff wire to clean out the drain passages as best you can. I then fill the block with rv anti freeze through the thermostat housing and let it run out the drain holes.

[@chriszavitz6407]

305 and 350 vortec heads are different from one another. 350 has a kidney been chamber 305 do not

[@larryw5429]

He has some good heads for that OBS chevy off that vortec marine engine! ANOTHER VIDEO IDEA!!!

[@DougsMessyGarage]

My family has a '92 Mercruiser 4.3l. When winterizing, we drain everything then add a little plumbers antifreeze to the exhaust manifolds. We found the drain on the exhaust manifolds isn't truly at the low spot and ended up with a little water pooled at the back. We got lucky and were able to get the manifold repaired but now we always add a little antifreeze just to be safe.

[@Dankcatvacs]

what about running lpg on said boat? loved the video my cousin had a 3.0 4 i called it the super duke damn reliable pushrod engines

[@waitemc]

I always pulled my thermostat out hooked my bunny ears up and dump raw antifreeze in the bunny until antifreeze comes rolling out and by using 💯 per cent antifreeze if you do miss some water the pure antifreeze fixes that .

[@asandberg6]

I've seen 4 bolts with the webbing busted out of the block. They crack at the outer bolts and all hell breaks loose. I think Two bolts are actually stronger, and a two bolt drilled fro splayed four bolt caps is even better.

[@radioguy1620]

Most engines in boats are operated at over 3000 rpms , in your car or truck that would be 100 mph or more, uphill. If you can keep the revs and the boat on plane under 3000 rpm they will last, running at over 3500 and your motor will not hold up. as an older mechanic of boats from the 60's and 70's, Chrysler 318's were near top of the list and 327 GM's, but really enjoyed a personally owned ford 351 windsor with the 3 inch mains and of course volvo 4 cyl's. GM starters are really hard to swap out in a boat compared to Fords. shame no more ford or chrysler marine engines. available new. when ford gave up on the business I could buy new 351 HO complete with carbs and flywheel , wires etc for 1650 $ the days !! wish I bought all of them.!.

[@kstricl]

"I'd never swap from Diesel to Gas." First thought - follows B is for Build 🤣 At least Chris' videos are a help in figuring out manifolds and such. I am actually happy to see the twin LS engines seem to handle his boat quite well. I will also be curious to see what you end up running for prop once you've got a lot more HP to work with, this should be a really fun boat.

[@gregorysoderlund8025]

First guy I thought of too when he said that 🤣

[@pugmahone]

Can I pick your brain? 1986 Mercruiser 230/V8 (GM 305?) Alpha One - bogs down at 10 mph and will not go over 10 mph. I've had the carb rebuilt twice, new gas line, new fuel separator (x 2), new fuel pump, then mechanic thought electrical - new alternator, coil, plugs, wires, and 2 new batteries - still NOT working. ANY IDEAS? Thank you in advance.

[@FUNKYTEE540]

Honestly though, who has actually seen a 2 bolt sbc block fail at the main bearings in a mild hp motor due to lack of main bearing support???? I'm guessing zero. FYI, I just tore down an original Mercruiser 2002' Alpha EFI 350 that was a 2 bolt main 880 block;) They do use them in marine apps with no problems to clear things up a bit...

[@OGJeff685]

Mine has had low compression in the rear stbd cylinder since I bought it.. wasn't aware of it until 2 years in when a mechanic found the problem

[@BackyardBeeKeepingNuevo]

I have a 2004 Sea Ray 200 Select with an Alpha One Outdrive and a 5.0 Mercruiser MPI. I want to LS Swap the 5.0 for a more modern and higher hp. engine. What year LS would make a good engine that I can bolt my outdrive to without modification? I will do a complete rebuild of whatever engine I get so this won’t be a budget build. I am in California so any suggestions you can give me is greatly appreciated. I just don’t know where to start. Thanks - Beeman John

[@DCFloridasport]

The thumbnail says it all...the same thing wrong with every new car or I/O or inboard boat engine, look at all the crap hanging off of an engine that requires nothing but a distributor, carburetor, and a few hoses here and there. 1000 points of failure.

[@ld5954]

I thought mercury was making their own engine blocks now? I was told they stopped using GM blocks.

[@StructEng12]

One thing to add - the Mercruiser 5.7 (and probably the other displacements) uses a roller cam rather than a your standard flat lifter setup you find in the on-road engines. This works well for extended idling, which these motors do. Solid motors for sure.

[@Supanova70]

On closed cooling stern drive boats if you put to much concentrated antifreeze in will it overheat? All passages are clean new pump risers manifolds but temp is 170 this year ntead of 160. Stat is new too. 80 ocean. Thta`s the only thing i can think of. Also guage and sensor new too.