2nd Gen Non-Engine/Transmission Clogged heater core options?

[Rhondasway]

My heater has not worked well in years though it defrosts and the blower works well. I need to troubleshoot the blend air door, but having blown a number of head gaskets and replacing a 90% blocked radiator because of oil it seems inevitable that the core is impacted too.

I have the motor out right now and am wondering if I should attempt the core removal (sounds like a major nightmare plus it's cold outside) or is there a cleaning option? I've tried flooding with pure hot water a few years ago to no avail. I mean, the water flows right through (both ways) but that doesn't mean it's not going around the fin area, right? If I did take it out, could it be cleaned or do I need a new one? If so, how much?

I'd appreciate any input. Keep in mind I will not leave my truck at a shop/dealer to replace it so my options are limited.

 

[georgej]

I would try cleaning the heater core,if oil contaminated, with a caustic cleaner such as "awesome" available at dollar stores. Pour some heated solution using a funnel into the core. When full clamp off the hoses and let sit for 10 minutes or so. Afterwards flush with hot filtered water. If the core is clogged with a calcium buildup try using heated white vinegar the same way. Please use goggles and good rubber gloves when doing this!!

When you replace the engine try going to a 190 degree t-stat and see if this doesn't help on those cold days.

Replacing the core looks to be the kind of job you want to do only once,and if necessary, some respected TDR writers suggest not to go cheap on a replacement core. Good luck

 

[Rhondasway]

Thanks, that sounds worth trying... I just cringe at the thought of tearing that thing apart, but it's silly to only have luke-warm heat. I think it's time for a shutoff valve to the heater core for competition purposes. Then even if I blow a head gasket it won't get in there.

 

[JMcCoy]

I would bet your heater core is just fine. I would check all your vacuum connections. Even the ones going to your transfer case and CAD. The door is probably not swinging all the way closed (or open). It couldn't hurt to clean it with something mild. CLR may also work. If water is flowing through it "freely", it is working. Mine was not working very good after I replaced the evaporator (the first time). I had a bad seal between the evaporator and the heater core. The cold wasn't very cold and the hot wasn't very hot. This was my fault though. Good luck.

 

[WestTN]

Defrosters are fedrerally required safety equipment, so they are spring loaded to assure defrost capability. Any failure in the control vacuum system will result in fulltime defrost.

 

[Rhondasway]

This is interesting...

Okay, so I plan to clean the core since I have to do a bunch of degreasing anyway. I will recheck vacuum lines.

What's interesting is the seal/evaporator situation. Excuse my ignorance, but is the evaporator the cylindrical unit by firewall that the tubes running to the front cooler go to? A couple of years ago I wrapped some reflective heat shielding around that as my turbos really crank out the heat right by it.

I also have crimped tubes from the last time I pulled the motor because I just pulled the cooler forward and backward several times... I would have thought that would just restrict flow for defrost effect, not heat, or leak the freon out. I'm not sure it could be related since the heat issue's been going on longer. Please tell me more! And thanks.

 

[JMcCoy]

Defrosters are fedrerally required safety equipment, so they are spring loaded to assure defrost capability. Any failure in the control vacuum system will result in fulltime defrost.

That makes sence. When I lost vacuum, I was stuck with defrost only (August in Florida).



Rhondasway, what you are refering to is the dryer. There is a large plastic box under the dashboard (mostly the passenger side). It contains both the evaporator and condensor. They both look like little radiators. After you remove the box, you have to separate it to remove the evaporator and condensor. There is a hot and cold side, divided by foam and seals. If It has never been taken apart, It is probably not the problem. Hope this helps.