Overheating

[cre]

Yup it happens. I just wanted it made clear that there are other things that can cause this problem besides a BHG.

Let's not forget that a faulty rad cap can cause a BHG.


For the benefit of those interested: The radiator is a pressure valve. The higher the pressure in the cooling system the lower the boiling point. Reduce the pressure the boiling point rises. So when a bad radiator cap starts venting coolant too soon it can release enough pressure that your coolant actually starts to boil. Water vapor takes up a lot more room than condensed liquid and the excess volume has to go somewhere. Once this happens both the coolant mixture and water vapor begin purging out of the system through the overflow.... they've got to go somewhere. As this continues the coolant mixture begins boiling more and more rapidly, and as such the purging gains momentum. You can actually end up running on less than half of your coolant in a couple minutes. If you're not paying attention you can overheat big time and then... you guessed it: BHG.

[igosaur]

So, here's the plan then.

Get a new radiator cap. If that doesn't work.

Change the gaskets. If that doesn't work.

Put in a new pump. And if that doesn't work.

Sell the car on eBay to someone who wants a challenge and buy another one, preferrebly one with a detachable roof

[cre]

Personally I'd start with: Replace rad cap, replace thermostat and pressure test coolant system, before replacing gaskets and the water pump.

[igosaur]

Hi

How do I pressure test the system?

Also, if it was a bhg, wouldn't there be oil in the coolant or coolant in the oil or both?

Originally Posted by cre

Personally I'd start with: Replace rad cap, replace thermostat and pressure test coolant system, before replacing gaskets and the water pump.

[cre]

There are kits for that purpose. Typically they include a pump (like a bicycle tire pump) a couple test caps (like ardiator caps, but they don't have a built in valve) and a pressure gauge. Auto parts stores around here will rent them out. If you rent or buy one make sure it's got a test cap that will fit your rad. Then you just hook everything up, pump the system up to a certain pressure (~5psi over high for the system) and watch to see if the pressure holds or if you've got a purdy green shower. I can't remember what the average pressure for our system is at the moment.

[igosaur]

Thanks for that, I'll have a look

Now that you mention pressure, I do remember opening the bonnet/hood after the engine was warmed up and hearing a slight hissing sound. Now that I think about it, probably comming from the radiator cap.

Originally Posted by cre

There are kits for that purpose. Typically they include a pump (like a bicycle tire pump) a couple test caps (like ardiator caps, but they don't have a built in valve) and a pressure gauge. Auto parts stores around here will rent them out. If you rent or buy one make sure it's got a test cap that will fit your rad. Then you just hook everything up, pump the system up to a certain pressure (~5psi over high for the system) and watch to see if the pressure holds or if you've got a purdy green shower. I can't remember what the average pressure for our system is at the moment.

[IHateHacks]

cre you said when you reduce the pressure in the cooling system the boiling point rises, right? Well you have it backwords. When you pressurize a liquid the boiling point rises.

Your cooling system should hold 13psi all day long. That's the factory spec. Mine held 16psi when I tested mine with a blown head gasket. You don't want to pressurize the cooling system over 19psi with the tester, that's in the red zone on the gauge on my tester.

[igosaur]

Bought a new radiator cap and almost instantly I had steam comming from the bonnet.

Took a look and found a hose tucked away that had been 'repaired' with electrical insulating tape!!! Took the tape off and found a lovely 1/2 inch split.

Now I've trimmed the hose and removed the piece with the split so fingers crossed.

I'm now hoping that this was the original cause of all the problems in the first place.

[f00g00]

Which hose? a hose for the TPS, ISC or back of the block?

[igosaur]

I have no idea!!

It was a narrow hose about 3/4 inch in diameter right on the top of the engine, on that block that stops me from changing the spark plugs.

I'll take a picture of it later, but it was definitely split and spitting out coolant.

Originally Posted by f00g00

Which hose? a hose for the TPS, ISC or back of the block?