quick question - tq spec for thermostat bolts? mine keeps leaking - The 1947 - Present Chevrolet & GMC Truck Message Board Network

neverwinter · 08-03-2011, 06:39 PM

time for another dumb question but ive gone thru two gaskets already. a 1.49 one and a 8$ one. both leak like a sieve. im sure i overtorqued one so i tried a diff one. just took the truck for a quick down to get gas and its losing its coolant too quickly for my liking lol.

any recommendations?
thanks all
- jason

markeb01 · 08-03-2011, 06:56 PM

Are you running a stock cast iron thermostat housing? Those almost never leak, and a torque setting of "snug" is generally good enough. And they aren't sensitive to the type of gasket used. I've used everything from gasket material to cereal boxes and never have leakage problems. About the only thing that will cause them to leak is excessive corrosion on the mounting surface or a crack on one of the ears.

If you have one of the aftermarket chrome versions, they are generally made of pot metal and warp, badly. And they get worse each time they are tightened until they simply can't be made to seal.

neverwinter · 08-03-2011, 06:57 PM

hmm it appears to be the stock one - i will go and try it again with another new gasket and do just snug. tho last time i did that my driveway had a nice green sheen to it!

markeb01 · 08-03-2011, 07:00 PM

While you have it loose this time, place a straight edge across the mounting surface of the thermostat housing to see if it is flat, all the way from bolt hole to bolt hole.

neverwinter · 08-03-2011, 07:12 PM

well that may have done it - had to reset the thermostat in its groove and just snugged up the gasket. seems ok for right now. def overtorqued the last ones!

wildearp · 08-03-2011, 11:34 PM

If the surface of your waterneck is pitted or uneven, you can lap it on a very flat surface with some 120 or 220 grit sand paper to get it smooth and flat.

I always use a paper gasket and put a thin coat of RTV on both sides. This method has never leaked for me.

Fancy O-ring gaskets have proven unreliable for me, and chrome waternecks or aluminum ones with an o-ring groove also tend to leak.

Lately I have started putting two hose clamps on each water fitting. New hoses always need a retorque after they get hot a time or two, or they will leak and blow off.

08-03-2011, 06:39 PM	#1
neverwinter Registered User Join Date: Jun 2011 Location: reading Posts: 113	quick question - tq spec for thermostat bolts? mine keeps leaking time for another dumb question but ive gone thru two gaskets already. a 1.49 one and a 8$ one. both leak like a sieve. im sure i overtorqued one so i tried a diff one. just took the truck for a quick down to get gas and its losing its coolant too quickly for my liking lol. any recommendations? thanks all - jason

08-03-2011, 06:56 PM	#2
markeb01 Senior Enthusiast Join Date: Feb 2007 Location: Spokane Valley, WA Posts: 8,356	Re: quick question - tq spec for thermostat bolts? mine keeps leaking Are you running a stock cast iron thermostat housing? Those almost never leak, and a torque setting of "snug" is generally good enough. And they aren't sensitive to the type of gasket used. I've used everything from gasket material to cereal boxes and never have leakage problems. About the only thing that will cause them to leak is excessive corrosion on the mounting surface or a crack on one of the ears. If you have one of the aftermarket chrome versions, they are generally made of pot metal and warp, badly. And they get worse each time they are tightened until they simply can't be made to seal.

08-03-2011, 06:57 PM	#3
neverwinter Registered User Join Date: Jun 2011 Location: reading Posts: 113	Re: quick question - tq spec for thermostat bolts? mine keeps leaking hmm it appears to be the stock one - i will go and try it again with another new gasket and do just snug. tho last time i did that my driveway had a nice green sheen to it!

08-03-2011, 07:00 PM	#4
markeb01 Senior Enthusiast Join Date: Feb 2007 Location: Spokane Valley, WA Posts: 8,356	Re: quick question - tq spec for thermostat bolts? mine keeps leaking While you have it loose this time, place a straight edge across the mounting surface of the thermostat housing to see if it is flat, all the way from bolt hole to bolt hole.

08-03-2011, 07:12 PM	#5
neverwinter Registered User Join Date: Jun 2011 Location: reading Posts: 113	Re: quick question - tq spec for thermostat bolts? mine keeps leaking well that may have done it - had to reset the thermostat in its groove and just snugged up the gasket. seems ok for right now. def overtorqued the last ones!

08-03-2011, 11:34 PM	#6
wildearp Registered User Join Date: Jul 2010 Location: Tucson Arizona Posts: 165	Re: quick question - tq spec for thermostat bolts? mine keeps leaking If the surface of your waterneck is pitted or uneven, you can lap it on a very flat surface with some 120 or 220 grit sand paper to get it smooth and flat. I always use a paper gasket and put a thin coat of RTV on both sides. This method has never leaked for me. Fancy O-ring gaskets have proven unreliable for me, and chrome waternecks or aluminum ones with an o-ring groove also tend to leak. Lately I have started putting two hose clamps on each water fitting. New hoses always need a retorque after they get hot a time or two, or they will leak and blow off.



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