Coolin 'n stuff

Ok- I have a couple Q's. I have been reading all the past months posting on cooling (a hot topic...) I almost blew up my engine a couple years ago when my water pump broke and now I'm totally paranoid about overheating. I've replaced the radiator but never the t-stat. I've never checked my running temp but it sure feels hot. I know they run at 210, maybe I just dont know what that FEELS like. So I changed my temp sensor (it was broken) and ended up breaking the electrical connector. Got new one from junkyard but..now although my temp light flashes constantly my electric fan is on all the time..is this ok? It sure feels like it runs a little cooler, although louder.
Other Q's: exactly What K & M (?) Air filter should I get to replace my current stock (and old) one? I've heard there are a few options for the 4.0, whats the best? Also, I've heard of people cutting holes and putting vents in the hood of the XJ- is this ok to do? Finally, if I have to knock my starter with a hammer to start it, what is going on and how to fix...?
Thanks for any help- this site rules.

I would say if your fans running all the time then you are hot,cant remember exactly but 220* should kick on fan automatically ?The first mod I did when I got my jeep was the gauge swap,you got to get rid of the idiot light setup.Keep hitting the u-pull-it's for gauges.

as for the starter keep hitting it

seriously your hanging up in there ,drop it an clean it out ,it might have many miles of dirt or rear main leaking oil might have gummed it up.If that dont work new might be in order,their a spendy part

The filter is a K&N... I have it one on my rig and can check part #'s when I get home. For what its worth if you look it up through them I only have the one that is a direct replacement for the ruglar filters. The flatty rectangle one. I don't know what the other guys are running, probably cone or snorkel or this setup. I have given serious consideration to a cone filter setup (probably fabed by me see no reason to buy a "tube" off someone.) The only thing keeping me away from it is the fact that the last two times I have been wheelin' I met up with some mud that spotters said I was "fine hieghth wise just power it through" and the next thing I know when I am airing up, I always check over stuff, I come to find mud and what looks like muddy water that dried... all over the bottom of my air box. I Have yet to think of a way to prevnt things like that with a cone. Maybe I need a snorkel! haha.

Okay...

K&N: K&N Air filters kick some ass! You can get a panel replacement for yoru current filter, it will fit in the air box and still be better than stock. Personally though I'd go one step further and get an air tube for it. Various parts houses have them, or you can make your own. If you live in an area with smog checks hold onto your old air box, you will have to use that for smog checks. Also, get a pre-filter (it's just a little black sock you slip over the cone), that way when you go out and play in the dirt you don't gum up your filter. K&N's are lifetime filters, all you do is take them out and clean and recharge them when they get dirty (they have FilterCharger kits).

Thermostat: The best way to go with a thermostat is 190° OEM (as in bought from the dealer). If you over heated the eingine awhile back I would change it for good measure. It's a simple change and not very expensive from the dealer. Do not get a cooler one (There are 180° and I believe something like 165° ones), these engines run best at their proper tempature, if you go lower than that you will have less power and bad fuel economy.

Electric Fan: I'm not sure when your fan should be coming on since you have a 1991. But I wouldn't worry too much about it being on as long as you're not getting hot. Personally I run mine all the time (I wired a bypass switch in), just because I'm paranoid.

Hood Vents: If you want to put them in there is no problem with doing this, I can't tell you how much they will help because I haven't done it, but a lot of people swear by them.

Starter: I'd go out and get a new starter, yours is going south on you. You don't want your starter to fail on you! It's simple to change out the starter (Disconnect the battery first!) and your XJ will be happy with a new one. (Jeep's are a lot like women, if you don't get them presents often enough they get cranky and don't, umm, take you anywhere. )

If you have any further questions do not hesitate to throw them up here.

Sequoia

Truckee,

Sounds like you got the temp sensor in the head is for a "temp gauge" not the one for the "idiot light". There are two temp sensors so make sure you buy correct one for your XJ - gauge or light.

When you change the temp sensor in the head you can face you XJ down hill then begin to fill the radiator, do this with the engine off. Any air in the system should come out of the temp sensor hole. Sometimes air can not work it's way out of the block. You don't have to change the sensor to do this but was suggesting a way to kill 2 birds with one stone.

I agree with what Sequoia said but want to add an over looked components to the list.

First, the fan clutch for the belt driven - mechanical - fan. The clutch wears out over the years and there is not 100% accurate test to determine if it is servicable or not. It may look like it is turning but it may not be moving air. Take off the fan clutch and take it to the parts store, make sure the one you buy looks like the old one, not taller or else you may have problems installing it. Read Craig H's write ups, they will tell you alot http://www.olypen.com/craigh/tech.htm

I recommend installing a new Mopar 195F themostat and a new radiator cap. They both work to keep the cooling system at the right condition.

I would avoid cutting holes in the hood, there alot of aerodynamic science for placement of hood vents. What you and I think would work well may work at idle but at highway speeds may cause problems.

I am confident your XJ can run at the right temperature buy replacing some components. You should not have to modify any chassis components to have it run right.

On the air path through the engine a K&N will give you more air in but your XJ of the age you may want to install a new cat converter first. They do wear out, create back pressure. A guy posted on here in the past month how replacing the cat solved his engine running hot problem.

Martin

The aux fan on 91-up should come on when the engine controller sees the temp sensor in the t-stat housing is around 219*F. The fan will run all the time if the wire to the sensor is open, unplugged, or corroded.

A new 195*F t-stat is cheap enough to change. I am running a 180*F one but do not expect it to run cooler with a different rated t-stat.

martin is probably right you may have gotten a sensor for the gauge instead of a switch. It it on the driverside of the cylinder head near the firewall.

Either get a new/rebuilt starter or take it apart and clean or put new brushes in it. The engine oil gets inside gumming it up.

Starter sound like it may have a couple of dead spots on it. Replace it.

K&N filter, there are two sizes, take your old filter in with you and measure the difference, if the XJ one is too small try one for a dakota, they are a bit bigger and won't fall into the air box.
I just pulled mine on sunday to do it's cleaning and have it sitting here in front of me ready to go back in, part number on it is 33-2018 and it fits my 98 perfectly.

Air vents, you really want the vent for slow speed crawling, to my way of thinking a vent that you can open and close is the best solution, Jeep installed them on the 360cuin ZJ or grand cherokee in 97/98, 5.9L, these vents are temperature controlled and are expensive from the dealer, you can ID the ZJ's that have them from behind, they have a gold colored V8 insignia on the tailgate.
Some of the experimental aircraft companies make V shaped vents called a NACA vent, that can open and close using a cable assy. Cost on those is around $80 ea in white gelcoat fiberglass or a bit more expensive in graphite composite, they sit recessed and kind of look like one of the vents used on a Z28 or Trans-am firebird.
Here are some links:
http://www.racerpartswholesale.com/naca.htm
http://www.up22.com/scoopw3.htm

thanks

Thanks everyone for the info. I got a new starter soon to be installed, the proper temp sensor as well. I may try to put in some sort of bypass on the electric fan though- I kinda liked knowing it was on. My cat is original and never looked at- can they be serviced or must it be replaced?

Again- this site rules!

- TJ

RichP said:

Air vents, you really want the vent for slow speed crawling, to my way of thinking a vent that you can open and close is the best solution, Jeep installed them on the 360cuin ZJ or grand cherokee in 97/98, 5.9L, these vents are temperature controlled and are expensive from the dealer.

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What ?. The stock 5.9L ZJ ones are just plastic and where did you get the idea that they are temperature controlled ?.

Re: thanks

truckeejeeper said:

My cat is original and never looked at- can they be serviced or must it be replaced? - TJ

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The cat can only be replaced. Usually they loosen up and rattle (or from trail damage). They can also need to be replaced if the smog testing indicates high emissions.

The two 360CuIn ZJ's I looked at had a controlled vent from the factory on the passenger side. The only difference I noted on the ZJ was that it had a Gold V8 on the back liftgate. One was in a dealers showroom that I looked at while I was having the airbag controller relocation recall done. The other one was at paragon.
However, you have my attention, that means that there is a factory non controlled vent out there, I wonder if it has the water channeling setup like I have seen in Chevy Z24's....

Ok after a search I found out that the 98 ZJ hood louvers are not temperature controlled. I did find someone else that thought the same thing on another board and I stated the same thing there. They consist of two parts a louver and water shield tray. The louvers originally were ordered by paint code to match (list price was $342) but now only come PAR (paint as required). The part #'s are 5014536AA and 5014537AA with list price $163 each. The water shield part #'s are 56022284AB and 56022285AB with a list price is $34.50 and $29.75. Also all 5.9L ZJ's used silver 5.9L Limited emblem on the hatch. The gold emblem you describe sounds like the one used on 93-95 ZJ's. Here is an article describing the hood louvers.


January 19, 1998 Design News

Patented part adds more zip to Jeep engine

Detroit--At a quick glance, buyers probably won't spot the difference, but the 1998 Jeep Grand Cherokee's new 5.9l V8 features a plastic component that helps make the vehicle's performance even more impressive. The part: a molded functional hood louver assembly.

The assembly resulted from a coordinated effort between Jeep-Truck Engineering and the Interiors & Molded Products Div. of Cambridge Industries, Inc. (Madison Heights, OH). Consisting of two molded parts--louver and water distribution tray--the assembly keeps the engine cool while allowing zero water intrusion. Chrysler considered the combination unique enough to be patented.

The louver, which requires extremely high heat performance, is injection molded from Amodel®, a 33% glass-filled polyphalamide from Amoco Polymers, (Alpharetta, GA); the water distribution tray is produced from Minlon®, a polyamide/mineral resin from DuPont Engineering Polymers (Wilmington, DE). The louver nestles into laser-cut openings in the metal hood. The tray design and material cost-effectively disperse water to the outboard side of the hood.

The two-component assembly combines design engineering skill with production expertise for optimum performance. The louver material, processed at 625F, offers high heat resistance without distortion or sag.

Cambridge Industries served as the Tier I supplier for the project primarily because of its performance on the louver for the Dodge Viper. While the Viper component provided only air distribution, the engineering assistance and production quality insured the timely, appropriate response required for the Cherokee project, Pat Muldoon, Project engineer, reports. "Most important," Muldoon continues, "the performance requirements-- including zero water intrusion--were met, with considerable part cost savings."

Very cool design and function, but darn thats alot of money. I wonder what I was looking at, some kind dealer add on. I was not aware of the XJ heat problem really untill the following summer. I didn't worry about it the first 2 years I had it.
I think I'm going to spend some more time looking in yards for a trashed ZJ hood and might even cruise a couple of body shops in the area.
I was looking at an old, ~51, pickup truck, hot rod, the other day, chevy I think, it had a pop up vent in front of the windshield, closed weather tight, about 8-10" long and about 4" wide, opened from the inside with a choke cable kind of setup on the dash from what I could see. Also had a screen built in to keep stuff out. I like that it closed tightly. I've been fiddling around with some drawings trying to come up with some kind of a slide opening vent using some extra flashing from the roof we just had put on the house. I hope I can come up with something, when I got home the other day and popped the hood a minute or so after shutting it off it was like walking into a 200 degree sauna.

RichP said:

I was looking at an old, ~51, pickup truck, hot rod, the other day, chevy I think, it had a pop up vent in front of the windshield, closed weather tight, about 8-10" long and about 4" wide, opened from the inside with a choke cable kind of setup on the dash from what I could see. Also had a screen built in to keep stuff out. I like that it closed tightly.

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Rich, you're not old enough. Up until the mid-to-late 50's all cars had those, but they weren't for the engine compartment. That was the fresh air intake for cabin air, and it was ducted directly to a heater box that hung under the dash and above the transmission tunnel. The ones on Hudsons had a lever to open and close -- I don't think a choke cable would work in both directions..

Sure, but how about one or two of those on the hood