My cars overheating strangly

[Harry fortney]

93 1.3L 180,000. I Just replaced head gasket, waterpump, flushed block, heater core, and new radiator and cap, thermostat also. I can fire it up and drive all over town car runs amazing has great power doesn't lack anything until u climb a mountain or drive roughly 45 minutes +. Then when I shut it off it will be spray steam from overflow reservoir. Occasionally it will also blow valve cover gasket also when it overheats as if I'm building pressure... Anybody know where to look? Car has alot of power and seems very healthy other than that is y I'm not junking it any help would be appreciated thank you

[bravekozak]

welcomsign
It could be a bad thermostat.
When you were flushing, did you reverse the hoses and backflush in the opposite direction? Was the water flow healthy?
I had to recore my rad because only three out of seventy-four tubes were clear.
Evan's waterless coolant won't sludge, boil over and make a mess like that.

[zoe60]

Could still have air in the system. Take the cap off and squeeze the top hose to get air out and then add coolant.

[FestYboy]

Where in pa? If close I can take a look at it.

[TominMO]

When cold, take off the rad cap, start it up, park it on an angle (or jack up the pass. side beforehand) so that the rad cap is higher than the top hose, and let it run a couple minutes. As it circulates, bubbles will rise to the cap and burst. Put the cap back on when the coolant is starting to rise to the point it will overflow. This might help.

[1990new]

This is a long post but bear with me.. I'm trying to give all the details in case everything taken together could ring a bell or indicate
something similar to your problem.

We are trying to figure out a similar situation with my friend Sam's car. The radiator had a small leak at the seal on one side where the top reservoir meets the radiator for a couple of months.
Sams engine had been running with the temperature gauge about in the middle between c and h. He knew the radiator had been leaking so every day he had been checking the water level and adding coolant as needed.
After I got back from Madness I installed a new radiator that I had ordered for him. We fill it with new coolant and he drive about 2 miles toward home and the heat hand start to creep up past the middle so he come back after driving only about 4 miles and the engine is hot. Assuming that the thermostat must be stuck, I put a box fan on top of the engine to cool it off, I remove the thermostat and we replace about a quart of coolant that has somehow disappeared. He starts up the car and we can see that the pump is working because coolant is flowing smoothly past the fill hole in the top of the radiator. I remove the wire form the fan switch so the fan will run all the time to rule out that as a problem. He drives home and calls to tell me the gauge is staying near the C marks most of the time. So I assume everything is fine and we just need to reinstall a good thermostat.
But this past Thursday, Sam calls to tell me the car had started to run hot again after driving it only a short distance and the overflow reservoir is empty. He lets the car cool opens the radiator and has to add about two quarts of water to fill it up. He say he sees no place where water is leaking out. So I tell him to fill up the coolant reservoir and let it sit overnight to make sure it is still full in the morning...and it is still full in the morning. The 13lb radiator cap is confirmed good. So now I think maybe a slow pressure leak at the water pump seal. I ordered a new water pump for him from RockAuto last night, but I'm not sure that will fix the problem. He is coming over later today and I will remove the top timing cover, let the engine run and look for water at the water pump weep hole to see if water is really being lost there after the engine heats up. I see not bubbling up in the radiator with the cap off and the engine running when the engine is first started and running for a minute or so; after that the water gradually begins to rise in the radiator and we have to put the cap on the keep it from overflowing.

Since you replaced the water pump that should not be a problem unless you got one with a bad seal.

Thinking about all this what comes to my mind is that there could be a tiny crack in the cylinder head between the combustion chamber and the water jacket that while not affecting performance much and not allowing water to get into the combustion chamber, is pressurizing the cooling system to the point where water is being pushed out through the cap into the overflow reservoir; then the reservoir is overflowing and as the engine cools the reservoir fluid is sucked back into the cooling system. Over repeated cycles of heating and cooling, the cooling is depleted to the point where the reservoir become dry and then the engine begins to run hot.

Re-read your post and I suspect that your are probably losing coolant through the overflow during those short driving times as well but not realizing it. Hope it isn't a head crack leak. Did you check the head for warping when your replaced the head gasket?

Back in the olden days before the advent of the overflow and recovery cooling systems and other performance improvements, it was routine for cars to overheat when driving up mountains. In addition to the added power needed to pull the car up the mountain which produces more heat, you are dealing with the atmospheric pressure drop as well. I remember back in he 50's (driving a late 40's car) we routinely had to stop half way up the Saluda grade to let the car cool off and refill the radiator.

Hope my thinking out loud helps... or triggers an idea from someone else.

[FestYboy]

Jess, I think you're close on this, but not the head... My brain is screaming gasket leak on the vacuum side of the combustion system. Note the new head gasket in the OP, depending on how it was done, there may be a tear or reversed gasket allowing violent to be drawn in while the system is under pressure.

[ryanprins13]

My cars overheating strangly

Another possibility- if the air is not properly bled out of the coolant system after a service then you can get an air pocket in the engine. That can cause the area where the air pocket is to overheat and blow the head gasket or crack something. It also can cause strange readings from the temperature gauge. Thats a common reason for head gaskets to go right after they or a radiator, thermostat and so on were changed.
Another possibility-coolant runs through the throttle body. If a gasket there leaks will it run into the intake or is it all sealed there and no possibility for leaks?


Sent from my iPhone using Tapatalk

[Harry fortney]

Thank you for all the information! Thermostat is new tried 2 of them and tried without a thermostat. Head was checked from cracks and warping and was good. I bled a few different times and haven't got anything good all I can think of now is would running straight water or a bad coolant to water mixture make a difference? And when it over heats the coolant reservoir overflow hose blows a strong steady stream of steam hot as hell! And radiator and resevior are always bone dry after cool down. And also no leaking from anywhere!

[bravekozak]

Could be a crack inside the intake manifold, allowing water to get sucked into the engine? Have you ever had your intake manifold off to do an inspection?
Get an HVLP pump and blow through the rad and engine.

[WmWatt]

When did you last flush the cooling system?

[Greywolf]

I'm going to suggest that you ask around to see if a shop near you has an exhaust gas tester for radiators. If there is a leak in the head gasket, the rad can over-pressure and drive out the coolant. A "Sniffer" can detect exhaust gas in the rad, that you may not be able to see. It would also drive exhaust gas into the coolant, that would act just like air pockets.

If it is a small leak, air may only blow into the coolant when running, but step number one is this:

CHECK YOUR OIL to see if there is any sign of "CHOCOLATING" from coolant getting into the oil.
* When coolant mixes with oil, it looks like a chocolate shake

[WmWatt]

If you remove the oil filler cap on the valve cover and turn it over you might see foam from moisture in the oil.

[1990new]

Wrong thread...