1936 Buick 40 running hot!

[rayclay]

The original engine is completely rebuilt. In summer, she gradually heats up to 200 at hiway speeds (42-46 mph). After parking, there's a gasto-intestinal rumbling and a pint of coolant is barfed up. On short jaunts she runs perfectly! I just installed a 160 thermostat that only delayed the symptoms. Would a bigger fan help? The 40 came with a 16" fan, all other models an 18". The radiator was re-cored many years ago. I am really afraid of hurting my new motor with heat!! I bought my '36 last year and am new to this. Any help will be appreciated! Thanks, Ray

[jeff]

When you installed the thermostat, did you notice a bypass valve? (my '38 has this) Its function is to open up when the thermostat is closed, to allow circulation through the block (since the thermostat is blocking the path to the radiator). So, when the thermostat is open, this bypass should shut, so all of the flow goes to the radiator. Make sure this guy operates smoothly.

Also, what concentration of coolant are you running? You may want to go down to about 25% for more efficient heat transfer. There was a thread on this topic recently - I think you can search for it.

Jeff

[1939_buick]

When the engine was rebuilt was all the rubbish (& 1938 sand) removed from the water passeages (especially at no 7 & 8) ? Gasto-intestinal rumbling is likely to be boiling at 1 or more spots.

[OLBUICKS]

My 38 started over heating last spring the same sounds... I had the radiator recored.. it fixed the problem..

[rayclay]

Thanks for the help guys! When I replaced my thermostat yesterday, ( a 160 unit from Bob's Automobilia) I did not see a "bypass valve". I couldn't find mention of one in my owners manual or in current catalogs. Who still stocks & sells these? I will start by replacing my almost pure antifreeze coolant to purified water. I also heard a squeaking fan belt sound & will check those. I hope to report some progress by Friday. Thanks, Ray

[jeff]

I could be that your '36 doesn't have this "bypass function" as part of the water pump design. I didn't mean to confuse the issue - maybe another '36 owner can help clarify.

If you can find the thread that discusses antifreeze concentrations, you'll find some good stuff. A couple of really knowledgeable folks supplied some theory with charts and graphs, etc. Good stuff. I guess the "heat capacity" and "thermal conductivity" were the issues, if I remember correctly. Anyway, you will want to keep some antifreeze in the mix for the rust prevention aspect. Maybe 25% antifreeze. Also, use distilled water, if your local water is "hard".

Jeff

[Seldenguy]

Rayclay -- Your 40 series has a by pass bolted on the front of the block. You seldom here of one going bad, but I guess it is possible. All '36 series have this feature. As suggested in a earlier post they allow the pump to "bypass" the closed thermostat using the water pump pressure to keep them open until the thermostat fully opens. Also I'm not sure if these bypass castings will inter change between the 40 and 60,80,90's or not. The senior series are the same engine, but somewhat larger than the 40 series engine. I would persue the posters suggestion and get a flow test of the radiator (inexpensive) to rule out the plugged theory! Good luck. Bob