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Changing Yamaha Jet Boat Pump (Duct Housing) Bearings and Switching to Oil Bath Lubrication

blacksapphirez

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i was going to wipe off as best I can and then add the gear oil & grease mix in on top of it.
 

swatski

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swatski

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Bruce

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i was going to wipe off as best I can and then add the gear oil & grease mix in on top of it.
You can wipe the grease out of the cone and maybe access 5% of the grease that is on the rear bearing. The grease in the cone would only come into play if it were hot enough to liquify. So I doubt you would accomplish anything.
 

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added to the FAQ under both fixes/mods and general mtc topics
 

KXCam22

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One of the less considered benefits of the oil mod is that it turns the pump bearings into a routine and easily serviced item. Every 2nd season i pop my jets off, clean up the impellers, change the oil and pop them back on. Even with drain plugs i still have to take them off, just don't have to unbolt the cone. Cam.
 

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Bruce

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I pulled the pumps to change impellers and found that after a year each side was down 30 cc of oil. The bearings look and feel great and there was no sign of water intrusion. With 40cc + of oil remaining the fill level had dropped from 54% to 31%.

I removed the washer on the front side of the housing and could not find any indication of oil getting past those seals. The boat lives in my garage and I do not have any signs of oil dripping on the concrete. Where the oil went is a big mistery.

I topped them up and will report back next year.

IMG_2525.JPG IMG_2533.JPG
 

subcritical71

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I pulled the pumps to change impellers and found that after a year each side was down 30 cc of oil. The bearings look and feel great and there was no sign of water intrusion. With 40cc + of oil remaining the fill level had dropped from 54% to 31%.

I removed the washer on the front side of the housing and could not find any indication of oil getting past those seals. The boat lives in my garage and I do not have any signs of oil dripping on the concrete. Where the oil went is a big mistery.

I topped them up and will report back next year.

View attachment 58030 View attachment 58031
Bruce, I converted to using oil several years ago and also experienced the loss of oil. I would say 30-40cc were left (no water!) This was after several years of operation without adding any oil. I have recently taken my pumps apart and rebuilt them with new bearings, seals and oil. I have had them on my bench for a few days now and both pumps are leaking a slight amount of oil. It seems to me that they will leak and then stop at a certain point. So far no harm from the lower levels.

I do have a question on your first post (second to last picture which shows the spacer). Great write-up BTW! I never took off my impellers until this year. When I did the spacer was installed with the cutout towards the bearings (aft) opposite of what is shown in the attached photo, but the same as what your photo shows. But since the spacers were damaged I ordered new ones (seems they were damaged previous to this operation as the spacers were the only things with grooves in them). These have a spot drill on one of the surfaces (the one without the cutout, so on the surface between 2 and 12 on the attached photo). I've seen several references that this should be towards the bearings, which would be opposite of what you have shown. Now that I'm questioning myself and before I put these back on the boat I'd like to see what references you've been using to do it your way? I've put a photo I snagged from another site which shows the orientation I am using.

Also, the seal (#12) in photo, doesn't look like its orientated properly from what I've read on several other forums... any input there? I've read to install the small seal first, flat side towards bearings (aft) and then thick seal with the flat towards the impeller... this is also the way I had it for the several years of operation without problems.

Thanks!

upload_2017-8-1_11-30-4.pngupload_2017-8-1_11-53-45.png
 

Bruce

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@subcritical71, thank you for sharing your oil leaking experience. I am glad to know I am not the only one and that it has not been an issue for you.

I believe I reinstalled the "spacer / washer" the same direction that it had come out. I likely filled the groove with grease on reassembly.

For the seals I followed the instructions in the PDF file that is attached to the first post of this thread.

"Grease the seal end of the housing and seals accordingly. There are 2 seals, the one with the “Spring-Ring” will have the flat side against the wall of the housing. The next and beefier seal will have its flat side against the “Spring-Ring” end of the first seal. Use a seal installation kit or an inverted 32mm metric socket and extension, press very straight. If properly greased it should go in with no effort. Greasing the area between the seals will help in maintaining water from entering the pump."
 

subcritical71

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@Bruce: Thanks for the reply. That is what I feared about the seals. I read that statement you quoted like 10 times before I put the seals in, then when I looked at it again I was like !!! how did I mess that up. That could be why I was experiencing the oil leak now (and in the past). Good news is, it was like that for 5+ years without issue before.

I'm still not convinced on the spacer/washer though but I'm also thinking there is no wrong way. From what I can see the only affect would be that the impeller would be a few mm out of position. I can't imagine that would make much difference. Also, from my experience the spacer/washer does not appear to rub/wear on the rubber seals.

QQ: How much clearance is between your impeller and housing? Mine is slightly less than 1/8" so re-orienting the washer/spacer would take a lot of that clearance out.
 

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I pulled the pumps and refilled the oil again. Was able to add 35cc to each. That was a little too much on one side. They had a vacuum seal that I had to overcome to remove the cone. Makes me wonder if some oil is escaping when it heats up and builds pressure.

I only took a picture of the starboard side but after two years the bearings on both sides still look like new.

D4908058-7331-421F-902F-E93473635414.jpeg
 

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This may be a dumb question but it doesn't seem to stop me,

When I put the impeller back on should I put anti-seize on it? since so many seem to have a problem removing them and they are reverse threaded doesn't the natural spinning keep them tight?
 

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This may be a dumb question but it doesn't seem to stop me,

When I put the impeller back on should I put anti-seize on it? since so many seem to have a problem removing them and they are reverse threaded doesn't the natural spinning keep them tight?
I believe it was originally installed with a thread sealant to keep liquid out of the threads.
 

swatski

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This may be a dumb question but it doesn't seem to stop me,

When I put the impeller back on should I put anti-seize on it? since so many seem to have a problem removing them and they are reverse threaded doesn't the natural spinning keep them tight?
I always have. Don't know how much it helps at the end but it certainly won't hurt.

--
 

Cobra Jet Steering LLC

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I add gear lube to the intermediate bearing and the pump . I pull the pump and the cone I use my plastic syringe to inject the oil in to the pump housing but I leave the grease in also, then seal the cone and wax the driveshaft splines and bolts that attach the pump so they don't corrode and get stuck. I believe the grease helps to lube the bearings better .
 

bronze_10

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@old thread revive. I. Gonna try to tackle this after I get all the trailer bearings and races replaced. After several years do u still recoment oil bath?
 

Cobra Jet Steering LLC

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I am at 800 hours and counting on the original pumps.
 

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@bronze_10, I am happy with the oil bath setup. A little oil seems to be lost each year but water is not getting in. The bearings still looked new last year. I will check them again soon.
 
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