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AQ205 & 290DP Primary Drive Shaft bearing - does this need an engine lift?

SlaveToMyCats

New member
Hi All,

Would really appreciate your expertise here. I have a Fairline Sprint with a rumble on acceleration and certain speeds. The rumble becomes quite severe on full lock.

It got called out as a worn gimbal bearing in a prior service, but in my view on this engine and drive its actually one a bearing on the primary drive shaft, located under bellhousing. Its been like this for some time before my ownership and now I just want it fixed as I'm sure things will only get more expensive if not fixed.

My boat is has fairly large engine bay, which would allow the engine to be moved forward at least a foot.

Does this job require the engine to be lifted out of the boat and put on a pallet or can they move the engine forward and do this in situ? I guess I want to understand how big a job this really is for an engineer. It seems like its been put off by previous owners which makes me think they got a huge quote!

Thanks!
Adrian
 
If you've never pulled the drive and checked the universals, I'd start there, since replacing the bellows is a routine, every couple of years PM anyway.... BTW...290 drives don't have gimbal bearings. Furthermore, having the noise change with drive steering angle points to the universals... Never darken the door again of whomever said... "gimbal bearing"...
 
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It got called out as a worn gimbal bearing in a prior service,
As Bob said, there is no Gimbal bearing in your 290 drive. In fact, nowhere in the AQ series drives can a Gimbal bearing be found.



but in my view on this engine and drive its actually one a bearing on the primary drive shaft,
Yes, referred to as a PDS bearing or bearings.

located under bellhousing.
Bellhousing is an automotive term. The Marine equivalent is a "flywheel cover".


Its been like this for some time before my ownership and now I just want it fixed as I'm sure things will only get more expensive if not fixed.
Yes, an AFT PDS bearing failure can become very expensive.
Change it/them now and avoid any future issues.

My boat is has fairly large engine bay, which would allow the engine to be moved forward at least a foot.
The red one piece flywheel cover will use the double bearing PDS.
The double bearing PDS does require engine removal, or at least moved forward for access.
If the flywheel cover is charcoal gray, and does NOT have the 12:00 O'clock location grease fitting, it will be a single bearing PDS, in which case the engine does not need to be disconnected from the flywheel cover.


Does this job require the engine to be lifted out of the boat and put on a pallet or can they move the engine forward and do this in situ?
If you plan to have the same shop do this for you (the shop who called it a "gimbal bearing"), I would find another shop.

I guess I want to understand how big a job this really is for an engineer.
Very easy and does not require much time.

It seems like its been put off by previous owners which makes me think they got a huge quote!
I'm sure that the quote was huge, mainly because there are few AQ series mechanics left these days, and the younger guys do not understand them.
PDS bearing replacement is often deferred, causing expensive damage later on.


Thanks!
Adrian

If you've never pulled the drive and checked the universals, I'd start there, since replacing the bellows is a routine, every couple of years PM anyway....
Bob's PM = preventative maintenance.

BTW...290 drives don't have gimbal bearings. Furthermore, having the noise change with drive steering angle points to the universals...
I would agree! However, I would not forgo replacing the PDS bearings. They are too dang important.

Never darken the door again of whomever said... "gimbal bearing"...
Agree again! Find another shop!


Here is just one example of the damage that may result.

PDS  bearing failure  Broken Flywheel Cover.jpg


Here is an example of the GM SBC double bearing PDS

PDS coupler and drive shaft 5.jpg



This image shows how the two seals install.

Notes:
..... use open bearings with the double bearing PDS.
..... the FWD seal should be glued and/or staked in position.
..... pre-fill the grease cavity while spinning the PDS.
..... do not install the AFT seal until you see grease exit the ball cage.
..... the AFT seal installs in the non-conventional direction.... I.E., with the seal lip and tension spring visible from AFT.

PDS info for Bruce.jpg
 
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Thank you both for the useful and detailed advice. Its a big help understanding this as it will help me in finding a credible engineer to do the work at a fair price. I'll check the boat and work out the flywheel cover type, and will definitely get the U Joints looked at as the first step.

Thanks again!
Adrian
 
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Thank you both for the useful and detailed advice.
You are most welcome!

Its a big help understanding this as it will help me in finding a credible engineer to do the work at a fair price. I'll check the boat and work out the flywheel cover type,
and will definitely get the U Joints looked at as the first step.
Please do a search for my posts regarding "AQ series bearing cross replacement" before you let someone attempt to remove the 4 clamping collar cap screws that hold the all steel bearing box into the main gear case (Pre-A transmissions).
If they round out the 4 socket heads, you'll be taking the transmission in to a machine shop for some rather expensive milling machine work.


Thanks again!
Adrian


And by the way, once the forward area of the flywheel cover is accessible, you're looking at only 1.2 hour to R&R the PDS and to replace the bearings/seals.
The Industry Standard Bearings/seals will run you about $45/$50 in the US.
 
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