Coolant leak

Asked by Sep 22, 2017 at 10:34 AM about the 2004 Chevrolet Suburban 1500

Question type: Maintenance & Repair

I have a coolant leak that wasn't a hose, as they looked to be in good shape.  
I replaced the water pump and refilled.  Drove around, no problem, no leak
under it after we parked.  Came back this morning and there was coolant all
under the truck.  Could it be the bottom hose (which looked a little swollen),
or the expansion tank?

This only happens when the truck is parked and off, or at a very, very long
idle (hour or so because the wife had it at idle for 20 minutes picking up the
kids from school and this did not happen).

7 Answers


which side and where. is it under passenger side front? under oil tank? little more info please

That's the thing, I can't pinpoint where it's coming from. It is definitely under the passenger side front somewhere.


check under the carpet on the passenger side? just pull it back and see if it is wet anywhere? that would be a heater core if it is but also look at the connections going into the fire wall on passenger side. do you notice your windshield you having to defrost it more?

I'll check the firewall, but inside is dry and we have never needed to run the defroster except in deep winter (Louisiana here).


ok, i am hoping it is not one your freeze plugs on side of motor. one thing you can do is rent a coolant pressure tester from autozone, they give the money back so its basically free. hopefully you will here and see it leaking after you put it under pressure

Thanks for your help, Luvmychevy! I HAD to drive to Dallas today, keeping an eye on the temp gauge the whole way. Made 3 stops with no leaking or temp increase. Got to Dallas and let the truck rest for an hour and came back to dry concrete! I think I overfilled the expansion tank last night after switching the water pump. It's the only thing I can figure. I put almost 4 gallons of fluids.


no prob, i can only suggest problems to look for. its hard when you do not have the vehicle to look at and inspect myself. glad it all worked out. holler if you have any more questions!

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