factory cooling

[pauldo39]

Hey guys, just checkin back in, made 2 100 mile trips pulling a trailer in 85*+, I didn't have time for the new radiator so before I left I took off both fans and unscrewed the front grille off, and I noticed that in the row closest to the engine had tons of the metal loops between the coolant passages that were bent shut. I couldn't figure out why, so I actually took a small flat screwdriver and opened them up/straightened them out, then took a hose without a nozzle and tried to spray through it. Where water was gushing back out as if hitting a solid surface, I took some Castrol degreaser (purple bottle, not the potent engine stuff) and coated the first rows, let it sit, then hosed it out. Couldn't believe the crap that came out. In the past I had always sprayed out the radiator from time to time but that must not have worked very well. I don't know if that was a great thing to do but I would sit idling in traffic after pulling the trailer for a good 15 minutes at a time and the temp would never get above probably 212 or so. I was thrilled. Jeepsrock, I don't know what to tell you since you have a new radiator. I've found in my experience and others too that turning the air on actually can help lower the temp at least when idling because the aux fan should come on. If i don't have air on my temp will raise when idling to that same point as yours but then the aux fan kicks in and the temp lowers, and the cycle just keeps repeating, up then down. but with air on the fan constantly stays on and the temp stays much more constant.

 

[krakhedd]

Hey guys i have the same problem as the initial poster...the temps in the valley here in CA are above 100+F a lot and even with no AC if i stop at a stop light or in trafic the temp climbs past the half mark (halfway between the 210 and the next mark). In the past i have had changed-
1. New Water Pump
2. New 3 core GDI ( purchased a while back)
3. New gatorback belt (belt tentioned properly)
4. New hoses
5. New Fan clutch (carquest brand)

What else can i do...?? I just flushed the system and nothing has changed ?

pete

Hood vents. They help more than you'd think. I bought a pair of $1.39 roofing vents (they don't particularly look good, but wtf, it's a Jeep, not a bling-bling contest). I can send you pics if you like, I need a request for the pics and an email address to send them to. They were very easy to install.

 

[krakhedd]

Oh really? Hmmmmm..
Please make me understand. Maybe I'm not thinking this through correctly.

K

It's all about the volume being pumped. Pushing the coolant through the engine block is also easier because the kinetic energy (heat) of the coolant is greater in the engine block than the radiator (duh). Hot exhaust is easier to push than cold exhaust, for example, because the gases are in an excited state.

The backpressure is a more minor factor. Also think about how much farther (relatively speaking) the pump has to push the water to get it into the radiator, as opposed to coursing it through the engine block.

I guess the only real way to test this out would be with a dyno. I doubt the difference is very large in the first place - I'm pretty anal about even the smallest gains - so if we still disagree on this, let's just agree to disagree. Pointless to continue arguing theoretical numbers rather than empirical, especially over a half a HP!

 

[langer1]

You can test it with a electric pump, the current draw on the motor is greatest at full volum and lowest at no flow. Water is heavy so the more you move the more power it takes.

 

[sacem]

All fluids when moved absorb power thats valid for water or air, so if the radiator is blocked by a sheet of paper the air drawn will be minimum and the power absorved by the fan also minimum, likewise if the pump can only move a small amount of water due to the tstat being closed then it will absorb the least amount of energy from the engine, when the tstat is opened then it will move more fluid (water) and use more power to do it, its just that simple, believe fisics. I do and one of my current product lines are industrial fans.

Here at home the least temp year round is 54ºF so I have removed the tstat from my 4.0L in order to keep the water moving and try to lower motor temp but to no avail. My car had a single wide row radiator (original from MOPAR) and I've changed it to a 2 row one, helped but not solved, after reading this I'm getting a 3 row with wide inside channels rad and see if the temp goes down.

SACEM

 

[krakhedd]

I get the general idea you guys are averse to the idea of installing hood vents. They are SUCH an effective upgrade - I just don't understand, I guess, why you wouldn't want to? I can understand maintaining the stock hood, but for Pete's sake, get yourself a hood from the junkyard and do it! I didn't even practice on a junk hood first, I just went straight at my original, and you cannot tell it was an "un-professional" install. I measured the lines almost dead accurate (I say "almost" because I cannot prove that they are within millimeters of each other, but I swear they are), they got cut well, and the vents installed almost dead accurate. The only mistake I made was I measured one of the sides about 1/2" too short, but you really can't tell unless you're looking at them from under the hood, and it still isn't apparent unless I either point it out, or you're examining them very closely.

After the scorcher summer we've had here in Buffalo, I can definately attest to thier effectiveness. They basically make the whole system work that much better. I will not be concerned with cooling until (if?) I build a motor, which would almost definately include a turbo, which would throw off a lot more heat than the engine block alone. I have yet to sample a winter with them, so I guess I'll need another 6 months to offer full testament of their functionality and practicality for year-round use.

 

[sacem]

Hello Krakhedd:

Years ago (early 70's) there was a Camaro Z-28 that was raced at the Trans-Am an was studied in airflow trials very closely (I think it was Roger Penske Team) and they did it by making a transparent plexiglass engine lid and tieying colored strings at different points around the motor and seeing how air flowed around the engine, out from the radiator and so on, they made it so slick underside that after winning over the other cars in several races the sanctioning body banned the "slickening of the cars" (that might be a new word) and they all returned to the usual, but just as I was driving last week a long 600 mi strecht of road I was wondering how to see the air flow around the motor, maybe the way to go is just trial and error and you have gone the first big step, I for one am going to follow your steps because it is a natural and logical idea,

What I would like to now is the following:
1) The slots in the motor lid were cut to allow air in or to get air out from the engine bay.
2) Are this slots cut looking forward or backwards
3) The location is at the front, middle or back section of the lid

I had been thinking of just raising the back hinge of the lid in order to allow air to flow along and exit through there but then I remembered that the Camaro Z-28 had the air INLET at the base of the windshield because that turned out to be a High Pressure area, even better than locating the air inlet on the front of the car, so that might cause a counterflow of air into the engine bay (that's when I started remembering the Penske team studies).

The old VW Beatle crowd uses that approach in the back lid to bring more cooling air into the engine bay but they have the motor at the other end so that does not help us much.

I'll keep you posted about the temp variations I'll find once I get the slots done.

Cheers

SACEM

 

[corbinafly]

It's all about the volume being pumped. Pushing the coolant through the engine block is also easier because the kinetic energy (heat) of the coolant is greater in the engine block than the radiator (duh). Hot exhaust is easier to push than cold exhaust, for example, because the gases are in an excited state.

The backpressure is a more minor factor. Also think about how much farther (relatively speaking) the pump has to push the water to get it into the radiator, as opposed to coursing it through the engine block.

I guess the only real way to test this out would be with a dyno. I doubt the difference is very large in the first place - I'm pretty anal about even the smallest gains - so if we still disagree on this, let's just agree to disagree. Pointless to continue arguing theoretical numbers rather than empirical, especially over a half a HP!

Krakhedd,

I'm pretty anal about the smallest gains myself. As far as agreeing to disagree. Sounds good, but I'm starting to lean more towards the "dark side" and beginning to change my mind on this. So maybe we agree after all.

All fluids when moved absorb power thats valid for water or air, so if the radiator is blocked by a sheet of paper the air drawn will be minimum and the power absorved by the fan also minimum, likewise if the pump can only move a small amount of water due to the tstat being closed then it will absorb the least amount of energy from the engine, when the tstat is opened then it will move more fluid (water) and use more power to do it, its just that simple, believe fisics. I do and one of my current product lines are industrial fans.

Sacem,

This is the most persuasive argument so far. I was thinking about this last night and I would have to agree. Okay. I admit it. I was wrong.
I think I'm on the road to recovery now. :laugh3:

You can test it with a electric pump, the current draw on the motor is greatest at full volum and lowest at no flow. Water is heavy so the more you move the more power it takes.

Langer1,

I was thinking the same thing.

K

 

[sacem]

Corbinafly I do hope you reached recovery fast I just wanted to share information I deal with every day.

Cheers

SACEM

 

[krakhedd]

Hello Krakhedd:

What I would like to now is the following:
1) The slots in the motor lid were cut to allow air in or to get air out from the engine bay.
2) Are this slots cut looking forward or backwards
3) The location is at the front, middle or back section of the lid

I had been thinking of just raising the back hinge of the lid in order to allow air to flow along and exit through there but then I remembered that the Camaro Z-28 had the air INLET at the base of the windshield because that turned out to be a High Pressure area, even better than locating the air inlet on the front of the car, so that might cause a counterflow of air into the engine bay (that's when I started remembering the Penske team studies).

The old VW Beatle crowd uses that approach in the back lid to bring more cooling air into the engine bay but they have the motor at the other end so that does not help us much.

SACEM

1) Allow air to escape.
2) I guess you would call it backwards. They vent air towards the windshield.
3) Back.

I had also thought about the "cowl induction" thing, and didn't know how well my setup would work at speed. I don't have a wind tunnel to prove how well my new setup works, but I figured that the additional air being vented out the top (which normally would have vent primarily out the bottom and sides) would actually create a sort of "buffer". It would act like an air hockey table against the puck, except the table in this case is my windshield, and the puck is the air passing over it. So basically, I reduced lift (less air should vent out the bottom), and also may have made the Jeep slightly more aerodynamic due to this "buffer" effect.

I must say that, even in 80*-85* F weather, my Jeep maintains temp at 180*F (the temp of my t-stat), and only rises slightly above that with the AC turned on, so long as I maintain constant motion at or above 30MPH/50KPH. Even in stop-and-go traffic, it takes considerably longer for my engine bay to become "heat soaked". The Jeep runs better, especially off the line in stop-and-go. It gets slightly better mileage (I think - I have a tendency towards lead foot, so it's hard to tell! ), and also seems to actually have an extra little bit of power, especially at speed. I was not anticipating this, but it happened. Also, the hood no longer gets too hot to handle, only the vents do. You can feel heat literally dumping out of them even at idle. I have the hood and vents completely separated by Super Black RTV (high-temp silicone sealant), and installed some screws as well for additional restraint. The only other mod I wish I had, at this point (for cooling anyway), is some higher-flowing fans. I am certain I could keep the Jeep running below 210*F constantly, even in stop-and-go, with enough airflow.

That being said, let me know if you need any help or anything. Email me at [email protected] with questions/concerns/etc.

 

[langer1]

Want to add something else to the mix. The rubber air dam that suppose to be up front just below the stock bumper. You will run about 30deg's hotter on the highway without it. With that air dam up front a vacuum is created under the car which will pull much more air through the radiator than any hood vent ever could.

 

[8Mud]

I´ve read the discussion and just wanted to add, that the thermostat isn´t open and closed, it begins opening at around 195 and is totally open near 218. If I remember the numbers correctly, even if my numbers arn´t valid the theory is the same. A 180 thermo opens sooner and is completely open at a lower temp. Increasing flow can help some, but is not nearly important as the amount of air moved through the radiator.
The water pump is centrifigal, if it isn´t moving fluid, it just spins and churns things up some. May be a slight HP loss, but probably insignificant.
I went to a a rather large (thick) two row, aluminum. The radiator has a bunch of excess capacity. It just depends on how much air I move through it. I turn on the aux fan (switch) and thunk, the temp falls 15 degress in seconds. The only reason I bought the aluminum (Modine) was it was mispriced, so I jumped on it and lucked out by accident.
I`ve written a bunch of posts, about washing out (or blowing out) the radiator and periodically checking the space between the A/C condensor and the radiator. I´ve washed handfulls of grass seed out of there, pollen, mud and dust. Cotton wood trees will plug off the air flow pretty quick. Some of the air restriction is between the rows and hard to see. It works better to wash from the back to the front. Don´t use excess pressure, or you´ll bend the fins and add to the problem. If you have bent fins, there is a cheap tool at most any Air conditioning shop called a fin comb. As a side note, organic material stuck in the radiator, eventually begins to rot and produces acid when it does. If you ever have the fans and shrouds off of there, pull the grill and shine a flashlight from the back to the front, you can see the restrictions pretty easy. It´s worth the effort if your in there anyway. Much of the stoppage seems to be around the perimeter (passengers side) and between the A/C condensor and the radiator.
I´m going to eventually install an engine oil cooler with a 180 deg bypass, bathing the inside of the motor with 180 deg oil, has always helped my race trucks and will probably also benefit the XJ. There is a neat spot under the radiator, for a good sized heat exchanger.

 

[krakhedd]

Want to add something else to the mix. The rubber air dam that suppose to be up front just below the stock bumper. You will run about 30deg's hotter on the highway without it. With that air dam up front a vacuum is created under the car which will pull much more air through the radiator than any hood vent ever could.

I've been missing mine for some time, since winter. I bought the truck in Apr 04, and also had a 99 for awhile. I noticed no difference in the cooling between the 2 vehicles until I installed the hood vents.

I run at a constant 180* on the highway. Always has, if the weather is cool enough, but now with the vents it doesn't have to be as cool.

I´ve read the discussion and just wanted to add, that the thermostat isn´t open and closed, it begins opening at around 195 and is totally open near 218. If I remember the numbers correctly, even if my numbers arn´t valid the theory is the same. A 180 thermo opens sooner and is completely open at a lower temp. Increasing flow can help some, but is not nearly important as the amount of air moved through the radiator.
The water pump is centrifigal, if it isn´t moving fluid, it just spins and churns things up some. May be a slight HP loss, but probably insignificant.

Yeah, I thought that too, but didn't stop to think about it until now. Somebody said something earlier in the thread (pg 2 or 3 I think) about the water pump constantly circulating coolant through the block. I realize now this is wrong - thanks for setting me straight!

The flow we're talking about increasing is airflow, or at least that's what I've been trying to get across. I'm glad somebody who has much more experience in this area agreed with me on that.

 

[sacem]

To 8MUD: I totally agree with you that installing an external oil cooler will do wonders for the life expectancy of the engine, I have a huge (for an oil cooler) 14" by 16" double row oil cooler in my VW buggy with an electric fan that blows air through it and I can be in the middle of the sand dessert at noon time and the oil pressure will still be above 25/30 psi at idle (a lot for an aircooled VW) the point is: I know how to take the oil out from the VW but I have no idea how to get a line from the engine to cool the oil and then reinsert it back into the engine to feed it with the cooled oil.

I'm sure that's a question that will be needing an exact answer before anyone starts installing the external oil coolers.

By the way, Do you think that eliminating the auto transmission fluid cooling interchange at the bottom of the rad and installing an external air cooled unit would help in lowering the water temp AND the trans oil temp?

SACEM

 

[langer1]

Want to add something else to the mix. The rubber air dam that suppose to be up front just below the stock bumper. You will run about 30deg's hotter on the highway without it. With that air dam up front a vacuum is created under the car which will pull much more air through the radiator than any hood vent ever could.

I want to add also that the more lift you have, the less the effect the air dam has. On stock height is does make a big differance though.

 

[90xj4x4]

I converted my '90 from a closed cooling system to an open one with a new heater valve and everything. I am using a GDI 3-row radiator and everything works like a charm. Heat is NEVER an issue now. I was running a 180* T-stat and switched back to the 195*. I noticed that my MPG dropped to like 12-14mpg with the 180. I put the 195 back in and it jumped back up to 14-17 around town. I also noticed that it smelled rich with the 180. After doing some research I concluded that the ECU stayed in "warm-up mode" when the 180 was in. This was because the engine never warmed up to the 190* or so that it takes to run the engine in normal mode. "Warm-up mode" is similar to choke. It feeds the engine more fuel to warm it up faster, thus the bad gas milage.

Conclusion. Leave the 195* t-stat in.

 

[corbinafly]

Somebody said something earlier in the thread (pg 2 or 3 I think) about the water pump constantly circulating coolant through the block. I realize now this is wrong - thanks for setting me straight!

When the tstat is closed, coolant flows from the pump to the block to the head to the heater valve to the heater core (if heat is on) and then back to the pump. Always (when the engine is running).
In addition to this, when the tstat is open, the coolant also flows to the radiator and back to the pump.

K

 

[8Mud]

When the tstat is closed, coolant flows from the pump to the block to the head to the heater valve to the heater core (if heat is on) and then back to the pump. Always (when the engine is running).
In addition to this, when the tstat is open, the coolant also flows to the radiator and back to the pump.

K

X2, I´ve seen guys use a generic gasket for the thermostat and plug off the bypass. The thermostat needs some bypass to work properly. Your temps will swing wildly, without the bypass.
Something else people tend to forget, is that the temp sender in the early renix is in the back and the thermostat is in the front. There is often a rather large difference in temperature between the two.

 

[pauldo39]

90xj you seem to have the exact same symptoms that i do with the 180 thermostat; smells like its running rich, and also exhibits poor fuel performance in town. After the knowledge I've gained after using lower temp tstats, I may very well put back in the 195, if your gas mileage is that much better and it doesn't smell so rich. I first thought maybe my o2 sensor was on its way out, but I also noticed the smell was gone after the engine finally got up to 200 or so, maybe a little warmer.

 

[90xj4x4]

Yeah I replaced my O2 sensor for smog reasons while running the 180 and it made no difference. Putting a NEW 195 in is a good idea.