Another cooling thread

[JefCooks]

Approx. 150K miles. Engine is clean aside from some oil in driver wheel well due to PS hose that was leaking. 

Where did you find an 18psi cap? Most of what I’m seeing is 13psi, with the occasional 16psi. 

I have a 9x11 transmission cooler that I’m gonna hook up later this week. We will see if that helps. 

The efan is pretty much on all the time because of the AC. 

Yes, PO replaced rad. and water pump. I’m assuming he delt with the same stuff I am because he claims it never over heated on him. I kinda believe him because i installed the xj gauges, he only had dummy lights. 

[JefCooks]

1 hour ago, WahooSteeler said:

JefCooks, I hope you don't mind but I'd like to ask questions on your thread because a lot of what is being said are related to a thread I was about to start. If you'd prefer to keep this thread strictly to your situation I respect that completely and will still start a new thread. 

 

Comment/question to your above post about burping the system. Since you have an open system, I thought parking the truck on an incline was not necessary, i.e. that was for burping closed systems? 

Go for it, more information isn’t going to hurt anybody. 

[WahooSteeler]

7 minutes ago, Jeep Driver said:

 

 

 

He's been dealing with this for months.

 

If you have air in your system you'll know it immediately.............not months later. 

 

True. As I mentioned in a post above, I am following this thread closely and one of the main reasons is my rad just sprung a leak. I am only the 2nd owner and it just may be the original unit. When I replace it, I want to disconnect the trans from running through it. I have the factory trans cooler with the tow package but was thinking of adding a second unit and run them in series like some others have done. Thoughts?

[WahooSteeler]

2 minutes ago, JefCooks said:

Go for it, more information isn’t going to hurt anybody. 

 

Thanks...........some people like to have their thread stay on point with their specific issues being discussed, and I understand and respect that. But when there is a chance to save another thread being started to discuss almost the same thing, helps when searching for info later! 

[Jeep Driver]

Burping, here's what I do that works for me-

 

Let idle and bring to temp, let rest for 5 minutes, idle to temp, let rest, idle to temp and top off rad and overflow...........will self burp. 

 

 

I've had a '98 XJ with an auto (others in the past) that never has over heated or ran hot, if it did- I'd do just as I described in the earlier post. I'd bypass the radiator all together.........trans heat is aggravating the situation. 

[smokey]

Another issue is the fan clutch, I did the test with cardboard to see if it was working and it passed.  The engine would run at 220 all the time.  I swap in a new clutch and runs 195 normal and 205 running uphill with the AC on.

[75sv1]

I'd also question the new water pump. I did have a '98 Neon that would all of the sudden over heat. I bought it used, and knw it had over heating issues. The water pump was old though. When I took it out, the impellor slipped off. Can't say that is your problem. Maybe try a MOPAR water pump. 

[JefCooks]

Just installed a new ZJ fan clutch a few days ago, definitely not that. Anyone know a way to test the water pump flow? The water pump will be a ways down the list of things to try due to cost. That being said, do they make a high flow pump? I’d prefer to keep it on the belt and not switch to electric. 

[omega_rugal]

WJ pumps are said to be more efficient, also if works ok in the highway and gets hot in traffic then you have an airflow problem, more likely your mechanical fan, lets say the fanclutch is useful to waste less HP at low temps but it not so good to cool the radiator at high temps, there´s always some slippage even if the fanclutch is new and working.

 

- add some hood louvers, draining any hot air out the hood helps a lot

 

- try a lower temp thermostat

 

- ditch the ,mechanical fan, go full electric fans, i recommend using 2 hi speed taurus ones, (the taurus has 2, main and aux, main pulls more air than aux, get 2 main fans)

 

- give the tranny its own cooler and don´t put it in front of the radiator geez...

 

- it may sound stupid but, have you cleaned the condenser and radiator? dirt can cripple a radiator

 

and last but not least, if you run the AC at max all the time while driving in a hot enviroment and stopped at a red light, the engine is very likely to get a little hotter than usual...

[Pete M]

do not use a lower temp thermostat.  the t-stat is for quickly heating up the engine and once it's open, it's open and does not affect cooling.   

[AZJeff]

7 hours ago, 75sv1 said:

I'd also question the new water pump. I did have a '98 Neon that would all of the sudden over heat. I bought it used, and knw it had over heating issues. The water pump was old though. When I took it out, the impellor slipped off. Can't say that is your problem. Maybe try a MOPAR water pump. 

Water pumps are all the same, in terms of performance, except for some of those super expensive, fully machined ones.  The only difference between a Mopar and some cheesy AutoZone pump will be in bearing life, NOT in pump flow.

[AZJeff]

If an MJ is equipped with all the original type parts (OEM or equivalent), and they are all in LIKE NEW condition, there is no reason for a 4.0 to overheat in normal use, even with AC on, and even in places like where I live, Phoenix.

 

Hood vents, dual electric fans, and other suggestions will make a BIT of improvement, but should NOT be needed to meet normal cooling needs.

 

If an MJ/XJ 4.0 is consistently overheating, it is ALWAYS traceable to missing parts (fan or shroud) or worn parts (fan clutch, radiator, thermostat, etc.)

[AZJeff]

On 6/24/2019 at 8:46 PM, JefCooks said:

 

Where did you find an 18psi cap? Most of what I’m seeing is 13psi, with the occasional 16psi. 

I got my 18lb cap on Rock Auto.  Or you can buy a Mopar.

 

Either way, it’s obvious the Jeep engineers realized the 4.0 was going to run hotter than the average engine, and bumped the cooling system pressure to delay possible coolant boiling issues.  The 18 lb is needed in hot climates.

[eaglescout526]

To back up AZJeff, I can say that I have rarely seen my truck climb over 212. I have seen it get to 220 but that was on a freeway drive and it stayed like that until I returned home. Course it’s the 2.5L and I drive mostly surface streets home but I never see the gauge go over 210. And I don’t even have AC at all but I have never had a overheat issue except for the time my head gasket was bad. That was the only overheating issue I ever had. 

[75sv1]

16 hours ago, JefCooks said:

Just installed a new ZJ fan clutch a few days ago, definitely not that. Anyone know a way to test the water pump flow? The water pump will be a ways down the list of things to try due to cost. That being said, do they make a high flow pump? I’d prefer to keep it on the belt and not switch to electric. 

HESCO makes one. I did buy one. Hornbrod I think had one on his MJ, and Go Jeep I think has one. I remember they had to put in a flow restrictor. So, I would not go that route. The WJ water pump will not fit. Or I should say the bolt pattern is a bit different. I think one extra bolt hole. One of the other bolt hole is off pattern. Also, I think it is reverse rotation. 

          Try this and remove the fan shroud. I know others say you need it. But if it is interfering with the fan rotation, it might impede air flow. I had some issues and removed mine. The temps dropped. Also, then I would look at the motor mounts. If they are shot, then is the fan dragging on the shroud. 

 

Edit: did some web surfing. Motorad makes Hi-Flow Thermostats.  PN 2000-195. Saw it on Rock Auto.

[Bty]

Not trying to hi-jack the thread from the original poster but, I'm having a similar issue. Overheats at longer idles ( stoplights, drive thru, traffic.......) while in motion it stays nice and cool. I noticed someone ask how the engine bay looked. Mine is as he was asking, not the cleanest, oil on the valve cover. Last year I did replace the plastic tank, cap, thermostat, water pump, rad hoses, and temp sensor to get rid of a worse overheating issue. Now its drive able but can't idle long. Its an 88 with the 4.0, only running a mechanical fan with no shroud (bought that way). I plan on grabbing an electric fan this weekend from a upull and throwing in it but is there more I should look for or grab to try and assist with temps while there?

[rokinn]

Make sure all of your rubber O-rings on the radiator are sealing well.  Not cracked or dried out.  Make sure all of your hoses are sealing well also.  You could see a little bit of coolant weeping on either or both.  On the open system when the engine cools down it's supposed to suck the coolant from the overflow bottle back into the radiator.  If you have an air/coolant leak of any kind it will suck air into the system instead/or as well as the overflow, which will lead to overheating (which also makes the cycle even more extreme).  A cycle, rinse, repeat scenario, if you will.  Within a very short time my new radiator was leaking from the o-ring seals as they were of the very cheap variety.  I bought the HNBR (hydrogenated nitrile butadiene rubber) assortment from HF and they are still sealing well.  Just a thought.  Good luck.

[DirtyComanche]

1 hour ago, Bty said:

Not trying to hi-jack the thread from the original poster but, I'm having a similar issue. Overheats at longer idles ( stoplights, drive thru, traffic.......) while in motion it stays nice and cool. I noticed someone ask how the engine bay looked. Mine is as he was asking, not the cleanest, oil on the valve cover. Last year I did replace the plastic tank, cap, thermostat, water pump, rad hoses, and temp sensor to get rid of a worse overheating issue. Now its drive able but can't idle long. Its an 88 with the 4.0, only running a mechanical fan with no shroud (bought that way). I plan on grabbing an electric fan this weekend from a upull and throwing in it but is there more I should look for or grab to try and assist with temps while there?

 

A fan shroud makes between a 30% and 50% difference in the efficiency of a fan...  They're $15 on Rockauto for the newer style one, which is backwards compatible with the old style.

[Ωhm]

Just a thought here. Are all these overheats running in closed loop? HO's run selftest, RENIX owners without REM, don't know what to tell you. Lean=Heat.

[PIKE]

20 hours ago, DirtyComanche said:

 

A fan shroud makes between a 30% and 50% difference in the efficiency of a fan...  They're $15 on Rockauto for the newer style one, which is backwards compatible with the old style.

 

Have not heard of this before. can you go into more detail about the differences?   Also could not find it on Rockauto.   Thanks.

[Jeep Driver]

5 minutes ago, PIKE said:

Have not heard of this before.

A shroud forces the fan to pull air through the radiator instead of from around the radiator. 

 

I don't do business with crockauto but here is a Mopar-

 

https://www.ebay.com/itm/1987-2001-Jeep-XJ-Cherokee-4-0L-Radiator-Cooling-FAN-SHROUD-new-OEM-52027501AC/231423893970?fits=Year%3A1998|Model%3ACherokee|Make%3AJeep&epid=1731171214&hash=item35e1f061d2:g:eTcAAOxyOlhS6rvo:sc:USPSPriority!37843!US!-1

[Jeep Driver]

22 hours ago, Bty said:

I noticed someone ask how the engine bay looked

Someone posted a pic of their oil saturated engine bay and I cannot find it at the moment.

 

Blow-by is when burnt and unburnt compressed gasses blow past the rings, this over-pressurizes the crank case. 

 

When you have blow-by you have power loss and heat builds under load. 

 

Essentially your engine is worn out.

 

People don't want to hear this........but.........that's what it is. 

[DirtyComanche]

29 minutes ago, PIKE said:

 

Have not heard of this before. can you go into more detail about the differences?   Also could not find it on Rockauto.   Thanks.

 

What Jeep Driver said is the easiest explanation.

 

Generic: https://www.rockauto.com/en/moreinfo.php?pk=684506&cc=1180370&jsn=2933

 

Mopar: https://www.rockauto.com/en/moreinfo.php?pk=10283388&cc=1180370&jsn=2934

[Bty]

55 minutes ago, Jeep Driver said:

Someone posted a pic of their oil saturated engine bay and I cannot find it at the moment.

 

Blow-by is when burnt and unburnt compressed gasses blow past the rings, this over-pressurizes the crank case. 

 

When you have blow-by you have power loss and heat builds under load. 

 

Essentially your engine is worn out.

 

People don't want to hear this........but.........that's what it is. 

 

I would not doubt this of mine, It was an old farm truck by the original owner. Ill be redoing the engine next year no matter what  but if the electric fan and fan shroud help for now it'd be great as I only use the truck for overlanding in the summer.

[AZJeff]

11 hours ago, 75sv1 said:

HESCO makes one. I did buy one. Hornbrod I think had one on his MJ, and Go Jeep I think has one. I remember they had to put in a flow restrictor. So, I would not go that route. The WJ water pump will not fit. Or I should say the bolt pattern is a bit different. I think one extra bolt hole. One of the other bolt hole is off pattern. Also, I think it is reverse rotation. 

          Try this and remove the fan shroud. I know others say you need it. But if it is interfering with the fan rotation, it might impede air flow. I had some issues and removed mine. The temps dropped. Also, then I would look at the motor mounts. If they are shot, then is the fan dragging on the shroud. 

 

Edit: did some web surfing. Motorad makes Hi-Flow Thermostats.  PN 2000-195. Saw it on Rock Auto.

As I said previously, a properly maintained 4.0 does NOT need an expensive, super-whammy Hesco water pump.  It WILL provide a bit more flow, but if the vehicle is already overheating, it's NOT becuase of water pump flow, it's because of something else that is more significant.  (OEM water pumps either flow or they don't, since the impeller is either corroded away or is not.)

 

DO NOT remove the fan shroud.  The fan shroud is NOT just a safety device to protect your fingers.  It actually helps channel the air over the propeller blades to improve it's effectiveness.  If the fan is rubbing on the shroud, it's because it's broken or installed wrong (or as you say, the motor mounts are bad.)