jesseusmc

Hey guys so I've been losing coolant rapidly from my coolant cap when the car warms up. I replaced the cap with a oem one and same thing. As soon as it heats up it just comes gushing out of the cap. What can cause this? Air in the coolant? To much pressure?

silverd2

How old is your reservoir? ..plastic turned yellow? If there is no cut, dent or breach of any kind on the reservoir (especially where the caps seals), then you may want to get someone with the set-up to test pressure at the reservoir.

Any other symptoms at all...hotter than normal, etc..?

jesseusmc

Reservoir is new also. And no other symptoms. It's fine but once it gets to operating temps coolant starts to come out of the cap. I asked a local mechanic. He said the thermostat could be stuck halfway open, or air in the cooling system. Or exhaust gasses getting in the system via bad headgasket. I don't have any running problems though. ALSO I did notice when the car warms up if I try and sqeeze the top radiator hose it is really really hard. It's soft when cold. Could this mean something?

BrianC72gt

Sure, you could have a blown headgasket pushing combustion pressure into the cooling system. Check the condition of your OIL...If it is a frothy milkshake, then you do indeed have a blown gasket(s).

If the thermostat is stuck closed, you could be heating the coolant, building pressure and the blowoff in the cap is doing what it is supposed to do - relieving excess pressure. Same for bad water pump, clutch fan, electric fan, sensors/wiring to activate electric fan, clogged radiator, or an air pocket...

Pressure in the upper hose had me thinking headgasket - hope I'm wrong.

It would also help if you keep the thread together rather than starting a Fourth one. In the OT, why did you do a flush and fill of the cooling system? Was it misbehaving before the service?

jesseusmc

I checked the oil and it looks fine. I first drained the coolant because it had alot of crud floating around in it. So I flushed it. And it was fine for about 2 days then I started losing coolant like crazy. I finally figured out when the car warmed up it would start coming out the coolant cap. So I went and bought a new oem cap and Same thing. I feel like I have air pockets in the system. I think I'm bleeding it right though. From the bleeder screw om the out of the heater core hoses. Another thing I noticed is when I turn the heator on sometimes it will be blowing really really hot then sometimes it will start to blow cool. Could that be trapped air?

twentysevenlitres

Just checking first, that you're not filling the reservoir right up?
They're designed to sit at the 'Min' mark when cold...

A down and dirty head gasket test:
From a cold start, take the radiator cap off and ensure the reservoir is at the min mark.
Leave the cap off.
Start the car and leave idling
As the temp builds, observe the coolant in the reservior.
If it blows bubbles like a soda (especially once near running temp), then you likely have a blown gasket.

There are two main types of blown head gasket - gas to water and oil to water. The former will blow bubbles, the latter will make a dirty milkshake out of your oil.
Your local mechanic can put a sniffer up the exhaust to detect coolant, and can test the coolant to detect hydrocarbons.