over heating at idle

[tinyman]

ok so i put a new thermostat in because my was sticking, i put a 175 in, and now i over heats when i'm idling. i have never had this problem before. do i need to get a new one or what??

[copley87blaz]

you might have a air pocket did you drain fluid all the way could be a bad t stat

[Bluesman]

^^What he said. Make sure the system is drained. I assume "idle" means "stopped" so you may have fan problems, too.

Dav

[coppergmc]

Try drilling 2 1/8" holes in the thermostat to help vent air. I've been doing this for a while. If you look in at some of the other posts you can see that I'm not the only one.

[Ryoung68]

what temp t-stat did you replace?

[tinyman]

what temp t-stat did you replace?

i think it was like a 195?? i replaced it because it would go from 195 to 215 all the time, and some time it would go higher. and especially when i was betting on it.

[Bluesman]

Yeah 195* is normal for more modern GM engines that have to meet smog requirements. If VT still has you smog your truck you may need to put it back in when you get it inspected (I have to do that in CA), or run it real hard just before the test to get the cats cooking.

[tinyman]

vt is very easy going when it come to that. i go to this guy, that checks lights, and that is it. i told him that i did not have a horn, and he asked me what sound does a horn make and i said beep, and he said it sounds like you have a horn to me!!!lol

[Bluesman]

Aww Man!!!! I'm movin'!! It took me 4 trips to the referee station to get my engine change approved and I have to smog it every 2 years. Every time the dude opens the hood and backs away!! I have to go through the whole song and dance to show him it is legal (he can lose his license otherwise). However, I have heard the AZ is even worse. I think they smog vehicles all the way back into the 1960s!!!

What's funny is that once it was "approved" I only have to meet 1991 smog standards. With a 1997 setup it is dead easy too do that.

Dave

[tinyman]

Try drilling 2 1/8" holes in the thermostat to help vent air. I've been doing this for a while. If you look in at some of the other posts you can see that I'm not the only one.


i bought a new thermostat and it sill oveheats. so when you mean drill a hole, you drill two holes it the thermostat right? where do you drill the holes? do you have a pic?

[Bluesman]

I have done this, too. I don't have a pic but you drill them in the round, flat piece of brass that moves on the spring (did that make any sense at all??). There isn't much room on most thermostats, and a 1/8" hole is about as big as you can put in it. I think mostly these are helpful in getting air out of the system, not really to increase the flow of coolant very much.

Dave

[tinyman]

ok, i tried it and it did not do much for it, it still overheats at idol. should i try draining the system?

[manyfire]

I just started having a similar problem, out of nowhere, I just rebuilt the cooling in January replaced the big bottom hose with a non collapsible hose, put a new water pump, aux cooling fans and a clutch fan. I was on the highway the other night and it overheated, has been overheating every since, changed out the thermostat and cap today still running over 200, dropping down to about 195-200 on the highway.

[adh383]

Hey tiny--- what fan do you have? My truck will run 210 at a lite--190 on the move-- that aint gonna hurt it.

[chris1972]

today cars run 210 some my mustang fun don't come on until 225...200 will not hurt nothing

[tinyman]

i have one of those fans that you put on the radiator. i control the fan with a switch.
and now it is taking a long time to heat up after i drilled the two holes in the thermostat, i could be driving for like 8 miles and the temp would be like 140, with is not normal for my truck. when i was sitting i traffic my temp got to 230 and climbing with my fan on and with my heat blasting. i really need to get this fixed, i do not need to be sitting i traffic and have it overheating.

[chris1972]

so you never had the problem untill you install a thermostat...right ..then there is only 2 things left..1st a air pocket ,try jacking up the front end making the rad the highest point fill the rad up then try it..if that does not help..then maybe looking in to a head gasket or cracked head....a blowen head gasket sometimes will not smoke at all..but can be a problem when motor getting warm..try the jacking up the front end frist making the rad cap the highest point..

[spacecadet]

Gotta agree w/chris1972 Don't see what drive line you have but the older sbc's w/624's were crack prone along with several other casting numbers.
If the truck is now down to 140o then the holes did what there supposed to.
I usually drill only 1 hole and put it in the frame of the t-stat. The goal with the hole is to allow air to pass easily and small stream of coolant to pass the t-stat so it will open faster and keep the motor cooler.
Another thing is if you have your heater hosesconneted from the intake directly to the water pump than your just pushing hot uncooled water back through a hot engine.
Space.