overheating

[Beefcake]

i had the same problem. Fixed it with the same solution. Drilled holes in the thermostat (3 to 4 holes actually). Workes great during while running. Just drill the holes in between the outer seal and inner diameter.

Now i have a new problem though. When i shut the motor off... my temp gauge goes all the way up to about 250 deg.

Hope the same doesnt apply to you.

[superman3405]

Originally Posted by Beefcake

i had the same problem. Fixed it with the same solution. Drilled holes in the thermostat (3 to 4 holes actually). Workes great during while running. Just drill the holes in between the outer seal and inner diameter.

Now i have a new problem though. When i shut the motor off... my temp gauge goes all the way up to about 250 deg.

Hope the same doesnt apply to you.

I hope drilling the holes in it did not cause that..

[Tx Firefighter]

His truck is heating up when he shuts it off because the coolant is no longer flowing. It just sets still and absorbs all the heat from the engine. Without actively circulating through the radiator there is no here for the heat to go, hence the rise in temp once shut off. All engines do this. Most modern day vehicles have electric temp gauges though, so you never know what the temp is once the key is turned off.

The holes in the stat are not a problem. Many OEM stats are this way now. It just makes sure that any air pockets migrate quickly up to the top of the radiator. If a big air pocket gets stuck under the thermostat, the stat won't get hot as fast (air does not transfer heat like water does) and the engine will sometimes even overheat before the stat gets hot enough to open and let the air pocket past. Air is a good insulator of heat.

There is no reason to fear the little bleed hole (or holes) in your thermostat. They don't pass enough coolant to affect anything significantly. Look at it this way, your heater core flows a whole hell of a lot of water through those 5/8 and 3/4 inch hoses. That water flows whether the thermostat is open or not. An 1/8 inch hole is nothing compared to a 5/8 inch hose.

[cstanley]

not intending to hijack, but where should the factory temp gauge ride? when at operating temp, it rides at halfway (needle straight up) if the heater is blowing, pulling the heat off the engine. if not blowing the heater, it creeps up between the middle and the first "hot" mark. is that about right, or should it be running lower than that?

[superman3405]

okay I hate to keep poping up with this but I took the thermostat and drilled the hole in it. Put back in, put 50/50 antifreeze mix in. fired the truck up and after a few minutes temp went way up. Oh and the flex hose is gone, I have a molded hose on there now, it is not bent in any way.
Do you think the Temp sending unit may be faulty or I have it located in a bad place. I have it on the drivers side right next to the 1st spark plug. I am running manifolds is it possible that it is reading heat from the exhaust?? How can I check this for sure???
Thanks

[Crank]

Very Possible something is screwy. I replaced the rad., fan and clutch, 3 thermostats and countless other things and my old '86 GMC pegged the very hottest mark on the temp gauge VERY often, it never boiled over tho, or let me to believe it was getting hot, the overflow was working the way it was supposed to and all that good stuff, my temp sending unit was in the manifold, I had an Edelbrock Performer on there. It was either the gauge or the sending unit and I'd bet probably the gauge
Brandon

[chipflyer]

When I bought my truck the temp gauge barely came up at all. I made a trip to Orielly's and bought a new sender, put it in and the gauge ran clear over to the hot mark but it wasn't ever over heating. I stopped by Chevy Duty a couple days later and picked up a new sender from them, put it in and the gauge runs right where it should, 1/4 of the way up.
The morel is don't overlook a mis-calibrated sender. You have fixed a few other issues that need fixing but if it is still running warm, try a manual gauge as someone else suggested or another sender for your electric gauge.

Good luck!

Jeff

[bcanini]

Superman,
did you ever get this resolved??? I'm having the exact same prob. New thermostat wayyyy hot long drives get's hot and at lights hot, no thermostat hot @ lights but fine on long drives.?? Killing me it's summer and I want to drive it. I'm stumped.
Help anyone..

B