Many of you have already helped. Still trying to get a real diagnosis before changing things.
Here it goes:
White smoke out back at start up but goes away in about 1/4 mile hmm condensation but seems like alot. Put hand infront of exhaust after it has stopped, no water or sticky build up--can't really smell anti-freeze smell.
1.Overheats at freeway speed, shoots up quickly
Leads me to think ahhh headgasket/crack somewhere
2. Hmmm oil and coolant bone clean
3. hmm could just be exhaust gases escaping into coolant passage hmmm
4. Did block tester to test for Hydrocarbons in cooling system did several tests and different conditions---nothing hmmmm
Burped coolant 50 times
Tried experiment of bypassing heater core--acutally took longer to overheat and slower--so did change things.
So I thought I had 2 pieces of evidence pointing to head gasket but the hydrocarbon test is supposed to be diffinative?
Just get a new radiator??
Haven't wanted to shoot parts at the problem but my finger is getting itchy cause after new radiator is pulling the heads off just to make sure?
Am I missing a step or troubleshooting point? Maybe water pump but its not weeping and seems to flow---suppose I could have it flow tested. Thermo is new and works. I suppose I could have a hole in the exhaust letting more water in overnight than usual causing the white smoke--but the two together made me really think headgasket.
Any thought?
THanks
Chris
