overheating (Kinda long)

[Dingo509]

Before i get yelled at for this let me give you a history:

91 XJ 4dr. 233K 4.0 aw4 with a/c
In order of install per item
2 Radiators a stock 2 core and currently a gdi 3 core
3 water pumps 1 mopar, 1 cheap rebuilt, currently new aftermarket
6 thermostats mopar, 4 aftermarket 2@180, 2@ 195, currently mopar
2 heater valves, both mopar
2 t-stat housings both mopar, currently hand ported
all hoses have replaced at least twice

Fan setup went from stock electric and mechanical to dual electric (1 stock 1 flex-a-lite 110) to dual flex-a-lite 110

Other mods 99+ intake swap, 60mm throttle body, donaldson airbox rated at 350 cfm, 98 5.2L durango injectors

I have pulled the head and it checked and machined flat (.007 max is .006)
I can drive it just fine if the temperature is below 60 otherwise it overheats
Mainly on the freeway, i can sit idle in traffic at over 100 ambient and it runs below 200 all day. it also overheats very fast when pulling steep grades, at any speed or ambient temperature.

Ive been fighting this for 3 yrs. now and basically can't drive it in the summer.
Any ideas?

Dingo

 

[Dr. Dyno]

Since your engine overheats on the highway and when climbing steep grades, the first thing I would think of is a clogged radiator. The problem is, you've already replaced it so I'm inclined to think of something that's not related to the cooling system itself i.e. engine running too lean under load.
Your injectors are probably a bit marginal since they only flow 20.8lb/hr at 39psi. I suggest you build a MAP adjuster and increase the MAP voltage above the stock 5.0v to hold the injectors open longer and richen things up a bit. It's a cheap fix and it might just work:

http://www.angelfire.com/my/fan/MAP_adjuster.html

 

[Sarge]

You don't specify what you mean by overheating. I only ask cause I've seen folks here claim their XJ is overheating when it was 210 or a wee bit over that. Is it boiling over? Hitting the red zone? The Dr is probably on the right track as it seems to happen under load.

Sarge

 

[RichP]

Just an aside here because of the electrics. The fan shroud is often overlooked as a really necessary item. The fan pulls air in thru the rad, the reason the fan is set back where it is makes sense if you think about it. The fan creates a vacumn inside the fan shroud, this pulls air evenly thru ALL the fins on the radiator. The mechanical fan handles about 50% of the fan square inches, top to bottom on one side of the rad, the electric side is not normally cooled by a fan pulling air, as the temp goes up and triggers the electric that covers the other 50% of the rads surface. The factory electric is not the most efficient due to its closeness to the rad surface but moving it futher away might even out the flow and pull more air over the areas it does not cover.
All the electrics I have seen sit either a hairs breadth or a 1/2 inch away from the radiator and leaves alot of the radiator not covered which creates hot spots in the rad itself. Most of those aftermarket fan shrouds do not cover and seal the rad surface like the factory shrouds.
Realistically the factory mech fan and clutch are really not running at hiway speeds, the mechanical is more or less moving air out of the way of the incoming air at hiway speeds.
The lean condition is a possiblity and should be looked at, the other thing I would do is put a 7 hour flush in there to remove scale from the passages, the scale that builds up from using normal tap water over time can and will act as an insulator so that you might not be getting enough heat transfer as the coolant flows thru the block.
I've seen this happen before, back in my navy days on the subs we used to make our own air and fresh water with sea water thru a distiller plant, we had to de-scale the flask on a regular basis and the stuff that came out of seawater was amazing when processing 500 gallons a day.
Just some ideas...

 

[Planetcat]

I replaced all the same things you did but not as many times, ran one flex a lite 110 + OEM electric fan, still overheated. I concluded (no proof though) that the 3-row rad (new Modine) didn't work for my setup because I had both the AC compressor and tranny cooler in front of it. By the time the air hit the 2nd and 3rd rows of the rad, it was already warm. So essentially, I thought it performed like a 1-row with very small diameter tubes. I installed a 1-row aluminum radiator (http://www.alumrad.com) with very large tubes and ripped out the flex a lite fan, replaced fan clutch with a fixed spacer from summit racing, and added water wetter. Now I can tow my 3200# boat in 100* temps all day long without even getting over 210*. The aluminum rad was something like $150 and fit like a glove. You might want to do the scaling flush first, 'cause you're probably sick of replacing parts. I also did hp mods thinking that would help, but it didn't. Before that, it boiled over constantly and soared engine temps to 260*. I dont' think the water wetter helped, but I like Redline products.

 

[Dingo509]

As far as defining overheating if i pull a continuous grade for like 5 mins it will boil over. if i let it i usually pull over pop the hood and let it run for a while then it will cool down and i can continue.

I have built a map adjuster however i have not had time to install it yet.
Dr. Dyno you said the injectors flow 20.8@39 psi is that the stock injectors or the 5.2 injectors?

As far as the electric fans go the Model 110 is a 12 fan mounted in a square "15"x13.5" i think" shroud with weatherstrip around the edge to seal it to the radiator. as the rad core is 31" x 11" i fabbed a aluminum bracket both top and bottom of the rad to help "seal" the fans to the radiator.

I really appreciate all your help so far. And i hope i don't sound like an unthankful ass from this last post but i need all the help i can get and if that means you need more info so be it.

Thanks again
Dingo

 

[Dr. Dyno]

As far as defining overheating if i pull a continuous grade for like 5 mins it will boil over. if i let it i usually pull over pop the hood and let it run for a while then it will cool down and i can continue.

I have built a map adjuster however i have not had time to install it yet.
Dr. Dyno you said the injectors flow 20.8@39 psi is that the stock injectors or the 5.2 injectors?

That's for the 5.2 injectors. The stock '91-'95 4.0 injectors flow 21.0@39psi so they're almost the same. The thing is, you've increased airflow to your engine with mods so it could now be running lean.
You said the coolant boils over. If the pressure cap on the radiator is working properly, the coolant should only boil over if its temp. reaches 250+*F. If your gauge isn't in the red when it boils over, you need to replace the radiator cap.

 

[trashedxj]

ok it sound really dumb but heres a temperary fix(ie fixes the prob. for a short time) i had a celica over heat all the time and the other day for the first time ever my xj was extending the red zone, (i.e. if this is the temp guage cold. . . . .mid. . . . .RED this was mine . .RED. . . . bout here! heres what i do when the temp goes bout mid way from mid to red i turn the heat on full blast!!! hey it works!! oh and i gotts a magazine bout heat, the xj because of the way the inline's are they produce more heat than most racing v8's!!! i recommend hood louvers aint that mush, a nice set is bout 100-150 bucks and cut the holes in the hood drill little ones around it and pop rivet the louvers on then just paint the hood again to the same color!!! louvers according to the studys in my mag reduce the overall heat my as much as 37 degrees at some spots(temp readings were taken from 15 places while engine was running!!!

 

[rsalemi]

I would go with the "too lean" condition producing more heat than the cooling system can handle. Because it can run at low speeds without overheating (where most XJ's have a problem) its not cooling system related.
Either go to larger injectors - 24# mustang or 53030262 MOPAR (95 ZJ?) or turn the map adjuster up to 5.5 volts and test it - running with more fuel should solve the problem - then invest in the larger injectors.

 

[boise49ers]

I had a similar problem for about 2 years and found after changing all the above that the little hose that comes out of the bottom of the tank(closed system) That hose was clogged at about 80 percent not letting the coolant circulate very well. Also check your clutch on your fan. If it is hot turn it off, if the fan turns by hand the clutch is bad and it isn't working to draw air at hi-speeds or RPMs.
Good Luck I know it is a Pain dealing with Cooling problems.

 

[Dingo509]

i've been thinking about the lean condition too
i thought the 5.2 injectors were bigger whoops!
I have got tholes cut in the hood and have run with the heater on. at about 90 ambient with the heater on full i can run about 20 mins before it's in the red.

With the 99 intake, the bored T/B and the borla header is that really enough to make it overheat that bad?
I pretty good at fixing stuff but i got half the shops in town puzzled too.

Thanks again i'll try and install the MAP adjuster this weekend and let everyone know what happens.

Dingo

 

[blaisetd]

Not sure if your jeep has the same cooling system as mine, a closed system, but converted it to open. I found this article and it worked great.
http://www.madxj.com/MADXJ/technical/technicalfiles/JTopenSystemSwitch/OpenSystemSwitch.htm

'90 XJ 4.0 auto trans

 

[jeepsrock]

I would get rid of the electric fan and put in a replacement fan clutch...that seems to work the best on these engines. Additionally i would convert it to an open system if its currently closed.

pete

 

[Dingo509]

update......

The system is closed but i am thinking about relocating the rad cap to the upper hose as this (in my system) is higher than the stock cap location on the radiator.

As far as it being to lean, i just got back from a test drive with stock 91 injectors. and the autometer ait/fuel ratio gauge. I noticed absolutely no difference with either of the injectors, and the gauge confirmed it. however the guage does occasionally dip into the severe lean condition and then stays there for almost a full second. but it does this only at steady road speeds, not when pulling a hill, where it reads stoich or slightly rich. as far as temp goes, with a 6 minute climb up a local road it had reached about 240 degrees. as soon as i come back down it cooled back down. This with an ambient of about 45 degrees. So i believe the cooling system is okay and it has to do with the injection system. But Im out of ideas. again. Am i still runnning to lean and the air/fuel gauge just a purdy light display or there something maybe im still missing.

Thanks
Dingo

 

[canadian-xj]

the autometer a/f gauge is nothing more than a pretty light show. It also will only read when u load the motor at wide open throttle. Most efi vechiles also ingore the 02's at wot. I would do a dyno pull to get correct a/f readings.

 

[themud]

i've been thinking about the lean condition too
i thought the 5.2 injectors were bigger whoops!
I have got tholes cut in the hood and have run with the heater on. at about 90 ambient with the heater on full i can run about 20 mins before it's in the red.

With the 99 intake, the bored T/B and the borla header is that really enough to make it overheat that bad?
I pretty good at fixing stuff but i got half the shops in town puzzled too.

Thanks again i'll try and install the MAP adjuster this weekend and let everyone know what happens.

Dingo

Hey thats what I did to mine k&n fipk with bored tbody headers and exhaust I could stand on it here in AZ from stoplight to stoplight and watch it shoot up at least 20-30* and freeway driving was much higher...super lean is the best way to describe whats happening to you I picked up hescos adj fuel pressure reg and it helped a whole hell of a lot...Now my only problem is getting the damn thing started it cranks and cranks and then catches and just kind of sputters for a sec or two the idles fine just like nothing happened...I might have either a vaccum leak(I didnt put a new gasket on when I changed the intake) or my fuel pump might be going on me...You could try the map adj first (its cheaper by far) put the stock injectors back in theyll be fine I had mine tested matched and cleaned they also ran them up to 65 psi and checked flow and they were still good...Ya just need more fuel its too damn lean...If you pick up this months jp the did the story on power upgrades and had the same problem as you...
luck
themud

 

[Dingo509]

Is there any vehicles that run 24# injectors stock? i was thinking about finding a set in a wrecking yard just to confirm the lean condition then buy a new set later.

Dingo

 

[FUNKYTEE5]

Is there any vehicles that run 24# injectors stock? i was thinking about finding a set in a wrecking yard just to confirm the lean condition then buy a new set later.

Dingo

All Ford 460's have 24's I think the SHO Taurus motor has them too?

 

[Gojeep]

You have a bad choice for fans there with the 110's. They only pull 1250 CFM which is not nearly enough. Should be at least 2000 CFM along with a 97+ stock electric to make it work. See my site for the write up. I run this combo in the Outback towing across deserts in deep sand with 100*F temps no problem at all. Just did another conversion for someone today and doing another next weeks as well for another as they work so well.
www.go.jeep-xj.info

 

[Dingo509]

got to thinking ( i know i shouldn't do that) but is it possible for the timing to change and the engine still run?

Dingo