Watch how to replace the impeller and pump housing on a Mercruiser Alpha One Gen II stern drive. You can do it the right way and save money. The left over seal was for the oil fill screw
Thanks for posting this. Finally doing it myself this year. Note: Last impeller change was done by an authorized Mercruiser shop. There was no sealant on any of the gaskets when I removed the old impeller.
Yeah, since these don't need to be water tight anyway sealer is unnecessary. Consider replacing the assembly seal underneath the pump as well. There's two orings that wear and will leak eventually. It's very easy to do while you have it exposed. Also ..putting the lower unit back on is a bit tricky. Have to orient the feed tube correctly and put the shifter in forward.
I wish all DIY videos were of this caliber. Your planning, thoroughness, clear explanations, and caution statements are confidence inspiring to those who believe in doing things themselves. And doing them correctly. Minor details are critical to mechanical maintenance and repair. Now I am hoping that you have posted the removal/ refitting process for the drive. Just a couple of mentions: (1) Since it is important for the shaft not to contact the impeller housing bore maybe a feeler gauge would be helpful. Better would be a piece of thin gauge sheet/roll metal, like deck flashing, that could be wrapped around the shaft as a spacer until the bolts are secured. This would help ensure the best possible coaxial alignment of the bore and shaft . (2) Is it not advisable to use an anti-seize compound on the fasteners in this application instead of marine grease? Knowing that it is not recommend to lubricate fasteners during assembly, anti-seize is made specifically for threaded unions. (3) You began threading the bolts in a diametrically opposite manner, then switched to a circular pattern. I have always stayed with diametrically opposite all the way through. I personally believe that it helps to achieve a better distributed clamping force. And on that note, I think this project is the one that finally sees a 3/8" drive torque wrench that I always said I would buy. (4) Do you recall the diameter and thread pitch of the bolts that you used as guide pins? I like to have everything I need before I begin work. And that will be the one bolt size I do not have in stock at 2:00am..
Thanks for words and glad it helped. Good suggestions. Those pins really are intended to max the alignment accuracy, they are thicker than the the bolts so cover doesn't move. I suppose antiseize would be ok, marine grease won't wash out. I don't recall thread specs, but I took a screw to hardware store and got exact match on a bolt, then I cut the head off. The oring I had was for the fill plug. Good luck.
Michael, you’re correct that torquing fasteners in a diametric fashion (star pattern) is necessary to achieve even clamping force; however, once all fasteners are torqued properly it is acceptable to check their torque in a circular pattern because all you’re doing is verifying none of them loosened. If you find any that are loose, re-perform the star pattern.
great video and I appreciate your attention to detail and organization. I did chuckle at the 2 interruptions. It never fails, anytime you do a "how to" video you become a magnent for your wife or kids or the neighbors leaf blower...
I like 2 things very much about this vid. first the wooden stand made from scrap wood is awesome. I will be making one of those for myself, and the cut off bolts used as guide pins. I know they are not needed , but I like this idea very much.Thanks for posting.
The only vid so far that mentions to make sure the shaft does not touch the housing. There for the only one i will recommend watching for this service. Great job! Those two extra seals are for the upper and lower gear drive drain screws. Well i got two anyway lol.
STEP # 1 on all DIY videos: TAKE PICTURES! Take them before you dissemble anything at every step of the way. Those pictures may save you a ton guesswork or re-work. Just about everyone has a cell phone these days or has access to one to take nice pictures, so there's really no excuse. Trust me on this one folks. TAKE PICTURES! A picture truly is worth a thousand words. Personally I don't use any sealer on the gaskets on the water pump. The latest kit has a steel gasket for the very bottom, then the contact plate, then another gasket that has sealant already on it (face it up when installing).
Actually you should take pictures anyway .. regardless of making a DIY video. Also, if you are making a DIY video... then you already have a digital record to refer back too and usually don't need pictures 😉. But yes it's a great point, I do it one way other the other .. especially on intricate projects like carburetors and chainsaws. Thanks for the comment!
If the extra piece is plastic and not rubber, it is for the gear lube drain hole. My kit actually came with two -- One for the drain and one for the vent.
Good video, well done. Only comment I would make is that rather than using grease on the inside of the pump housing, use dish soap. Some greases will cause the impeller rubber to degrade over time. Dish soap will provide the lubrication you are looking for and wash out the first time the pump is run with water in it.
It's a good suggestion if you don't have marine grease. I used what is recommended in the manual and by mecruiser. You are correct, petroleum lubes like vasaline can degrade rubber.
This video was perfect for me. The only thing that would've also been helpful is if you showed how to detach/reattach the lower drive piece. That part I had to go find on some other RU-vid videos. But the replacement of the impeller and the details were amazing and I got mine done. Thank you much!
@@jonparkmac Luckily I had a buddy tell me about that shift lever so we were good to go! My wife helped me stick a couple bolts back in so I didn't have to hold it the whole time and then buttoned everything back up, filled it with lower gear oil, then ran it with the muffs on. No problems! Thanks again fro the video!
@Adam Dirks Pump the oil in from the bottom until it overflows out top hole to remove all air, then fill reservoir. Also good to put a good marine grease like Aquaguard on those nuts so the threads don't lock and easier to remove next time. Glad you gott'd done!
Excellent video - very well articulated. I have an older 470 drive which is going through its annual pre-season check-out. The alignment pins made out of commonly available bolts(screws) is a terrific idea. Many thanks for posting your work.
Nice work on this video! I'm replacing my first Alpha 1 Gen 2 water pump impeller tomorrow morning, and this video was so much more helpful and "human" than the usual Professional Disco Boy (Mika Marine) stuff that Mercury puts out on their website or in their service manuals.
Edward Morton I’m going to do mine tomorrow. I’ve heard something about needing to put the gear selector in forward prior to separating the lower unit. Is this necessary ?
Well done. I would recommend to others you skip buying the extra housing (in most cases) and buy that lower carrier seal below the impeller. Mine started leaking (out the weep hole) with the new fresh thinner oil so I had to take it all part again.
Figured out what the remaining seal washer was for. Its for the lower oil drain plug. Replace it with the new one, even if you don't think you need to.
Thank you. This is exactly why I was watching the video. I was wondering what those gaskets were for. I had two in my kit. I assume one for the upper vent plug and the other for the drain plug.
JesterStrike yes, the upper one is a rubber o ring and it's for the gear oil transfer from upper to lower unit. without it, oil leak and possibly water in oil, both bad.
nice vid, i would not use the grease on rubber though. it eats rubber just like oil dois. use vaseline on the rubber parst like the rings and the impellor itself... and the insite of the housing. the little o ring is for the gear oil channel that runs up to the control container i guess. cheers. happy boating!
Yeah its probebly ok. I am just always very carefull whit rubbers. I even saw people use dishwashing soap to put on the impeller. Thats a real big no no. :)
@@ikkebuyckx why is dish soap a big No-No? Grease is a big No-No of any kind. I'm surprised they recommend Grease. Have you ever seen grease and water whipped together? It basically Foams up and expands. It can clog up passages. The dish soap does the same job of helping the impeller slip in the housing and it simply disappears when the water circulates through. Actually have you ever heard of salt Terminator? Guess what it's made of...
Good job..I know you put ALOT emphasis on the direction of the veins of the impeller.... But it's really not an issue at all...even if you turned the shaft counter clockwise when pushing down the impeller housing, the first time you turn the motor on the impeller WILL correct itself on the very first rotation .....
@@jonparkmacnot sure what out drive you have, but my alpha one gen 2 has a drain/fill plug on the bottom of the skeg and a VENT hole in the upper portion of the out drive. It's the screw you remove when you are filling the outdrive with gear oil that tells you the drive is full....buy an actual Manuel, but please don't stay things that you have no idea to what you speak.
I have a Mercruiser 260 with a Alpha 1 Gen 2 (I thought anyway). The impeller is much smaller with smaller blades. Maybe I have an Alpha 2 pump kit installed? The boat has run great over 10 years even though it's not taken out often.
Well done. Very clear. The other rubber seal, I believe goes on the stern drive upper section. At least, I believe I watched another guy place one there. Would that be the oil seal you are mentioning?
It was. The ones in that kit leak. So I now use ones that have thin rubber coating and a tad thicker. I also replace that yellow assembly seal each time now too.
Actually no, nothing touches the top of that seal. That's why they provide that plastic tool. It's not for oil, it's to keep water from spraying up into the upper unit and of course keeps pressure up. It's not supposed press down onto the housing very tight. I see people leave the plastic tool in there thinking it's a part lol
Did you ever figure out what the extra gasket is for ? I'm thinking maybe the drain plug but who knows....also are there any videos showing that water tube and pocket cover replacement....I'm new to a boat . I like to watch and make sure I do stuff right haha
Thanks, nice video. I thought you were not supposed to use vaseline or petroleum-based grease on the impeller as install lube because they might not be as safe for rubber. I have used water-based lube (e.g. KY jelly) although it dries kind of fast. You could probably use silicone lube (such as for plumbing seals) also.
Great Video. I have to not only do that, I may have to replace the main shaft seal. Somehow gear oil is coming out of my water pick up holes. Any help would be appreciated. Thanks for the great video.
If the shaft spins either way (forward or reverse) why does it matter which direction the impeller fins are placed? they are going to move in either direction depending on if your in drive etc
The down shaft always spins in the same direction. Shifter is below the pump to change direction of the impeller shaft at the 90 degree junction joint. In fact I suggest testing that manually just so you learn how the shifter operates
Thanks for the detailed video - very helpful! I am in the midst of changing the impeller on my Alpha One Gen 2. When I removed the lower unit from the upper, the entire tube on top of the impeller outlet pulled out from the upper. So I not only had the white plastic sleeve attached, but also a rubber hose of some sort from the upper. Is this normal and can I just press-fit to reinstall that tube into the upper? It appears as though the white plastic sleeve is designed to fit into that rubber hose as the lower is being installed into the upper. Another concern I had was that there was no seal on the main shaft above the impeller housing. It either disintegrated or was never installed (or not installed during a previous impeller replacement by the former owner).
The inner tube is actually the water feed and ok to take out and put back in. It has a curve so don't get it backwards or you'll crimp it. The white PVC is only a guide. You want the inner tube up in the upper and white on the lower. Put gear shift in forward and make sure the shift lever sits in the saddle. Also connect the speedometer tube. Use grease on the bolts and nuts. Don't forget the oil oring. It should go together easy no force. Pump oil backwards from very bottom till it comes out top hole, then put top screw in and keep pumping till it comes into reservoir. Small seal above pump housing should be in your kit ..there are orings up in the upper unit. You need the seal or it will spray water up into the upper unit. Grease the splines and little grease on shaft. Don't leave that plastic ring from the kit on the shaft. It's a tool to seat the seal and not a part.
Thanks Jonathan! One question on the water feed tube - should the curve go toward the stern of the boat or out toward the prop? Wanted to double-check before I reassemble the lower later today. The other question I have is why can't the gear oil be poured in through the Reservoir on the engine? I understand it's there as an indicator and gear oil can be added through there if it ever runs low, but was confused as to why the gear oil can't be poured back in through that reservoir in the engine. I do have the Quicksilver quart bottle hand-pump however and know that I need a bit more than 2 quarts of gear oil to top it off. I replaced the oil O-ring with the one in the kit, and knew that plastic ring was a tool thanks to your video. I also replaced the orange O-rings inside the plastic outlet that connects to the impeller housing since the kit included them. I always grease the new O-rings before fitting them back in. I put generous amounts of 2-4-C Quicksilver grease on the shaft spline as well as the main shaft, and greased the bolts (I generally do this to prevent future seizing, but you have to be careful torquing them down as grease makes the bolts much easier to torque). I'm not sure which tube is for the speedometer - is it that small black tube on the lower with the O-ring? Otherwise I didn't see any other tubes on the lower.
@@jonparkmac Figured it out...tube had to curve inward toward the boat, behind that plastic insert inside the upper housing. Got the lower back in no problem, started the engine, new impeller seems to be working perfectly. Thanks again for the video tutorial!
@@ChrisG9978 glad to help. The reason you shouldn't just pour it in from the top is because you'll trap air pockets in the oil system and you cannot know where those are. Can lead to a lack of oil when you need it most
could someone please provide a link to the kits you or mr mcclure have used? quite a few on the market that all seem to have different components. 1995 alpha 1 gen 2. thank you
It'll be a week before I get to it, but basically you build two squares with height 1" taller tgan the length between bottom of rutter and the lower horizontal fin. Then set the prop on those and put 2 cross mbrs on each end to secure it. I drilled and used wood screws.
Hey John, I just did impeller, gimbel bearing, a few o rings out everything back together filled with gear oil, took a look and noticed water leaking from top cap of outdrive. I noticed the guide tube was a little cocked. Not sure if that was the problem? Another thing my impeller gasket kit didn't come with 2 paper gasket it was one paper, the plate then a very thin plate?
Hi just wondering about the yellow dome looking thing under the water pump gaskets. Picked up my rebuild kit the other day and that part was included and I can't find any videos that explain how to remove and replace this part. Any help would be appreciated. Thanks
That seals the bearing underneath and is not part of the pump assembly. You don't need to replace it unless it's several years old with a lot of hours. And if you do, may as well replace the bearings.
Please tell me in what osition the front controller is in ? Do you squeeze handle and push all the way forward before you start lower drive removal ? Thx in advance.
yes, I put it in forward gear first. You can actually see where the lever mates with shift cradle and see if it detaches. Patience and even downward pressure is key..just don't beat with a metal mallot
Is it critically important to put it in gear before taking the lower unit off? I took mine off while gear was in neutral and am worried I might have screwed this up by not putting it in gear....
@@chadpapineau9209 just put it in gear before putting lower unit back on. It’s nice to have another person helping that can turn prop shaft for alignment.
I have the same lower unit and I had to remove it for a skeg repair. However, there is a part that came out of this unit that I cannot see on any parts list I cannot remember how it went in. The part is a white rectangular piece of plastic about 4x3 inches with an X from corner to corner on one side. Anyone know anything about this part?
My Chriscraft has a raw water thru-hull intake and belt driven pump to cool the engine. It also has an Alpha 1 outdrive and pump that does nothing...or maybe cool the outdrive? I've never really found out. When running on land, I've always connected two hoses, one for the engine and another for the outdrive. Am I doing this correctly...I've never really found out?
Just fininshed my winterization about 2 months which included changing the lower unit gear oil, always a bit messy. Was recently checking my maintenance records and think its time to replace the impeller which was done 3 years ago. Some other videos direct you to drain the lower unit gear oil prior replacing the impeller. Do I need to do this? Seems to me that if I take care to temporarily cover the gear lube transfer hole from the upper supply reservoir I save myself from having to drain and refill the unit. Can you comment. Thank you for a well done video.
nazmen040 good question, definitely drain it. Gear oil is relatively cheap and good to change anyway. Remove the top vent screw, then the bottom and let it all out.
Glad it helped. I'll post the dimensions but it'll be a week. Honestly, have a bunch of 1x2 a drill and some wood screws and build it on the spot. That's what I did as sort of a last minute thing.
@@jonparkmac you must be mistaken on the question or maybe he worded it wrong but you put on some gasket sealer with a paint brush while putting on the gaskets
No mistake. No need for sealant. The gasket is for adequate pressure and not for absolute leak prevention because both sides are in contact with water anyway. So adding sealant doesn't add any protection or value. Use if you like. Really is unnecessary.
Does the impeller move when not in gear as in forward or reverse position it seems like fish after that is turning turns the prop as well and what have to be in gear to turn so how does the engine get water 1 in neutral is it sucking it impeller is only used for when the boat is in motion this might sound like a stupid question but I'm new to boating
t's not a stupid question at all. The impeller is always turning so water is always impelled to your engine water pump. The shift tongue on the lower unit moves the gears to be in forward, reverse, and nutral. When you have it off, you can move that tongue back and forth and then twist the shaft to see the prop shaft rotation to see how it works. Your shifter cable connects to that tongue.
@@jonparkmac I appreciate your reply I was using text-to-speech so that's why there are some typos in there but none the less I sort of figured that but I assumed since the engine has a sea water pump on that would not emotion that would pull from that I made an observation of it not being in motion when it's not and gear because I noticed that the shaft turns and the prop turns with it but it may have just been when the lower unit was taken apart it was put into gear someone that is put back together it goes together correctly
Hello Jonathan. Terrific job on your part. Very helpful for me with my same unit. Can you tell me how long between changing water pump and how will I be able to see your comments after I sign off here. Thank you
Part is Sierra 18-3570 from wholesale marine. www.wholesalemarine.com/sierra-18-3570-water-pump-kit.html?gclid=CjwKCAjwssvPBRBBEiwASFoVdyU8gPXgMcJj8fQUpxWmQtYoyy1MQIRkSSZx_2z9wVSfkcQbgvz7JxoCjzUQAvD_BwE
Excellent. I have been searching all of these videos to find what the hell these 2 extra seals were for - hadn't got to refilling oils yet, so didn't see the old ones come out! Thanks.
Yes or it will come out anyway and make a mess. I empty the reservoir too since it will drain all the way down and takes a while. When you reinstall you have pump the oil backward from bottom to top until it comes out plug in upper unit. Otherwise air trapped, no oil .. bad news.
@@ryansimnacher5459 most definitely .. I'm doing that right now in fact. I didn't in the vidi only because it was brand new. Use the one made by mercury .. part is 807929A1.
Check to make sure the shift tab is aligned. I think you have to put the shift in forward position when you mate the lower unit back on to the upper unit. I think you need to take it off, shift, and out it back on.
Robert Gary nope, didn't need to and that does not come with the kit. This video is for the standard impeller maintenance. That said, you can do it if you like.
Hey I removed lower unit in neutral and then shifted in forward now I can’t get it to shift back in neutral or if I redo it goes to neutral but not reverse please help
You'll have to take it back off and orient the shift tongue forward which is FWD. Then put your console shifter in FWD. Then reassemble and put your eyes on the tongue to make sure it mated ok. The shift tongue rotates from strait ahead to one side going thru neutral and reverse ..so it's not left to right ..it's 12, 1, 2 o'clock for fwd, neutral, rev.
Take the unit off and rotate it to 12:00 with your hand ..that's FWD. Play with it by grabbing the shaft with a rag and twist it to see which way the prop is rotating and then move the lever by hand from 1 to 2 and observe how it works. You'll see it change direction. Move it back to 12
Also ..don't get that plastic water pump tube in there wrong or it will bend and pinch ..I did that once. Use marine lube on the threads and flange so it will come off easier next time.
You never want to keep your old impeller. Rubber gets brittle over time which increases the chances of the impellers lobes to break off. Lube the impeller with a bit of silicon grease, not petroleum based grease which encourages rubber to swell, when installing the new impeller.
You guys love that stand. Sorry I don't have dimensions. But you just cut to fit. Take some 1" x 2" pine and just cut it and screw it together. Measure thickest, by width and height on unit, and then add 1" to all 3 for inaide dimensions
