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Author Topic:   Lower unit off-kilter
specktrout posted 07-24-2002 10:15 PM ET (US)   Profile for specktrout   Send Email to specktrout  
I recently paid to have my water pump replaced on my '89 johnson 90hp on my montauk. I can see definite improvement in waterflow while flushing the engine in the yard. However, I am concerned about how the mechanic re-bolted my lower unit on. The front is slightly to the left and the back is slightly to the right- the result is a slightly mis-alligned lower unit. It runs fine and I noticed nothing unusual about the lower unite oil when I recently changed it. I did howerver notice that some of the water from the exhast does leak out from the sided at the junction of the lower unit to the rest of the engine. The mis-alignment is slight, 1-2mm. Does anyone think this is a problem? If so, to fix it is it as easy as loosening the lower unit bolts, realigning, and re-tightening? Thanks for any advice.
Tom W Clark posted 07-24-2002 10:31 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
specktrout ,

I suspect the misalignment was there before the servicing. You are just noticing it now because you are scrutinizing the repair and the exhaust leak has drawn you attention to this part of the motor.

This slight misalignment is very common, especially on the Mercs, but I've seen it on the OMC motors as well. It matters not at all except in terms of aesthetics. You could try loosening and realigning the gearcase if you like.

The exhaust leak is not uncommon either nor does it really matter. The remedy is to apply some sealant like the old Permatex 2B (sticky, non-hardening) sealant but I'm sure some RTV silicone would work fine too.

What happens is that some corrosion roughs up the surface of the aluminum where the gearcase meets the mid section and a little exhaust leaks out. If possible, I like to sand the aluminum down flat before reattaching the gearcase. You might be able to do this if you just loosen it enough to drop the gearcase 1/4" or so.

specktrout posted 07-24-2002 10:39 PM ET (US)     Profile for specktrout  Send Email to specktrout     
Thank you for the reassurance. I don't really care what it looks like, I just want to make sure no damage would occur. I will probably just leave it alone until the next time the pump is repaired. Thanks again-
Dick posted 07-24-2002 11:08 PM ET (US)     Profile for Dick  Send Email to Dick     
I thing this is a first, I have to disagree a bit with Tom.
I have never seen this as a common problem on Merc or OMC.
I do agree with cleaning up the surfaces so they mate properly, most shops would have done that prior to putting it back together. I disagree about using a sealant between them. The manufacturer doesn't require or suggest a sealant, why deviate.
In my shop you could expect an extra hours labor to clean the sealant off if you brougt it in for lower unit service.
Clark Roberts posted 07-25-2002 06:18 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Most outboards have locator pins in mid section which must align with blind holes in lower unit (only about 1/8" deep and 1/4"dia)so that alignment is assured (you seldom even notice these). If you have visual misalignment you should check it out although seems as though you don't have a problem. Loosen, align, retighten as you describe and things should be ok! Happy Whalin'... Clark... Spruce Creek Navy
Bigshot posted 07-25-2002 01:25 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
My guess is close to Clarks, That pin could be missing, making alignment tough. Loosen the nuts and align it(takes 2 minutes). There is one bolt under the trim tab as well.

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