Lehman 120 thermostat

Anyone replace one lately?

Looking for info on if the gasket goes on top or under the thermostat lip.

It would seem to go on after as the small indent to accept the thermostat is in the block, not the expansion tank.

What is throwing me is the exploded parts diagrams (I know not always assembly instructions)...they show the gasket going on first then the thermostat, then the expansion tank....

Just doesn't feel right...any thoughts, pics or links?

I did mine but honestly can't recall.
What was the arrangement when you took yours apart?

jleonard said:

I did mine but honestly can't recall.
What was the arrangement when you took yours apart?

Click to expand...

Unfortunately....

Anheuser-Busch disease set in and I forgot.

Pretty sure it has to be the thermostat sits in the groove and the gasket goes on top of the 2 now flush mating surfaces, but like I said...the parts diagrams make it look different.

They do show the temp spring down in the block side correctly at least so I have to question myself at least a little.

psneeld said:

Unfortunately....

Anheuser-Busch disease set in and I forgot.

Pretty sure it has to be the thermostat sits in the groove and the gasket goes on top of the 2 now flush mating surfaces, but like I said...the parts diagrams make it look different.

They do show the temp spring down in the block side correctly at least so I have to question myself at least a little.

Click to expand...

I placed the thermostat on first, then the gasket. There was some pitting so I added a small amount of the blue gasket seal from NAPA. No leaks.

By the by, I used 180 degree thermostats for replacements.

TONTOROSS said:

I placed the thermostat on first, then the gasket. There was some pitting so I added a small amount of the blue gasket seal from NAPA. No leaks.

By the by, I used 180 degree thermostats for replacements.

Click to expand...

Thank you....sounds right.....

Thanks all....
A call to American Diesel confirmed gasket on top......

psneeld said:

Anheuser-Busch disease set in and I forgot.

Click to expand...

Ahhh got it!!

Use Permatex #2 on the face of the gasket that goes toward the tank and then Super Lube or something like it on the surface of the gasket that goes toward the block.

That way in most cases it will come apart easy later and you can reuse the gasket.

The Right Stuff gasket maker by permatex.

Use on pretty much everything on the engine. Don't even use Garlock or paper gaskets anymore.

Good info for me and all...thanks!