2007 Pontiac Grand Prix GT leaking coolant between the block and transmission down on

**DeionT** · 10-02-2017

I have a 2007 Pontiac Grand Prix gt. I have a coolant leak coming down from between the block and transmission. It's coming down on the driver side. I can't seem to see the exact location without taking the transmission from the block. Car starts and drives fine but over heats after a while due to water leaking out. I have checked oil and radiator caps and they are not milky. There is no coolant in the oil also. As soon as I add coolant I look under the car and it's coming out (dripping down) between the transmission and the engine block right off the fly wheel. I have checked the lower and upper imtake gaskets and they are not leaking. I also checked the head gasket and it's not coming from it. I checked the throttle body and it's dry. Would there be a freeze plug or some kind of gasket behind the transmission that would cause it to leak from there.

**Gregorius** · 10-02-2017

Poke this:

http://www.grandprixforums.net/threa...gine-(pic-now)

**DeionT** · 10-02-2017

Thanks I read it and will take a look at everything again. I wish he would of said what was the cause of the leak after he fixed it.

**Scottydoggs** · 10-02-2017

only way you leak coolant between the block and tranny is that rear cover. and the only way to replace that gasket is to pull the engine or tranny, pick one.

**DeionT** · 10-02-2017

Oh wow. Thanks. I was dreading that. Is that the rear main seal ? Or do they call the gasket something else ?

**Scottydoggs** · 10-03-2017

the rear crank seal is in that cover. should change it too. all i know is its a rear cover gasket, comes in a gasket kit.

**DeionT** · 10-03-2017

Ok thanks a lot !!! Will do

**rickisrad** · 10-04-2017

best to get it pressure tested to be sure. It may be leaking down from the intake or intake end cap.

**DeionT** · 10-04-2017

Ok I will do a pressure test on it this weekend hoping that's what it is before I may have to pull the engine.

**DeionT** · 10-06-2017

I found the leak. I can see it coming out from the rear main seal housing. I haven't taken the transmission out yet but looks like I may have a pin hole in the housing cover plate. It's leaking about a inch away from a blot to the inside of the bolt. I will have to pull it to see exactly what's going on.

**Scottydoggs** · 10-06-2017

the rear cover bolts have a very low tq value, they tent to just come loose, or the gaskets fails. the coolant is all the way up at the top of the cover, so it has to leak down to where you can see it.

this is what the rear cover looks like engine pulled out. with a bad gasket. them bolts have a plastic spacer in the hole, try not to break them, or lose them.

**Scottydoggs** · 10-06-2017

and what it looks like off. you also want to add some blue loctite to the bolts. then just snug em up real good. all i did over 2 years ago, no leaks.

you also want to rtv the bottom two inches of both sides of the new gasket where it meets the oil pan, and a bead across the pan too.

and a how to. http://www.clubgp.com/newforum/print...heck=944790476

**DeionT** · 10-07-2017

Ok thanks for that info. I will start taking it down today. I'm just glad I see exactly where it's leaking at. No more guessing games for me.

**Scottydoggs** · 10-07-2017

for sure if the leak is between the trans and engine, its that damn cover.

i didnt use that J tool, just smeared some grease on the crank had the new seal in the cover already and pushed in place. i used a straight edge to make sure the bottom of the cover was flush as i had my pan off, yours is still on so that should level it out for ya.

for real tho, pulling the engine might be easier then the trans to do this.

engine pull how to. http://www.grandprixforums.net/threa...illBoost-Style

tranny pull how to. http://www.grandprixforums.net/threa...a-transmission

if you pull the tranny keep in mind you'll need an alignment afterwards cause you removed the sub frame.

ive had to do both these jobs, engine out seems much easier to me.

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