Thread: Engine not warming up

So I've had this problem for a while and I've exhaused my options. The car is acting like it's got a stuck open Tstat, but I've replaced it twice. The car has a brand new tstat, rad, both rad hoses, rad cap, and a new tstat housing. I've bleed the system properly with the little bleeder on the heater core lines so there's no air in my system. When I'm going down the highway the needle on my guage stays pegged cold, rarely does it move, only when driving in town with a lot of stop and go, then it will move up into the lower portion, but it still says it's cold. If I let it warm up before I go anywhere the heat is mildly warm, but it won't cook you like any other vehicle I've ever owned. Latly the temps have been around 10-15* F for the highs and the lows around or below 0. Don't know if that's playing a role or not.

This only happened once, but while letting it warm up the system created so much pressure it started pushing coolant past the lower rad hose and leaking onto my tranny. I hooked up a pressure guage and let it run for 10-15min in the shop and it built 25psi. I bleed the cooling system again and did the same test for the same amount of time and it only rose to 13psi and it hasn't created enough pressure to cause the lower rad hose to leak again, but I'm still not getting much heat and the car is still not warming up properly.

I was thinking that the only way it could create that much pressue is if the head gasket was blown letting psi into the cooling system, but I ran a co2 test on the coolant and there was none present, and I'm not burning any coolant, or loosing any for that matter.

I'm stuck here, I don't know what else to do except for trying to replace the tstat for a 3rd time. Any other suggestions?

Same thing is going on with my Avenir equipped SE-R. No pressure build up but the car will warm up fine to normal operating temps when sitting still but the minute I start to drive it it drops all the way down to C. Please gurus help us please!!!!!!!!!!

Just wondering how are the fans in your cars are they oem or aftermarket and are they always on like wired to constant power or are they to a switch or just wired like factory

aftermarket fans running through my aem ems they only come on when the car is at 180 degrees man they dont run constantly. can anybody out there help us?!?!

As far as I know mine are factory fans and they kick on when they're suppose to, they're not constintally on.

I too experience this issue and all of my parts (radiator, Tstat, hoses, etc) are pretty new. If I let the car warm up in the driveway it goes straight to the middle. If I drive the car around down all is fine. However, on the highway, if I go over 60, the gauge starts to head south. Not all the way, just a 1/4 of the way. If I punch it and really get things going, the gauge will drop more. If I start my car and it is 30 degrees outside, immediately jump in and go, I can drive for 10 miles or more before the gauge even starts to move.

I've noticed that it is not as bad when the heater is off. Almost like the heater is pulling away so much heat that the water is returning to the engine too cold.

My engine is an Avenir and I wonder if I connected the hoses incorrectly when doing the swap? It has been so long that I can't remember what I did.

I don't think the outside temp should make a difference when you have a properly working cooling system. The tstat should remain closed until the engine temp reaches normal. Then it will open to cool things off. Maybe for use guys running in sub freezing temps, a higher degrees tstat is necessary??

Pisses me off for sure. Hope someone figures it out so I can have some killer heat soon.

It sounds like a bad coolant temp sensor. The engine is actually warming but the guage doesn't show it.

Check the coolant temp with a consult hookup. That uses a different temp sensor. The stock gage is not very usefull in my opinion. The car can go from normal temp to overheating and the gage hardly moves at all. There is about a 20 degree band where the gage needle doesn't move at all.

If it is just the heater that is not working properly it could be that your antifreeze is not strong enough and things are freezing, you should definitly check that.

Other than that if it warms up fine at idle but cools off at higher speeds it is something with the thermostat or flow that is by passing the thermostat.


With a sensitive coolant gage and cold weather you can actually see when the thermostat opens a bit and the temp drops a few degrees then it closes and the temp goes back up a bit.

ls4546, if this were a VW I'd say your plastic water pump impeller blades had separated from the shaft and are no longer spinning. Causes all your symptoms.

But you don't have a VW... =(

The coolant is plenty strong, it's only been flushed 5 times in the last year with replacing two tstats and 3 radiatiors

I'm 90% sure it's got to be the tstat, again. I'll be throwing in a factory one this week or next week, whenever I get a chance and I'll report back.