Heater core leaking for 3rd time on '95 Blazer

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#21

03-29-2006, 07:29 PM

magtec

Join Date: Feb 2006

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RE: Heater core blew AGAIN... SOLVED, Though

shadowhawk, i feel your pain. haven't had to replace the heater core in my blazer, but i did in one of my lebarons (only once, though) -
http://magtec.rvglug.org/misc/lebaron/heatercore/

#22

11-10-2008, 05:18 PM

Psychropod

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RE: Heater core blew AGAIN... SOLVED, Though

Quote:

ORIGINAL: ShadowHawk

HEy all,

My radiator cap had the mechanical pressure overflow for the coolant to flow to the overflow tank... Well, I think the nechanism was not allowing the overflow to vent to that tank.. so as coolant temp increased in the radiator circuit, it expanded, and the weak point happened to be the heater core.. which has been springing leaks on me.

I checked the level of fluid in the overflow, and it wasn't necessarily high after a hard drive... so I changed the radiator cap.. and NOW I'm getting the proper overflow into the overflow tank. I hope my problems are solved, now with my heater cores... Lesson learned: When changing the coolant fluid or other coolant circuit items, check / change that radiator cap... it's cheap insurance for proper overflow. The heater core blowing was a symtom of another (cheaper to fix) problem.

Rex,

My heater core recently blew (mine's a '96). Six months ago I replaced the water pump and radiator cap, and did a system flush. I'm not completely understanding how the radiator cap could cause the heater core to blow. Do you think you could explain it again? I'm wondering if that's what also caused my problem. However, after looking at all your pix, I don't think I want to do this job myself, especially since the weather's getting cold. I may pay someone else to do it. LOL

#23

11-10-2008, 06:20 PM

ShadowHawk

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RE: Heater core blew AGAIN... SOLVED, Though

It's not specifically the heater core that may blow.. but simply - whatever the weakest link is in the coolant circuit. When the radiator cap fails to relieve pressure by allowing overflow to the reservoir.. pressure builds up. Most caps are designed to relieve the pressure at 15-17psi. If the cap fails to open, then pressure goes much higher, and then the weakest link will fail. In some cases, it's an old hose... in other cases, it's a weak spot in the heater core...

All I'm saying is that when you change the heater core, or flush the system, etc... it's probably good preventative maintenance to go ahead and spend $8 on a new radiator cap.

BTW - I've been running on my "bypass valve" for the last 2 years... and have never installed my latest heater core. The kids complained of being cold last week in the Blazer, so I'll probably go ahead and pull the dash again this week and do the change-out.

#24

11-12-2008, 01:50 PM

Psychropod

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Posts: 544

RE: Heater core blew AGAIN... SOLVED, Though

Okay...well, then that ticks me a off a little, because the cap is almost brand new. But then, I dont know if the heater core has ever been replaced on this truck, so my issue may well not have anything to do with the radiator cap.

Since I just finished rewiring my headlights again, my dash is already half out, so I might as well just do it myself. <sigh>

Thanks for the help.