Damn Air!

[Mudderoy]

As many of you know I've been fighting a "running hot" problem on the highway for years now.

I've made several modifications to the cooling system all of which have done wonders for low speed travel, but has not cured the running hot at highway speeds issue.

Conventional wisdom states that if you run hot at highway speeds there is a problem with the radiator being having a blockage, the lower hose collapsing, or not enough air flowing through the radiator.

I have replaced the radiator, the lower hose has been replaced several times, and it does have a spring. Many other mods have happened so I am back to the original things, air flow.

My latest attempt is to replace the mechanical fan with a high speed electric fan. My first attempt failed as I need to get more goodies to complete the conversion.

Conventional wisdom says that at highway speeds you don't need a fan. Well I can understand how a much higher speed fan might PULL more air through the radiator than what forced air may flow, but I still don't understand why at 70 mph not enough air is flowing through the radiator.

I think back to when I first starting having this problem. When I lifted and put on bigger tires.

I looked at this as more heat because of the larger tires, more heat generated by the transmission. More effort by the engine.

I added a 13k BTU transmission cooler, problem continues.

I was doing to general research into "runs hot at highway speeds" via Google search. I found several mention the air dam, various vehicles.

I don't have an air dam now. It was part of the front bumper that I replaced with the winch bumper. The air damn is that bit that hangs down from the nose and runs all the way across from flare to flare.

What if the problem I am having IS air flow because instead of the air flowing through the radiator it is being deflected above and below? Specifically not only because I don't have an air damn, but because the Jeep is 7 inches higher than it was originally.

The air dam would have the effect of causing the pushed air to collect in front of the nose of the jeep. It would have to go above below and to the sides, but the air pressure would increase on the nose forcing more air through the radiator.

I know several other people with XJs have the same problem I do. Has anyone resolved it? Have you seen anything with your problem that would point to or away from the air dam theory?

:popcorn:

[msmoorenburg]

got cardboard to play with???? I've seen that issue before on other rides. Whenever you want come up and we can test and tune :thumbsup:

[Mudderoy]

got cardboard to play with???? I've seen that issue before on other rides. Whenever you want come up and we can test and tune :thumbsup:

lol problem is I need to fix it before I take a long road trip like that! :smiley-laughing021:

[msmoorenburg]

lol problem is I need to fix it before I take a long road trip like that! :smiley-laughing021:

:shocker: take a lunch break half way :smiley-laughing021:

[ice_cold]

Every time you mention this, I look at the picture of your Jeep and wonder how air gets past those lights and everything out there?

This is just a thought, but think of what the front would look like in a wind tunnel...at slow speed the air probably tumbles over the top and the fans can draw the air in. Now at highway speed this "pressure point" will move back towards the cab as speed increases. Now the air is dumping some place on the hood and behind the radiator underneath. This might cause a "dead zone" in front of the radiator..ie. nothing for the fans to really pull in.

Its just a idea, but maybe try a scoop of some sort on the side like a ram air to take air from in front of the bumper and push it thru the radiator.

Mike

[4.3LXJ]

I have the same thoughts about mine Muddy. Although I can stay cool, it is marginal at higher speeds

[pvt.tadpolxj]

Hey Muddy I remember everybody discussing this earlier this year. I did Install a cowl piece onto my hood at that time and I am very happy with the result's. Air find's it's way up under the front-end and flushe's most of the heat out thru the cowl piece. It keep's everything under the hood a lot cooler..:driving:

[Mudderoy]

Every time you mention this, I look at the picture of your Jeep and wonder how air gets past those lights and everything out there?

This is just a thought, but think of what the front would look like in a wind tunnel...at slow speed the air probably tumbles over the top and the fans can draw the air in. Now at highway speed this "pressure point" will move back towards the cab as speed increases. Now the air is dumping some place on the hood and behind the radiator underneath. This might cause a "dead zone" in front of the radiator..ie. nothing for the fans to really pull in.

Its just a idea, but maybe try a scoop of some sort on the side like a ram air to take air from in front of the bumper and push it thru the radiator.

Mike

Yes I do understand the logic of this however please keep in mind that this didn't start when I added the bumper it was doing it, only worse when it was all stock with the exception of the lift, wheels and tires. PLEASE HEAR ME ON THIS.

LIFTED 4.5" WHEELS AND TIRES, 3.55 gears, etc... etc.. etc... running HOT at highway speeds.

[Mudderoy]

http://industryfigure.com/berkeley/Jeep/c4x4f/fwbflowers.jpg

This just feels right! :smiley-laughing021:

[Mudderoy]

http://image.automotive.com/f/features/10134149+pheader/0701or_01_z+1989_jeep_cherokee_xj_4x4_chill_pill+d irt_off_roading.jpg

What is the large piece of metal under the front bumper? A skid? Would this serve as an air dam as well?

[msmoorenburg]

Sorry gotta ask :thumbsup: How old is the fan clutch?

[ice_cold]

Yes I do understand the logic of this however please keep in mind that this didn't start when I added the bumper it was doing it, only worse when it was all stock with the exception of the lift, wheels and tires. PLEASE HEAR ME ON THIS.

LIFTED 4.5" WHEELS AND TIRES, 3.55 gears, etc... etc.. etc... running HOT at highway speeds.

Sorry, must have missed that in the post. I was under the impression it started when you did the mods.
So it is bad now but was worse when stock?
You have changed out just about everything in there that you can. Have you tried the GC fan swap?
I would be curious if the temp jumped around if you were able to go electric on the pump. It sounds like you have more than enough air flow, heck you could pull small animals thru the grill.:)
If its flow, I am sure you know, if the flow is to high, it wont stay long enough to be cooled off. Maybe try to slow the pump down...
Just thinking out loud here...

Also seem to remember that there was a issue on some FSJ, running to lean at highway speeds. Dont know what you can do about that.

[Mudderoy]

Sorry, must have missed that in the post. I was under the impression it started when you did the mods.
So it is bad now but was worse when stock?
You have changed out just about everything in there that you can. Have you tried the GC fan swap?
I would be curious if the temp jumped around if you were able to go electric on the pump. It sounds like you have more than enough air flow, heck you could pull small animals thru the grill.:)
If its flow, I am sure you know, if the flow is to high, it wont stay long enough to be cooled off. Maybe try to slow the pump down...
Just thinking out loud here...

Also seem to remember that there was a issue on some FSJ, running to lean at highway speeds. Dont know what you can do about that.

I'm already frustrated with a problem that has been going on for years. I got sick yesterday and I'm not feeling very well so I should probably ban myself from the board for a couple of days until I get better.

The problem was actually worse, and it is possible that I have resolved the original problem and introduced another with the winch and the lights, but I don't think so.

When everything was stock, except for lift and wheel/tires it would run all the way to the first hash mark past 210. I've learned the hard way that this is the danger mark at least for my XJ. In the past when I did have cooling system problems it would sit on that hash mark for a few minutes the BAM all the way over to the first hash mark in the red.

I've learned I don't want it close to that hash mark, so logically I've just been trying to get it to the normal level, just a hair under 210 hash mark.

Now I can drive 70 mph and it will creep up near the first hash mark past 210 but doesn't get there. 65 mph does maybe a hair's width better. So I have seen improvement with all the money and work I have put into the cooling system and cowl induction scoop.

I can drive 70 mph with A/C off and electric bypass fan switch on and it will run just above 210, which really is acceptable to me (being realistic) but not having A/C isn't. Especially since the point is to be able to take the family on road trips.

[Mudderoy]

Sorry gotta ask :thumbsup: How old is the fan clutch?

No, no problem. Ask away I appreciate the help.

It's a Grand Cherokee heavy duty fan. I'd have to go back and check but it may be 2 years old now. It was another step in resolving the high speed over heat.

No cooling issues at all low speed stop and go driving. If it gets above 210 usually after a fast acceleration to 50 or 60 mph (a mile) then stop at a light.

Once I get moving again it quickly drops to just under 210.

The heat creep is related to effort of the power train. Makes sense that more effort = more BTU and more demand on the cooling system. Problem is my cooling system isn't quite up to matching the BTUs. With A/C and e-fan on it gets much closer.

[msmoorenburg]

No, no problem. Ask away I appreciate the help.

It's a Grand Cherokee heavy duty fan. I'd have to go back and check but it may be 2 years old now. It was another step in resolving the high speed over heat.

No cooling issues at all low speed stop and go driving. If it gets above 210 usually after a fast acceleration to 50 or 60 mph (a mile) then stop at a light.

Once I get moving again it quickly drops to just under 210.

The heat creep is related to effort of the power train. Makes sense that more effort = more BTU and more demand on the cooling system. Problem is my cooling system isn't quite up to matching the BTUs. With A/C and e-fan on it gets much closer.

The reason why I ask that my old 318 Dakota had a fan clutch that wouldn't fully disengage ,and it caused the same symptoms on the highway. (it was preventing the ram air by creating a blockage)

[Mudderoy]

The reason why I ask that my old 318 Dakota had a fan clutch that wouldn't fully disengage ,and it caused the same symptoms on the highway. (it was preventing the ram air by creating a blockage)

Well could be I guess, but both clutch's had the same running hot problem.

I could always try the old one and see what happens.

[XJ4IV]

I know you probaly dont wanna hear this but when I have tried pretty much everything and I STILL have the problem I choke up 50 bucks and let the dealership tell me whats wrong... get it in writing and see if they will give you a money back garauntee basically ststing that if their diagnosis is wrong and you have fixed the issues they claim are the culprits and you STILL have the issue then you get your money back OR they keep diagnosing at no additional charge, basically tell them " I paid you to find out WHAT the problem IS not what it COULD be, I fixed what you said it was and still have the same problem. I expect you to DIAGNOSE the problem and give me a professional accurate diagnosis of the problem"... Allen Samuels over on 10 does 50 diag... thats where I go when Im out of options ALSO they offer a 10 oil change with no perks ... which is what other places do anyhow seriously when was the last time you asked for a lube oil and filter and they ACTUALLY greased all the fitting on your jeep THATS WHATS INCLUDED IN A LUBE OIL AND FILTER your supposed to LUBE the chassis remove and replace oil and get a new oil fiter

[ice_cold]

Need to get a running diagnostic...they hook up and you drive and then they DL the info and run it. This way they can see what the issue is and when. I have a feeling if you have access to a A/F meter...or build your own. You might find that the XJ is running lean..something is not reading something right. And the only thing that does any reading is the Computer...you sure you dont have a Cali comp? They were designed to run a little leaner.
As to the A/F..I built one of these to run in my SHO.
http://www.scirocco.org/tech/misc/afgauge/af.html

If this dont work..I will join you with the banging of head on brick wall. lol

[Mudderoy]

Need to get a running diagnostic...they hook up and you drive and then they DL the info and run it. This way they can see what the issue is and when. I have a feeling if you have access to a A/F meter...or build your own. You might find that the XJ is running lean..something is not reading something right. And the only thing that does any reading is the Computer...you sure you dont have a Cali comp? They were designed to run a little leaner.
As to the A/F..I built one of these to run in my SHO.
http://www.scirocco.org/tech/misc/afgauge/af.html

If this dont work..I will join you with the banging of head on brick wall. lol

It's been running a little rich, according to the OBD II data I collected on my laptop. I changed the front O2 sensor a few months ago, and I need to check it again to see if the running rich problem is still occurring. The gas mileage didn't change so I think it is the same as it was with the NEW non-OEM O2 sensor.

As far as collecting data, that's no problem. I'll collect it and put it on here!

[4.3LXJ]

http://image.automotive.com/f/features/10134149+pheader/0701or_01_z+1989_jeep_cherokee_xj_4x4_chill_pill+d irt_off_roading.jpg

What is the large piece of metal under the front bumper? A skid? Would this serve as an air dam as well?

Yes it would. I have the same problem with my front skid. When I remove my hood, I have absolutely no problems with cooling. You might try that for a day or two just as an experiment.

It also protects the steering box

[ice_cold]

I know its a long shot...have you access to a different comp? Maybe there is a glitch in yours that is not reading something right. Its the only thing I can think of that has anything to do with everything. And its the only thing you have not tried...next to moving to Alaska. ;)

[Mudderoy]

I know its a long shot...have you access to a different comp? Maybe there is a glitch in yours that is not reading something right. Its the only thing I can think of that has anything to do with everything. And its the only thing you have not tried...next to moving to Alaska. ;)

It runs hot in cold weather as well. I call it heat creep!

I changed the temp sensor and it read higher! Turns out that about 90% of the stuff I was fighting was due to the new sensor displaying more accurate information. When I finally put the old temp sensor back in I started seeing normal temps all the time, just not during the highway excursions. It was lower.

[bluedragon436]

I am glad that right now mine is staying at constant temps even on the highway... especially since I drive the highway too and from work every day... I think I am going to install some sort of hood vents though to see if I can't help the temps just a little bit.. just an idea... as this would allow more air flow through your radiator... or so one would think, as the hot air would have more places to go once it went through the radiator...

[gary63]

you said it runs cool at slow speeds and heats up at high speeds you need to sine a way to get the air out of your engin compartment.it making a air dam
behind your radater and slowing or stopping the air flow.the same thing happens to race cars that is why they put portholes in the wheelwells.so if you can open the wheelwells or get some air going underit to make a vaccum
to help pull so air out that is what airdams do in the front.

[Mudderoy]

you said it runs cool at slow speeds and heats up at high speeds you need to sine a way to get the air out of your engin compartment.it making a air dam
behind your radater and slowing or stopping the air flow.the same thing happens to race cars that is why they put portholes in the wheelwells.so if you can open the wheelwells or get some air going underit to make a vaccum
to help pull so air out that is what airdams do in the front.

Would you think this would accomplish that?

http://lh3.ggpht.com/_b0ViaGso2Ko/TB0lKI657mI/AAAAAAAAAQg/b5JF8UoH8wQ/s800/2010-06-19%2015.13.47.jpg

http://lh6.ggpht.com/_b0ViaGso2Ko/TBRnY5ca_YI/AAAAAAAAAP0/G7dVU8vVczI/s800/2010-06-12%2022.16.31.jpg

[gary63]

that would if lift open but when you put the cover on it wuold at slow speed
but at high speed it is desine to suck air in not blow air out. if you put vents
in or if you can get more air moving faster under your jeep.also you have a large tran. cooler check it to see that the fins on it and your radaiter lines up.
that willdo it I have see that people put a tran. cooler to help cool the trans..
And end up slow the air flow and making there engin run hot. so it you can look strate though that would be good if you see fins or dark try moving it alittle.also check the opening around your engin and body if you can move some hoses large groups of wires. also some time putting something around
the top and side of your radaiter to stop the air from going around and filling up the engin coprtment with non cooling air.

[gary63]

also if your bumper is strate up and down it will deflict air from going under
something a skid plate on the underside of the bumper will help.

[Mudderoy]

that would if lift open but when you put the cover on it wuold at slow speed
but at high speed it is desine to suck air in not blow air out. if you put vents
in or if you can get more air moving faster under your jeep.also you have a large tran. cooler check it to see that the fins on it and your radaiter lines up.
that willdo it I have see that people put a tran. cooler to help cool the trans..
And end up slow the air flow and making there engin run hot. so it you can look strate though that would be good if you see fins or dark try moving it alittle.also check the opening around your engin and body if you can move some hoses large groups of wires. also some time putting something around
the top and side of your radaiter to stop the air from going around and filling up the engin coprtment with non cooling air.

Yeah I moved the transmission cooler...

http://lh3.ggpht.com/_b0ViaGso2Ko/TGYzNRff7pI/AAAAAAAAAZA/tCxEv4HWhlw/s800/2010-08-14%2000.26.54.jpg

[honesT]

Higher hieght of tires and lift will change the drag of the air flow probably causing the air dam... I`m no expert so correct me if i`m wrong.

If you want to get perfect about it you could get a white hood and of course the grill behind it and put heat vents in the hood.

I have a Dark Blue 96 cherokee and I`m thinking of this myself but I`m also going to do my roof like the new ford Flex.

Have you ever leaned on a black vehicle in the summer with short sleeves on:stars:

You could rollaround nude on the roof of a white vehicle parked in the middle of the desert on a hot summer day and have no worries:thumbsup:

[gary63]

that plat under the jeep how far (long) is it.
A nother way is to run some runners like you have for your fresh air vent toob
you use for your intake and run it and point it at the rear of your engin and down. It will cool the back and your trans. at the sametime make a vaccum
to help pull out hot air. You don't have to run the same size you can go smaller. Hope you figer this out you have a nice jeep. I'm figering you have
already change or check water pump,thermastat, and you have good flow
(you look inside the radeator fill opening ). A nother check is get a temp gaudg that goes were your cap so you can check the temp. at the radeator.

[Mudderoy]

that plat under the jeep how far (long) is it.
A nother way is to run some runners like you have for your fresh air vent toob
you use for your intake and run it and point it at the rear of your engin and down. It will cool the back and your trans. at the sametime make a vaccum
to help pull out hot air. You don't have to run the same size you can go smaller. Hope you figer this out you have a nice jeep. I'm figering you have
already change or check water pump,thermastat, and you have good flow
(you look inside the radeator fill opening ). A nother check is get a temp gaudg that goes were your cap so you can check the temp. at the radeator.

Yeah it doesn't go very far back. Interesting information. I'll get a better picture of the underside and what I have in mind. I was thinking of placing a cover from the bumper back a couple of feet. Maybe something flexible and heat resistant. I was thinking metal, like aluminum at first, dunno.

[gary63]

will I don't know what you are useing but here is a site that you can get a HIGH FLOW thermostat that around here people use in the summer but have to take out in the winter. and it been lotting people run at around 190 to
200. and some as low as 185 witch realy screw up there gas mileage and power that is to cool. http://www.hesco.us/shop.asp?action=details&inventoryID=43007&catId=

[Mudderoy]

will I don't know what you are useing but here is a site that you can get a HIGH FLOW thermostat that around here people use in the summer but have to take out in the winter. and it been lotting people run at around 190 to
200. and some as low as 185 witch realy screw up there gas mileage and power that is to cool. http://www.hesco.us/shop.asp?action=details&inventoryID=43007&catId=

Here is the BOOK that I've written if you are so inclinded. :link: (http://www.xjtalk.com/showthread.php?t=706&highlight=flowkooler)

Readers Digest version...
All new hoses (lower hose with coil)
3 core all metal radiator
high flow thermostat
high flow thermostat housing
hight flow water pump FlowKooler
Grand Cherokee Heavy Duty fan clutch
13k BTU transmission cooler (recently moved out of radiator air flow)

Radiator recenly had a tiny tiny leak so I have it repaired. Flow rate was checked and was VERY good.

[gary63]

ok here is something to think about timing have you checked you time at low speed and at high speed it my be advansing your timing witch will rase your
engin temp..I read some thing that you can get data from your jeep wile you are driving if so can you check the time at low and high speed. At the sametime check the vaccum you may be getting a spike of very high vaccumat high speed or your fuel systom may be running lean at high speed.
what got me thinking of this is you said it was running alittle rich but I don't
remember if you said if that was just driving around town. Hope you get it
running right I will keep thinking about it.

[Mudderoy]

ok here is something to think about timing have you checked you time at low speed and at high speed it my be advansing your timing witch will rase your
engin temp..I read some thing that you can get data from your jeep wile you are driving if so can you check the time at low and high speed. At the sametime check the vaccum you may be getting a spike of very high vaccumat high speed or your fuel systom may be running lean at high speed.
what got me thinking of this is you said it was running alittle rich but I don't
remember if you said if that was just driving around town. Hope you get it
running right I will keep thinking about it.

Yeah driving at highway speeds it runs a little rich. I'll have to collect new data.

[ice_cold]

Runs rich at highway speed? Well that makes no sense. Rich would equate to running cooler, you would think.
I am still thinking that if all sensors and such have been changed and it still runs hot, And its done it since you have had it.
The computer thats doing the reading is some how incorrect. I mean, computers are never wrong are they? (major sarcasm).
You have changed the TPS, right?
Mike

[Mudderoy]

Runs rich at highway speed? Well that makes no sense. Rich would equate to running cooler, you would think.
I am still thinking that if all sensors and such have been changed and it still runs hot, And its done it since you have had it.
The computer thats doing the reading is some how incorrect. I mean, computers are never wrong are they? (major sarcasm).
You have changed the TPS, right?
Mike

Correction. It did NOT run hot on the highway for the first 9 years I had it. It started running hot on the highway after the 4.5" lift and wheels and tires were added.

It has over heated on the highway before, and in the fast food line, blah blah blah, but never a go 70 mph and it will run hot situation until the modifications.

After all I have been through it must be an air flow issue, and that issue must be primarily how the air flows under the Jeep now.

[ice_cold]

I tripped across this little piece of information, it concerns your hood. It may, along with the lift be causing a high pressure area under the hood....no flow!
You have a remote barometer? Bet it goes to high pressure at highway speeds.

"Cowl Induction" was a sort of Chevrolet thing in the 70's,,,
one of a wide variety of Detroit's fresh air induction schemes.

It depended on body aerodynamics which created a high-pressure cell at area between the back edge of the "air scoop" and the windshield base.

Airflow Over and around the Hood Hump made turbulence and drag which sorta "packed" air Back in towards the scoop.

Same type effect which drags air into the back window of a Van or Stationwagon.

Cowl Induction setups were SEALED from underhood area,,thus no hot air extraction.

Otherwise the Hi Pressure would have Blocked the exit of engine compartment heat,,,and induction system woulda been
inhaling hot ,turbulent air.

[Mudderoy]

I tripped across this little piece of information, it concerns your hood. It may, along with the lift be causing a high pressure area under the hood....no flow!
You have a remote barometer? Bet it goes to high pressure at highway speeds.

"Cowl Induction" was a sort of Chevrolet thing in the 70's,,,
one of a wide variety of Detroit's fresh air induction schemes.

It depended on body aerodynamics which created a high-pressure cell at area between the back edge of the "air scoop" and the windshield base.

Airflow Over and around the Hood Hump made turbulence and drag which sorta "packed" air Back in towards the scoop.

Same type effect which drags air into the back window of a Van or Stationwagon.

Cowl Induction setups were SEALED from underhood area,,thus no hot air extraction.

Otherwise the Hi Pressure would have Blocked the exit of engine compartment heat,,,and induction system woulda been
inhaling hot ,turbulent air.

Well my understanding is that the cowl induction scoop allows air to escape at low speed like off road stuff, and at high speed it sucks air into the engine compartment.

I like the first part of what you were saying. This makes sense. If I'm getting high pressure in the engine compartment then air will have a hard time flowing through the radiator. As heat generation increases and air flow decreases coolant temps creep up. I slow down and heat and pressure decrease which equals coolant temp rapid decline.

I think the air pressure is being read by the ECM by a sensor that is in the engine bay, but a remote sensor would be a good thing to have to double check.

Now I'm wondering just how much of the opening under the engine I need to cover. I guess covering it is a good way to find out.

[ice_cold]

Cover it to the axle, then find a way to manually open and close the cowl opening...I hate to say this, but...we may be on to something here.

[Mudderoy]

Cover it to the axle, then find a way to manually open and close the cowl opening...I hate to say this, but...we may be on to something here.

I had already considered putting a cable control flap on the back of the cowl just for those really really cold days.

When you say back to the axle you mean as far back, not as far back and down to, right?

[4.3LXJ]

Cover it to the axle, then find a way to manually open and close the cowl opening...I hate to say this, but...we may be on to something here.

You could try that. But I don't think that will work. Here is a pic of mine.

http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0419.jpg

My skid plate was designed to deflect animals (deer) under the vehicle instead of over the top when hit. I have the same problems as Tony has. I have eleviated it a lot by venting my hood heavily right behind the radiator area.

http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0420.jpg

This is most effective, since this is an area with a slight vacuum where the air breaks over the hood. This has gotten me from trapped air and loosing head gaskets to keeping it cool. But I am still marginal on a 100°+ day at freeway speeds. At slower speeds it is not a problem. If I just take the hood off, problem solved. It is all about getting that air out of the engine compartment.

[Mudderoy]

You could try that. But I don't think that will work. Here is a pic of mine.

http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0419.jpg

My skid plate was designed to deflect animals (deer) under the vehicle instead of over the top when hit. I have the same problems as Tony has. I have eleviated it a lot by venting my hood heavily right behind the radiator area.

http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0420.jpg

This is most effective, since this is an area with a slight vacuum where the air breaks over the hood. This has gotten me from trapped air and loosing head gaskets to keeping it cool. But I am still marginal on a 100°+ day at freeway speeds. At slower speeds it is not a problem. If I just take the hood off, problem solved. It is all about getting that air out of the engine compartment.

Actually because of this picture (seeing it in the past) I thought about putting an electric fan under the cowl induction hood. 1000 CFM to suck the air out of the engine bay and push it out of the cowl. Do you think that would be enough? Of course the fan would be pushing the air to the top of the cowl so it wouldn't really be 1000 CFM...

[Mudderoy]

You could try that. But I don't think that will work. Here is a pic of mine.

http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0419.jpg

My skid plate was designed to deflect animals (deer) under the vehicle instead of over the top when hit. I have the same problems as Tony has. I have eleviated it a lot by venting my hood heavily right behind the radiator area.

http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0420.jpg

This is most effective, since this is an area with a slight vacuum where the air breaks over the hood. This has gotten me from trapped air and loosing head gaskets to keeping it cool. But I am still marginal on a 100°+ day at freeway speeds. At slower speeds it is not a problem. If I just take the hood off, problem solved. It is all about getting that air out of the engine compartment.

So the reverse cow catcher wasn't enough to keep it cool?

[4.3LXJ]

Actually because of this picture (seeing it in the past) I thought about putting an electric fan under the cowl induction hood. 1000 CFM to suck the air out of the engine bay and push it out of the cowl. Do you think that would be enough? Of course the fan would be pushing the air to the top of the cowl so it wouldn't really be 1000 CFM...

I would double that if I could.


So the reverse cow catcher wasn't enough to keep it cool?

No, it stays cool, but it is just marginal at speed on really hot days. Doesn't overheat, but the fans stay on all the time indicating that it is just keeping up and not staying ahead. I haven't had it on a road trip more than 40 miles to see if it ever gets heat creep.

[Mudderoy]

I would double that if I could.



No, it stays cool, but it is just marginal at speed on really hot days. Doesn't overheat, but the fans stay on all the time indicating that it is just keeping up and not staying ahead. I haven't had it on a road trip more than 40 miles to see if it ever gets heat creep.

Can I get the approximate dimensions of that skid? Maybe a picture from behind? No rush.

Also I'm assuming that it has sides.

[4.3LXJ]

Can I get the approximate dimensions of that skid? Maybe a picture from behind? No rush.

Also I'm assuming that it has sides.

Total dimensions are 25" long and 34" wide including the 2.25" OD tubing for sides. It basically is as wide as the frame rails plus two 3/8" bumper mounts. It stops just short of the drag link but protects the steering box completely so that it does not interfere with any steering components. One big advantage is that when splashing through the deep puddles it keeps the muddy water out of the engine compartment.

[Mudderoy]

Total dimensions are 25" long and 34" wide including the 2.25" OD tubing for sides. It basically is as wide as the frame rails plus two 3/8" bumper mounts. It stops just short of the drag link but protects the steering box completely so that it does not interfere with any steering components. One big advantage is that when splashing through the deep puddles it keeps the muddy water out of the engine compartment.

Yep, that was the previous main reason I wanted to have something like this. Thanks.

[gary63]

you may have too meany holes in your hood try covering up like the front 2
and just use the big main one. that way the air coming in wil be going down the back of the motor. witch my make a vaccum to pull air though the front
and may even help around the trans. most of the hoods with cowl have hole in the back.

[honesT]

Scroll down to Jeepdude89 Maybe you already now this but it`s new to me...
http://www.jeepforum.com/forum/f11/98-xj-blown-head-gasket-1042117/

If you want to check the head gasket yourself this stuff should do the trick I paid $54 but she wanted to charge me $78 I just told her the parts on the phone told me it was only $54.00 (He really did give me that price)Combustion Leak Detector from Lordco ($54, refill bottle $10).made by Lisle part# 75500

[Mudderoy]

UPDATE!

Matt is letting me borrow a hood so I can work on bonding the cowl to my hood. Here's the $15 hood I'm borrowing...

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