Replacing Your Mercruiser Marine Engine Sea Water Pump Impel

Performance Product Technologies website www.perfprotech.com is one of the Top Rated online Mercury Mercruiser Parts dealers. PPT handles a variety of Marine Cooling System components including Water Pumps, Impeller Kits, Heat Exchangers, Closed Cooling Kits and Oil Coolers. This particular How-To video illustrates Step by Step instructions to follow when replacing a Mercruiser sea water pump impeller.
MerCruiser Parts & Diagrams
www.perfprotech.com/mercury-m...
Link to Impeller & Sea Water Pump Kits
www.perfprotech.com/product/se...
Video Timeline
Identify Inlet & Outlet hoses before removing 0:10 - 0:49
Pump Removal & Disassembly 0:50 - 1:28
Remove Impeller 1:29 - 1:49
Evaluate Pump Housing 1:50 - 2:10
Inventory New Parts 2:15 - 2:45
Reassembly 2:50 - 6:20

[@briansmobile1]

Thanks for the video- it's both concise, complete, AND well edited.

[@1grinnbareit]

When the boat is in the water, before removing the two big hoses, have a tapered shot glass ready to push into the hose then clamp it tight. That's what I use every time, works great!

[@jt6878]

Is it easier to remove the engine or loose 100 lbs. so I fit?

[@pwcopy1]

This procedure also applies to several tow boats with direct- and v-drive inboards and engine-mounted pumps like my 1995 350 EFI Magnum Tournament Ski. I pull the the whole pump and use dish soap for the impeller.

[@michaelrodriguez8299]

Was it easier to remove pump? Did you have to loosen the belts? My impeller housing cracked and I’m about to replace it myself just looking for the easy way and how to do it lol

[@thescinfidel]

Only video I could find on this. Comments r helpful also. THANK YOU!

[@SkypowerwithKarl]

The damage seen(little black fuzzies)is exactly what you find when a new impeller is ran dry. In fact, it got so hot it cracked the housing. When replacing, never use petroleum based lube on a water pump impeller, it causes it to swell and soften. Use dish soap, but the ultimate is silicone grease. Mercrusiers are one of the most difficult to change in the boat. It’s good for people to see it out in the open because many times you can’t see it and you’re doing it “brail”.

[@SenorDennis]

Just what I was looking for thank you

[@tannermartin2738]

I took mine off yesterday and put it back on . when I started the boat the housing broke and smoked the impeller. how tight do the bolts need to be.

[@justonemorecast]

Very simple procedure, thanks for the video.

[@Paul.Douglas]

Thanks for the helpful video (even if it was made 9 years ago). Just took the pump off mine and the impeller is freakin' backwards! I got the boat 3 years ago, and I've had it in the water twice. How the heck did it not overheat? Went to run it with ear muffs and it wouldn't draw water up. That's what made me look into it. Found your video and voila!

[@brucewayne2984]

Thanks for this video! I had my hoses on backwards!!

[@bsgraham]

Thanks for posting this. My wife forgot to turn off the engine when I trailered and pulled out at the lake recently. I thought "My impeller is shot", so I pulled apart my Mercruiser MAG 350 today, and turned out everything was still good as new. At least I now know how to do this, and will have parts on-hand just in case I have to do this again.

[@av8tordobbie131]

Question , is this the same procedure and impeller location for a Rinker mtx220 with a mercruiser 350 ?

[@baseline6786]

I have a 1988 bowrider. Omc cobra 3L. 130hp. Inb/outb. It only goes 10kms an hr and just revs up past that. The engine will over heat as well. Any idea what could be the issue?

[@njblanco10]

Thank you, sir! Very helpful.

[@PerfprotechMarineProducts]

Thanks for the feedback!

[@djnemesis82pluss1877]

I have a 97 boat with i believe is alpha 1 gen 2 but the pump is just like the one in this video I know the engine was replaced in 2001 or 2002 you think they just put a new style one on ?

[@georgespapillon364]

Thank you for this video. How much do you tighten these bolts ? Do you have to torque them to a specific strength ?

[@bishopcherrycoke6654]

just the info i was looking for, thank you.

[@PerfprotechMarineProducts]

+Bishop Cherry Coke Thanks for the feedback. We're really happy the video was helpful for you.

[@jorgelopez3922]

I have 2008 searay 210 with a bravo 3 mercruuser 5.0 I will try and do my best to change out due to over heating at high speed or RPMs. Wish me luck. Thanks for video.

[@aquaymizmo8754]

The new kit has two shorter bolts, but I can't figure which holes they go into?

[@Rabbydabbydoo]

I have a leaky front seal. I have a rebuild kit. Can it be done in the water. I’ve seen no videos of it done in the water.

[@sofitness]

Thanks for this very good tutorial. Very helpfull for us.

[@PerfprotechMarineProducts]

Thanks! Very glad it was helpful.

[@edwardmiller5296]

can u cange impeller when motor is inboat yr 06 bravo 3 350 mag how ?

[@jaya.buerger-realtoremerit6840]

Hello, what are the torque specs for those housing bolts? I heard not much pressure is needed. Thanks!

[@Marynova666]

OH, my goodness, all these years Ive been doing it wrong! Much easier to do this impeller change if you take the engine out of the boat first!!! LOL!!!

[@chriscarter974]

perfect. Thanks!

[@Kendoe0341]

My Mercruiser 205/V6 alpha one equipped boat started to run a little hot when I'm idling in gear but cools when I increase speed. Do you have and idea what it could be ? should I start at the Out drive . We are going to go to Lake Powell in the first of August and do not want to get stranded . Grateful for any info, ideas that can help

[@1951RKP]

Good video. Unfortunately it is much harder to change the impeller on these pumps when the motor is in the boat.

[@AlexGrigolia]

Hello can this be done while the boat is in water? Or does it need to be out?

[@jmagana31]

Where did u get the parts from ? Thanks for the video

[@captainwilliam5771]

DO NOT use grease on an impeller. It will break down the rubber more quickly. Use either dish soap or plumbers non drying silicone. Dish soap is actually the one all the marine mechanics I know use.

[@gtvgtv4004]

Vaseline eer petroleum jelly

[@SkypowerwithKarl]

Never use petroleum based lube on the water pump impeller. Use dish soap but the ultimate is silicone grease.

[@jimbeam9176]

Dish soap great idea

[@richardpalleschi4807]

Exactly correct. Petroleum based lube is poison to rubber & causes the rubber to go bad. Dish soap, silicone, or water-based lube. Is best.

[@kirk8100]

this is awesome. Thanks. this is going to be a hell of a job inside the boat but there's no way I'm getting that engine out! LOL

[@Hoobz01]

@thebuilderdude68 Yes, I just triple checked. He did twist it the wrong way when reassembling the housing to the pump body. But I doubt it would re-orientate the fins of the impeller. If doing that was enough to change the blade direction then as soon as the engine was turned over it would fix itself again probably. Not the best procedure though, but that's what the pressure of having to narrate on vid can do.

[@pptave99]

I agree this is much easier when the pump is off teh motor. The front mounted crank driven pumps are easier to service with the pump body left on the motor.

[@PerfprotechMarineProducts]

Thanks!

[@WoodandBricks]

Thank you!

[@edwardmiller5296]

how do u change inpeller motor is in boat 350

[@edwardmiller5296]

greatvideo

[@15569903]

Well done, nice vid

[@PerfprotechMarineProducts]

+Sean Willard Thanks Sean. We're glad it's helpful.

[@RobertWermuth]

Thank you

[@mobilemike8500]

Yeah use Dawn dish soap for installation non-toxic I use it on my ski bindings works good on impellers also and what he doesn't tell you is that you should check the bearings for roughness and the O-ring can easily slip out of place on this model I like to use a little Right Stuff gasket maker underneath the lip of the seal between the bearing and the housing and you can put a little more outside of that for extra protection against water leakage on the back side and definitely look for broken pieces of your impeller in the lower hose section where it goes into the transmission cooler make sure you get all the pieces out of there some really tiny ones can work their way through but you definitely want to reach in there with a pair of tweezers or something and pull them all out and sometimes the housing is slightly scored on the inner Edge where the center part of the impeller rubs against the inner part of the housing I take some 220 paper body work d a paper works good because you can stick a small 3/4 inch piece to the end of the your thumb and just sand It Down Smooth again and finish up with some thousand Grit as long as it's not scored or damaged anywhere else it'll run you won't have to buy a new housing for a little bit of scoring on that end and there's always the stainless steel upgrade for 350 bucks Hardin Marine makes a good one

[@mikebartlett9736]

Good call! Great info mobile mike!

[@edwardmiller5296]

THANK YOU

[@djnemesis82pluss1877]

this shit just went out on my boat as I was selling it haha great timing shit ran just fine the night before watching this now probably wasn't a great idea to spin the pulley both ways to free it up think I may be attempting this replacement while its in the water

[@1951RKP]

Can be done in the water but you need a cork to insert into the inlet line once it's removed from the pump. Just need to be aware of what's going on and don't panic when you see water coming out the hose until you get the cork in it. Done right you will not get more than a quart or two of water in the bilge. Large cruisers or houseboats with these drives can't be easily pulled out the water for this service.

[@riverking4u]

Thanks for the vid, also the bolts should only be tightened to 18-20 lbs. I fould this out after a new install - day two of vacation:)

[@mnmank8619]

My inlet housing,where I connect the hose is cracked Water is coming into the engine compartment.Can you buy just the housing or does anyone have one for sale? New sea pump is too much $$$$

[@5472bookum]

"This engine is obviously out of the boat" . LMAO . Show me how to do this in my driveway.

[@MrDynafxdc]

I've done this many times over the years the hard way. This year is going to be different with the electric ratchet i just purchased.

[@MrDynafxdc]

I just got her done, the electric ratchet is the best two hundred bucks i've ever spent.

[@skjhotdobell4536]

Same way in the drive way brah

[@barrynawa9763]

I usually pull the pump off the motor.

[@yelenakruzhkov8431]

Got a question does it matter which way you put the metal plate? Seems like on forums they say it only goes in one way or your motor will heat up? Any inputs please thank you

[@PerfprotechMarineProducts]

+yelena kruzhkov Woth certain models this can be true. However, with the Bravo model this video is referring to the plate can be installed either way.

[@PerfprotechMarineProducts]

You're welcome!!

[@AlexGrigolia]

Also, there is a strainer next to the 2 seacocks or at least i think it is, its a blue corroded thing which prbabaly has a strainer in it so if thats the case i think i can unscrew it and then check it for debris

[@AlexGrigolia]

I do it’s a big yellow lever it’s in up position, I see what you mean now, I need to close it and then disconnect the hose. That makes a lot of sense thank you pptave99 So if I want to push water through it to clear debris, It would have to be out of water otherwise it will flood in

[@pmsenterprises]

Paul Smith I have a 1987 Alpha on 260/V6 and it runs hot immediately when put under load. Hadn't been in the water or run for about 3 years. what might be the problem. Thanks.

[@PerfprotechMarineProducts]

Check out this article www.perfprotech.com/blog/articles/impeller-installation#

[@openopen1203]

You have to check for pieces of the impeller in the hose that goes to the oil cooler-the hose that goes under the engine very important remove at oil cooler and check oil cooler tube where hose clamps on

[@danbraun8430]

Thank you. So outlet hose than?

[@1951RKP]

If its an Alpha Drive, Gen 1 or Gen 2 Mercruiser the boat does have to come out of the water because the impeller is located in the lower unit. Mercruiser Bravo Drives the pump is as in this video and mounter to the engine and is belt driven and can be change in most boats while in the water.

[@1grinnbareit]

I have the Mercruiser 7.3 MPI engine, with engine in the boat, I always remove the serpentine belt & remove the sea water pump completely out to R & R the impeller. There's no way I could work on that pump with the pump not removed, just no room. Removing all the bolts but one, then it comes out of the mounting bracket. If your in the water, one of those tapered shot glasses works great. Just have it ready when you remove that hose, water will come in fast!

[@disasterpiecemusic]

hi, thank you for the vid - same process for Merc 8.1S Horizon?

[@PerfprotechMarineProducts]

+Aaron Burke You're welcome. The 8.1 engine uses a similar pump so the process is similar but not exactly the same.

[@disasterpiecemusic]

Performance Product Technologies thank you for replying! Is there somewhere I can see the service instruction for the 8.1? I'm almost certain I'm in need of impellers

[@PerfprotechMarineProducts]

We have not done a video for the 8.1L. The only place to get the instruction would be with a product service manual.

[@bobcassells6690]

Performance Product Technologies I was thinking about taking the hose off the thermostat housing and dumping water to the impeller so I don't dry start the pump

[@PerfprotechMarineProducts]

Learn how to replace your Mercruiser Marine engine sea water pump impellers and be sure to subscribe to our KZbin channel for more informational videos: Replacing Your Mercruiser Marine Engine Sea Water Pump Impel

[@elimonjal]

now i am confused, i have a mercruiser and the only impeller i changed was the one in the outdrive pump, didnt know about this pump. my boat has a circulating water pump, but its all metal. so this is different. ?????

[@clintleffingwell8129]

Is your outdrive an Alpha One? Those have the impeller in the drive, while the Bravo 1 and 3 have it mounted to the engine.

[@jackmehoff4613]

He did not clarify that the system he was replacing only pertains to a Bravo 3 outdrive. Most other outdrives have the impeller in the outdrive, not on the engine.

[@frankiekay2989]

Can you do this with the engine taken out of the boat. Most people don't just yank their engine when it's needs something.

[@danbraun8430]

It’s a bastard in the boat at least mine. 7.4 liter in Baja but it can be done.

[@Sandpiper270]

Great video, but I would recommend one more thing. This particular setup has the fuel pump integral to this unit. Fuel can slowly leak by the diaphragm, and dilute the lube in the front part of the unit. I would recommend to at least drain out the oil and replace it at the same time. I normally remove the whole unit from the boat to do this, and flush out the small oil reservoir for the fuel pump, then put in new oil.

[@PerfprotechMarineProducts]

Great point. Thanks for the feedback.

[@RickAce23]

Sandpiper270 When you say "drain out the oil" are you taking about the crankcase oil? And how does "flush out the small oil reservoir for the fuel pump" stop " Fuel can slowly leak by the diaphragm" ? As you can tell, I am a bit confused.

[@fahrvergnuugen]

Rick, he's talking about the oil reservoir IN the fuel pump (yes, it has it's own reservoir). It's something that is easily overlooked, and having it get diluted with gasoline will cause the pump to eventually fail. They aren't cheap if you have to replace the whole thing!

[@galionpd418]

some have one flat head screw, some replacements (my new one which is expensive) have 2 oil screws. the screws are directly below the mechanical fuel pump if you have the pulley, fuel pump, impeller combo. Drain it and I use Lucas gear oil in it too keep from another $4-700 (parts only) mistake. I actually found my complete replacement on eBay with a removable pulley on the front that makes life easier for maintenance.

[@mt_sinewavetrader2126]

@@fahrvergnuugen Can't believe I asked this question 6 years ago. Thanks for replying (2 years later) but better late than never 😉. I am now well versed since with the Sea Water Pump.

[@michaelwalkermw83]

great video I am getting ready to own a sterndrive boat and this will help me in the long run and I knew how to fix a sterndrive and the good bit is I save on shop time and do it all myself and as an old salt I knew sterndrives pretty much myself how do you replace the sea water pump when im doing it for the first time and what cautions I need to take when doin the job for the 1st time and how I know when the sea water pump needs replacing how long it takes to do it and I knew im learning all the time and I knew that I am gettin there as an experienced boater I am learning all the time so can you help me learn about sterndrive care this will be for my 1st bayliner with the 4,3litre Mercruiser V6 im keen to learn all I knew over time that's why im learning all the time thanks!! from mick the old salty walker

[@PerfprotechMarineProducts]

+michael walker Thanks!!

[@michaelwalkermw83]

and I knew the routine of fixing the sterndrive and I knew how to do it myselfand I knew the procedures on how replace the sea water pump and I knew the ways of doin it this video will help me as an old salty I knew whats have to be done and I knew all the Mercruiser engines and drives as well I knew how to perform the work myself this video will help me save on shop time and costs too as a old salty I knew how to fix a Mercruiser sea water pump and the other bits of the Mercruisers I knew how to fix them that's how from mick

[@michaelwalkermw83]

i knew the video will help me fix my 1st sterndrive and all the videos will be of much help to me that's the old saltys way

[@PerfprotechMarineProducts]

+michael walker Thanks!

[@michaelwalkermw83]

I am getting close to having my first sterndrive boat as I get nearer to the day I get one mines going to be the bayliner 1850LS Capri boat as I knew the motor was the Mercruiser 4,3 litre V6 as I will be doing all the maintenance all the service work will be done by myself as im a experienced mechanic from the time I knew how to service these motors as I read up on a lot of the stuff on these engines that's the Mercruiser V6 its the 4,3 litre sterndrive motors how I go about servicing my Mercruisers as I am a well versed old salty and im gettin the nice boat am gonna do all the service work myself this will save me the wasted time in the shop can you do a video for us old saltys on how to service a sterndrive engines and related components as well show us old saltys like me how to fix the engines when the boat is at home say we had to fix something that's wasn't right say for a example the sea water pumps and other things like how to check the power steering fluid levels and other levels too and also show us old saltys like me how to replace the drive belts on the engines and also teach us old saltys like me how to care for a sterndrive for the 1st time we us old saltys like me are willing to learn as we are good old saltys I as an old salty I love learning to care for our boats with the sterndrives im eager to learn as I go we keen old saltys

[@PerfprotechMarineProducts]

This really depends on how much space you have available around the engine. Also if you do it with the boat in the water you will need to shut the inlet water off somehow.

[@simplyharpreet]

Can I change just the impeller or do I change to little seal also?

[@PerfprotechMarineProducts]

+simplyharpreet Normally you would want to purchase the water pump repair kit that includes all of the normal replacement items vs just changing an impeller.

[@mikebartlett9736]

Can u replace just the impeller or do i need to buy the the kit?

[@michaelvaralyai995]

hi, i have a 07 496 and it is overheating and water in the oil, besides a blown head gaskit, is there anything els that can cause this, thanks mike

[@PerfprotechMarineProducts]

That is certainly one common cause. I have also seen times where the valves leak due to ongoing water ingestion issues and this allows water to accumulate in the oil over time. However the most common is the head gasket or cracked head/block.

[@michaelvaralyai995]

Thank you

[@philis52]

michael varalyai Don't remove the heads yet! ...Big blocks are fairly resilient. I would venture to say; Check for Exhaust Elbow(s) and or Exhaust Manifold(s) water leaks.

[@vrso2]

if motor is in the boat, remove whole pump assembly and remove whole pump out of the boat. It took me 10 min to get it out of the boat. Just take serpentine belt off, remove two bolts which holds mounting bracket, pull pump away from engine block and remove hoses.

[@michaeltschannen4523]

if boat is in water without manual shutoff you could put 2 pieces of wood and big c clamp to stop water flow

[@Dan-uv3vf]

For a boat to be without manual shut off seacock is just plain stupid.

[@ainstaink8312]

You were rotating the housing the opposite way!

[@frankscott4915]

Help not working for me .

[@johnpapazoros4132]

It was easier for me to remove the entire pump from the engine.

[@pptave99]

Unless you have a manual shut off valve on your inlet water line the boat would need to be out of the water.

[@jackmehoff4613]

Great vid, except he neglected to advise the checking of all the hoses AFTER the pump, for remnants of the old impeller. Typically the chunks flow through the system and collect at the inlets of all the accessory coolers and the thermostat housing.

[@PerfprotechMarineProducts]

www.perfprotech.com/blog/articles/mercruiser-impeller-installation#

[@joncrisler6001]

See this video on a very good description of locating the missing impeller pieces.

[@montanaboatcenter]

You should never use oil or grease on an impeller it will reduce its efficiency you should use a water soluble lube like baby oil. Also you spun the impeller the wrong way which is bad because when the engine is turning to start its almost instantly up to 500 rpm which will force the pump to change the blades not what it is designed to do, also I've seen blades break off the impeller because it was spun backward. Lastly this is the rarer type of pump for mercrusiers (will be this on most inboar

[@1grinnbareit]

I thought grease was not to be used when installing the impeller, grease will not wash out and can attack the rubber impeller? What kinda grease are you using in this video? Can't you use dish soap to ease the installation of the impeller. When you start the engine with water attached, it washes out the soap and your ready for some boating!

[@tesla1961]

vaseline

[@Sunfadedlovejaded]

Saliva. This guy salivates a lot, we call him Spitty. His saliva along with the heavy bacteria in his mouth create a natural lube for machinary

[@pbt109]

I have a 1990 Mercruiser 454/Magnum Bravo one drive and I want to replace the raw water impeller. I want to order the part and install this my self as in the past I have always had this work done. On the actual part there is a number 46-807151 on the housing. When I do a search for this part# I found the same number with additional numbers and letters like (46-807151A14 46-807151A7 807151A14 for MerCruiser Bravo Water Pump Impeller Kit 807151A7) Can you please let me know what is the correct part number for my specific motor to order so I get the right part the first time I order? Thanks in advance. I really like your video and this will help me do this work myself. Thanks, Phil Also, I have the engine serial number if you need that. Be the first to review this item

[@markjones8944]

Please email [e-mail] and we will be glad to help you with this.

[@pbt109]

thank you

[@davidandersen9186]

how often should I do this

[@PerfprotechMarineProducts]

+David Andersen Every 100 hours or 3 years whichever comes first.

[@davidandersen9186]

I just bought a 1998 bayliner 175. has 54 hours on it. not sure if it's been done.

[@aguyandhiscomputer]

David Andersen I'm actually changing out my impeller as I watch this video. I bought a 2004 four winns 170 with a volvo penta 4.3 last summer and want to be safe since I don't know how old it is.

[@fahrvergnuugen]

can confirm the three years part. My boat has very few hours on it since I changed the impeller 5 years ago and it shredded itself!

[@johnalbe6026]

You turned housing the wrong way. Lucky you had it greased...

[@rho1782]

Use vegetable oil to lubricate the impeller, never use grease or any other type of oil. At least this is what I was told by a very wise man, lol!

[@NunYa953]

grease? 😬😬😬