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Old 05-07-2013, 13:32   #1
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Need Yanmar 18 & SailDrive help

Just had the Yanmar 18 hp engine rebuilt on a friend's catamaran and we're installing it now. We're trying to figure out the shims that were in between the saildrive bell-housing and the engine flange.

Anyone know why the shims are there and how can you tell what the right shims are? The manuals don't mention aligning the engine and pinion shaft of the saildrive.

What happens if we get it wrong?

Thanks,

Ron
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Old 07-07-2013, 09:26   #2
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Re: Need Yanmar 18 & SailDrive help

Quote:
Originally Posted by Capt RonB View Post
Just had the Yanmar 18 hp engine rebuilt on a friend's catamaran and we're installing it now. We're trying to figure out the shims that were in between the saildrive bell-housing and the engine flange.

Anyone know why the shims are there and how can you tell what the right shims are? The manuals don't mention aligning the engine and pinion shaft of the saildrive.

What happens if we get it wrong?

Thanks,

Ron
captain ron hello
do you mean shims between engine flywheel housing and saildrive mounting flange.what is the thickness of these shims?
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Old 07-07-2013, 09:53   #3
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Re: Need Yanmar 18 & SailDrive help

Yes I suppose that is the correct terminology. There are 8 bolts and when it came apart there were semi-circular half-moon shaped washers, one on each bolt. Each washer was about .5mm thick although I didn't measure them.

When my friend bolted it up he did so without the shims since he lost about half of them. Then the engine wouldn't start ... by not starting, I mean the starter couldn't turn the engine past the compression. With them compression levers off, the starter would barely turn the engine over. We tried three different starters including the one from the other engine that we knew to be working fine. No Joy same issue.

Anyway since we didn't have a ready supply of the half moon shims, my friend made some out of plain stock. I have no idea what the thickness of those washers are but when he installed the washers, the engine now starts and runs fine.

I guess now that we know the shims need to be there and my little online research turned up a manual that describes how to calculate the shim thickness, my question would be this:

What was binding that would cause enough resistance that the starter couldn't overcome it?

AND related to that, is there some alignment that should be done between the engine mounts and the pinion shaft and or the mating surfaces?

I did notice that when we nudged the engine onto the pinion shaft that the whole drive leg had to be tilted a bit down to fit and that the flanges between the engine and transmission were not perfectly parallel. My thought was that the engine need to be raised up via the front mounts to get a better alignment and therefore less stress on the pinion shaft and pinion shaft bearing. But that's just the Saturday mechanic in me thinking out loud.

I cannot find a Yanmar manual that describes the process of mating the engine to the sail-drive and what the tolerances should be.

Thanks,
Ron
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Old 07-07-2013, 10:24   #4
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Re: Need Yanmar 18 & SailDrive help

captain ron as i can understand because my english are not perfect :-)
these shim thickness are for adjusting the backlash between the upper pinion and upper gear , so by decreasing this thickness(lost shims), the upper pinion contacts more the upper gear these 2 must have standard backlash so they keep between a film of lubricating oil and not pushing each other, just touching
an example try to run and somebody from your forward tries to push you backwards , that what happened to the engine.

about the adjustment you ask, first of all remember always before you do anything on an engine that will affect alignment & mounts to have with you 2 feeler gauges to measure engine mounts & flange to flange alignment
on the saildrives engine-saildrives must be parallel.so by tilting down the saildrive as you mentioned your back side of the engine was down so you have to raise up your forward side so your thought is correct.
before you tight the 8 bolts measure with a feeler gauge up & down gap and sides the same way you would do in a revesing gear flange to shaft flange.
my concern is to check the thickness of your shims you installed now compare it with the manual because you must have a standard backlash as per yanmar
in the service manual i have this thickness is called T2
service manuals for yanmars you can find in yanmarmarine.co.uk
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