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Bad Heater Core?

Jeeperz83

NAXJA Forum User
Location
Illinois
Hey guys, the answer to this is probably obvious but I want to double check before I begin the work. On my 2001 XJ Sport, when I turn on the heat or defrost I get the smell of antifreeeze immediately until its almost overwhelming. I assume the heater core sprung a leak and is leaking into the heater box or vents?? I have looked up under the dash on both sides and checked under the hood but I do not see a leak. I am assuming it is just leaking into the heater box. Am I right or could it be something else? I need to fix this ASAP as the fumes make me sick just driving 5 minutes to work and its getting pretty cold to have the windows down. Thanks..
 
that sounds like what it is...
i popped my heater core in my '90 (long story...) and i smelled it way before i saw it puddling in the passenger floor.
when you aren't using the heat there's a heater core bypass valve that opens or closes to kinda help the A/C work more efficiently.....so when you turn the heat on, coolant starts flowing through the heater core...and so on...
 
I remember a 99 taking one of our techs 6 hours, the whole dash had to come out, then he broke a bunch of heater controls, hopefully my 89s better when the time comes
 
8 hours labor on that, have the evaporator done at the same time, they are also a problem in 97+ XJ's.
 
bcmaxx said:
I remember a 99 taking one of our techs 6 hours, the whole dash had to come out, then he broke a bunch of heater controls, hopefully my 89s better when the time comes

That tech is a MORON... I did this on a 99 with basic tools, it took about that long, and everything went fine and it all works. Interior work is not the place for clumsy idiots.
 
yeah we put him on flat rate from straight time, he didn't make it long
 
having put my time in a shop, you're gonna get boned to have someone else do it.
we had to pull a dash on an older grand cherokee for an evaporator and the bill ran about $1100 or so.
this was at a precision tune autocare.
i'm not so certain on '97+ models...but i know pre '97s are cake.
i've pulled the dash on my '90 twice now....2 hours and some change...in and out.
first time to clean out and check leaks on the evaporator, second time for the heater core
 
zukimike said:
RichP, know a good price on an evap? 99 XJ

I was going to have my evap done at county who is our club sponsor for bmja for $900 but it's a 90 min drive there, drop for a day, then drive back to get it. I'm picking up a 98ZJ limited next week and will be taking my XJ over to my friends shop where I can work indoors and will be doing it myself when I get time. I just [knock on wood] thank god it wasn't the heater core, no AC I can suffer thru, I just use the TJ :D when it gets that hot. The wife has already taken ownership of the bright red 97ZJ I picked up last weekend and in no uncertain terms either.
 
i believe my freind also had a bad heater core (90 xj sport), it blows air in defrosters and down to feet. however, its not warm air, does anyone have a how-to on how to do this? we dont really want to pay someone else to do this and its getting cold outside (35F ATM). the heater core is inside the passenger side dash correct?
 
Serveck said:
i believe my freind also had a bad heater core (90 xj sport), it blows air in defrosters and down to feet. however, its not warm air, does anyone have a how-to on how to do this? we dont really want to pay someone else to do this and its getting cold outside (35F ATM). the heater core is inside the passenger side dash correct?

Sounds more like the mixing valve. Is the 90 an open or closed system, does it have a turtle on the firewall or a plain old overlfow tank ?
If it's the mixing valve in the engine bay they carry them in the parts store, the temp control is done with a cable on the slider and there is vacum involved too.
Might want to pull the two heater core hoses and flush it out with some water and a garden hose, see what comes out. Then go from there.
 
wow, i thought it was going to be an involved process to fix the heater, it turned out to be as simple as spraying the lever (connected to the cable under the heater core) with some wd-40 and giving it some elbow greese. problem solved. :p
 
Serveck said:
i believe my freind also had a bad heater core (90 xj sport), it blows air in defrosters and down to feet. however, its not warm air, does anyone have a how-to on how to do this? we dont really want to pay someone else to do this and its getting cold outside (35F ATM). the heater core is inside the passenger side dash correct?

even tho you already fixed it...i just kinda wanted to voice this issue i had with heat in my 1990....
(also...if you don't have coolant leaking inside the passenger area, thats a pretty solid sign that your core is still good...maybe clogged or other, but no holes)

RichP- the 1990s are the last of the closed systems.

but, i have a "chronic" no heat problem now thats actually a vacuum issue. the right-angle boot that hooks the vacuum line to the heater core by-pass valve. the valve is closed (to by-pass the core) when pressure is applied.....and the boot has a habit of "sucking" itself to the valve, so when pressure is released when i turn the heat on, the boot stays stuck to the valve and i never get flow through the core unless i pop the hood and pull the boot off.
kind of the same principle as when you make a drinking straw "suction" to your tounge or lip.....

im actually using the old valve off my 1989 because the 1990 was plastic and broke.....so the boot on the 1989 could have been different to avoid this problem *shrugs*

just figured i'd throw that out incase someone does a search for this problem =P
 
KinesthesiaDrums said:
even tho you already fixed it...i just kinda wanted to voice this issue i had with heat in my 1990....
(also...if you don't have coolant leaking inside the passenger area, thats a pretty solid sign that your core is still good...maybe clogged or other, but no holes)

RichP- the 1990s are the last of the closed systems.

but, i have a "chronic" no heat problem now thats actually a vacuum issue. the right-angle boot that hooks the vacuum line to the heater core by-pass valve. the valve is closed (to by-pass the core) when pressure is applied.....and the boot has a habit of "sucking" itself to the valve, so when pressure is released when i turn the heat on, the boot stays stuck to the valve and i never get flow through the core unless i pop the hood and pull the boot off.
kind of the same principle as when you make a drinking straw "suction" to your tounge or lip.....

im actually using the old valve off my 1989 because the 1990 was plastic and broke.....so the boot on the 1989 could have been different to avoid this problem *shrugs*

just figured i'd throw that out incase someone does a search for this problem =P

I *think* though I have not seen that the newer replacement valves in the parts stores are metal vs plastic, being a closed system I don't really have that much experience living with one as all my jeeps are 97+ models.
It's snowing out now and I still need to replace the tstat in the ZJ we just picked up, it's running cold loop with a stuck open stat and at $3+ a gallon that sucks...
 
darjevon said:
ACKits.com has one for 78. AutoAirPlus.com has one for around the same.

What I would like to know is who makes the best one, cheap is NOT the way to go when that much labor is involved, I want to do it ONCE and then never have to again. I'll take a $200 one that will last 10 years + over a $100 that might not...
 
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