Bad lower crankshaft seal on Merc 9.8

[britabroad]

I'm trying to split the crankcase on my 1984 merc 9.8 block to replace the lower crank seal - but having trouble getting the phillips bolts out. Is there a knack here? It's really hard to get any sort of torque on them before the screwdriver pops out.

 

[Laddies]

Re: Bad lower crankshaft seal on Merc 9.8

Use a screwdriver with a good bit or a 3/8 drive with a phillips bit and put a small amount of valve lapping compound in each screw head when removing it.

 

[James R]

Re: Bad lower crankshaft seal on Merc 9.8

The only way to remove these is with an impact screw driver. Without this all you will do is chew the heads up. Smack them hard.

 

[britabroad]

Re: Bad lower crankshaft seal on Merc 9.8

Thanks - I'll try an impact dirver.

Just to check - do I definitely need to split the case to replace the seal, or should I be able to get at it from underneath?

 

[Laddies]

Re: Bad lower crankshaft seal on Merc 9.8

The seal sets above a flange in the block so the crankcase has to be split

 

[britabroad]

Re: Bad lower crankshaft seal on Merc 9.8

Fantastic recomendation on the impact driver thanks. Bolts all turned on the second smack!

Crankshaft seal was clearly ripped to shreds. So many engine problems for such a small part.....

 

[britabroad]

Re: Bad lower crankshaft seal on Merc 9.8

I have the new seal on order - couple of questions though:

- when I install it, should I bed in Lithium grease or such?
- the space for the seal in the block is much bigger than the seal itself - am I missing something? Should it be installed in a pair?

 

[Laddies]

Re: Bad lower crankshaft seal on Merc 9.8

You should always grease seal lips to prelube them on startup. Here is a link for your engine and it says 1 seal. http://www.mercruiserparts.com/Show...97&bnbr=80&bdesc=CYLINDER+BLOCK+AND+CRANKCASE