summerst

Had some problems with the defroster on my 1991 the last two months. Steamed the windows up pretty good when in use. No antifreeze smell though. Noticed today that I am leaking small amounts of antifreeze underneath the car on the passenger side behind the front wheel. The heater core was replaced in January 2007 (about 3K miles ago) by a Chevrolet dealership. The core they used is referenced on the receipt and appears to be a GM Part number (19131989). I took it to them back then because I had antifreeze dripping on the passenger side carpet. WHEN I CHECKED THE CAR TODAY I FOUND THAT THE CARPET IS DRY. I understand that the new core may have developed a leak but its weird that there is no antifreeze inside the car. Could these symptoms point to the slim possibility that one of the heater hoses is leaking where it connects to the heater core and, if that is the case, could that problem create the steamed windows (by leaking antifreeze into the heater box) and be the reason I am seeing antifreeze on the ground behind the passenger side front wheel instead of inside the car?

LoneStarV

To trace a small slow leak take some paper towels and wrap them around the connections where the hoses meet your core. If they don't stain your core has probably gone south on you.

WW7

It starts off steaming the windshield, it ends up dumping coolant on the carpet.Check the clamps where the 2 hoses hook to the core in the engine bay, but I believe for it to be fogging the windsheild the core has to be leaking in the casing under the dash......Sorry....WW

summerst

Thank you all for the input. I guess that I am fortunate that the service advisor at the dealership that replaced the heater core back in 2007 is still there. My '91 goes in Monday for a determination. I will keep you advised of the outcome.

Purple92

IF you want to try to figure it out yourself, you have a couple of options:

1) Get a hold of a Cooling System pressure tester (you can buy one - or some of the chain Auto Parts stores have them in their loan a tool program). With the cooling system topped off, pressurize the cooling system to about 10 psi, and see if the system holds pressure. If it doesn't see if you can see where coolant is leaking. Can you see (or sometimes hear) anything oozing from the firewall where the two heater hoses connect ??? If so - try tightening or replacing the clamps, or you could try removing the hoses from the connections - cutting an inch or so off the hoses, and reconnecting them.

2) Many of the Better auto parts stores sell a flourescent dye that you can add to a cooling system. It should run less than $5 for a small bottle (a couple of ounces). Add a bottle to the cooling system and drive around for a while. Then after driving for a while, wait till dark, and look under the hood with a blacklight. Any coolant leakage will be quite obvious. Don't see anything under the hood - look under the dash.

It's never a bad idea to have a good idea about where the problem is BEFORE you talk to the dealer or the mechanic. The more you know - the lower the probability that someone will be successfull at putting one over on you.

GOOD LUCK !!!

summerst

Turns out that it was the heater core. Dealer said that GM doesn't make the heater core anymore (I guess that is good considering the last one installed by the dealer was a "genuine" GM part and lasted less than 3K miles! The dealer said that he had to get the heater core from Corvette America. They had the car for a little over a week. Total for the repair was $750 with the 10 percent discount that they gave me for having to do the same repair job twice. The good thing is that everything works and my son, who drives the car, is happy he is back in his own wheels (he drove my "hot rod" 1990 Corvette in the interim).