Thermostat Use?

I can't think of a negative to using a thermostat. Anyone want to mention the drilling of additional 1/8 inch holes in the thermostat?
 

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If anyone looked at those videos in post #25 you'll see that the water neck is sitting 50-60 degrees colder than the rear of the engine. That's because the water is not circulating through the engine with the thermostat closed. The coolant in the rear of the engine could flash boil before the thermostat opens. You need to drill a 1/4 hole in the thermostat or install a thermostat bypass tube to even out the temperature gradient from the front to the rear.
 

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FWIW, I took many videos of my engine's heat before the installing the thermostat, you'll see the rear of the engine is hotter as well... I would guess if the intake of the cool water was not in the middle but the rear it would have likelly less of a temperature differential.
 
AL in NY said:
If anyone looked at those videos in post #25 you'll see that the water neck is sitting 50-60 degrees colder than the rear of the engine. That's because the water is not circulating through the engine with the thermostat closed. The coolant in the rear of the engine could flash boil before the thermostat opens. You need to drill a 1/4 hole in the thermostat or install a thermostat bypass tube to even out the temperature gradient from the front to the rear.
Click to expand...

Now this is exactly why I started this thread...

It seemed to me that you could get hot spots in the head and block if there were no circulation with the thermostat closed...

Many engines have a bypass on the head or a hot water heater to allow coolant circulation through the block.

With the holes in the thermostat housing though there is quit a bit of circulation.

I let it warm up last night, drilled 3-hole thermostat installed, and the temperature across the head, block and radiator was pretty uniform as it warmed up.
 
The thermostat housing I have (shown in post # 17 & 22 above) has a couple of bypass passages built in to the housing to allow "some" circulation when the thermostat is closed. If you look closely in the post # 22 exploded view, you can see them on either side of the seat where the thermostat goes. No need to drill extra holes whenever you change out the thermostat.
 
1955cj5, I hope when you drilled the thermostat, you used something larger than an 1/8" drill. IMO, minimum size should be one 1/4" hole to provide some coolant circulation with the thermostat closed.
 
AL in NY said:
install a thermostat bypass tube to even out the temperature gradient from the front to the rear.
Click to expand...

Al in NY, I like your bypass tube. Is it tight around the throttle linkage?

I can actually "see" when my 180° T-Stat opens. When the temps get to ~ 185° the temp falls off to ~140° then swings back to ~200° before settling out at 180°f. Don't know how hot it gets at the back of the engine until the T-Stat opens but I don't "see" any real high temperatures on the gauge.
 
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I drill two 1/8" holes in my stat, and it works fine.

A hot water heater would also make a good bypass system for the engine.
It also gives the added advantage of being an auxiliary radiator for someone with a borderline radiator.
 
AL in NY said:
1955cj5, I hope when you drilled the thermostat, you used something larger than an 1/8" drill. IMO, minimum size should be one 1/4" hole to provide some coolant circulation with the thermostat closed.
Click to expand...

The thermostat came with one hole already, and I added two more 1/8" holes.

With the radiator cap off, thermostat closed, there is lots of flow through the radiator.

It warms up rapidly enough so I don't think the "bypass" flow is excessive...

I expected the thermostat to be pushed up the hose to the radiator over time, but it happened almost immediately...gotta get one of Tom W's barbs....!

Randy
 
I use a piece of lower hose inside the upper to hold it in place.... I have a few laying around to cut up... Tom and I researched the extra holes which work well..
 
Mitch//pa said:
I use a piece of lower hose inside the upper to hold it in place.... I have a few laying around to cut up... Tom and I researched the extra holes which work well..
Click to expand...
They work well in the UPPER end of the hose, HEAT goes UP:rolleyes:
I don't know about youse Guys & your "HOLES":confused: Most have a dingle valve or a tiny hole, to prevent air lock & the valve isn't a "perfect" seal & the water pump pressure helps it to open a trifle.
I remember at least 3 times in the past, we've posted this same old stuff------AND, once I saw them being made, on, "HOW IT'S MADE"--------
SA Dad
 
Slowplane, the thermostat located in the upper part of the upper hose is, IMO, too far from the source of heat. Ideally, it should be in the engine block or the head. See post #17 for a new style waterneck outlet that puts the thermostat where it needs to be to perform correctly.
 
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