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[jeff]

just wondering how hot do the heaters get in 4.0l xjs my heaters are quite crap in my facelift 97 4.0l.Things i have done , flushed out heater matrix about 5 times full flow going in and out, reversed flushed as well,Hi flow thermostat/hiflow thermostat housing/hesco hiflow waterpump,checked temperature heater control knob seems to be closing blend airdoor (can here blend air door opening and closing) blend door cable is tight ,air gets warm(not hot) out of drivers side vents but only cool air comes out of passenger side vents, Taken heater control panel cover off and all the connections electrical and vacum related seems to be okay. So my question to all you fellow jeepers out there with 4.0l engines is  How hot does your heaters get in the cold weather, Cause mine is crap!! Oh forgot to mention jeep cames up to temperature quickly and sits one digit under 100 on gauge when moving at speed then creeps up to just over 100 stationary then electric fan comes on , converted viscous fan to electric. Christ havent written so much since i was in school. Jeff

[Dave69]

my mk1 xj has no problem in warming up and the heat being given out is very good. on max heat i have to turn it down after 1/2 hr on the coldest of days, unless the wife turns it back up again

[micky57]

hi,
  just an idea but you could remove the back seat,giving you enough room for a small or a large fire depending how cold it is.
but dont forget to open a window fumes can be dangerous,good luck

[greggmo]

the high flow water pump and thermostat is the cause of your problems. both of these will cause the engine to run cooler as the stat opens wider it doesnt hold the water in the block for as long as normal. combined with high flow water pump and bingo...cooler heater.

[Dave69]

hmmmm

ive got std water pump and thermostat and housing and still get too much water flow giving me a constant temperature fluctuation from 80 degrees to 95 degrees, might consider fitting a blanking plate in the top hose return to the pump.
see link below
http://www.go.jeep-xj.info/HowtoRadiatorRestrictor.htm

other useful info
http://www.go.jeep-xj.info/HowtoWaterpump.htm


the rest of the site has useful tips as well and general information for the xj owner

[garyf]

Mine is a '98 facelift and the heater is superb, you couldn't run with it on hot for a long put it that way, far better than the one I had in my earlier XJ.

The slow to warm up bit is strange though especially with it running at the temp you say, within half a mile mine is upto running temp, same as yours 1 notch below 100.

I would check thermostat isn't sticking open this is the only thing that should give any problems with it being slow to warm up??? the heater hose outlet was clear on the new housing wasn't it, i'm sure it comes out of there directly but without checking I could be wrong.

Have you reverse flushed the heater matrix itself directly onto the heater connections on the bulkhead if not this may be worth a shot.

Hope this helps

[jeff]

Yes,I have reversed flushed the heater hoses a couple of times i get full bore through pipes, when the engine gets up to temperature flow and return pipes from heater are almost to hot to hold , I dont think high flow  
thermostat could be problem because it does the same job as normal stat it is the same temp setting as original so it should open and close the same keeping the hot water in block/heater for the same amount of time it just leaves more flow through to rad when it opens , The cool heater was the reason for installing high flow bits in first place thinking there would be more flow to heater it just has not made any difference heater is still crap Any more suggestions are welcome i am thinking it must be blend door  but i can here it closing and opening and i really dont fancy taking all the dash out just to find it is working.

[greggmo]

if you just run a hose through the heater matrix is there a good flow or does it slow the water? also check where the heater draws its air from. not sure where on a cherry but it might be a case of leaves bloking a vent or somethin daft like that mate.

[garyf]

Got to say it looks like you are going to have to take dash out to look in heater box, I have just changed heater matrix on one and yes it is a good job, I did learn the hard way though to cut a very long story short, totally stripped every bit of dash down, changed matrix refitted got all dash back together came to put heater switches back in (1 of last jobs) and hey guess what couldn't find the fan wiring , I had trapped it between the heater box and the bulkhead :idea: I removed the parts of the dash that I really needed to removed heater box, freed wiring and rebuilt it in less than 2 hours, well please .

Good Luck

[jeff]

garyf, You say you have recently changed the matrix, could you explain what needs to come off and what doesnt ,how did you manage with airbag,could i just strip off enough to check if the blend door is closing fully?cant understand why my heater is crap and everything appears to be working as it should

[garyf]

You will need to take heater box out fully to get into it I think, there are some screws down the bcak of the box that you can't get with out removing the full unit.

I will try and sit down later and write you a detailed list (lot of writing to get it nright for you) of what you need to take off,

the air bags all you need to do is disconnect battery and leave for a short while before disconnecting it. Believe you me the think won't or shouldn't go off on you.

Gary