2007 S40 coolant leak

Craigd2599 · Post by **Craigd2599** » 24 Sep 2015, 09:00

Okay so I got the head gasket replaced, new head bolts, everything done. To be honest...it wasn't as hard a job as I thought it would be. I got it all back together and last night as i was filling the expansion tank, I noticed that the coolant was running out almost as soon as I was putting it in. It was coming from the center, rear of the engine. I can't tell if that is the source of the leak or if it's just looking that way because of the skid plate and that's just where the fluid escapes from. Is there a coolant hose or port back there? I thought maybe the water pump bypass was the culprit because the car is cold and hasn't been started yet. Wouldn't the coolant stop at the thermostat until the car reaches operating temp?

Post by **cuhfs** » 25 Sep 2015, 11:11

Use a low pressure coolant system tester. Put low pressure around 2-3 then 4-5 lbs of pressure (do not go above 10) in the coolant tank and you will find the leak. They have loaners at Advanced Auto and other parts stores. Go low and slow. Thats what I did after my head replacement . Found the leak at the t-stat housing.

Craigd2599 · Post by **Craigd2599** » 26 Sep 2015, 07:48

funny...that's where my problems began. The thermostat stuck shut, causing the overheating, and in the process it cracked the housing. I replaced the housing during the head gasket replacement but this leak has yet to be found. I'm thinking it's the o-ring on the metal coolant pipe in the rear of the car.