Engine Coolant, overheating, help diagnose

[misho]

Hey guys. This is gonna be long so be prepared lol.
So, a while ago, coolant was leaking near the exhaust gasket, and i suspect the head gasket is blown. Every week i needed to add coolant, and leave spots on the ground everywhere i parked.
Anyway, so i got some head gasket sealant, and it did the fix. The next day car didn't leak coolant.

But 2 days later, I start driving, and the temp gauge was working and raising to normal temps, but it kept going till the max. I turned on heater etc, to cool as fast as possible, and shut it off. My overflow tank was overfilled, and coolant all over it. I checked the radiator, and it was half full. waited a few minutes, and then i started the car up. The temp dropped to below operating temp immediately. So i drove off. Then the car reached op temps fine, and kept steady near it.

Problem 1: the rad does not suck in the coolant from the tank :S, So i filled in the rad myself.

So a few hours later when the car was fully cold, i drove it again, and SAME issue happened. I drive, overheats, let it cool, then runs fine at normal op temps.*

This ONLY happens when the car is FULLY cold, ie more than 2 hours since last drive.
So what i think, since the head gasket is probably blown, air gets in the system, and pushes out the coolant from the rad, into the overflow tank :/

*Another thing i notice is that since this started happening, the temp sometimes drops a bit if i run heater, or drive faster at low RPM or in neutral down hill.

Basically same issue as this guy: http://www.explorerforum.com/forums/showthread.php?t=304082

Background info: Temps are about -10C here, 14F. Car has 122k miles on it.
1999 explorer 4L ohv.
Note: There is no coolant mixed in with the oil.

So whats going on here :S
Help guys
Thanks

 

[1AJeremyD]

If the truck is not sucking coolant back into the radiator it might be the cap. As the engine cools there is a vacuum which sucks the coolant back into the rad/engine. Change the cap and see if it happens again.

 

[JCat]

To know for sure you would need to conduct two tests.

1. There is a tool that attaches to the radiator cap location that you can pressurize the cooling system. Once pressure is applied, you look for leaks, and notice if the pressure drops on the tool's pressure gage.

2. The second test would be a commpression tester that you would screw into the spark plug hole. When you crank the engine the tool would tell you the maximum pressure that the cylinder is able to achieve. Obviously, if you had a problem, the pressure would be low.

If it is a head gasket leak, then you will need to replace it. There is no other fix that will work.

 

[Dre]

you might also have a problem with thermostat... take it out and test it.

 

[misho]

If the truck is not sucking coolant back into the radiator it might be the cap. As the engine cools there is a vacuum which sucks the coolant back into the rad/engine. Change the cap and see if it happens again.

OK, will give this a try first.
An interesting read here: http://www.tegger.com/hondafaq/overheating/index.html#airtop

Then I will try changing the thermostat.

But again I am expecting the worst since the head gasket was leaking already to the exterior of the engine, chances are there is an internal leak inside too and air is getting in. We'll see.

 

[my98nnj]

This thread is a perfect example of why coolant is the ONLY thing that should be in your cooling system. That stop leak crap causes more issues then they fix.

My .02 your opinions may vary.

 

[misho]

This thread is a perfect example of why coolant is the ONLY thing that should be in your cooling system. That stop leak crap causes more issues then they fix.

My .02 your opinions may vary.

Hah, you are not the only one, I knew that from the beginning, once i add **** like that then everything is done.
But if i left it to leak coolant, then the hole is going to get bigger and bigger and just mess everything up.. Kinda like now.

Anyway that gasket fix liquid just has some random liquid + small ?copper? particles. I checked out all of the coolant additives, the expensive and cheap, and they we are all the same.

So yea, my question now, what could have this stop leak crap contributed to this? Maybe clogged something??
Thanks anyway

 

[1AJeremyD]

The stop leak can get clogged up in the radiator and cap and prevent the coolant from returning to the bottle. I have also seen it get caught up in the thermostat as well as the water pump. Pretty much the stuff finds any hole regardless of the size and tries to fill it in including bleeder valves and everything else in between.