Hi everyone, I have a 1987 XJ that I switched over to an open cooling system awhile back. Heater has never blown hot, just kinda warm. I flushed out the heater core twice and both times had some pretty nasty stuff come out. Heat improved some but not much and eventually went back to just blowing slightly warm. Im sure the whole block can use a good flush, thinking the water pump may be restricted as well with all the junk floating around in there and im also guessing the heater core keeps getting full of junk because of the nasty stuff sitting in the block as well. Ive seen some videos of replacing the heater core and im really trying to avoid that mess of tearing the whole dash out. Does flushing the entire system and replacing the water pump seem like a reasonable option to try before considering a heater core replacement>
thank you
thank you
Yes I would try flushing the whole cooling system and flushing the heater core again. Water pump is a maintenance item and not a bad idea if it is suspect. Does it still have the heater control valve? Is it working? Is one hose HOT and the other cooler?
You could try CLR or some other kind of chemical flush on the heater core, or blasting it out with compressed air, but theres always the chance you will end up springing a leak if you get too aggressive with it.
You could try CLR or some other kind of chemical flush on the heater core, or blasting it out with compressed air, but theres always the chance you will end up springing a leak if you get too aggressive with it.
Quote:
You could try CLR or some other kind of chemical flush on the heater core, or blasting it out with compressed air, but theres always the chance you will end up springing a leak if you get too aggressive with it.
Originally Posted by 89Laredo
Yes I would try flushing the whole cooling system and flushing the heater core again. Water pump is a maintenance item and not a bad idea if it is suspect. Does it still have the heater control valve? Is it working? Is one hose HOT and the other cooler?You could try CLR or some other kind of chemical flush on the heater core, or blasting it out with compressed air, but theres always the chance you will end up springing a leak if you get too aggressive with it.
heater control valve has been removed. One line does feel warmer than the other. It eventually warms up but not quite hot like the radiator hoses
I just did a cooling system rebuild on my 88 MJ last week and have a couple ideas.
For context: About 24 months ago I converted to open loop. Swapped radiators, capped the top port of the coolant reservoir, and drilled a vent in the cap. After that, i didn't have great heat.
I changed my heater core 18 months ago, it lasted 12 months before leaking (Amazon Spectra 93024). I went the last 6 months without heat, then just replaced the core, radiator, and all the hoses last weekend, I'll list parts below. Now it works 100% perfect.
What's interesting:
1. the new heater core didn't fit worth a heck in the HVAC box. The spectra was pretty bad, but the one I put in last weekend had an even bigger gap. It came with a strip of foam, but it only covered maybe 1/4 of the gap. I ended up stuffing it with fiberglass insulation around the edges of the heater core, but would have rather used thicker foam if I'd had it on hand. After installed I still had to bend the tubes pretty good to get it to poke out the firewall straight.
2. The air blend door inside the box was pretty sticky, so the first time I did the heater core I cleaned and lubed all the vacuum controlled air vent doors and the cable controlled air blend door. After cleaning and lubing I can slide hot to cold with 1 pinky and it sets the door tight in hot or cold position, and the vent selection all works correctly.
3. My original brass radiator only had 1 pinhole in it. I took it to a radiator shop thinking it was worth repair, but the guy basically said for the cost of repair I might as well buy a new brass one for $300 and to junk it.
4. The second time I did the heater core I was able to complete the whole job in about 4 hours. I'll outline that process below.
5. I've had issues with my temp gauge bouncing between 180 and 210. On the highway it takes about 2 minutes to climb to 210, then the tstat opens and it drops fast to 180, then slowly climbs again. It was so bad it would sometimes put me back in open loop mode while going down the highway. I've tried multiple thermostats, including the vented, unvented, two leg, three leg "OEM replacement" and none of them helped. While i was cleaning the shop last week i found an old OEM one with the ball bearing bleeder hole, tested it, and put it in with the rebuild. The temp barely moves now, and it holds steady in closed loop mode.
6. The heater hoses seem backwards but are correct. The hot water from the t-stat housing goes through the larger hose into the top of the heater core, then back to the water pump through the smaller hose on the bottom. In this configuration bubbles have to get pushed down to escape, but mine seemed to bleed out just fine with only 1 test drive.
How to do the heater core with minimal disassembly:
Take the knee panel off, let the wiper delay dangle and unhook the parking brake release (if bench seat)
Take the defrost vent cover off and then the 4 screws that hold the dash (not all of them up there need to come off, you can tell which with close inspection). I use 18" of drill extensions on my impact to reach them easily.
Pull the plastic panels from the a-pillars by your feet to get access on both sides, a few phillips screws.
Loosen the two bolts that hold the bottom of the dash to the A pillars, they don't have to come out all the way since the dash can "unhook".
Remove the 2 nuts holding the steering column.
Remove the little nuts from the firewall that hold the air box in, 5 or 6 of them, the innermost two being behind the motor. Might want to lube them first since the other end of those studs just screws into the plastic airbox and come out pretty easy.
Disconnect vacuum lines and heater hoses where they pass through the firewall
Lift the driver side of the dash about 2-4" and hold up with a helper or bungie straps, this just keeps it from binding when you lift the passenger side.
Disconnect passenger door wiring and FM antenna connector. Toss the spring if you still have it in the FM connector.
Lift the passenger side of the dash as high as you can without breaking anything and hold it with bungies or a helper. Should just about reach the top of the door frame.
Reach up and unplug the vacuum connector from the back of the HVAC controls. Unhook the blend air door cable at the air box.
In this state, the whole airbox can wiggle out under the dash without removing anything else. The entire dash stays assembled.
Remove the airbox, split with 2 screws and 1 clip to access the heater core. Clean, replace the core, lubricate mechanicals. Make sure to seal it up good.
Install is reverse.
Here's the list of parts I used:
Radiator: ULTRA-POWER 1193 - quality seems fine but the filler neck touches the core support so a cap can't go on without trimming the core support (which I did)
Heater Core: OSC 98024 - Build quality seems fine. Absolutely terrible fit. I thought I was going to crack it getting it in.
Upper radiator hose: GATES 21821 - This is the short one for no A/C. Kinda hard to find sometimes but Rockauto has them.
Lower hose: GATES ?? - Same for all of them, easy to find. Came without the internal anti-collapse spring so I cleaned and re-used the old one.
Heater Out: GATES 19038 - this is the smaller pre-formed line from later years without the valve
Heater In: GATES 19039 - This is the larger pre-formed line...
Coolant: Yellow "Universal" antifreeze and distilled water as suggested by the guy at the radiator shop.
@Mlopez I hope this helps.
For context: About 24 months ago I converted to open loop. Swapped radiators, capped the top port of the coolant reservoir, and drilled a vent in the cap. After that, i didn't have great heat.
I changed my heater core 18 months ago, it lasted 12 months before leaking (Amazon Spectra 93024). I went the last 6 months without heat, then just replaced the core, radiator, and all the hoses last weekend, I'll list parts below. Now it works 100% perfect.
What's interesting:
1. the new heater core didn't fit worth a heck in the HVAC box. The spectra was pretty bad, but the one I put in last weekend had an even bigger gap. It came with a strip of foam, but it only covered maybe 1/4 of the gap. I ended up stuffing it with fiberglass insulation around the edges of the heater core, but would have rather used thicker foam if I'd had it on hand. After installed I still had to bend the tubes pretty good to get it to poke out the firewall straight.
2. The air blend door inside the box was pretty sticky, so the first time I did the heater core I cleaned and lubed all the vacuum controlled air vent doors and the cable controlled air blend door. After cleaning and lubing I can slide hot to cold with 1 pinky and it sets the door tight in hot or cold position, and the vent selection all works correctly.
3. My original brass radiator only had 1 pinhole in it. I took it to a radiator shop thinking it was worth repair, but the guy basically said for the cost of repair I might as well buy a new brass one for $300 and to junk it.
4. The second time I did the heater core I was able to complete the whole job in about 4 hours. I'll outline that process below.
5. I've had issues with my temp gauge bouncing between 180 and 210. On the highway it takes about 2 minutes to climb to 210, then the tstat opens and it drops fast to 180, then slowly climbs again. It was so bad it would sometimes put me back in open loop mode while going down the highway. I've tried multiple thermostats, including the vented, unvented, two leg, three leg "OEM replacement" and none of them helped. While i was cleaning the shop last week i found an old OEM one with the ball bearing bleeder hole, tested it, and put it in with the rebuild. The temp barely moves now, and it holds steady in closed loop mode.
6. The heater hoses seem backwards but are correct. The hot water from the t-stat housing goes through the larger hose into the top of the heater core, then back to the water pump through the smaller hose on the bottom. In this configuration bubbles have to get pushed down to escape, but mine seemed to bleed out just fine with only 1 test drive.
How to do the heater core with minimal disassembly:
Take the knee panel off, let the wiper delay dangle and unhook the parking brake release (if bench seat)
Take the defrost vent cover off and then the 4 screws that hold the dash (not all of them up there need to come off, you can tell which with close inspection). I use 18" of drill extensions on my impact to reach them easily.
Pull the plastic panels from the a-pillars by your feet to get access on both sides, a few phillips screws.
Loosen the two bolts that hold the bottom of the dash to the A pillars, they don't have to come out all the way since the dash can "unhook".
Remove the 2 nuts holding the steering column.
Remove the little nuts from the firewall that hold the air box in, 5 or 6 of them, the innermost two being behind the motor. Might want to lube them first since the other end of those studs just screws into the plastic airbox and come out pretty easy.
Disconnect vacuum lines and heater hoses where they pass through the firewall
Lift the driver side of the dash about 2-4" and hold up with a helper or bungie straps, this just keeps it from binding when you lift the passenger side.
Disconnect passenger door wiring and FM antenna connector. Toss the spring if you still have it in the FM connector.
Lift the passenger side of the dash as high as you can without breaking anything and hold it with bungies or a helper. Should just about reach the top of the door frame.
Reach up and unplug the vacuum connector from the back of the HVAC controls. Unhook the blend air door cable at the air box.
In this state, the whole airbox can wiggle out under the dash without removing anything else. The entire dash stays assembled.
Remove the airbox, split with 2 screws and 1 clip to access the heater core. Clean, replace the core, lubricate mechanicals. Make sure to seal it up good.
Install is reverse.
Here's the list of parts I used:
Radiator: ULTRA-POWER 1193 - quality seems fine but the filler neck touches the core support so a cap can't go on without trimming the core support (which I did)
Heater Core: OSC 98024 - Build quality seems fine. Absolutely terrible fit. I thought I was going to crack it getting it in.
Upper radiator hose: GATES 21821 - This is the short one for no A/C. Kinda hard to find sometimes but Rockauto has them.
Lower hose: GATES ?? - Same for all of them, easy to find. Came without the internal anti-collapse spring so I cleaned and re-used the old one.
Heater Out: GATES 19038 - this is the smaller pre-formed line from later years without the valve
Heater In: GATES 19039 - This is the larger pre-formed line...
Coolant: Yellow "Universal" antifreeze and distilled water as suggested by the guy at the radiator shop.
@Mlopez I hope this helps.
Quote:
That's what I did. Use Irontite Thoro flush coolant system cleaner, but it on Amazon.Originally Posted by lawsoncl
You might just need to keep flushing the core back and forth until it runs clean.
Quote:
Originally Posted by lawsoncl
You might just need to keep flushing the core back and forth until it runs clean.
both times I flushed both lines until clear. Thinking whatever crud is in the rest of the system is clogging up the core. This why I’m thinking a complete system flush may be needed