TAZMAN2010

Im going to give you guys the back story to problem because i believe it might have something to do with whats happening. Alright so last week it was 95+ degrees outside for most of the week and i noticed my car was running hotter then it normally does. I have a 1990 s5 non-turbo so the temperature sensor was running at about 3/4 of the way up ( scared the crap outta me ). I noticed that it only increased to there when i accelerated to speed, and then it started to level back out to half after cruising at speed, took a few minutes to get back to normal. I immediately figured that it must be a stuck thermostat, so i took it out and tested it. I let it sit in boiling water for about 20 minutes and it had not opened even a crack so i figured it was toast and ordered a new one ( It should be here tomorrow, oem mazda from dealership ). So in the meantime I have been running without a thermostat without any issues until yesterday....

I noticed yesterday after starting the car that there was a stream of coolant pouring out from under the car. I traced the leak to somewhere infront of or above where the lower radiator hose connects to the engine ( i cant really see because there is stuff in the way and i dont have a lift to get under the car ). The coolant runs down and drips off the lower radiator hose. It only does this when the car is cold and when it warms up enough it stops leaking. The part that gets me is that it didnt leak like this following the removal of the thermostat, it took a few days. I was thinking that maybe its a bypass hose thats given out but i really dont know. I know its not from the lower or upper radiator hoses or from the thermostat housing. Any ideas or comments would be greatly appreciated.

p.s. yes im a noob

RotaryRocket88

iTrader: (7)

If the only thing you did was unbolt the thermostat cover, then the logical source of your leak is going to be at that point. There is a gasket where the plastic cover connects to the thermostat cover, so if it wasn't replaced or RTV wasn't used to reseal it, you'll get a leak.

TAZMAN2010

I checked all around the cover and its not coming from there. There was a rubber gasket around the thermostat itself which i left in place. The leak is coming from somewhere behind where the lower radiator hose connects.

Also only leaks when its running and cold and the leak is more like a stream.

RotaryRocket88

iTrader: (7)

If the leak is coming down the front cover, it can be from the gasket that seals the thermostat housing to the front cover. You've also got the water pump in the area, which can leak from its gasket or from the weep hole (internal seal failure). Other than the upper and lower radiator hoses, what's been listed will be the only sources of leaks in that vicinity.

TAZMAN2010

Alright so I got the new thermostat, installed it, and presto! the leak stopped.... So i guess it was leaking from the housing and running down the side of the water pump and i must have just not seen it. My guess is that the rubber seal that i left in there was pretty old ( it was hard and kinda cracked up ) and couldnt hold a seal. So with the new thermostat i got a new seal it seems to fixed my problem.

Well thanks for the help!

RotaryRocket88

iTrader: (7)

Glad you found it. As I mentioned before, reusing gaskets is always a risky proposition. Whenever I tear anything down, it always gets new gaskets regardless of age.