drill holes in t-stat?

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73goldduster

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lots of overheating issues/questions these days, so heres one more.
hottest day of the year yesterday, 101f, cruising at noon down the freeway, engine running around 210-220 (2/3 to H on gage)for 15 minutes or so. later, when the outside temps went down, the car ran perfectly cool. this is a recently rebuilt slant 6, new water pump, flushed radiator, used t-stat (the new one i got didn't fit well, so i saved a trip to the parts store.) stock 4 blade fan. also, no fan shroud.
anyway, a friend told me about 'an old-timers trick' to drill holes in the t-stat to allow more coolant to flow through. anyone ever try this? seems like a good idea.
 
I would suggest two things.

1. Have you had the radiator cleaned recently. Flushing doesn't always clear it and more flow through the thermostat won't do any good if the radiator is partially clogged.

2. There is high flow thermostats made that you can use but in my experience, if you are using a used thermostat, I would replace it.
 
Well I guess it would work but if it were me I would like to find out whats causing it to over heat in the first place. Check to see if the t-stat is in correctly. then not sure if its possible but is the fan on backward? or maybe the temp sensor is going bad.
Does your car have an overflow bottle? if so, is it catching anything? If nothing is going into the bottle then I would not think its overheating. I would just keep an eye on it if it has not overheated yet. Some motors may run a little warmer than others. just my .02 and that my opion may not be worth that much. good luck.
 
Are you sure 2/3 on the factoy guage is 210-220? The reason I ask is I was concerned about mine reading on the second highest line on the factory guage, but I found out that is actually 196 degrees. I have confirmed this as many ways as possible with an infrared gun... not sure if this helps, but I don't trust my old guage.
 
I always drill a small hole in the t-stat, have been doing it since my old man showed me that when I was a kid. Can I verify that it helps? no. But it don't seem to hurt anything and if it does help thats great because it costs $0 to do it. I would be searching for a shroud and a 5 blade fan...
 
The small hole in the t-stat is to help trapped air to escape. Once you have the system purged it doesn't add enough flow to contribute to the cooling.

I agree with the other posters you need to measure what the temperature actually is, the factory gauge is really only good as an idicator that something has changed. Flushing the radiator at home with a flush won't get rid of hard build up. And an old t-stat could very well be sticking and not opening all the way so for sure get a new one in there.
 
the hole is mainly for air pockets, i would say your temps are normal for that 101 temp on the pavement, following other cars throwing off heat, the real temp going into your grill may have been as high as 110 or more. I would pull the rad and have it cleaned buy a shop if your still concerned.
 
dgc333 said:
The small hole in the t-stat is to help trapped air to escape. Once you have the system purged it doesn't add enough flow to contribute to the cooling.

I agree with the other posters you need to measure what the temperature actually is, the factory gauge is really only good as an idicator that something has changed. Flushing the radiator at home with a flush won't get rid of hard build up. And an old t-stat could very well be sticking and not opening all the way so for sure get a new one in there.
Click to expand...
i totally agree with this post because tstat is used to keep coolant in rad so it can cool down
 
Get a Milodon HF one at 160 degrees...drill two small 1/8" holes in it also to help purge air trapped in the block...if you have access to a thermal gun shoot the top and bottom of the radiator...if temps seem to be the same or way off have your radiator rodded out...I would also get a shroud and run a seven blade heavy duty thermal clutch fan...I just put in a mechanical water temp guage...first line is 160...a little past is 180 and two thirds is 205-210 degrees
 
well, lucky for me the heat wave ended and the dusters been running cool. new t-stat going in. (with holes for purging air :-D)
thanks for the tips!
 
Hell I didnt know T-stats had the little weep hole in em till a couple months ago, never gave it any thought and was wondering how the motor managed to purge the air out on its on. Thats about how often I mess with my own thermostats is like close to never.
 
Put a shroud back on. You air flow directed through the radiator. With good pressure cap you are still well below the boiling point of the coolant.
 
at 101* out how cool do ya expect it to run? are you sure of the temp? the stock gauges aren't always reliable..

drilling the the stat is really more for making sure there are no air pockets when filling the system.

how much did the outside air actually cool down before the car went to normal..
 
Drilling a hole in the t'stat ( about 2.5mm diameter ), is for stopping heat shock at the radiator......also helps with bleeding air out of the system.
A fan shroud makes the engine fan more effiecent.....placement of fan depth in the shroud is also a key.....needs to be half way in/out...centre line of fan blades....makes the fan way more effiecent.
Running the correct mix of anti-freeze/anti-boil can raise the boiling point by 9*C.
An alloy radiator is far more effiecent than a brass/copper one too.
 
73goldduster said:
lots of overheating issues/questions these days, so heres one more.
hottest day of the year yesterday, 101f, cruising at noon down the freeway, engine running around 210-220 (2/3 to H on gage)for 15 minutes or so. later, when the outside temps went down, the car ran perfectly cool. this is a recently rebuilt slant 6, new water pump, flushed radiator, used t-stat (the new one i got didn't fit well, so i saved a trip to the parts store.) stock 4 blade fan. also, no fan shroud.
anyway, a friend told me about 'an old-timers trick' to drill holes in the t-stat to allow more coolant to flow through. anyone ever try this? seems like a good idea.
Click to expand...
Also remember this...a current article in Mopar Muscle Magazine was written by Richard Edenbourogh...I think I spelled his name right...but anyways he went over all kinds of cooling fans and stated that these cars ran 210 degrees right out of the factory...if you are running 50/50 mix and a 16 lb cap the boiling point will be raised to around 244 degrees...M2C
 
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