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early 80's merc 50 4 cylinder, missing spring on top of driveshaft?

L

leaky

Regular Contributor
Hi,

I've got a 50 HP Merc 4 cylinder w/ serial 0a131953..

Doing the water pump today I noticed it's got a pin on top of the driveshaft. That immediately made me suspicious and I went looking at the parts breakdown. There, sure enough, it shows a spring, part # 20254 (NLA).. I don't think it ever had one (will look around to verify it's not still up in the crank but I don't think so because I did inspect that area to verify splines were good)..

What it does have, which similarly is odd and not shown in the parts diagram, is a sort of plastic splined bushing that seems to go on top of the driveshaft, fitting over it such that you would not be able to push it up too far into the crank I guess.. possibly this part takes up some space and replaces the spring?

I did find an old stock new spring on Ebay and bought it just now, however not sure if I need it with the bushing that's there or what the deal is. About 10 years ago I did the water pump on this engine and probably went through the same thinking (but do not remember)... Can anyone comment on what the deal is with these parts?

Thanks,

Jon
 
This is the pre load pin and if you push the pin you should find it is spring loaded.But that is the spring you see in the parts diagram
 
Hi guys - the serial was in the first sentence of my post, 0a131953.

I'm gonna try pushing on that pin - hopefully there is a spring under there. Where I was looking it's funny it said "NOT AVAILABLE" but looks like there are tons of them here...

Sounds like most likely #1 I didn't loose it, #2 they probably had the $4.00 part at the dealer down the street ;).. Will check for that spring and put it back together.

Thanks!
 
So, that is correct on the spring being under the pin. The diagram makes it look bigger but actually there is spring under the pin. All set, thanks!
 
It takes a press and a heavy duty punch to dimple shaft to hold it in place, the plastic/rubber bushing is to seal water out of crank spline as it will climb drive shaft a low speed.
 
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