Tore it all down, still can't find the problem! This is one for the records...

[IDoSeaDoo]

I sort of regret buying a new front motor mount. The one I fixed is so strong, I think I can hang the whole boat from it. It's probably going to be much stiffer than stock and maybe lead to more vibration/noise, but I have 0 worry about it's strength. I ran a SS bolt through the middle of it and threaded it through the top plate of the bushing. It's essentially a mounting stud now. That flex seal is really strong and holding fast. I could probably use this indefinitely... I think 5200 would have been another good substitute for the flex seal.

Also, the new thrust bearings came in. I popped them in and it really solidified the crank's side-side movement. I'm not sure how I can possibly get a micrometer in there, but I don't think I need to. There is much less play in the crank than even the connecting rods, and those I verified are w/in spec. I suppose I could remove the crank and mic it and mic the bearing width and do the math, but I am 100% convinced I don't need to. Will be reassembling tonight, hopefully testing tomorrow.

 

[mikidymac]

Don't you typically measure the crank front and back play with a feeler gauge?

Though strong, I think you are correct that the through bolted engine mount would transmit a lot more vibration and stress to the hull than the standard one.

 

[IDoSeaDoo]

I guess i can try to stick that feeler gauge in there, but it's tight. the thrust bearings are on the bottom and I'm not removing the head or pistons this go- round.

 

[Rikky001]

You don't need to stick a feeler gauge there but measure the axial play on the crankshaft. New this is 0.08 to 0.22 mm, service limit 0,35 mm according the manual.

 

[BTR]

Can you post pictures of your motor mounts?

 

[IDoSeaDoo]

Only way to tell they were bad is rocking the motor, but even it was tough to know. Taking the not off, the mounting points peeled off the bushing.

 

[IDoSeaDoo]

Replaced the thrust bearings only and resembled with great results. Engine runs great, but has a little more vibration at times. I feel that it's from that bolt I put through the front mount. I'll be replacing it with a new one at some point. The boat is a blast. The prop is taking off without cavitation. I'm on plane instantly! Seems the troubles just won't end though. My Polks took a crap on me. Both speakers stopped playing the main cone, just the tweeters. Crazy that they did it at the same time. Tested another speaker and it's not the amp. Getting a set of infinity 652M

 

[Sportster-2001-951C-Stock]

I was gonna say, why not run without the bolt through the motor mount? I think you already said difficult to remove.

 

[IDoSeaDoo]

Well, I was scared to risk the thrust bearings again. I know the pain and cost if it were to happen again. I will have to remove the drive shaft and realign once the new mount comes in. I wonder if I can suck out oil from the pto housing via the oil filter housing... I have a thin tube attached to my oil suction pump. Last time I sucked it out via the supercharger hole, and it prevented that huge mess you get pulling the drive shaft

 

[IDoSeaDoo]

Well, the damn thrust bearings failed again. I had brand new motor mounts this time, and know for a fact the prop didn't come loose. The boat did have a vibration at some rpm, like the prop was unbalanced, but it was only at WOT and seemed like it was intermittent. We were running it pretty hard all weekend. It failed while I had it at about 5500rpm steady. Seemed like I hit a log. The boat lurched a little and we lost some rpm. Then that growing bearing noise came back. I literally thought it had a stick poking out of the intake grate. Anyone have any idea why it keeps doing this? Could it be a bad prop? Bad pump?

 

[Sportster-2001-951C-Stock]

I'm curious to know if you have an oil pressure gauge. Not saying the thrust is failing due to low oil pressure but for some reason nobody seems to have slapped a gauge on and reported oil pressure as far as I know.

 

[IDoSeaDoo]

Haven't tested it, but the fact that the main bearings all tested fine with plastigauge suggests that's not the issue. I can't imagine that a failing pump or unbalanced prop would kill a thrust bearing in less than 8hr...

 

[Sportster-2001-951C-Stock]

I agree, the only cases I've seen thrust failure other than Seadoo are when forward thrust is excessive and when the thrust flange on the crank is finish machined improperly. If it was an oil related issue I'd expect the crank journal(s) and more likely rod bearings would show damage.