Coolant leak. . . HELP!!!

[Shaffsduramax]

Well, let me try and make this short and sweet. . .

So last week i started my truck in the driveway, it ran for about 15 min. Came back out of the house and it was pushing coolant out the over flow tube. Shut the truck down and decided i would try and replace the cap since that was a cheap fix and ive had problems like that before. Well, that was not the problem to say the least.

I noticed the truck would stay at 160degrees for like 10-15 min while driving, then all of the sudden shoot up to like 210, so i shut the truck off and started back up 30 seconds later. . . truck ran fine the whole way home, about 10 miles and stayed at normal operating temp. I decided to replace the thermostats and that seemed to fix that problem, but the problem im having now is anytime im under load like going up a hill or something, temp jumps up to almost halfway on the gauge, and now i seem to be loosing coolant somewhere in the back of the motor. It drips right at the bottom of the bell housing where it and the engine attach. It isnt really a major leak, but it isnt small either. The drips are about 3 seconds apart when they hit the ground. I am completely lost at this point.

Any Help or suggestions on this one guys? I was told to check the coolant line to the turbo, but i didnt seem to find anything when i did that.

I have also tried opening the bleeder screw ontop the thermostat housing a few times, when running the engine and when shut off to see if i could get any air out of the system. . . i have got some air out, but nothing major and now it just seems to be coolant.

Sorry for the long post, but figured id better give all the info i had. I hope this doesnt cost me a fortune!!!

[IdahoRob]

"pushing coolant out the overflow tube" is a sign of head gasket leaking. Need to get the system pressure checked.

Good luck, hope it's something minor.

[Gibson]

Hey, if your truck is leaking coolant from the back of the motor and its not coming from the top there is a plate between the trans and engine, which coolant passes through from head to head. There is o-rings that seal this to the back of block this also holds engine rear mainseal. Not a fun job to repair,trans,frontdiff, both pieces of oilpan all have to come out to repair. Make sure its not leaking up top. This is not fun job.. I have done 2 of these now.... Sorry for the good news.

[Shaffsduramax]

That def. sounds like that has to be my problem. I can not find any other places that this is leaking from up top. . . Everything is dry. Also, seems like there may be just a hint of oil w/ that coolant, nothing major at all, just a very small amount. So what your saying makes a lot of sense. Do you know if there are any DIY posts about this. I need to take my trans out anyways, ive got a slow tranny leak from the pump seal that ive needed to drop the tranny for some time now to replace. this would be a great time i guess. Is this job just a pain, or is it a hard job. Im pretty mechanically inclined, ive done pretty much everything except rebuild a motor. Thanks for the info

[Gibson]

The job is just a pain. If you feel comfortable with pulling trans frontdiff and both pieces of oilpan its not to bad. The only real bad part is changing rearmainseal, you need a tool from the dealer. And a hoist makes the job better to. The ringgear is held on with 14 or17mm allen keys cannot remember which size for sure right now. Also there is a few other gaskets in there. So look at picture from the dealer to order gaskets and seals before you get going. Good luck if you give it a try..

[Shaffsduramax]

hmmm. . . . that really does sound like a pain in the a$$

[FLCBRXX]

Ok, I just had my truck fixed for this problem on my 2007 and this is what GM told me.

I was told that I was the 108th problem like this. But the truck would run just like you said and then jump to 210 and above in a second. Cooland was full the day before and then empty the next day when I took it to the shop.

First remove your radiator cap from the jug and start the truck. If coolant flows back out the cap it is your EGR cooler, it has ruptured internally and coolant is going out the exhaust. The pressure from the exhaust is pushing the coolant back out the rupture and out of the reserve bottle. That is what GM told the tech to do and if it did that then the cooler needed replaced. Got the truck back yesterday and it is running like a new one.

Hope this helps everyone.

[muddinredneck730]

not trying to hijack a thread, but i changed my thermostats a month ago and just yesterday it started leaking coolant out the overflow tube. its like the 2nd thermostat doesnt want to open or something. anything?

[FREIGHTTRAIN]

josh look at the last time they were on this thread the last post was 2007 a lil old

[Toypuller]

Either injector cup is cracked, or headgaskets. Either way they are both out when you do headgaskets. Good luck, those kind of suck to do.