Coolant System Pressure

A new radiator cap is usually pretty cheap, and very easy to install. It’s hardly worth checking the 8 year old one.

Well…
For some reason I can’t up load pictures to the forums.
But i’ve added some links.
I don’t see a vent any where on there.
And nothing on the cap that looks like a vent.



I’d love to help you more, but I’m not familiar with that specific vehicle. Only with the “theory”, as it were. I did check out your pictures, but I can’t seem to locate the overflow tank cap in them.

A new radiator cap is an easy, cheap parts toss, but it may not fix the problem.

There has to be some sort of a vent somewhere. It can be very small, as it only has to allow air through. That’s the basic premise of the system…hot motor, push coolant to the reservoir, cool motor pull it back into the system. How it’s happening on your car, I can’t say at the moment. If I come across one I’ll check it out, but in the meantime, you should see what you can find. It may be very small…as small as a pinhole in the overflow cap itself.

It looks like the hose from the radiator cap to the overflow goes to the bottom of the overflow tank, is that correct? The third picture looks like something that melted in one side or blew out, is that correct?

Ok, so more info.
I went from last Thur to today without over heating.
maybe cause it’s been slightly cooler out?

@ChasisSOS Here is a better picture of the overflow tank cap.


I’m not seeing a vent.
Not ever a pin hole.

@Keith Yes the hose does connect at the bottom.
I was wondering about the melting myself.

At first I thought this was completely unrelated,
But i just replaced the battery too.
And it was covered in blue corrosion gunk.

It seems to me that this corrosion might have dripped down and gotten on the overflow tank.
I can see spots where the plastic is stretched.


The last two are not available, either they expired or you did not give permission for viewing according to facebook.

@Keith Try these.


Was there a wire close enough to melt this? If the battery shorted, wires got hot, then I’d expect a few more problems than just this, though.

The battery didn’t short,
It was corroded.
It was almost a year and a half old.
The corrosion seems to have dripped onto the tank.

I’m thinking it was more of a chemical melting than heat related.

You need a new tank. Bottom line, that tank has to hold coolant up to the hot line and it has to vent. Until those two criteria are met, you cannot determine if the cooling system is otherwise OK.

Before the overflow tanks were added to cars, there used to be an airspace at the top of the radiator. These cooling systems held about 16 qts of coolant. The turbulence in the top tank used to trap air in the coolant making it less effective. The overflow tanks increased the efficiency of the cooling system to the point that most are now only 4-5 qts. Of course the engines are smaller too, but there were inline sixes back then that were only 2.5 to 3.8 liters in size but had huge cooling systems.

I have a tank on order.
They said it should be here either Fri on Mon.

You may also have a water pump problem, loose/slipping belt, low coolant level, or faulty replacement thermostat. You may want to have the dealer or competent mechanic diagnose.