too much pressure at expansion tank ?

Hello ! I have a mk1 golf cabriolet 1.8 -91, the problem ? is that i think i have too much pressure at expansion tank at sometimes. So when the car is idling and i throttle it, coolant comes to the owerflow from expansion tank. When the engine is cold and i open expansion tank cap, i dont see any bubbles and the coolant flows great. Oil looks good, and also the coolant. I have no changed water pump, radiator, expansion tank cap, and coolant, few weeks ago i just changed tha radiator and coolant. Any ideas, i mean it gets a wet at coolant is going away but it doesnt seem to be like big problem. Coolant doesnt smell like exhaust gass, everything seems to be okay but it seems that it might get little too much pressure ?

When you changed the radiator and coolant did you let the system bleed air out by running engine until hot with the expansion cap off, to let any air locks out?

What colour cap do you have on the expansion tank?
If you have a black cap change it for a blue one as black ones are more prone to failure.

Hi, i have the blue one, bought new one, well i runned the engine and pressed upper pipe that connects the radiator, i think its possible that i did not let the engine run hot, but the cap was away for a time and the engine was running.

I was afraid that head gasket might be failing, but the symptoms dont really fix to that kind of problem ?

Well, try this quick test.

Parts needed
2 Latex gloves, Big Lipped Balloons, or Condoms.

Cold engine.
Remove expansion tank cap.
Tie the Glove over the opening tightly.

Start the car, and from under the hood REV the engine to 3000 RPM for 30-45 seconds, if the Glove or condom inflates and gives you the finger… Bad Head Gasket, or Oil Cooler.

I personally don't like the Water filled Oil Coolers as they can intermix.  Usually you don't get a/f in the oil, but you get oil and pressure upto 4.5 bars injected in to the cooling system.. Ballooning the hose, and things.

If I had an Original Oil cooler on my car, I would replace it first, and retest to eliminate it as being the issue as head gaskets are a wee bit more costly, and what if you replaced the head gasket, and the cooler was the issue to begine with.

well now when everything is at parts, head gasket it is !

Also exhaust manifold is cracked

Depending on what manifold and down pipe you have fitted but maybe a good time to throw the "toilet bowl" down pipe and manifold in the bin and free up some more horses with a 4 to 1 stainless manifold.

I'm pleased with the results I got fitting mine, the engine is pulling much better above 4,500 rpm and the standard exhaust I still have even sounds much better.



I did wrap mine to keep the heat down in the engine bay, I also covered my rubber UJ joint with a plumbers soldering mat to stop the gater melting.

now its almost done, headgasket changed and valves and also exhaust manifold, i think there is still a hole in the expansion tank because fluid comes still over from the level meter. i am going to change the tank next