heater core broken again

[SAAAAAC]

I have a 1999 GM and about two months ago the heater core started leaking. I had it fixed and everything has been fine until today. Its doing the same thing. Any ideas why this is happening? The only thing I noticed that might have something to do with it is, when I start the car and the heat is on, it will make a loud thud. It doesn't do it all the time and I think it only does it when its on blend. You can feel the thud too. Its kind of scary sounding actually......

Thanks

[4play]

Weird. All I can think of is your antifreeze isn't strong enough and it started to freeze or the heater core u got was defective

[Dan04Merc]

You paid a shop to do the work? Take it back...

[SAAAAAC]

ok so..... the heater core has broken for the third time. I've taken it back and my mechanic hasn't charged me, but he's tired of taking my dash apart and i'm tired of leaving the car there. So, any ideas? I read a thread somewhere about an after market stereo and grounding issues causing the problem. That last two times it broke I did upgrade my sub amp. My anti freeze is fine. So I don't know what to do. Here is the thread I found:

http://forum.sounddomain.com/ubbthreads.php/ubb/showflat/Number/350161/page/212/fpart/1

[fastblackmerc]

ok so..... the heater core has broken for the third time. I've taken it back and my mechanic hasn't charged me, but he's tired of taking my dash apart and i'm tired of leaving the car there. So, any ideas? I read a thread somewhere about an after market stereo and grounding issues causing the problem. That last two times it broke I did upgrade my sub amp. My anti freeze is fine. So I don't know what to do. Here is the thread I found:

http://forum.sounddomain.com/ubbthreads.php/ubb/showflat/Number/350161/page/212/fpart/1

Read all the posts.....

It's BS that your stereo is causing the problem..... That's the first time I've heard that and it's a load of crap!

Are you getting new heater cores or remanufactured heater cores?

[Blackened300a]

Did he show you where to other two failed? If its breaking in the same spot, I would blame the guy doing the installation for not using the proper padding or forcing it in. Also too much water in the coolant would cause it to freeze and expand the coils inside. A simple hydrometer test will tell you that you're fine for the lower temps.

[prchrman]

Did you see the old heater core? I have replaced many and have had 1 or 2 that were bad brand new. But I have also with my own vehicles just put in some stop leak and turn the heat on wide open and fixed it that way, which only lasts about 6 mons to a year.

I would like for him to explain how in God's green acre a stereo causes a cooling system component to go bad, love to hear that.

[BLACKMARAUDER04]

That loud thump was you blend door opening/changing positions.