New Member, Lack of heat...

Hello everyone, I just joined up, so first I'll say hi! :wave:

I just purchased an '88 Limited Edition, power everything, security system, Full-Time 4WH, Part-Time 4WH, and Part-Time 4WL, blah blah blah, and it's my third XJ.
I'm having an issue with the heat, because, well, it's not really heated... It's a few degrees warmer than the outside air; just enough to barely defrost the windshield if I let it warm up for 15 minutes or so.
I searched the forum, and found some good tips, but none that really apply to my particular situation, except maybe a clogged heater core.
- The engine reaches operating temp in the dead center of the gauge, and it's full of coolant. I might need to burp the system, but I don't believe it's severe enough to cause a consistent lack of heat.
- I verified the blend door is moving properly by watching the end of the cable, as well as hearing the slight *thunk* as the door closes at each extreme.
- I verified the vacuum controlled solenoid on the heater line is operating properly.
- Both heater lines seem to feel warm, but seeing as how that's kind of relative, they may not be as warm as they should be, so that's why I'm here.
Before I start on the quest of pulling the core, do any of you have any other suggestions of areas to check?
Thanks so much for your time and assistance!

Welcome. I too have a 1988 limited. Almost every topic you can think of (including yours) has been covered in detail at some point on this forum. Using the search function can help you to acess this information. Here is a "how to" on searching http://www.naxja.org/forum/showthread.php?t=80053

There are many things to look for with your heating problem, thermostat, heater core, blend door, vacuum lines, etc. The best thing to do is search, and through process of elimination, find your problem without throwing parts at the problem. Good luck.

I'm not sure how your situation is different?

Have you flushed the core as outlined in various posts? Personally, I would try this before pulling the core.

88 Wagonman said:

Welcome. I too have a 1988 limited. Almost every topic you can think of (including yours) has been covered in detail at some point on this forum. Using the search function can help you to acess this information. Here is a "how to" on searching http://www.naxja.org/forum/showthread.php?t=80053

There are many things to look for with your heating problem, thermostat, heater core, blend door, vacuum lines, etc. The best thing to do is search, and through process of elimination, find your problem without throwing parts at the problem. Good luck.

Click to expand...

As mentioned in my very first post, I have already searched the forum, and I've already read many posts concerning no heat. I have also already read the how-to on advanced searching. I realize you probably get a lot of new members that seem to be incapable of reading & research, but I am not one of those members, hence the reason I outlined the troubleshooting steps I've taken so far. So I'm guessing that means you don't heave any other suggestions?
I hate to sound like an a-hole on my first post in this forum, but I think that you could have taken a little more time to read my post rather than just throw an answer at me which I already knew (and even stated that I already knew). Thanks anyway though.

Flush the core before you try to replace it. The heater in line should be as hot as the upper radiator hose. You gave a good description of your problems (unlike many). You should be able find the flushing info pretty easily, but I've often been unable to understand why searching is so difficult sometimes myself. If you need more on flushing, just go ahead and ask.

1.) Flush the core, back and forth, top to bottom, several times, alternating direction, independently of the rest of the system. If you've never done this before you should get gunk. If your core is even slightly clogged, you'll get heat, but not much. If your core is LEAKING, it'll need replacing.

2.) Make sure there is vacuum to the heater valve. I know that the pre-91's don't have the plastic heater valve but the metal one in the closed system is also vac actuated. If there is no vac there, fix that issue. Otherwise, I think there is a way to completely take that valve out of the loop.

3.) Replace the t-stat (195). Drilling two 1/16" holes in the t-stat flange, one at 12 o'clock, one at 6 o'clock should make the system self burping.

4.) Since it seems like you've already addressed the blend door issue the only thing left is hot water/coolant flowing through the core, key word there is FLOWING.

winterbeater said:

Flush the core before you try to replace it. The heater in line should be as hot as the upper radiator hose. You gave a good description of your problems (unlike many). You should be able find the flushing info pretty easily, but I've often been unable to understand why searching is so difficult sometimes myself. If you need more on flushing, just go ahead and ask.

Click to expand...

Hey, thanks for the input! I already have a flush kit that I've never used, which makes things easier, I just haven't had time to actually flush it yet... Plus the winter temps tend to restrain motivation... The reason I went straight for replacing the core is because in other vehicles, flushing has never really done much good for me, mainly because the previous owner decided to throw loads of stop-leak in the system... and it definitely stopped the flow, just like it was supposed to. Is there an effective and somewhat simple way to flush it with maybe some drano or CLR without ruining/causing corrosion in the rest of the system? I've got a small 12v sump-pump; what do you think of pumping a mix of water & drano or CLR just through the core, from a bucket with the sump pump?

Your flush kit will end up flushing the whole system, which is OK, but doing it directly would do the best for the heater core itself. If you disconnect the heater hose from the water pump (heater in), and from the thermostat housing (heater out), you can best flush the heater core. The crud came in from the water pump, so you first want to flush backwards (thru the thermostat hose). Once that runs clean, you can flush back and forth to try to break more crud loose. Don't use too much pressure though or you will end up replacing the leaking heater core. Then add in your coolant to the heater hoses before you put them back on.

Shouldn't need to tell you this, but the coolant is very poisonous to animals who like its sweet taste. This causes slow and painful death due to kidney failure. Please don't kill anyones pets.

OH, no caustics, just water.

winterbeater said:

Your flush kit will end up flushing the whole system, which is OK, but doing it directly would do the best for the heater core itself. If you disconnect the heater hose from the water pump (heater in), and from the thermostat housing (heater out), you can best flush the heater core. The crud came in from the water pump, so you first want to flush backwards (thru the thermostat hose). Once that runs clean, you can flush back and forth to try to break more crud loose. Don't use too much pressure though or you will end up replacing the leaking heater core. Then add in your coolant to the heater hoses before you put them back on.

Shouldn't need to tell you this, but the coolant is very poisonous to animals who like its sweet taste. This causes slow and painful death due to kidney failure. Please don't kill anyones pets.

OH, no caustics, just water.

Click to expand...

Got it. Thanks, I'll try to get motivated to do it when I get home from work today. :badpc:

The flush kit didn't work for me. I installed the T on the upper hose into the heater core after the coolant vacuum actuator, hooked up the hose and let it flush. I still didn't get any heat. I ended up taking it somewhere because I didn't have any more bottles to dispose of the coolant. They said a lot of junk came out of the heater core by disconnecting the hoses at the firewall and flushing it that way. At the time I didn't know that the Vacuum actuator was normally open, so If I would have applied vacuum to close that door, that would have forced more water through the heater core while flushing. I still don't get much heat when it's below zero, like around -25F, but above zero it's more that sufficient. I'm thinking of trying to make some valve so I can pull inside air like the recirculate function on newer models when it's that cold.

Not recommended to remove hoses at firewall as this is the weak side.

if you have an air compresor you can blow out the heater core with low air pressure all you have to do is remove both heater lines blow through the inlet side and block the out let with your thumb and releace the pressure repeat several times thats how I got my heater core cleaned out after it sat in the woods for 7 years and my heater works great