Needs a burping but high idle smoke

[ImUrOBGYN]

Here's the deal, hopefully someone will have an idea...

 

A short while back, I had a hose pop off coming from the heater switch valve on the firewall. I thought I had it burped completely after going thru the process and then driving it around with no problems or loss of coolant even after cooldown. The following time I drive it, it starts to get a little hot so I pull over. Seems it's burping itself again and is releasing coolant thru the overflow. I'm not far from the house and the needle has settled back to a normal spot. At high a higher idle, it smokes like burning oil, not coolant. It doesn't do this when it idles normally or while driving. At least not noticably at all.

 

I decide maybe I hadn't burped it enough and try again a couple days later. (I use a giant cup/funnel just for burping a coolant system that you can fill and effectively makes it the hightest point in the system.) Anyway, after refilling the system, I begin running the car upto operating temps. Once it starts to get hot, it begins smoking profusely. Lower the idle back to normal, smoking lessens and then stops. Up the idle to aoround 1500rpms to finish burping, smokes again. I try to finish up the burping process without high idle and when there seems to be no more air, I take it for a test drive. (Car had been running for at least an hour already.) Anyway, I find no problems. Runs great normally and flatout.

 

Next day, goto Krogers and on the way home, my temp gauge gets a little wacky but settles back to normal before I get home without overheating. However, I can hear what sounds like air in the system. No smoking though unless the car is parked and high idling. Get it home and I'm unable to burp because I cannot let it high idle and it won't get warm enough just idling normally. Do a pressure test on the coolant system with the car off and it seems to hold pressure. So, released the pressure, started the car and let it idle to recheck the coolant pressure. Good news is that when started, the pressure didn't jump up as if exhaust gasses were getting in, however, after waiting sometime, the pressure was only about 4lbs. Again, it was taking way too long to warmup enough so I gave up as Icouldn't justify it smoking like hell while in high idle.

 

So, for those who've managed to read through all that, what are your ideas? I've got a couple of them, but I figured I'd put this out there and see what you guys think before I have the chance to get back out there again. Thanks all.

[Dave1647545494]

check to see if it is circulating coolant

 

I'm going to guess sticky thermostat or weak waterpump

[ansonivan]

Quick check for head gasket leak:

 

Start car with cold engine, within 30 seconds remove radiator/expansion tank cap, if pressure then damaged head gasket.

[Richard Cranium]

Sounds like my fight with my motor a couple summers ago. Over heating and always had air in the coolant. Was a head gasket leaking exhaust into the coolant passages. The smoke could be coolant flowing back into the combustion chamber when the engine shuts off and there is more pressure in the coolant than in the cylinder.

[ImUrOBGYN]

check to see if it is circulating coolant

 

I'm going to guess sticky thermostat or weak waterpump

The thermostat should be relatively new, but the thought has crossed my mind. Waterpump definitely shouldnt be an issue, but who knows.

 

Quick check for head gasket leak:

 

Start car with cold engine, within 30 seconds remove radiator/expansion tank cap, if pressure then damaged head gasket.

 

Tried this with a pressure tester. Didn't seem to be the problem.

 

Sounds like my fight with my motor a couple summers ago. Over heating and always had air in the coolant. Was a head gasket leaking exhaust into the coolant passages. The smoke could be coolant flowing back into the combustion chamber when the engine shuts off and there is more pressure in the coolant than in the cylinder.

 

This thought is the one that/s stressed me the worse. However, the smoke that does come (and only during a high idle) is smelling and looking like burnt oil, not coolant. Also, my oil level hasn't risen on its own or gotten milky (from coolant mixing), though that's not always a guarantee.