OEM Thermostat small hole to assist air release

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virginoil

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Location
western australia
Hi

I bought an aftermarket OEM equivalent thermostat ie 195 deg F that came with a small hole to release trapped air in cooling system and installed it worked very well.

I have since replaced it with an OEM and did not keep the old one.

I am considering drilling a 1/16 inch hole (0.8mm) diameter in the flange area and checking if this is sufficient.
Some sites mention 1/8 inch (3.2mm) dia hole and I feel this is TOO large.

The hole is to allow air to be released and allow a tiny amount of coolant to flow throogh not to shock the cooling system.
At the same time with minimal impact on the warm-up time required to get to operating temperature.

I understand not to mess with the cooling system and proper bleeding can release air during filling.

Thermostat 195 deg F. for Holden Commodore V6 3800 ie Buick L36 similar.

There are no system cooling issues just want to go back to the previous arrangement.

Comments welcome.
 
Last edited:
Originally Posted By: Chris142
No reason to drill.if they needed to be drilled they would come pre drilled.the aftermarket stats use cut outs around the piston instead of a captive ball


I want to drill small size hole diameter please.
 
Originally Posted By: virginoil
Originally Posted By: rooflessVW
I drill all of my thermostats.


Hole diameter ??


I know you said you threw the other one away, but could you go look at one at a parts store?
 
Originally Posted By: JHZR2
Originally Posted By: virginoil
Originally Posted By: rooflessVW
I drill all of my thermostats.


Hole diameter ??


I know you said you threw the other one away, but could you go look at one at a parts store?


Yeh looks like I will have to based on the negative responses.

Hoping some experienced cooling system dude would give some info.

And get to the answer quicker.
 
Last edited:
Originally Posted By: virginoil
Originally Posted By: rooflessVW
I drill all of my thermostats.


Hole diameter ??


They all get 3x 1/16" equidistant holes, with one always at 12 o'clock.

It makes bleeding much easier and can smooth out temperature swings
 
Originally Posted By: rooflessVW
Originally Posted By: virginoil
Originally Posted By: rooflessVW
I drill all of my thermostats.


Hole diameter ??


They all get 3x 1/16" equidistant holes, with one always at 12 o'clock.

It makes bleeding much easier and can smooth out temperature swings


Thanks Roofi
 
I would drill and have done that when the aftermarket had no hole, oem did.
aftermarket cheap bad design, hole helps air get thru, also helps with warm up so thermostat can sense the water temp better (water not trapped around the stat_)
 
Last edited:
Those engines have a bleeder valve right on top of the thermostat housing; I'd be more inclined to crack that open while filling the system rather than drilling, or do both for good measure.
 
The hole with a little ball is called a "jiggle valve." If your thermostat does not have one, you can hold the thermostat open with a Tylenol pill. It will dissolve, but keep it open long enough to bleed the system.
 
Originally Posted By: bdcardinal
The hole with a little ball is called a "jiggle valve." If your thermostat does not have one, you can hold the thermostat open with a Tylenol pill. It will dissolve, but keep it open long enough to bleed the system.


Is an aspirin too acidic?
smile.gif
 
Originally Posted By: dailydriver
Originally Posted By: bdcardinal
The hole with a little ball is called a "jiggle valve." If your thermostat does not have one, you can hold the thermostat open with a Tylenol pill. It will dissolve, but keep it open long enough to bleed the system.


Is an aspirin too acidic?
smile.gif



Probably almost anything would work, I usually have Tylenol on hand.
 
You can buy 195F, 180F, and even 160F with or without 1/8" pre-drilled holes for the GM (Holden) 3800 from ZZperformance.com. I like the 180 without the hole (like another poster said, there is a factory bleeder valve on top of the thermostat housing). http://zzperformance.com/3800/engine/thermostats.html?SID=76tndji6grrofuhgaqud3oht67

ZZPerformance is the world's largest aftermarket supplier for the 3800. I am running a number of their performance parts; in addition to the 180 thermostat, I have their PCM 1.0, HV3 intake runner, HV throttle body, 4" Dia. Intake, Front Power Log, 10.5mm spark plug wires, NGK plugs, etc. I get 36-38 mph cruising @ 70 mph with a full size Buick and I can pass going uphill. Not like a pregnant roller skate of a car.

These engines are great once you get the upper and lower intake manifold gaskets replaced. Use the aluminum lower gaskets: http://zzperformance.com/3800/gaskets-adhesives/intake-gasket.html and while you're there replace the upper intake with the ZZ one, it has stiffer reinforcing: http://zzperformance.com/3800/air-intake/l36-upper-intake.html
 
Turbo Tim at ZZ has my seal of Approval ,
01.gif
they are stand guys at his shop
did great work for mean while out on the road doing sales calls they gave me a loaner ,,,,, a fast one!!!!!!!!!

you might want to get a tuner and dial down your fan temps as mine from the factory were set at 214F Tim Dialed it down to 194 easier on tranny life he said
 
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