Liquid is boiling out of the pressure cap

[Ron616]

1999 Grand am, V6, 3400.
Just bought this car and with lots of problem.

About temp 205 liquide is start boiling out of the pressure cap.

since it is overheating have change thermostate,radiator cap and temp sensor.also have flush the radiator with water hose.

Radiator and water pump was change about six month ago.found the paper work in the car.

Still have problem with it cooling fan is not turning on so change cooing sensor learn from here it is sat to turn on at about 220 temp.but as soon as temp is at about 205 to 210 most off the water is start comming out off the reservoir tank pressure cap.and its happen all the time.

At this time running car with A/C on cooling fan work with it, and without thermostate and water in radiator is it ok.

I do have LIM problem too it is leaking but just a little.

Need Help Please Thnaks in advance.

[Blackhawk]

Get your cap pressure tested. It doesn't matter how new it is, if the rubber ring got damaged or the threads are stripped from the cap or the tank it will allow liquid to come out of the overflow tank.

[pcprophet]

your cap isnt holding the 15 psi needed the keep the coolant under pressure, pressure is used so that the coolant boiling point is increased. liquid under pressure has a higher boiling point. probly best to go buy a new radiator pressure cap and that should solve your problem.

hope this helps

edit, opps didnt see that you changed the cap, well from what i have read there is a leak somewhere which is allowing the pressurized air to escape, not to sure if the lim is the cause, hopefully someone will help yah out more or give yah more into detail

[tenspeed]

Is it boiling or can you see air bubbles?

A blown head gasket will push air into the coolant system and cause overheating.

[TA^Guy]

Everyone talking about the pressure cap, does a 5th generation even have a pressure cap?

[Ron616]

Drop my kids at school this morning took me about 15 min when i came home car had about 180 temp put the towel on cap and open the cap slowly there was no pressur at all .
Where did all the pressure go is it leaking out of LIM.

Tenspeed you said A blown head gasket will push air into the coolant system and cause overheating

If i have blowen head gasket then i have oil leak but i do not have any oil leak in engine beside LIM leak

[RazorDX]

Originally posted by TA^Guy
Everyone talking about the pressure cap, does a 5th generation even have a pressure cap?

I think it has a pressure cap, just no overflow tank.

[rixGAphx]

Originally posted by Ron616
...If i have blown head gasket, then i have oil leak ... Not so.
In the V6, there is no pressurized oil passing-thru the head gasket.
Only the drain-back oil from the valve train, which flows easily thru sleeved passages.
So it's extremely rare that a blown headgasket on the V6 will exhibit any oil leak.

From what you describe, I would *guess* your pressure leakage is due to the LIM.
But I would make sure by adding some UV dye to the coolant and then illuminating it with a Blacklight to see where it escapes.

May even be bad threads on the plastic reservoir, preventing the new pressure cap from sealing.

BTW, do NOT overtighten that cap!! Doing so will cut or distort the delicate rubber washer.
Only tighten as much as an average woman can easily do on-handed.

Only fill the reservoir to the 'Full-Cold' line, being about 1-1/4" below the bottom of the filler neck; the coolant needs the 1-1/4" airspace to expand into as it heats.
Without the airspace, it just spews-out thru the pressure cap AS THO boiling, when actually it's just expanding.

Finally, your coolant level has gotten pretty low, so you now probably have a large air bubble trapped in inside the V6 (the 4-cyls don't have this problem).
You must bleed the air or you will continually have problems (which the prior owner apparently had).

Good luck,
-Rick

PS: There are several threads in this Forum about 'Disappearing Coolant' and where ELSE the GA cooling system leaks (radiator side tanks, heater core hose nipples, waterpump weep hole, timing case, etc.) as well as the 'Burp' procedure for teh V6.

[rixGAphx]

Originally posted by RazorDX
I think it has a pressure cap, just no overflow tank. All GA's, 4-cyl or V6, from '94 until the end-of-production, have:

* A plastic coolant RESERVOIR (not an 'overflow tank').
* A plastic Pressure Cap on that reservoir, rated at 14-15 psi.

*SOME* '94 4-cyls apparently had a factory radiator with a filler neck and old-style metal Radiator Pressure Cap.
No other radiators had this feature.

Up until about '97, the relief/overflow from the reservoir pressure cap just spewed-out from the underside of the cap; sometimes into a mechanics FACE :eek:
Beginning *about* '98, the plastic reservoir neck had a 'drain hose' and nipple; when the pressure cap relieves, the water travels thru this hose downward so it exits safely at the bottom of the engine bay.

Hope this clarifies,
-Rick

[Ron616]

Got It

Picked up use Reservoir tank with cap from wreck yard sims like working now.

Problem i think was reservoir tank where cap sits on it had some cut mark on it some one had try to cut it with blads it was not even smooth.

At this time I am running with tab water on radiator until i will get my LIM fix is it goen a be any problem doing it or I have to add
DEXCOOL Antifreeze.

Thanks for all help

[rixGAphx]

Originally posted by Ron616
At this time I am running with tap water in radiator until i get my LIM fixed.
Is it going to be any problem doing it, or do I have to add
DEXCOOL Antifreeze?Should be OK for a month or so, not any longer.

Even for a month, I would add a least a quart of some antifreeze; reasons:
1. Antifreeze is ALSO 'antiboil'; the boiling point of water is 212*F; with 15 psi pressure, that boiling point rises *about* 33*F, to 245*F.
If you add 1 quart of AF to 2 gallons of water, you have a 1:8 mixture, or 12.5%; the boiling point rises about 4*F.
At 50-50 proportion, the boiling point rises about 15*F
Altogether, the 15 psi pressure and a mixture of 50-50 antifreeze-water creates a coolant system that won't boil until 260*F, which is a lot of protection.

As the weather gets warmer, you will need this extra boil-over protection.

2. The waterpump bearing lives INSIDE the water system, and it has no grease, silicone, oil, or other lubricant to prevent wear.
One of the MAIN additives in all antifreeze is a waterbased lubricant that prevents wear of the single moving part in every cooling system: the waterpump shaft and its bearing.

Just bum a quart or so of antifreeze from a buddy or brother or whomever has an open, partially-empty jug in his garage.
IT DOES NOT MATTER if it's DexCool or any other type of antifreeze!!!
1. Your system has only water in it anyhow.
2. You're gonna get a complete flush/refill after the LIM gasket repair, anyhow; (right?).
3. EVERY antifreeze maker states that it's OK to mix up to 10% of their product with 90% of the 'other' product, and vice-versa.
(The exception being "Sierra" and other 'enviro-friendlier' antifreezes, which use a different base chemical solution).

Good luck,
-Rick