Hey guys, I have a 97' 3800 v6 Camaro with around 90k miles. The other day I took it to get the oil changed and they said I have oil in my coolant and I probably need a head gasket...granted this is coming from just out of high school kids who are working at the oil change place.

So I went home and drained the coolant...it had like brown swirls and crud in the coolant. I was told that the Dexcool stuff can look like this if it's been in the engine awhile which the coolant hasn't been changed for probably 5-6 years....at least. I flushed it all out and put on a new thermostat, took the reservoir off also and flushed it out with a hose, then refilled with coolant.

Now it seems to be fine, start the car, let it idle, thermostat is opening at 1/4 of the way up on the gauge and works perfect....until I drive around for awhile. Then if I just let the car idle for awhile after I've been driving it, it will start to heat up, but once I start driving again it's fine.

I guess my question is could this be air in the system still? Or is it really a head gasket? I've also been told a faulty radiator cap can do these kinds of things? There are no other signs of a head gasket other than this...the oil looked perfect before the change and still does.

Thanks,
Lee

 

Similar experience with my '96 3.8.

When I first got the car, DexCool had always been used, and the factory shop manual also said to add a GM sealer (akin to Barrs Stop Leak) to the cooling system. There's where the brown, goopy, stain your fingers, stuff comes from.

A good two flushes, and refills with a 50/50 mix of real coolant & distilled water, and the car now sits at the lower 1/4 mark on the factory gauge, that is 190*F in mine.

When just sitting in traffic on a warm day, the gauge will go a needles width above the 1/2 mark, which is right at 210*F, and then the fan(s) come on, dropping the temp down to just under the 1/2 mark, that being right at 200*F.

When I can get out of traffic & rolling again at any speed above 30mph, the gauge drops back down to the 1/4 mark, or 190-195*F

If you fear a coolant leak, pressure test the system.

Most internal coolant leaks will show up by coolant in the oil, causing a milky appearance on the dipstick, and in the oil itself.

If you have an automatic trans, most coolant leaks into the small trans fluid cooler (located in the passenger side tank of the radiator, and not very common), will cause an over-full condition of the trans, and a milky color of the trans fluid.

'Burp' the coolant system by bleeding air out of it, at the bleed valve on the thermostat housing as you warm the engine up, close the bleed screw, and fill the overflow bottle to the mid-range mark. Then just let the car cool for several hours.

It's also not uncommon for a pint or two of coolant to be drawn back into the radiator/coolant jackets after several heat/cool cycles of the engine.

Hope this helps

 

park the car (with the front on the up side) on the steepest hill in your area. let it cool, open radiator cap and check level, if its low add till full. run around the block and do it again if you have time. or run it a day and do it again. if it is at full or stays at full your good to go at the fluid.
you should check and make sure your air dam is still under the front of the car. common cause of running hot at idle is someone decides its not needed and remove it.
make sure fans are coming on.

 

Thanks for the quick replies guys. I actually did the trick with parking it uphill to get the air out when I first did this...not sure if it worked or not...It seemed like when I had the cap off and the car was running, even before it started to get hot, the coolant was rising in the radiator...and going into the reservoir...which I'm not sure is normal or not...my coolant level is remaining the same in the reservoir and radiator.

I also checked my transmission fluid the other day too, and it looks perfect.

Air dam is also there...no problems there. Also, I heard the fan come on when I let the car get up around the 210 point. I didn't want to risk it getting any warmer, so I shut the car off at that point, but I'm assuming the fan would have brought the temp down. This car typically never got up that high is the main reason I am concerned. Usually it always stayed right around the 1/4 mark on the gauge.

And Jim, I'm pretty sure that was the Dexcool stuff, sounds exactly like what you are describing.

I don't think I have any sort of coolant leak, and my oil is definitely fine, so I think I'm ok there.

So I guess I'm wondering the proper way to bleed the air out with the bleed valve on the thermostat housing? Start the car with it open, let it get hot, then close it? My reservoir is already at the midrange point..

Thanks again,
Lee

 

Your primary (low speed) cooling fan will turn on when engine temperature reaches 221 degrees. The secondary (high speed) fan turns on if the engine reaches 235 degrees. Your fan turned on at 210, according to your cheap, sometimes inaccurate factory gauge. Next time, let the engine keep running after the fan switches on and see what the temps do, because according to your description, the cooling system is working as designed.

 

Yep. Just like that. The coolant will start to expand as it heats, pushing the air out of the system at the highest point, which it the thermostat housing with the open bleed valve. As the temp comes up, and you get a steady dribble out of the bleeder, close it.... and you are done, except for watching the overflow tank for several heat/cool cycles of the engine.

Thanks Craby & Camaro 69, and you are correct about the inaccuracy of the factory gauges. They are an approximation only, unless double-checked against a known accurate thermometer.

 

Ok, so I think I've got all the air out of the system for sure...Took the car for an 150 mile round trip yesterday...On the highway the needle stays perfectly at 1/4 of the way up on the gauge, but once we got to where we were going it started to climb right up to about half...but it would never get to halfway, which is 210 degrees on the factory gauge. So would you guys pretty much assume I'm good?? This car never used to go past the 1/4 mark, but it seems like everyone thinks 210 isn't out of the ordinary from what everyone is saying..

Thank you guys for all your help and advice, it was very much appreciated.

Lee

 

i think you said the fan is coming on so you should be good to go. on hot days,,, (80 on the wash coast) mine will climb up to half city driving. always makes me nervous too.

 

210 as you're getting it is pretty normal. I find it more odd that it stays at the 1/4 mark (185) when on the highway, but don't look a gift horse in the mouth!
Could still be gauge/sending unit inaccuracy too.

 

mine is on the first mark almost all the time too. i have a 180 thermostat in the 93 lt1 though so thats about right.