• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Thermastat talk

pearljam724

Well-Known Member
Local time
5:09 PM
Joined
Oct 14, 2018
Messages
1,260
Reaction score
555
Location
U.S.
I had a small thermastat housing leak Im repairing. In the mist, I was contemplating drilling a hole in the thermastat. Like we’ve all heard or understand. Drilling a whole will help the engine warm up quicker. Well, wouldn’t this be the opposite of that theory allowing the engine to take longer to warm up being coolant would be allowed to leak to the head through the drilled hole ? Thus, taking longer for the engine to warm up upon initial start up ?
 
MoPar thermostats I have seen have a small bleed hole already.
 
The hole is so small that it's irrelevant with flow to delay warmup, your point is moot. Have you ever seen how open a thermostat is when hot and open?
 
The small hole may delay warmup, but likely not much. It is there to get the air out of the cooling system when filling it.
 
The hole is so small that it's irrelevant with flow to delay warmup, your point is moot. Have you ever seen how open a thermostat is when hot and open?

Your didn’t read, what I said. You’re point, is the exact same point I made. Lol ! Im agreeing with you. Lol ! Yeah, mine has a bleeder too. Im simply saying, that’s what people believe and say all the time. Yeah, if a thermastat doesn’t have a bleeder, sure drill a hole. But, no one can deny that we haven’t heard in our lifetime. Someone said “ it helps the engine to warm up faster. “ Which isn’t true.
 
In my 36 years of working on cars and engines, I have NEVER heard that the "AIR" bleed hole is for anything other that just that, a hole to allow air trapped behind the thermostat bleed out when filling the cooling system. Good thermostats and European thermostats have a brass poppet valve in it, lower cost domestic ones have a small "V" notch in the water opening. These all are for the same purpose, to allow trapped air to bleed out when filling. When I build a motor, if the thermostat does not have the larger poppet valve hole, I drill a 1/8" hole in the large portion of the base. Sorry to put a "hole" in your theory of everyone hearing about it helping the engine warm up faster. Just so you know, that is what the "By-Pass" hose or passage is for. It allows water to circulate in the engine, allowing it to heat up faster.
 
Any "leaked" coolant through a drilled hole would go to the radiator...
Not what you want for a faster warm up.
 
Stant Superstat 180 only game in town for me. Avoid chrome housings. Put on a Mancini Billet housing and no leaks. Pre boil to be sure. Green only of course.
 
I second the "chrome housings" . After filing flat twice I was done with it.
 
Having a bleed hole in the T-stat will help eliminate an air pocket in the housing. If there is an air pocket at the T-stat it takes forever to open, being that coolant will transfer heat better than air.
 
Never heard that bleed hole had anything to do with heating anything up faster for slower.
 
A bleed hole will keep temps more consistent once warmed fully.
On the 1st gen Kaw Concours the thermostat wouldn't open until the gauge was almost in the red. Once it opened the gauge almost hit C. And back and forth. Drilling a bleeder hole allowed coolant to flow long before the stat opened. The hot/cold cycles were greatly reduced.
 
Then there is something wrong with the stat. No hole needed.
 
On modern thermostats the temperature sensitive component opens the valve, as temperature rises it continues to expand and the valve opens more.
So the valve movement goes paralel with the temperature but the bi-metal has a certain reaction time and all this prevents extreme fluctuation of the valve.
"Old" style thermostats did not function as precise and therefore some could jump from fully open to fully closed instantly and not able to set to a certain flow to maintain a pre-set temperature as the modern variant.

The small air bleed does allow some flow and slowly displaces the cold coolant from the radiator which will mix up in the engine.
Think it might help preventing the "cold shock" from the extreme temperature difference once flow starts coming through the radiator?
When the engine is still warming up towards normal operating temperature, with the temp gauge still on low you do feel the radiator core does warm up a bit.
 
Auto Transport Service
Back
Top