Thermostat By-Pass Concerns

[SasquatchSanta]

I have concerns about a thermostat we installed in my M37 today.

I swapped the existing, stock 180 degree thermostat for a 195 degree unit because the engine wasn't heating up and I was about to freeze my "whatever" off.

As you may know, the M37 has a by-pass on the top of the water pump and a rather large, conventional looking old style thermostat. The thermostat the parts house delivered was a different style thermostat --- new style --- that looks more like a flying saucer than the old, original thermostat. The new unit sets low in the head/neck and therefore, from what I can tell isn't going to allow the bypass to work.

Some of the 230 civilian flatheads had a different water pump without the bypass BUT there was a bypass port (hole) in the front of the block and engine head.

Given that the M37 block and head doesn't have the bypass port I'm concerned that I may be making a mistake by installing a thermostat that "MIGHT" not allow the bypass in the water pump to work properly.

I tend to be a worrier therefore I may be jumping at shadows. BUT, I sure as heck don't want to kill a perfectly good engine because of something as simple as a thermostat.

Is the bypass really needed?

Any input would be appeciated.

 

[lstmate]

FYI... Not realy sure about your question but for the difference in cost I would only install a "Fail safe" thermostat if they make one for your vehicle. They are designed that if they fail they will only fail in the open position. Not in a closed position like the old style did.

 

[M543A2]

I would be concerned with blocking the by-pass. It is there to keep water moving through the block and head to prevent hot spots from developing as the engine warms up before the thermostat opens to allow normal flow. You might check with one of the military vehicle parts dealers or with Vintage Power Wagons (they have a website) for higher temp thermostats in stock configuration to allow your bypass to work as it should.
Regards Marti

 

[Bill W]

I believe it is nessasary
otherwise the coolant flow will deadhead and cause the pump to cavitate. I got my stats from NAPA: THM 55 ( 160o ) or THM 155 (180o) they worked/looked just like the original ones., unfortunatly I don't have any # for a 195o.

 

[SasquatchSanta]

Thanks for the input all. You've confirmed what I thought I already knew but put it in a context that made it clear. I had concerns about the hot spots but it never occured that the pump could cavitate.

I've ordered a 180 degree military style thermostat and a NOS winter front from John Bizal at Midwest Military.

Thanks again.