C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Thermostat Mod

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Old Jun 19, 2005 | 06:33 PM
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Default Thermostat Mod

I've read several threads in the past where members have said to drill a small hole in the thermostat. Could someone please give me the exact details on this? Thanks in advance....
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Old Jun 19, 2005 | 06:44 PM
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I've had the same question since thermostat failure has cooked many engines. Stant(I think this is their name) is advertising a thermostat called "Failsafe" that solves this problem according to their ads. I wondered what some of you thought about the mod, or, this new stat. regards
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Old Jun 19, 2005 | 06:50 PM
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Cheap stats fail closed. The better stats fail open. A "Fail Safe" stat isn't anything new, it's just new marketing.

Drilling a couple of 1/8th" holes around the flange can help a little with expelling the air in the system (burping) after a flush and fluid change. It would not have prevented the "meltdown" caused by the cheap stat that failed closed.

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Old Jun 19, 2005 | 08:07 PM
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Its just better for burping and is a big help if the stat fails.

Its not something you necessarily need or have to do.
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Old Jun 19, 2005 | 08:26 PM
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Originally Posted by kmath3
I've read several threads in the past where members have said to drill a small hole in the thermostat. Could someone please give me the exact details on this? Thanks in advance....
Not the correct why to "burp"......but I suppose it would work.....

I think it was a "trick" to make the engine run a little cooler.....

I tried it.....put in 3 or 4 holes, don't remember exactly.....but the result was in the end the car didn't run any cooler when it was really hot outside.......but when it was cool the car NEVER would warm up......seems like if it was 60 out, the temp only reached 150......and it really delayed warm-up.....

Bottom line, it is nonsense....don't waste your time, more bad effects than good....

BTW certainly won't prevent overheating if the stat fails in warm weather...

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Old Jun 19, 2005 | 08:33 PM
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Originally Posted by kmath3
I've read several threads in the past where members have said to drill a small hole in the thermostat. Could someone please give me the exact details on this? Thanks in advance....
Here you go....


http://www.stewartcomponents.com/tec...ech_Tips_3.htm

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Old Jun 19, 2005 | 08:51 PM
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From what I know, you drill ONE small hole to prevent thermal shock to the head. (A surge of cool coolant into a hot aluminum head) More holes are ok but the car will take longer to warm up or may not warm up at all. I used a balanced type thermostat in mine. Some thermostats have a small poppet valve instead of just a hole. I'm not sure when the hole drilling came about but maybe it was from thermostats that in the past didn't work as well. Check into a balanced thermostat, Summit has them!
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Old Jun 19, 2005 | 11:17 PM
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One 1/8 hole is all that's needed. Drilling anymore will probably change flow. This is the first I've heard anyone trying more holes looking for better cooling or whatever. The intent of a small hole is only to avoid burping and getting coolant up to the thermostat when refilling the system.
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Old Jun 20, 2005 | 07:45 AM
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Default Tstat----

1996 A4, When I first purchased it I drilled several holes (1/8"),I think I drilled four. I liked the difference and removed the tstat. Now I run around 188-190. I think this works well in very hot climates like South Florida.
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