Just can't win

[acdc96]

So I got my new thermostat for my 1988 Nissan 18hp and I put it in and put a new gasket on and start putting the thermostat cap on and it splits in two. So I just ordered a new one.
It's been a week now since I started to get the lower unit off and it still has not budged at all. I tried using wedges, rubber mallet, and soaking it in penetrating oil. The motor pumps water fine and I'm not too concerned but it kinda bothers me.
I decided that I'm not going to take the power head off cause the head gasket and cooling ports were clean. I feel like taking it off will open another can of worms.
Paid $340 for the motor and costed $100 bucks so far.

 

[Sea Rider]

Re: Just can't win

ACDC,

How do you know all internal cooling water paths are clean if you haven't removed cylinder head from powerhead to have a visual inspection ? Peeing through port is no indicative of clean water paths condition. If that thermo lid broke due to detereoration, can't imagine other internals...

Anyway if lower unit can't be removed so far, the only option is to remove powerhead from pan. Is not that you'll open a can of worms, you could have a pandora box sitting already there..

Happy Boating

 

[acdc96]

Re: Just can't win

ACDC,

How do you know all internal cooling water paths are clean if you haven't remove cylinder head from powerhead to have a visual inspection ? Peeing through port is no indicative of clean water patchs condition. If that thermo lid broke due to detereoration, can't imagine other internals...

Anyway if lower unit can't be removed so far, the only option is to remove powerhead from pan. Is not that you'll open a can of worms, you could have a pandora box sitting already there..

Happy Boating

No, I did pull the head off the motor and replaced the gasket. I didn't pull the powerhead off.
The thermostat lid is kinda my fault now that I think about it I did use a impact driver to take it off.

 

[Sea Rider]

Re: Just can't win

How did you managed to torque to factory specs both powerhead's lower bolts which are very unfriednly and unconfortable to reach ? What was the condition of both cylinder head and powerhead mating surfaces after 26 years of use ? Did you find light or heavy internal corrosion ?

Happy Boating

 

[pvanv]

Re: Just can't win

No, I did pull the head off the motor and replaced the gasket. I didn't pull the powerhead off.
The thermostat lid is kinda my fault now that I think about it I did use a impact driver to take it off.

Might I suggest that you are getting in above your head?
- With the possible exception of removing the flywheel nut, there is no place for any impact tools on that motor.
- The LU is not stuck; the driveshaft is stuck in the crankshaft. There are techniques to address that.
- RTV is never an adequate substitute for gaskets on the base of these powerheads.
- Banging on the LU with a mallet is never appropriate.

If you continue with these techniques, it will be a long, difficult, expensive road to success with your obsolete motor. Should you still want to get it running, I suggest you enlist the assistance of someone more knowledgeable with outboards -- either your local dealer, or a friend/neighbor who has the skill set to complete the repairs.

OTOH, it will certainly be educational for you to complete the job (I am sure it has already been -- to a degree) -- which may stand you in good stead for years to come. Still, I would recommend you garner some local assistance, if for no other reason than to reduce your frustration level.

Please don't take my recommendations the wrong way -- we all must start somewhere; I just hate to see you expend a ton of effort breaking things just to learn "the hard way".

 

[JustJason]

Re: Just can't win

Paid $340 for the motor and costed $100 bucks so far.

I'll give you 250 for it, but you have to ship it to FL.

 

[acdc96]

Re: Just can't win

I'll give you 250 for it, but you have to ship it to FL.

Too late the lower unit dropped today on its own while I was at work. Didn't drop far maybe a 1/4" but I was able to pull it off. It couldn't fall more than an inch cause my stand has the skeg only a inch off the ground. Replaced the impeller with ease. Greased everything and slid the unit back on still waiting on the thermostat cap and thermostat to come in.

 

[pvanv]

Re: Just can't win

I trust that you replaced the complete wp kit, not just the impeller, right? And you should not grease the impeller; it's water-lubricated. That grease will now attack the impeller, shortening its life, it will also send that grease through the cooling system.

You want to grease the splines of the driveshaft; just don't get grease on the end of the shaft, lest you get liquid lock when re-inserting the shaft in the crankshaft. The LU will drop easier next time if you grease the splines; without that, it can get stuck.

It's a good idea to use blue loctite on the wp bolts, as well as the LU bolts.

Info is in the highly-recommended Factory service manual.

 

[Sea Rider]

Re: Just can't win

Yep, for such an oldie a complete WP kit change is recommended, cup could be severely worn with slight less diam which will produce less pressure when pumping water upwards. A OMC OB tech used to add 1/4 can of grease when changing new impellers, no traces of grease were found on next yearly change. Spinning at high revs on salt water took care of the grease.

Happy Boating

 

[acdc96]

Re: Just can't win

I replaced the water pump completely. Greased the splines with marine synthetic grease and put a very light coating on the shaft and in the impeller cup.
I put some loctite on the impeller housing bolts and a new lower unit stud cause one broke off.