Heater Core Hell.....there and back again.
Wow, it's been a long time since an update on the DD. Life, the Wife, a SAAB convertible, and building my auto hobby workshop have gotten in the way of further refinements of the 940 (now disguised as an S90).
I knew some time ago that the heater core had failed on the beast....had the dreaded white fogged windows that just wouldn't clear even on defrost, missing coolant, and that sick sweet smell. To boot, the cabin of the car always had another rather "funky smell" that I couldn't ID.....suspected it was from the PO's chain smoking wife stuck in the headliner. I made it thru the winter of 2012-13 without heat in the car, and then drove it right thru the summer & fall of 13. When winter 2013-14 arrived in Georgia, it came hard and cold...... I decided this repair could wait no longer. Once I got the first couple rooms in my basement car shop relamped and insulated, I decided it was time for the dreaded heater core replacement. I'd previously bought an all metal heater core, so that was on hand.
How bad is it? The BB experts say the 7/9 replacement puts the 2 series heater job to shame....plan on 20+ hours if it is your first one. I knew there was no avoiding this....the 9 is destined to be my DD for many many years to come, in all seasons. In we go.
FWIW, anyone who takes on this task, print the Brickboard 7/9 Maint. Pages writeup on how to R&R the heater core. Their explanation is excellent, and will guide you past the pitfalls.
I removed both seats.....for the reason of easier access to the heater, and another motive. You can do the job seats in situ, but I don't recommend it unless you like pain and contortion. You need all the room you can get. I'm not detailing the whole process, but you will get the overall scope from these pics:
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Coolant leakage is evident:
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Getting closer to the beast:
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After many hours & pictures, we arrive at the bugger:
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Now the replacement heater core gets a JB weld reinforcement; OE is brazed here:
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Heater core cavity cleaned out with new seals to force air across the core:
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While in, I decided to use Gary's heater core valve upgrade, using the NAPA 4 way valve. I'll link the thread from maintenance to detail the whole deal. In short, the NAPA valve always allows head coolant to flow back to the waterpump suction pipe.....the OE valve used on the 7/9 is a 2 way, and closes under certain "cabin climate control" conditions. Here is the valve installed:
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Finally, the new heater core (matrix) installed and pressure tested. Unbelievably, the damn thing leaked!
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I've learned the hardway to TEST new parts before you button it all up. Perhaps the wrestling of the in/out pipes of the core thru the firewall caused the input side to break at the solder joint.....or it came out of the box bad. Doesn't matter, it must be fixed before I button this up! I soldered the joint to restore the seal:
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I won't bother showing the rebuild and restoration of the interior....just suffice to say I had 20+ hours in the job. Of course a repeat would go much better with the discovery now done.....but I sure hope to never have to do this task again. Heat has been restored to the beast, and the completed car smells much better inside after all the old coolant soaked pads & carpet have been removed. Much better.