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 :)

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

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?

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.

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.

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.

You are correct. I seriously have no idea what I was thinking when I posted that. Guess I should stop posting from work. :P

However, a BHG is not the only thing that will cause your coolant system to purge.


EDIT: I remember what I was thinking... the relations between temp, pressure and volume. Damn I had some wires crossed yesterday. Thanks for the knock on the head IHateHacks.

The volume of a liquid is inversely proportional to pressure in which it exists and proportionate to its temperature. If the pressure drops the volume increases. If the temperature rises the volume increases. If the system's coolant begins purging at a lower pressure than the system was designed for the rate of exchanged energy begins decreasing and the temperature of the coolant increases. As the temperature increases, the volume of the fluid again increases resulting in another increase in the system's pressure and more purging.

The cooling system is well planned and there are a lot of physics involved in the design, implementation and operation of an effective system... admittedly more than I have a handle on.

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.

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

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.