Johnston 1996 8hp lower end will not drop

[Andrew Benjamin]

Hi
I am trying to service the water pump and cannot get the lower end to drop.
I have removed the 3 bolts and the lower unit now wiggles. I have hammered the lower end using a block of wood and still cannot get it to budge. Manual does not detail any other screws or bolts ......... Any suggestion? Can I get to the top end by taking the motor apart?

 

[AlTn]

Re: Johnston 1996 8hp lower end will not drop

how about posting your engine's model no.?...there are 32 numbers listed on marineengine.com...someone here will give you some insight into removing it

 

[Andrew Benjamin]

Re: Johnston 1996 8hp lower end will not drop

Difficult to read model number . Please see photo

 

[Chinewalker]

Re: Johnston 1996 8hp lower end will not drop

These 8hp models seem to have a frequent issue with the driveshafts rusting into the crankshafts. Not sure if it's by design or just poor maintenance, but I've seen several of them like that, and it's not an uncommon issue here on the boards. What generally happens is the driveshaft ends up pulling out of the lower unit, breaking the pump housing in the process. Once that happens, you can grab the driveshaft in a non-bearing area with vice-grips and tap it out of the crankshaft. Some have had success tipping the motor upside down and running various penetrant oils down the driveshaft up into the crankshaft area to help free it up. Be careful what you bang on or pry on, as the castings can, and will break if hit too hard.

If you get it apart without breaking anything beyond the waterpump housing, be sure to reassemble with good grease on the driveshaft splines and a new o-ring in the groove at the top.

 

[nwcove]

Re: Johnston 1996 8hp lower end will not drop

These 8hp models seem to have a frequent issue with the driveshafts rusting into the crankshafts. Not sure if it's by design or just poor maintenance, but I've seen several of them like that, and it's not an uncommon issue here on the boards. What generally happens is the driveshaft ends up pulling out of the lower unit, breaking the pump housing in the process. Once that happens, you can grab the driveshaft in a non-bearing area with vice-grips and tap it out of the crankshaft. Some have had success tipping the motor upside down and running various penetrant oils down the driveshaft up into the crankshaft area to help free it up. Be careful what you bang on or pry on, as the castings can, and will break if hit too hard.

If you get it apart without breaking anything beyond the waterpump housing, be sure to reassemble with good grease on the driveshaft splines and a new o-ring in the groove at the top.

just had a look at a similiar model 6 hp driveshaft, and there is no groove for an o-ring on the ds, which could explain why there have been so many issues with those seizing into the crank. ( also double checked on marineengine and shows no o-ring either).

 

[boobie]

Re: Johnston 1996 8hp lower end will not drop

There is a seal on the c/s that says " seal, c/s to d/s ". I guess that's why there is no oring. Look it up in a parts break down.

 

[nwcove]

Re: Johnston 1996 8hp lower end will not drop

yep, thats the seal that gets damaged the first time the impeller gets changed and the ds doesnt find the hole on the first try.

 

[Andrew Benjamin]

Re: Johnston 1996 8hp lower end will not drop

Any suggestions for the best way to drop the lower end. Or to I just beat the hell out it?

 

[Chinewalker]

Re: Johnston 1996 8hp lower end will not drop

Ah, yes, I forgot they changed that design from the o-ring to a seal in the early 1990s. Bottom line is the same - the seal goes bad, or the splines don't get re-greased (or a combination of the two) and the two shafts become one. If you can get the lower unit free of the driveshaft, you might be able to pull the powerhead to get better access to the driveshaft (not as hard as it sounds.) Wooden wedges like the shims you use to square up doors and windows, can be used to pry the unit from the exhaust housing while minimizing the chance of busting the housings.