Thermostat Gasket Problem??

[Randy W.]

On my 1976 75HP the Thermostat is not located under a 4-bolt cover. You have to actually split the head to get in to remove and replace the thermostat? The problem is that I cannot find a new gasket for that area. I destroyed the old one upon removal.. It's not even on the parts diagram? Model 757HB. Although in the immediate area of the head gasket, it's not the same one. Can anyone help on this??

 

[john from md]

Re: Thermostat Gasket Problem??

Use red or blue permatex gasket compound. There is little water pressure in these engines and the silicone works and stays put.

John

 

[Frank Acampora]

Re: Thermostat Gasket Problem??

YUP! Big pain in the butt. To change the thermostat you need to remove all the head bolts and then torque them back down. Then likely as not, the damn cover will leak or weep water even using Permatex. See if you can find any three cylinder head of any year Chrysler or Force with the separate thermostat cover, cheaply, on the auctions.

Just don't use a head from a 70, 75, or 90 HP Force since the bore is larger and you will slightly lower the compression ratio of your engine. Not that you can't use it, they are all swappable, but you might see a slight loss of power.

Let me re-phrase that. They are all swappable onto the small bore engines (Chrysler 70,75,85, 90 and Force 85.). You can not use a small bore head on a Force 70, 75, or 90. The piston will hit it.

 

[Randy W.]

Re: Thermostat Gasket Problem??

Per Frank's suggestion from last year, I was able to find a head with a removable thermostat cover. This is a much better and serviceable solution, but I can't get the cover screws to screw out of the head! Does anyone have any experience or tricks on getting these out. They are very TIGHT. Thanks!

YUP! Big pain in the butt. To change the thermostat you need to remove all the head bolts and then torque them back down. Then likely as not, the damn cover will leak or weep water even using Permatex. See if you can find any three cylinder head of any year Chrysler or Force with the separate thermostat cover, cheaply, on the auctions.

Just don't use a head from a 70, 75, or 90 HP Force since the bore is larger and you will slightly lower the compression ratio of your engine. Not that you can't use it, they are all swappable, but you might see a slight loss of power.

Let me re-phrase that. They are all swappable onto the small bore engines (Chrysler 70,75,85, 90 and Force 85.). You can not use a small bore head on a Force 70, 75, or 90. The piston will hit it.

 

[Frank Acampora]

Re: Thermostat Gasket Problem??

Thw of those screws enter the water jacket and almost always corrode. Use plenty of penetratin oil and our friend heat. An impact screwdriver helps too. After you get them out, replace with stainless Allen head cap screws. Use plenty of anti-seize on them. Search other threads on removing stuck screws. Plenty of advice there.

 

[Randy W.]

Re: Thermostat Gasket Problem??

Awesome! Thanks Frank. Used an impact screwdriver and MUCH Liquid Wrench to break loose. Then worked screws out slowly 1/8 turn out followed by 1/16th back in repeatedly until removed. Took a risk, since I didn't apply heat but with patience, they were extracted without incident.