Mike1998XJ

Well I guess I should come clean then... You did not bust my ego one bit.
Just the facts... I am not bragging I just want you to know where my experience comes from...
1. I am a degreed Mechanical Engineer with a Masters degree in Mechanical Engineering.
2. I worked for GM for 6 years
3. I worked for Ford for 4 years
4. I currently work for a large tier 1 Supplier my main Customer being Chrysler. (Hopefully that lasts...)
5. I have been an Engineer in the Automotive Industry a total of over 17 years.
6. I have always worked in production at assembly facilities.
7. I have been troubleshooting and brainstorming problems in this industry for that whole time.
8. I am a certified Green Belt in Six Sigma. I lead Teams in troubleshooting problems on the production floor.
9. I have participated in more simple tests like the one I am proposing to do on the air flow than most people could comprehend.
10. I know inside and out what it takes to set up simple tests like this one. Believe me Automotive manufacturers do this kind of thing all the time.
So that's it in a nutshell!
This test is simple to understand. I just want to prove that utilizing a fan shroud draws more air through the radiator. Or not... As I have said I have driven, towed and so on for a year without a shroud or electric fan and haven 't had the slightest problem... You need to keep an open mind because from a test like this comes knowledge... Don't worry... If I overheat I will do my own troubleshooting.
So I am one of the people you refer to that builds cars. Thanks
Just out of curiosity what do you do for a living?

a1racer

if that is what you do then post that so people understand that you know what you are doing and understand the use and why it is there. not just a oh this is a simple test. and i don't think it is necessary i still disagree with people saying that it is not a necessary part. or that they have been running with out it and have no issue. but do your test and i will watch to see what happens

mud-dog27

wow thats a whole lot of bickering but for the most part the shroud is there for a reason safety and the purpose of making the the airflow more direct as for Mike1998XJ and his pulling (i might have missed this) but you guys are forgetting the fact that '98s had a lot better cooling than the '89s and im assuming the OP hasnt converted his system to a larger rad with an open system and for all those who have owned closed system XJs you know the cooling sucks no matter what you do which is why most convert to an open system with the larger rad i did after i wrecked my frontend and needed to replace the parts anyway and the thing hasnt come close to overheating since and its much less hassle to flush the system

and BTW i dont care what anyones job is when your comparing an 89 to a 98 and wahat was is better the 98 is gunna win as the 89 at that point had only been running the I6 for 2-3yrs they were still workin the bugs out and making it better

a1racer

don't worry we where talking and pming and he is an OK guy and i want to see what happens with the experiment. it should be interesting

a1racer

and yeah the closed system is junk and should be shot

mud-dog27

i forgot to add that a large piece of tissue paper is good for checking suction from the front as you just lay it over the grill and the more suction the tighter it pulls and you will see the circles where the fans are more so with the elec. as its shrouded better

i got bored one day and wanted to see how much better my electric fan pulled than my mech. fan as i was debating going dual elec. but decided against it as i was scared of the electrics both dying

but i run the elec for my tranny cooler especially when towing cause the AW4 dont like heat....they can however handle it nicely you just gotta let em cool down

4.3L XJ

I read through most of the posts on the fan shroud. Here is the skinny. If you are traveling down the interstate at 60 mph, you don't even need a fan. The amount of air going through the radiator exceeds what the fan can pull with or without a shroud. You don't even need a fan under these circumstances.

You do however need a fan when driving below 25 mph in town, wheeling or idling and not moving. During these times, the fan is needed to pull enough air through the radiator to cool the engine. The fan shroud on the engine driven fan is kind of mickey mouse anyway, but it does help boost the efficiency of the fan by not allowing the air to be thrown out centrically. Thus once in the fan blade it will have to go all the way through the fan and thus be replaced by more air.

So do you have to have it? that depends on how good your cooling system is operating and how hot it is outside and how hard you work the engine. most of the time you can get by without it. But it is there for those times you work it hard.

Mike1998XJ

Tissue Paper! Excellent idea... That's what I'm talkin' bout'
Here's a picture of what we have so far. We should be able to check across the whole radiator this way.
I'm thinking I'll check it a idle. (Both idle at 700 rpm's) then 1000rpm's then 1500 and maybe 2000. I'll have both of them in the garage out of the wind. I have a tailpipe exhaust collector for the fumes so I can shut the door during the test. I will have the axel holding the antenna in the same place and heigth on each. Hoods closed.
Anyone else got any "Positive" ideas?
I need to cut shims or something to prop in the throttle cable to hold the throttle steady at the higher rpm's. Don't want any operator error introduced into the test. Any ideas on that?

mud-dog27

could just adjust the throttle screw.....but i havent looked at a HO throttle body in a while so not sure if thats as easy as the renix TB when it comes to adjustment

Mike1998XJ

I agree thats why the fan has a clutch, so it disengages at higher speeds. What I will say is that going 60mph down the highway towing an 1800# trailer and a Jeep causes the tranny to generate lots of heat. Since the tranny fluid runs through the radiator I knew the stop and go might be touchy. I was ready to pull into a parking lot and shut her down if need be. When I got off the highway I have to go through a series of 6 stoplights. If you hit one red you hit them all red. And I hit them all red. Takes 6 or 7 minutes to get through them all. I kept a tight eye on the gage and it stayed where it always runs. So I'll be darned she held in there fine! I was looking through the paperwork and noticed the previous Owner had put a new radiator in 2 years ago. That is the key! My system is running optimally aside from the missing shroud and electric fan. Other people that live up here in the north that have overheating problems might want to think about a new radiator and a flush. If you live in the desert or wheel a lot a fully functional cooling system is optimum. That is why if you look at my pictures I put all that in the Red Jeep I own. That's going to be my wheeling Jeep.
I only bring all this up to share what I have learned. My $1000 purple Jeep is just a daily driver that I just drive and maintain for cheap transportation.

mud-dog27

i know what your sayin bout towing ive got a 1500Lbs tent trailer and it likes to make the tranny work especially with 32x11.5s and 3.55s and if you havent already toss a gauge and a B&M cooler in line or seperate from the one that runs through the rad helps keep it a bit cooler and longer before it starts slippin and you gotta pull over

BTW what thermostat are you running while towing

in colder months i run regular 195* but in summer months i run a 180* probly not neccesary but its one less thing to worry about makes towing a little less worrisome especially if your towin on FSRs

Mike1998XJ

Where do you mount the gage inside? I saw an article where someone took a cooler out of a Ford Explorer and fit it in real nice on the Jeep. I was thinking about doing that. I four wheel at a place called Silver Lake Dunes in Michigan. (You'd like to Google it.. awesome place). Mostly all sand dunes so a cooler will be installed eventually on my red jeep one way or another. I thought running a lower thermostat would make these modern engines run rich... So I just called my Brother in Law about the lower thermostat. "Retired Ford Engineer in Powertrain" (Not trying to pull!) and asked him about that. He tows a Cherokee behind his motor home. He said NOT to do that. It will make the computer think the Jeep hasn't reached the proper operating temperature so it will stay in closed loop mode. That makes the Jeep run rich, wastes fuel wrecks the cat and so on... You could verify that by checking your gas mileage on each thermostat. I run the stock 210 degree thermostat. I agree with a1racer that keeping our trucks as close to stock as possible is the safest way to keep them running right. That's what I preach to my Sons... I just don't always practice it! I suppose you could put the lower thermostat in for towing or wheeling then take it out afterwords...
What did you think of the setup for the experiment? Any other conditions you can think of you'd like to see tested while I'm at it?

mud-dog27

my gauge is mounted on the a-pillar with the pedestal mount

its just in there with thin 2sided tape between mount and pillar small piece between pod and windshield aswell as below on the dash

i know it seems shotty but its been in there for 3yrs and hasnt moved and i couldnt bring myself to run those "universal" pillar pod packs

and i have the probe mounted in the front left corner of my trans pan and the colloer in mounted infront of my condensor and rad on the driver side

as for the thermostat yes it will run rich but id rather run a bit rich than over heat and for the most part due to coldair intake and 2.5" exhaust my jeep runs a bit on the lean side but it deffinatly runs richer as i found out when i bombed aircare when i forgot to swap in my 195* (my grandfather suggested it and i took his word on it 50yrs ownin his own radiator shop i figured he knew a thing or 2) i figure nothings gone terribly wrong yet that i can relate to the thermostat and like i said i only leave it in for the hot summer months which around here is june to september

RedBaron

XJ Cherokee over heating problems are the rule here in the Southwest. The XJ's engine compartment was designed for a 2.5L 4-banger or a 2.6L GM V6. When AMC installed the 4.0L inline 6 the air flow has been iffy ever since. Out here, no fan shroud and no aux A/C fan and the buzzards will be sitting on your opened hood sizing you up for supper..

Schmoozer

Sorry, nothing against you I just hate lean.