GT V6 Coolant leak - radweld???
Hi, I've been having problems with my coolant level since I bought the GT in December. Had presure test done at a garage (non-alfa) and said it was radiator leaking so had them replace it only to find that the coolant level still goes up and down considerably when hot or cold. The engine indicated that it was overheating on a long run 130 degrees but when I stopped the temp instantly reduced to 100 (normal 90). I hoped it was just an airlock! I described symptoms to an alfa garage and they suggested leaving cap of expansion tank over night to allow trapped air to find it's way out.
I did this and found a puddle on the floor in the morning, so I presumed it was still leaking. I asked the garage to presure check again and they said that they couldn't see anything unless it was the pump but they couldn't see that without taking off the undertray.
I had changed the cap to see if it had failed and that was where the coolant was escaping when the engine was warm (only seem to loose when warm and obviously under pressure!). This didn't help so I was also wondering about a head gasket (no mayo in oil and no bubbles in expansion tank with engine running and cap off though). I wasn't convinced by the garage either so I decided to do a diy presure test as I didn't want to spend at least £70 on a testing kit for one test. I used the old cap, cut out the pressure valve and drilled a hole in the top, then glued a valve from an old bike innertube and replaced the original sealing washer which I glued to the inner tube rubber just for good measure! Pressured the system with a bicycle pump and low and behold....coolant running from the engine!....why the garage didn't see it I'll never know!!
Anyway, seemed to be coming from the lower fat pipe that I think either supplies or returns from the radiator, at the end where it meets the engine (3.2 V6), right hand side looking from the front. Also there are two smaller pipes connected to the same part which I presume are for the heater, they go off towards the cabin, one of these had a drip or so of coolant and slightly chalky corrosion with a bit of coolant colour (pink). I've tightened the clips and it has reduced the main leak but it is still there. You can see dried coolant in this area on the engine too so surely the garage should have spotted this and investigated further!?
My question though, is should I use radweld or similar to fix the small leak, are there any down sides to using it?...bearing in mind I want to keep the car for quite a few years. Or should I take the hose off, clean any corrosion off the engine connector and pipe then reconnect with some type of sealer if one exists??? Could the radweld foul any sensors or cause the thermostat to stick??
Thanks for any replies,