Chev Rad issues

[pop larkin]

Ok, so when I am running my engine water seems to be coming from the rad. I have removed the rad, and today i have been testing it. I have connected the top and bottom hoses, and filled the rad through the outlet for the bypass valve. I blocked the overflow pipe, with my finger and left the hose running. No water from anywhere, until it started to blow past the seal on the rad cap!!

 

It doesn't leak from the rad cap when on the engine, but surely if the pressure is sufficient to blow past the cap on the hose pipe, then it should be coming from any leaks in the core. Yes? In which case, why does it leak when fitted to the engine?

 

Note, when its fitted to the engine, I can't see where the water is coming from, only it dripping off the bottom of the rad. HELP :banghead:

 

[Richard Farrant]

Paul,

 

Two possibilities;

First, is that assuming the coolant was hot, so the rad would expand slightly, opening up a cracked solder joint.

Second, is also connected with above, but when bolted to its mountings it may be under slight stress, again opening up a cracked joint.

 

When you test rads for leaks, the orrifices are blocked and rad is pressurised then put in a water tank, you then look for bubbles, this is more practical than looking for a water leak, if you see what I mean.

[Rick W]

Rad needs to be pressure tested when hot and under pressure. Tseting it by plugging it with your finger and running water through is a waste of time. Plumb the rad back in and find someone with a pressure tester, it should screw onto the rad where the cap is. ;-)

[TooTallMike]

It's not running or spraying onto the rad from elsewhere is it?, such as a hole in a hose, or the water pump, thermostat housing etc. Water will find the most annoying routes and can be very misleading

[pop larkin]

Thanks for your suggestions. I don't think its being sprayed into the rad from anywhere else. The front end is completely stripped down so I can see all the hoses, stat housing etc. I am going to have it pressure tested at a local centre, so I will know for sure if its ok (or not), I have a pressure tester at work but it doesn't have a large enough adapter to fit where my cap was.