Model B Thermostat Housing Bolts


New User
Back in April '05, JR3 posted this question regarding the thermostat housing of a Model B, "What keeps the water from leaking out around the two bolt heads at the top of the thermostat housing?" No one ever responded and now I've got the same question .... can anyone provide the answer?? Thanks, John
I tried to find a picture of housing and found one but from the wrong angle to see. My memory says the bolts go through the casting and are sealed by the gasket between it and the head.
Thats a darn good question. If I remember right the bolts are in the water as they pass through the housing so water could push up the bolt holes and leak at the bolt heads.
Maybe because the housing sets high on the engine and the water has a place to go the bolt heads seal it enough. Very low pressure in this system.
Thanks, Now I won"t be able to sleep tonight.
I can't remember if the bolt holes are drilled the whole lenth of the housing or not. If they are then the gasket on the bottom of the housing would seal the bolts.
For some reason I thought the bolts were exposed to water in the housing.
Copper crush washers, like on brake hose connections. Do NOT use lock washers. If possible, use stainless bolts, not studs, not cheap bolts. They sit in the coolant and will rust away.

Thread sealer on the ends, and copper washers. A little gasket cement if you think appropriate.
Isn"t there a full face gasket between the top of the housing and the hose connection body? The bolts are definately wetted and I replaced them with grade 8 bolts. Use a soft copper washer under the bolt head.

the bolts are open to the cooland and need to have copper washers on the outside to seal.i put a small bead of RTV around the washer also. the bolts dont have to be stainless if you use antifreeze inside. the entire motor is cast iron and it dont rust much if you use the correct coolant. most old B were filled with creek water- thats the problem.
I did the same thing. Anti-seized the bolt threads on a new pair of gr.8 bolts, and used two brake caliper copper washers up top. Its been almost 7 years and not a drop of coolant coming out upstairs...
The upper alnd lower bolt together with a gasket. The main bolts reach all the way thru into the block.

Oddly enough, I stopped in the local AGCO dealer and asked, they pulled out the parts list and there they were, 'Copper sealing washers (2)'. I used stainless bolts because all of my engine bolts are poilshed stainless, puls both of the others were rusted and broke off. that way I know I'll never have a problem.

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