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An idea on improving the XJ's heat

Jeepguy03

Jeepguy03

NAXJA Forum User
Location
Connecticut
2000 XJ 4.0L/AW4 117k miles

Where I live in CT the winters can be a bit chilly. Yesterday the temp was around 18*. My cooling system is basically new, with a 195* thermostat, new hoses, pump, 3 core radiator, etc. I've confirmed the thermostat works, and flushed the heater core until it was clean. My heat has never been hot in the Jeep. Right now its warm, but not hot.

Even in the summer, my jeep never gets above 202*. I think this is due to the 3 row rad, and the fact that I removed the entire non-functioning A/C system including the condenser, which probably helps flow more air through the rad.

My question is: Would removing the mechanical fan in these winter months provide slightly better heat since the jeep may warm up faster? I barely hear my mechanical fan in the summer, and with a short 15 minute work commute I doubt it will help during winter. Any ideas? I'm curious to see what the outcome will be. My e-fan also never turns on during the summer unless I idle for a long time in a parking lot.

I have a scan gauge II so I can post the temp comparisons if anyone is interested.
 
i would cut out a piece of cardboard and partially block off the radiator. I used to do this when i couldnt afford to replace my thermostat. basically just cut some away if it gets too warm
 
I could do that too. It runs right at 206* or so on the highway and the heat is a bit warmer. Around town its a little cooler. Maybe I will get some black cardboard and put it behind the grill so it won't look so redneck. :viking: I should also mention my fan clutch is stock. The hottest my jeep gets according to S.G. II is 211* if I floor it up a long hill. Then the T-stat opens and its at 198* again.
 
Cardboad on the RAD is the best way to take care of it. Can't go wrong at all. easy to adjust and cheap. That and you aren't screwing with anything that can get expensive.
 
If your temps are that low for the duration of winter, I know ours are, just pull the mechanical fan all together.

I am running dual electrics, but my temps don't hit over 205 to kick the primary on unless I am idling in the garage... any airflow causes the needle to drop to ~175.... plenty to keep my tootsies warm.
 
Corprin said:
If your temps are that low for the duration of winter, I know ours are, just pull the mechanical fan all together.

I am running dual electrics, but my temps don't hit over 205 to kick the primary on unless I am idling in the garage... any airflow causes the needle to drop to ~175.... plenty to keep my tootsies warm.
Click to expand...


I spent the winter of 2002 in Waterbury. I did not have dual electric fans at that time. What I did was to remove the mechanical fan and did not have a problem with heating or over cooling unlike when the mechanical fan spun all the time the engine was running pulling -30* air through the radiator.

If the XJ was to remain stationary for long periods of time with the engine running, the single OEM electrical fan would be more than adequate to keep high temperatures in check. Blocking the radiator in front of the mechanical fan would also help. This is not necessary if that fan have been removed.

This is based on personal experiance.
 
I have had the lack of heat due to air bubbles in the cooling system????
 
techno1154 said:
I spent the winter of 2002 in Waterbury. I did not have dual electric fans at that time. What I did was to remove the mechanical fan and did not have a problem with heating or over cooling unlike when the mechanical fan spun all the time the engine was running pulling -30* air through the radiator.
Click to expand...

^^^

I just reread my post, sorry about the confusion. I meant to just yank the mechanical fan, no need for a primary electric in cold temps. Bonus is... faster warm-up, higher overall temps for the heater, better fuel economy. I got 3mpg by pulling the fan and removing the roof rack cross bars :D
 
I don't have any cardboard at the moment (weird since I usually have tons). I'll try pulling the mechanical fan to see how that does. Faster warm up is what I'm looking for. My commute is 7 miles to work and by the time I get there, the heat is just getting warm. This weather is annoying because this morning was 21* but friday is supposed to be 55* and rainy. :flamemad:
 
Where I live in Colorado the winters can be a bit chillier.

Sometimes the morning starting temperature is -15F.

I have heat before 5 miles and the thermostat is slightly open and regulating temp at about 5 mi. (stoplights up to 40 mph) 2001 XJ. I don't have cardboard blocking the airflow, I haven't removed any fans. I do use an oil pan heater on a timer on those mornings but there's no indication of heat on the temp gage when I do. (It just cranks a bit easier than I would expect at those temps)

I suspect the problem isn't airflow thru the radiator. If your thermostat is working right and the temperature gage indicates 200F or so it could be lack of flow thru the heater core (partially plugged) or the air mixer door isn't moving to the full hot position in the cabin.

If you are getting full heat if you drive 10 miles or more then finding ways to accelerate the warmup would be helpful. Blocking airflow would help as would using a block heater or oil pan oil heater before starting.
 
2X_01_Jeeps said:
Where I live in Colorado the winters can be a bit chillier.

Sometimes the morning starting temperature is -15F.

I have heat before 5 miles and the thermostat is slightly open and regulating temp at about 5 mi. (stoplights up to 40 mph) 2001 XJ. I don't have cardboard blocking the airflow, I haven't removed any fans. I do use an oil pan heater on a timer on those mornings but there's no indication of heat on the temp gage when I do. (It just cranks a bit easier than I would expect at those temps)

I suspect the problem isn't airflow thru the radiator. If your thermostat is working right and the temperature gage indicates 200F or so it could be lack of flow thru the heater core (partially plugged) or the air mixer door isn't moving to the full hot position in the cabin.

If you are getting full heat if you drive 10 miles or more then finding ways to accelerate the warmup would be helpful. Blocking airflow would help as would using a block heater or oil pan oil heater before starting.
Click to expand...

What kind of pan heater do you use? I've seen those magnetic ones on Amazon.com but the quality seems to be hit or miss. I do get heat after 10 miles or so, or if I drive the jeep a bit more. My heater core has been flushed a few times and seems clean. Before my new radiator I used to get decent heat, but the jeep was also running hot at like 215-220* constantly. Now even on 95* days and idling my jeep never hits 212*. It doesn't run too cool either, since water temp never gets below 190*.
 
jeepkid03 said:
What kind of pan heater do you use?
Click to expand...

Wolverine 250W oil pan heater. It's a flat heating pad that can be slipped thru the horizontal slot under the grill then glued to the front portion of the oil pan. (I tuck the plug behind the license plate.)
It has a self-adhesive material (peel and stick) to stick it to a cleaned and roughened surface then you seal the edge with high-temp RTV. Can't put it on the bottom of the pan because the pan isn't flat - it has X shaped corrugation. But the front surface seems to work just fine.

I think it's better than a block heater because it has no gaskets to leak. (unlike the block heaters I've had on a Chevy and my '84 XJ which both leaked with age and can be difficult to reach for repair)

I should also mention that I have plumbing for a coolant filter on the return hose from the heater core and even with slightly reduced flow from that setup I can still get fierce heat out the vents on a -15F morning (driving 70 mph and about 15 miles downrange on the commute) I recommend the coolant filter too. Keeps crud from plugging the cooling system - and you'd be horrified to see the amount of crud the filter traps.
 
If you are confirming the coolant temps as being 190+ (indication that the thermostat is working correctly) I'd be wondering if the heater core (even after flushing) is blocked up or if the blending door isn't working properly and allowing cold air in past the heater core. The heater in my XJ is the best one in any of my vehicles (when the thermostat is working right anyways, which it sounds as if yours is). Generally mine is putting out full heat within 2 miles.
 
The heater core has been flushed multiple times. I used to have no heat when I first got it, now there is heat, just not great heat. My 1990 XJ could get the cabin so hot I had to crack the window. How could I tell if the blend door is stuck? Is there a better way to flush the heater core? I'm not familiar with the HVAC system on the XJ.

I did pull the mechanical fan and that did help a bit. It was also 38* out so if it gets colder then the heat might not be as good.
 
The heater in my 200 dollar XJ is stupid hot! Even when its on low it drives me to crack a window. I would recommend checking the blend door. I cant remember if it is vacuum operated or cable on your year. I know that my 85 was cable operated. Also if you want instant heat get a coolant heater/circulator like this one http://www.amazon.com/Kats-13100-Aluminum-Circulating-Heater/dp/B000BO8X9K.
They work pretty good to a point once it hits zero or below they kinda just keep the coolant luke warm. Block and oil heaters are better for cold starting than instant heat
 
FWIW, I only have my stock electric fan and I don't have any problems staying cool during the winter or the 90+ degree summers. I have a champion 3 core and a stant 180 t-stat.
 
Glad I'm not the only one!
My situation is similar and has multiple symptoms:
Last summer I was overheating bad! I replaced: radiator, fan, clutch, thermostat, both hoses. water pump.
now the temp will never go over 160ish. tried 3 different thermostats 220*
it can idle for hours, crawl in 4x4 ir fly down the highway, it will never get warm.

all the hoses including the heater hoses feel like they are roughly the same temp after it gets as warm as it will get.

things I have tried. Cardboard......did nothing. new thermostats...nothing.....flush core....no change.

additional problems, the blower is just about shot any quick fixes? i know i have vacuum leaks and the heat/ac module is crap. but the biggest problem right now is the lack of warmth......it is cold here!!
 
I'm not sure about the whole "not getting up to temp" thing, but as far as the heater goes, I was having an issue with not getting enough heat unless I was on the hiway. It turns out that the blower motor was going out. Now it is toasty once the engine heats up.

I have a short 7 mile commute as well. On cold mornings I just let the Jeep warm up for 10 minutes. No worries. I also have my suspicions about the OEM temp gauge. I kind of feel like it really has no clue what it is saying. I honestly wouldn't trust a reading from it.
 
My engine is definitely getting up to temp. I've verified the temp a few different ways. My blower motor works fine. Since flushing it out before seemed to help, I'm going to try and flush the heater core again myself. I had a shop do it before. Any products that are recommended or should I just use the Prestone rad flush?

When I first bought the jeep about 3 years ago it overheated due to a clogged up radiator, so I don't doubt that the cooling system might still be dirty even after a few flushes while I've owned it.
 
My issue is someone bypassed the vac. Heater valve thing on my heater hoses and idk if directing it thru the heater core first will do anything, even as I were my jeep right now see's the line below the 210 mark which seems pretty cold IMO, I myself want more heat, I think I'll try the cardboard trick first and see how it goes. Anyone know the best way to run the heater hoses and still have the bottle up top? I have a mostly stock besides lift and tires 89 xj 4.0 auto btw
 
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