What Pressure Radiator Cap?

[Ian Anderson]

Car has been on the road for a number of years and goes well, but the core plugs weep and despite being changed a couple of times are still weeping.

So thinking, and I know I should not, I looked at my pressure cap and it is a Stant 21-25 lbs pressure. Is this to high, which in turn could be putting too much strain on the core plugs causing the leak?

So what pressure cap do you suggest, I have a few on order from Amazon and cand do trial and error but would rather not end up spewing coolant miles from home!

Thanks
Ian

 

[Don]

Hi Ian,

Mick at Southern GT says that you should not need to go over a 15lb pressure cap on the radiator. I was loosing water once the engine was up to temperature, I thought I would get a stronger cap, but Mick said raise the header tank, and it did the trick. I also have reduced the amount of fluid in the header, water expands by about 4% so my 22 litres was increasing to almost 23, it was escaping as there was too much to contain.

Cheers,
Don.

 

[JP Verweij]

Rover specifies a 15lb cap for their V8 engine.

 

[RichardH]

Further to Dons reply above, I have fitted a water level sensor in my header tank, as I was having similar problems with water being pushed out of the overflow. I now only fill the tank till the warning light goes out and it is ok, unless I sit with it stationary for a long time. It can still push a pint out under those circumstances. Having a water level sensor connected to a warning light on the dash, is a very useful tool.
I did try a higher pressure cap, but it tends to blow the radiator apart!!