How to service and replace your water pump impeller on a mercury outboard. 75hp, 90hp, 115hp, 125hp. Larger Optimax outboards run the same water pump, as do Mercriuser alpha sterndrives.
Very good thanks! I watched this and it gave me the confidence to clear the sand and shells out of my impeller rather than taking it into the shop. Used a water blaster through the top hole of impeller rather than disassembling it and a few 5mm x 5mm shells popped out! Impeller now pumping water as usual. Many thanks.
Good video - I always put the motor in forward gear before dropping the lower unit and make sure the lower unit is fully in forward when reinstalling unit. It is possible for the shifting gear to be moved to neutral or reverse. If you reinstall the lower unit with the lower unit in a different location that the powerhead, the unit can start in gear.
Thanks for taking the time to make your video! I own a 1987 Mercury Mariner 75HP and have hesitated to replace the water pump myself. Thanks to you I will be doing it in a few weeks. You took the mystery out if it and made it clear and simple to understand. Keep on making videos! Thank you.
Hi Geoff, i just subscribed to your channel. I have to change mine on my mercury 90 HP outboard motor this week. This was the best detailed video i found so far. Thanks for helping us boaters out. Now i know how to handle. I am use to working on my LT1 trans am.
Great vid, well done and nicely explained. I recently learned that Honda 40hp OB flywheel/shaft turns counter clockwise where upon we also discovered that someone incorrectly installed the impeller meaning the impeller splines "scooped" not "swept" the water. Not sure if you know what I mean. I plan to replace the impeller on my 2004 125hp merc shortly so thanks for this video. Cheers
@petieohalloran The pressure relief valve is a valve that 'pops' off it seat when the engine rpm is increased which increases the water pressure. It bypasses the thermostats etc and make the motor run cool at higher rpm. It has a rubber grommet that gets squeezed in by salt build up and pinches on the plastic valve. There is also a diaphragm that needs servicing/replacing if it is stretched, perrishing or gets a hole in it.
I'm going to comment here so that another "home mechanic" researching this topic doesn't have to go through the pain that I did. First of all, thanks for making this video. I watched several videos before trying my impeller change for the first time. So long story short, nowhere in the the service manual or owner's manual does it say to drain the engine oil before dropping the lower unit. To my surprise, I had a flood of engine oil pouring out when I removed the shaft and dropped the gear box. I tried to research the problem on line and found a few people who had the same problem, but what they were being told was they had a costly engine oil leak and would need major repairs. This just didn't sound right to me, because I could see a hole at the top of the opening where the drive shaft stops, so I started to do more research. I won't go into detail, but the bottom line is that at least on my 2013 115EFI Four Stroke, you need to drain the engine oil before removing the gear case. I confirmed this with three different Mercury certified mechanics and called Mercury customer service.
Wow! AMAZING video with all the info I really needed. Well done mate, well done. Saved me so much time and mistakes I would have made with just my book.
Dad (90 yrs old) wanted fishing trip with his two sons.I fly to SLC UT. Brother picked me up at airport, drove to dads, picked up him and his boat and headed to Flaming George. Got boat down to dock and thats when things started to unravel. 1. Batt dead - jump cost us $10.... then learned it's been one year since boat was in the water !! 2. Five minutes into lap close to marina to make sure engine can burn older gas mixed with stabilizer plus five gal new - a warning alarm came on - ZERO water pressure on gauge - no cooling water coming out of port. Marina tech stated impeller problem (dad has never changed it in 9 years ownership). One week to get part. at $145 - Two weeks to work it into schedule at $125 labor. Ok - back to brothers house - trip over. On a whim thought about youtube... Watched your video.. then found impeller kit online on Amazon - $38 + $4 overnight delivery! Watched video again - I can do this! Had it apart in 20 minutes... 5 being used finding a 15mm socket in brothers very limited tool assortment. Thanks so much for your help saving a father/sons 4 day fishing trip!!
Very helpful, thanks. I can probably fix my 1984 merc 115 6 cylinder. Not passing water out telltale (i cleared it, doesn't have obstruction) or at prop. Cheers.
@ober51 Thanks for the feedback! You will probably find it is exactly the same water pump. If it has the quickfoot gearbox I think. So if you follow the video you should be great! The only thing I have noticed from comments is the gearshift. Before putting the gearbox back onto the motor, rotate the prop shaft and confirm that it is still in neutral and you havent accidentally turned the shift shaft. Good luck!
@radoslavrigas Hi, yes some kits come with the black tube. Depends what kit you get. When you remove the gearbox the tube can stick onto the water tube. You simply reach up and pull it out then fit it into the water pump. It is there as a guide for when you install the gearbox to get the water tube to slide into the water pump housing.
Great video, thank you very much even all these years later. A couple notes - one, you can't really see the orientation of the face seal you put on top of the waterpump housing, I had to look that up elsewhere. My kit came with the seal and an install tool. The seal goes with the wide thin flange down against the top of the housing - the tool keeps you from pushing it inside and helps seat it nicely. Two - the bottom gasket on my kit was a thin metal one, and according to the papers that came with it replaces the large fabric gasket. Must be a new version or something. Finally, the rubber seal that you see at the end of your video on top of the housing water jacket did not drop out when I removed my lower unit. I ended up just greasing it a little in place, since the kit did not come with a replacement and I didn't want to risk trashing it. Thanks again! I don't know what people would do without tutorials like this one on youtube.
Did we miss the part of disconnecting shift linkage First? Not sure how to do that part. Mid 80s 75hp 2 stroke. Please explain shift linkage unhook Thank you
What a great tutorial. I've watched several on here and this one is by far the best presentation .. I like the fact that you didn't get overly technical, but kept it easy for the everyday "shade tree mechanic" to understand. I will be changing the impeller on my 75hp Merc in about 2 weeks and will have my laptop on the workbench for reference with this video cued up!! Thanks again!
Remove the propeller and have a look for any signs of fishing line behind the prop. The gear shift shaft seals are usually the cause for water in the gear oil on those boxes in my experience. The only true way to find out is to pressure test the gearbox. Can you get hold of a pressure tester and/or vacuum tester? The gearbox should hold 15psi pressure and 15 inmg vacuum. Also check that your gear oil drain screw washers are in good condition. They should be replaced when changing gear oil.
Thanks everyone for the great feedback and comments, really appreciate it. This was my first tutorial video so its a bit budget. I do plan to do more maintenance videosbut have been busy with work. If you do want to get notified about new videos you can subscribe to me.
I'm about to do this on my 1996 90HP Merc. I have a question. I've read to put it in forward from the start, then move to neutral before reinstalling. Is that correct? Thanks!
hey Dale..if your not using the boat , at least try starting it and letting it run for 5 to 10 minutes every couple of weeks. If you don't use it... you know the rest
First off, thanks for the video its a big help. I have a 2006 mercury 115 4 stroke and removed all 5 bolts(left on threaded a couple turns do the housing wont fall off. I cant get get the housing to come loose. Not even enough separation to wedge something between the housing and the drive shaft housing. I've tried spraying wd-40 around all 4 posts and banging with a rubber hammer. Still won't budge. Any suggestions for breaking this loose. Thanks, ps I copied this to your FB page.
Hello. I changed the impeller on my 2002 Mercury 90hp and I placed the gear in forward before dropping the lower unit. After I finished and placed the lower unit back, the gear seems to be stuck in forward when I move the shift in the control box. I move the shift to Forward Neutral and Reverse and the prop doesn’t spin one way and ratchets to the other. I know I have to drop the lower unit again but then what do you recommend. Thank you
Great video. Some years ago I had an old 1971 2-Stroke 7 1/2 HP Mercury Outboard. I changed the water pump impeller several times. Kept going out. I then changed the whole housing everything thinking something was wrong because it kept eating impellers. I think it lasted longer after replacing all of it. Boat we have now has two Mercury 4-Strokes and have never had water pump go out. Replace the impellers every three years.
Great video. I just changed the water pump impeller on my Optimax 115. The only difference was that mine is a long shaft and the gear shift selector rod is longer. Great advice to put the motor in forward gear as it makes it easier on the install.
Please Can Someone HELP ? I Have an Early 80's Mariner 50hp 4 Cylinder 2 Stroke. I Want to Remove the Gearbox BUT It Will Not come off = GGGrrr ! 1) Placed Gear-Shift into Neutral, 2) I Removed the 2 Front Nuts & the 3 rear Nut or Bolts around the Zinc Trim Tab = 5 in Total. 3) I Tried to Pull the Gearbox Down BUT it Only Comes Down 10mm & Will NOT Come Down Any Further. I Don't want to use Force & Cause Damage * I Can't Disconect the Gear Shift Shaft as it is ALL Internal BUT I Can See it's Top Underneath the Carbs. Do I Unscrew it There ? * Please Can Someone HELP ? THANK YOU.
This is a GREAT video! Not just for boats but overall this lays to shame alot of other instructional videos. Well thought out. Good tips. Showing everything being done. NICE WORK!!1
I have an older mercury 1992 100hp im assuming its a pretty similar procedure? My overheat buzzer went off first time in 10 years, I noticed the pressure out of the tell-tale was alot weaker than normal.
I have mariner magnum 40hp i think its a 1990 is this the same way the gear shift un hooks because i cant find it any where on the out side of the motor
Only thing lacking was he already loosened the 4 bolts holding the pump before video.I let mine set overnite after spraying jb blaster on them and I still had to heat them to get them to turn while not wringing them off.MAIN THING'DON;T WRINGE THE 4 PUMP HOUSING BOLTS OFF.BE GENTLE LOL.
Excellent video Geoff! Thank you. I Have an 89' 40hrspr 2 stroke 4 cylinder merc. Could i follow the same steps or is this specifically for the classes of motor noted? Thanks again!
I changed mine... no problems BUT... I had oil coming out from somewhere. My question is where was the oil from and how can I prevent it from happening again? Thank
By the way, on my 1998 Merc 5hp, and others with a similar build, the drive shaft can be a real bugger to get back into place. The reason for this is that the drive shaft tends to miss the tube that it's supposed to go into. This is made worse by the task of aligning the shift shaft with the shift shaft clamp. This process causes the drive shaft to go in at an angle. When the drive shaft misses the tube, it will go up into the housing to the SIDE of the tube. Then it will go no further when the lower end has about two inches to go before the two halves are mated. If this is happening to you, I suggest you take a flashlight and carefully make sure the end of the drive shaft is heading toward the tube while aligning the shift shaft. I finally gave up and took the shift shaft clamp OFF and just concentrated on getting the drive shaft where it belonged. I was able to attach the clamp with a pair of needle nose pliers through the side port that is provided for loosening the clamp. I Hope this makes sense. It will to anyone who has spent the hours of frustration that I did trying to figure out why my drive shaft would not go all the way in!
OK, I didn't remove the old pump, but trying to install the new. The keyway is longer than the indentation for the keyhole! How can that be? The keyway is the one that was on it originally and one didn't come with the kit!
Thanks for the great video. I see in the video you use the quicksilver kit. When I go to Mercury's parts finder it does not show me the kit item number, just the impeller. How do you find the part numbers for the kits? I have a 1996 115 HP 2+2 serial# 0G386904. Thanks.
Thanks for the video . My kit came with two identical gaskets for the plate it was very helpful that you showed one going under the plate. Should the other be left out or go on top? Also I saw silicon being used sparingly but not gasket sealer is gasket sealer necessary?
Also I appreciate you showed the seal going over the shaft and into the housing .I have orings left over but nowhere to put them on the shaft .It is an old Mercury 500 50 horse out board . Thank you for any help, dont want to have to do it all over again
Question I have a 1998 mercury force I ordered a new pump kit it came with some rubber gaskets do you know what there for 2 round 1 inch rubber gaskets and a small rubber gasket
Hi Jeff. I just changed water pump on a 1983 Mercury outboard and can't figure out where a rubber washer goes. I did a RU-vid video and was wondering if you might view it and see if you know it's location and purpose. Thanks, matt
Really great video. I`m about to change the impeller on my 75HP Optimax. But some people also put some silicon on the seal kit on the impeller house, is that really necessary? I thought the metal seal and paper seal should do the sealing itself.
Thank you for posting this video! Going to try my hand at helping a mate get a 115 pumping water again. You saved me quite a bit of time by describing the impeller renewal process brilliantly.
Thank's for the video, really informative, I have a 2016 tracker pontoon with a 90 hp 4 stroke Merc. doing a 20 hr service, every thing went well till I tried to go back up, got nut's started but when I went to tighten hit a brick wall , think shift shaft's aren't aligned properly couldn't get shifted into forward before dropping lu figured it would go back the same, didn't, I noticed my motor just has a short splined shaft did part stay in upper leg? I was within half an inch of up propeler turned motor, I believe water was right, could turn shift shaft and raise it so I don't believe it was stuck. any help or idea's greatly appreciated. David O
Thank you for this! I have a 1998 Force 90hp and could not find a video. This engine lower unit is identical to mine. Thank you so much! Worked like a charm.
hi there, i get to the point where you turn the flywheel but i can't get it to go, we've tried everything and it just doesn't go back in. any help is appreciated. thanks a million. oh its a '73 merc 150.
Thanks for the video. I have a 1982 Ventura Vendetta with a 115 hp Mariner outboard. It has been sitting (covered) for over a decade. Would there be many differences between changing the impeller on the 115 hp Mariner and the one you show in the video?
Ty dude they wanted 800 to change I did for 75 but I was looking on top of motor were water comes out your video is gonna make make owners of companies mad cuz it was easy once shown Ty again
I know this is 9 years old but today I did my 75hp merc and there was no face plate gasket, but one is included in the rebuild kit, did the last owner forget to put it back on? Or do I not need it. Thanks for the kick ass video.
so i hav a 50hp, i wanted to ask, you dont have to remove the shift linkage before dropping unit just asking becuz i had to on my 40hp, i want to do my 50hp today or did i miss something here, thanks
You are a champion! Short, consise, and to the point. One thing I would add is the ft-lbs or whatever torque measurement you use for the bolts on the pumps housing. Some guys are sticklers about that sort of thing :)
