overheating problem

[skeeter123]

Pressure test results?

http://cgi.ebay.com/ebaymotors/Snap-...item2a07be20c2

[uspres2020]

I have not done a pressure test. Although I did replace the cap so pressure is not being lost through that.

It appears though that my cooling problem is directly related to the appearance of air being introduced into the coolant system somehow. I am pretty sure there is no other way for that to happen other than coming from the exhaust gases. Since all the gaskets were just replaced yesterday I am thinking it could be a crack in the head although nothing was seen.

Is there a brand of stop leak that someone would recommend over others?

[skeeter123]

It sounds like the air being introduced into the cooling system is steam, from boiling coolant. Coolant boils at a much lower temperature when it's not under pressure. Most cars cooling systems will run at 7-10 psi after warm-up. Parts of the engine (near cumbustion chamber) get really hot, and will boil coolant unless its under pressure. I'd really check the coolant reservoir, cap, and hoses attached to it for pressure leaks. The reservoir itself may have a fine crack in it, typically where the top and bottom halfs are pressed together. The caps have a rubber o-ring that can get crimped/twisted. A new reservoir = $40; or get one from a parts yard. I had one that leaked from around the cap; it wasn't the cap but the reservoir itself.

If its not the reservoir, it may be that some coolant passages are clogged (even though you did the flush). If the heater isn't working, it may be a clog in the heater core.
Are you running Dexcool in it? Dexcool has a tendency to gunk up (brown waxy gunk)when some air gets into the system, which is why its so important to bleed the air out. It will also form a real nasty gunk if it's mixed with regular "green" coolants. Do you know maintenance history, if coolant is dexcool, or was switched to green stuff? Many people have switched from dexcool to green coolant, but you really have to flush out all the dexcool before introducing the green stuff.
I'd stay away from stop leak stuff, if there's a clogged passageway causing the problem it sure won't help. Do you see coolant leaking anywhere? White smoke / coolant in the oil / etc? Once the air is bled out, there's nothing but liquid coolant in there and you should see it leaking out as the engine warms up, if its a leak. The only place where "air" can leak out is the upper part of the coolant reservoir/cap.
Hope this helps.

[uspres2020]

I sit there with the car running and bleed valve open and the temp will be at 200 and then water will stop coming out of the bleeder and the temp will start rising. Straight water boils at 212, 50/50 boils at 257 I believe. The air will start to form well before it ever gets close to those temps regardless of which I am running in the car.

I believe I have thought of a simple enough way to check the coolant pressure though and I will do that tommorrow before I use the stop leak,


It has not been running dexcool for at least the last 25,000 miles since I have owned it. Before that I really don't know.

As I said I have already replaced the cap but I will check the pressure being held in the reservoir. I didn't do anything to it today.

I am thinking that if I somehow connected the bleeder valve to the expansion tank that it would then have a reservoir for constantly venting off all of the air that forms in the system and that would give me a way to continue driving it for a few weeks until I have time to replace the head if that is the problem.

[uspres2020]

Well I did my pressure test and it didn't seem like the system was holding pressure so I went to advance and borrowed the coolant system pressure testing kit it most definitely was not holding pressure. With the help of a little soap it is obviously coming from the neck where the cap goes on. Time to find a new expansion tank tomorrow at the junk yard.

Hopefully this fixes the problem, thank you skeeter. You were right all along.....I hope.

[3100]

try some Teflon tape around the treads of the reservoir.

[mlw_1987]

sounds like the thermostat

[uspres2020]

I thought about maybe trying some tape of sealant of some sort but I am going to check the pick and pull too I think. Maybe I will give some teflon tape a shot tomorrow morning before I head out to the junk yard.

[3100]

Originally Posted by uspres2020

I thought about maybe trying some tape of sealant of some sort but I am going to check the pick and pull too I think. Maybe I will give some teflon tape a shot tomorrow morning before I head out to the junk yard.

i have teflon tape on mine, and no problems it stays in place even when you remove the cap. Its part of the tread now trust me

[uspres2020]

3100, it seems like the leak is actually right through the plastic and not around the threads. Maybe it is through the threads though actually now that I think about it. I am going to try the teflon tape first thing. Man these caps go on hard enough already though.....We'll see.

[skeeter123]

The threads are only there to hold the cap in place, not to hold pressure. It's the rubber o-ring that forms the seal between the inside neck of the reservoir and the cap. If the o-ring doesn't seal (twisted/out-of-round, or because neck is scored or out-of-round) pressure will leak into area above o-ring, which leads out to the overflow hose. That's what happens when the pressure gets over 15psi: the cap has a pressure-relief valve built in that lets pressure through, it comes out slots in the cap above the o-ring and goes out the overflow tube.

The cap shouldn't be so hard to screw on; it's a sign of trouble. Try lubricating the o-ring with wd-40 and see if it goes on easier. But I'd still get a new reservoir.

[uspres2020]

6$ reservoir from the junk yard. Now the system holds pressure, too bad it still overheats though.

I think it was on the inside by the o-ring that it was leaking.

I put the bars leak in last night, time to go find out if it works now.

[uspres2020]

Still not working.

[doctorhrdware]

sound like a gasket problem now. I would retest the pressure on the cooling system and see if the pressure leaks down. If it does might be a gasket faliure, causing the cooling pressure to leak down?

[uspres2020]

I already replaced all the gaskets. They really didn't look that bad. I had a friend with me that is a mechanic and he said that he doesn't believe the head is warped at all. So I think maybe there is a small crack in the head that is big enough to allow exhaust gases at pressure to go through but not big enough to allow any liquids through it.

I created a rig that connects the bleeder valve above the water pump to the overflow tank. So that it can vent off air constantly by itself. That was not enough to fix the problem. Now I am going to remove the thermostat and see how it runs like that. I'm not really in the mood to replace the head if I don't know that that is the problem.