I have a recuring problem with the heater on my 86GT. I am on the 4th heatr core and it is leaking also the water lines under the car are starting to have leaks replacement are not available. Does anyone have a FIX? Open to sugestions.

4 heater cores over 30 years is almost reasonable, but my car is on #2. Either you are buying junk heater cores, or something is wrong with your coolant. Are you using just water?

[This message has been edited by Gall757 (edited 11-02-2020).]

Jack, I found copper/brass heater cores at Rock Auto. But, like everyone else's aluminum cores, they are about 1/4 inch short. Best thing is that they are new copper/brass and I think solder probably takes better to that than aluminum.

quote Originally posted by Gall757: Are you using just water?

That's what I was wondering.

quote Originally posted by Gall757: Are you using just water?

Yes or Even weak coolant, < 50% Coolant, can cause problems.

Electrical problems can kill coolant parts too as coolant tries to be a ground to whatever.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
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Using a coolant mixtture and have started adding tablets to cut down on electrolis. Recommended for the 4.9 auto.