Please help! Coolant leak after thermostat change!

[AntMk3GTi]

Hi,
I'm really stuck with this one. The car is a 1.8t AUM. I changed the thermostat on the weekend and had a leak straight away.

I then found out that I fitted the o ring on the inside of the t.stat instead of the outside. I took it all apart again today and fitted in this order:

thermostat into engine

O ring

plastic housing

i did it up as tight as I could (without rounding the bolts) and checked for leaks. There were none. Now every time I drive it I get the 'check coolant?' Warning, then find that the level has dropped. I keep adding about 2 litres and there's a pool of water under the car where ever I stop, but only leaks when it has been driving. When not moving there are no leaks!

It can't be head gasket as I see the water dripping under the car, but only happens when it's been driven! If I top it up where it is and leave it parked, it doesn't leak.

any ideas / advice would be really helpful.

Thanks

[dom]

Can you see pink coolant residue anywhere that would point to the leak? You may have damaged the o-ring by fitting it in the wrong place.

[AntMk3GTi]

I first thought it was from the thermostat housing cos the pool of water is under there, there isn't much pink residue anymore cos ive watered it down so much when topping it back up.
It doesn't leak at all when it's cold, then I go for a drive and it pours out!

[dom]

You haven't cracked the housing have you? They can become brittle...

[AntMk3GTi]

I've checked the housing and couldn't feel any coolant on there. I didn't handle it much, I left it connected to the radiator hose and just moved it to the side when fitting the t.stat.
The rad hose was bent round a bit but I've checked that for leaks too.

It seems like the engine pressure is forcing the coolant out somewhere, but the housing always looks dry and I didn't touch any other parts where a leak could come from.
When I removed the t.stat housing the second time, no coolant leaked out so the t.stat was firmly in.
So I tightened the housing as much as I could until I felt the bolts might start to round off.

[mcgee9t2]

Have you done up the radiator tap?

Make sure you have the correct oring. When I got mine Paige's didn't know what o ring I needed so sent me 6 and I could compare new ones with old. There was two really Simelar. Fitted one. Coolant poured out. Fitted the other fine.

[Nino]

Have you used oem parts?

[AntMk3GTi]

Hi,

I didnt undo the radiator tap (I dont know where it is  ), I just let the coolant drain out when I removed the T.stat.
I got the T.stat from Euro car parts and it came with a new O ring. I checked it against the old one and they look the same. They didnt have any markings or anything and the new O rinb fits nicely around the T.stat.
A bit more info, I looked under the car when the leak was actually happening after driving it. The coolant was trickeling down along the left had side (if looking at the front of the car) of the sump, then I check the t.stat housing and it feels dry.
The only thing I can think of is that the lower bolt on the housing isn't done up tight enough becuase it was quite difficult to get the socket on there, or the lower rad hose has a small split somewhere.

[hardmonkeys]

I had this..mine was a cracked radiator..replaced and all is fine now, not sure if it was a coincidence or not, but all is fine now..

[AntMk3GTi]

I don'tthink it's the radiator, I had a rad leak on my previous car and it constantly dripped.
The leak I've got now only happens after being driven, and the coolant is running down / under the sump.

I'll try tightening th bolts on the housing without rounding off the bolts.