Racing Green 89 Mini

[cstudep]

As a side note, these are the adapters I almost always end up using. You can usually get one of them to fit what you need. They also work with other pressure testors like Matco, snap on etc....maybe the parts store has this style of adapter you can borrow too? If not maybe their pressure tester would fit these adapters so all you had to buy was the adapters. I think my pressure tester is an old Napa brand but I use it with these harbor freight universal adapters.
https://www.harborfreight.com/universal-radiator-adapter-set-56204.html

[MiniDave]

I went this morning and bought the HF pressure tester setup, if it works I'll keep it, if not I can return it....it looks pretty complete, so we'll see. If this radiator has a leak I'll get a new one on the way, we have a Brit car show this Sat so I'd like to drive it and see if my motor mounts made any difference in the vibes. If not, I'll clean it up and put it back in and test the whole system and see what I can learn.

[MPlayle]

If the leak test indicates no actual leak in the radiator, could the cap spring be a bit weak and letting operating pressure push a bit out the overflow tube to stain the area at the end of the tube?

[MiniDave]

Well, good news and bad - the coolant system pressure tester I bought this morning from HF fit this rad perfectly and the test proved exactly what I thought it would - a very fine stream of water jetting out of that stained area on the radiator. So, good news - I don't have a bad head gasket (really didn't think I did anyway) bad news, I need to order another radiator.

I buy these on Ebay pretty regularly for other Mini owners, and pretty much every engine I overhauled got one too. The first ones I found today were a bit more than I've been paying plus they wanted 12-15 shipping, but digging a little deeper I found one for $69 shipped - it's on the way. I don't know if it will get here in time for sat's Brit car show, but here's hoping.

Aluminium Radiator

Edit: Looking a little further down the page there's one for $59 and free shipping too!

This one has been in my car for 10 years already, so it owes me nothing, but I am a little curious how/why it's leaking there, pretty impossible for a rock to hit it there, and there's no rub marks so it hasn't been hitting the body. I guess it's just a failed tube.

One thought, it seems that when enough of the water comes out of the top tank, it no longer can refill that tube, so it stops leaking there till I top it off again, and the hole seems small enough that it doesn't start leaking again till the pressure builds back up, starting the cycle again.