Technical Coolant issue - no pressure!!!

[ianlewis]

Hello all.

I've got a P reg Mk1. I have an issue with my coolant system. The system never hisses when I remove the expansion cap - there seems to be no pressure. Also the only time my radiator fan comes on is if I hold my hand over the expansion tank when the engine is running.

I have changed the thermostat and fan switch.

If anyone has any ideas I would be extremely grateful!!!!

 

[thelad]

It will only "hiss" if the engine is up to temp, however its not a good idea opening the cap when its up to temp as it can throw boiling hot water out, open the cap very slowly to let pressure out. Is it overheating?

 

[fingers99]

Try replacing the pressure cap?

It would help if you told us what else the car was doing. Is it overheating? Is it loosing water, etc.

 

[ianlewis]

Thanks for the quick replies. The system seemed to ditch quite a bit of water last night. I have put some pans underneath tonight to try and find where it is coming from.

In terms of overheating, the engine was bouncing above half on the temp gauge, particularly when at traffic lights, but the fan never kicked in.

I was convinced it was the cables going to the fan motor, so was relieved when the fan kicked in when I had my hand over expansion tank.

Should an expansion cap have some sort of seal or spring in it?

Thanks

 

[fingers99]

Well, it has a mechanism inside. But you really can't see it. They're pretty cheap -- any factor should have one in stock.