yellowTz28

Hey guys,
I understand that this might be a breech of existing threads, but I have a cooling problem that I can't seem to get my head around, and wondering if someone could set me straight on the matter.
Back story: Got car from old man who let it sit. For better for worse I bought the car. Old man had heater core bypassed with a plastic fitting, and one day the fitting sheared while driving, causing an overheat. The heater core was replaced and the car seemed to be ok for a bit, now the car seems to be acting up again.
Symptoms: Temp seems to rise when car is under acceleration, petal to the metal makes the temp jump, sometimes to under the red line after a long enough car ride, but mostly sits at about the middle seg(220?). Once the car is off after a drive, and I've tested this with the ignition rolled forward but not on, the temp seems to spike and coolant backs into the reservoir and boils. Weird right?
I figure it could be one of a few things like head/gasket, radiator/pump, or something like this guy: https://www.thirdgen.org/forums/cool...le-i-cant.html
Telling me what it sounds like or what to do to check this issue would be awesome, or even just telling me where i should be looking in other threads would be good too!

Ozz1967

iTrader: (4)

When you first refilled the system, did you "burp" the radiator to get all possible air pockets out of it?

Is your air dam on/installed/not broken?

Does it do thsi while sitting or only up on the highway? Only under acceleratoin?

Do the fans work properly? Should come on just over 225* or so.

yellowTz28

Have mech fan, plan on getting electric(s) soonish. I haven't just let the car run sitting for super long to see if it does, but for the short time that I have let it sit, there doesn't seem to be any problem there. So I would say that it does it only on the highway, or at least highway driving. I have not really checked the air damn, and now will check that. To the burping I have to figure that I could do a better job I guess, prop the front end up and run with the rad cap off sounds right?

Richboll

You need to do the obvious things as Ozz1967 states, especially the air dam.
Have you seen any white smoke coming out of the pipes? Have you also checked the oil for water and water for oil? I'd replace the thermostat and check your hoses to see if they are exceptionally soft or spongy as they can collapse at speed.
And while this is obvious, it's worth repeating, make sure the engine is cooled down before you take the radiator cap off.

Richboll

I just looked and realized you don't say what model/year the car is. Can you give us a little more information?

Ozz1967

iTrader: (4)

Ensure the heater is on full blast when "burping" the motor. Run the car up to operating temps with the radiator cap off. At 220 or so, or whatever the Thermostat is in the car you'll see the water start to move as the thermostat opens up. As the water moves through the engine/hoses etc, it'll burp as the air bubbles come to the surface at the radiator cap. The coolant level will go down at this point. Add more coolant. May do this 2-3 times before it stops.

Also, very valid what Richboll said about the hoses, especially older ones, they can collapse in on themselves at speed as the suction from the water closes them off. This could be contibuting to your issue.

I'd probably start with new hoses and then a full flush of the system afte rmaking sure the air dam is intact/present.

You must have an airdam at highway speeds.

I didn't know these cars had mechanical fans except maybe on some very base 4 and 6 cylinder models.