Still no heat, and I've had it. - Page 3

car5car · 12-07-2008, 10:20 AM

I don't understand how light plastic air door can be stuck? Maybe vacuum motor stuck? The only reason I can imagine it can happen if there is a dead rat inside! Do you smell it?
One more thing to keep in mind-there are plenty of morons among auto mechanics, so don't trust them too much. Make some kind of heat inside Jeep so you can work, like electrical heater and do it yourself. Good luck.

wantabe23 · 12-07-2008, 10:52 AM

personally one of the main reasons I like to fix my own stuff, is that once I have fixed a problem, for the most part I learn how that peticular system works, and I know what I have (like if its in good shape or will need to be replaced soon). I really dont like getting new/used vehicals, then I have to start the hole process of getting to know my vehical again.

I have an 87 xj that has needed a lot of fixing, and it is a lot of work from time to time, but when I compare it $ wise to buying a newer modle, and haveing payments on it, high insurance and such is just does not make sence. I also dont like it when I have no other choice to trust a mechanic I dont know.

So I would say fix it your self or with a friend, learn something in the process and then you can say that you won the battle.

car5car · 12-07-2008, 11:13 AM

Quote:

Originally Posted by wantabe23

fix it your self, learn something in the process and then you can say that you won the battle.

Good one!!!

kadetklapp · 12-07-2008, 11:55 AM

Ok, I'm at the shop now (I work part time as a wrecker drive for an auto repair/24 hour towing and recovery service, so I have access to a warm shop and limited tools during off-hours) and I just spent the last hour and half flushing the system again, this time after using the Prestone system flush. Some nasty water came out, of course, but it's still a lot cleaner than back in October. I have a question:

With the truck running, I popped the LOWER (skinny) heater core hose off, and got a nice, even, steady flow from the heater core. The big hose, upper, is the INLET, right? Because with the upper (fatter) hose off, and the skinny hose on, I got no flow from the core.

If the big hose is INLET, then I've got adequet flow thru the core, because it was running out perfectly.

Ed Rico · 12-07-2008, 12:17 PM

I'm not looking under the hood at the moment, but from what I remember, the lower tube is the inlet to the heater core. This makes sense to me based on the skinny/fatter hose sizes since it wouldn't be good to have an inlet larger than the outlet (could lead to heater core "ballooning"). In any case, the hose coming from the thermostat housing goes to the heater core inlet and the hose to the water pump is the heater core return if you want to double check.

From what you describe, it sounds like your heater core is plugged.

-Ed Rico

kadetklapp · 12-07-2008, 12:40 PM

Bigger (upper hose) goes to thermostat, smaller (lower) hose goes to Waterpump....

210000cherokee · 12-07-2008, 02:03 PM

Is there only 1 blend door in the heater box? I am having the same problem with mine. I have changed the waterpump, t-stat, coolant lines, and heater core while I had the heater core out i checked the blend door by the heater core and it seemed to be working correctly. Also the fresh/rec door is working correctly I have evan tested for a bad headgasket. I am lost at what to do from here.

superbeeman69 · 12-07-2008, 02:55 PM

Not to thread jack here, but im having similar problems. Ive got all the same symptoms, so ill list mine just a compairsion. kadetklapp is the pressure building up in your rad too? If i take off my rad cap at operation temp the coolant is pouring out and stone cold. Lower rad hose has pressure, upper one doenst. New theromostat as of today. Both heater hoses are warm.

Sat night im driving home and its surging between blowing hot and cold. So i found it was leaking out at the overflow hose by the rad cap. Almost home and the guage says its overheating. Understanbly upset cause its overheating and blowing cold air! After i put in the new T-stat today, i have my lukewarm heat back but its still leaking coolant which is prolly why it overheated. Again, ill replace the overflow hose but the bigger problem is finding out why the lack of heat, like you kadetklapp because it was never leaking before. I have yet to backflush, but given the responses so far, it might be more than buildup.

kadetklapp · 12-07-2008, 03:21 PM

I'm not getting an inkling of warm air, ZERO. HOWEVER, it's not COLD outside air blowing, meaning that the blend door is stuck on the cold side but the warm side is cracked open enough not to freeze me to death.

I still need to know if the bigger, upper heater hose is inlet.

Ed Rico · 12-07-2008, 03:37 PM

Just checked under the hood of my '97 XJ and can confirm that the upper hose is from the thermostat housing and is the heater core inlet. I didn't measure the hoses but if it's a larger diameter than the lower hose, it isn't by much.

-Ed Rico

210000cherokee · 12-07-2008, 03:39 PM

The bigger hose is the inlet off the t-stat housing. the waterpump sucks the water threw the lower house. As the way i understood it

kadetklapp · 12-07-2008, 03:41 PM

Sweet Jesus Mother of Mary, if that's the case then my heater core is fine

So, that leaves the blend door/easy fix with "Heater Treater." I'm going to go get drunk now....

**TallyZJ** · 12-07-2008, 04:08 PM

A heater core doesnt have a valve that prevents water from flowing backwards through it. You should get flow no matter which way the hoses are installed.

It is designed for hot water to enter the top of the heater core and let gravity aid the water to travel down to the lower outlet.

kadetklapp · 12-07-2008, 04:50 PM

It flows backwards with a garden hose, it's fine.

There is no water pressure going that direction when the upper hose is off, and lower hose is on. Hence, nothing would come out the top port. It flows both directions freely when I use a garden hose on upper or lower.

**TallyZJ** · 12-08-2008, 07:57 PM

That would have to do with water pump and a bypass issue. If you have an open line, the hose you pulled off the core inlet, then the system may not be able to produce enough internal pressure to push the water through the core.

The heater core isnt inline with water flow exactly. If your supply hose to the heater core is pinched off coolant/water will simply bypass the heater core and continue to flow water through the engine and radiator. The heater core is sent water only if the system has produced enough pressure to first flow the engine and then the excess will push some water through your core.