Some of you may remember I recently had to get my intake manifold replaced. That was almost 2 wks ago, runs great now.. Yesterday I ran it harder than before on the highway and noticed the temp gauge went up much farther than before, so I slowed down, off 75mph lol by the time I could exit the temp gauge was reading normal. I pulled over and the antifreeze level was fine. I squeezed the top rad.hose (it was pretty warm but not hot) and could feel the water surge after I let go, not a big surge but it was still there. So i'm wondering is the water pump just not working well enough under a load? There was zero heat inside the car at this time too btw, but it started working again later after I shut the car off and started it again. I think maybe the heater control valve was going bad so I bought one but can't find it under the hood. I see the 2 hoses going to the heater core and straight into the intake and block. Guess the HCV is behind the firewall w/the heater core? Was also thinking maybe the thermostat is sticking so I got one of those, but it was just replaced w/the intake. Where do you guys think I should start? thanks!

I would start by checking for air in the cooling system.

remove the upper hose from the t-stat housing and fill radiator until water begins to come out the top of the t-stat housing then replace hose and fill resivour then start car let it get up to operating temps and allow the t-stat to cycle a couple times then top off radiator if needed.

Temp gauge will fluctuate some especially during play time.

There is no "water valve" that controls coolant flow to the heater core like on many older cars. An electric blend door in the dash controls how much warm air comes through the vents from the core. I agree with the above poster, there is air in the system.

when i replaced my intake, the first test drive the temp went up one bar (elec guages) but came right down. if you have been driving it for 2 weeks i doubt air is in the system still. unless u have not really driven the car much. you will need to check for air. make sure there is no junk between rad and a/c cond. you replaced the thermostat with the intake swap so that would not be a place to look, but not out of the question. i good way to tell if ur new t-stat works proper is to heat it up. some use the oven as long as u can monitor the temp of it and watch it open. and have you noticed any other slight temp rises since? or just the one time?

at least pick up a chilton or haynes and read up on the car

sounds like you do have some air in the system

follow procedures outlined and you should be good to go

the blower motor heater control you bought only controls the fan operation. As stated, this is a more modern car now and the blend doors adjust the mix of heated and unheated air and A/C

so unless your fan was not working properly you did not need that part

FIRST, check your coolant level. It sounds like its low SINCE you have no heat when the car runs hot. If it is low, keep an eye on the level. It may be leaking somewhere.

If you had a failing water pump the car will Leak antifreeze and/or Create a funny noise. ALSO, theoretically (sp) the belt COULD be slipping on the WP pulley. This should cause a noise. Check the belt tensioner.

Ok I'll check for air in the system and after that replace the new thermostat. Autozone's website said it had the old style heater control valve, i'm glad it doesn't now. Just seems odd their could still be air in the system after driving soo long, I drive 80 miles a day roundtrip and have checked the antifreeze everytime I check oil which is about every other day. Probably should just test the new thermostat and put it in..

Dan.

It doesn't leak any antifreeze at all, belt is quite also at least when I noticed when its idling. Maybe it slips at highway speeds.. I'll check that too thanks.

Dan.

when you are running the car turn the A/C controls to heat and run it on heat full blast while you are cycling the T-stat. It is not uncommon to get a faulty T-stat right out of the box.

Getting the air out can be a real biotch. As mentioned above, I fill the radiator up through the upper rad hose barb. And then also fill it through the Tstat opening (tstat out). Alternatively, you can remove one of the coolant temp sensors at the front of the manifold and fill through the hole with a small funnel.

Even after getting enough air out for the system to function properly, I still have to add some coolant to the overflow tank a day or two later because some air still has to make it's way out.

well at 124K miles the water pump is a good choice for replacement.

I wouldn't really trust the stocker over 150K.

EMP Stuart makes a nice high quality water pump (yes get this one), you'll probably see a nice increase in performance in your cooling system.

Other than that, T-stat may be bad, air in the system.

How do the fins on the radiator look? If your radiator is rusty and nasty and many of the fins are gone - replace it - this also could be why it's running hot.

Lastly power flush and fill the whole system.

+1 this is true.

Ok good news, looks like it was air in the system. I still don't know how it could have had an air pocket after being driven so long and not show low fluid level but the heat works good now. I'm going to replace the thermostat next, think the mechanic that did the intake put in a 185deg instead of 195 since the heat doesn't get as hot as before.