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Cooling issue--exhaust related?

P

pantherchams

NAXJA Forum User
Location
norcal
Hi guys,

So i have been having some cooling issues. Its fine when im moving, can get up tp 235ish in traffic, and to the border of the red on long, slow, hills (slow as in off-road, not paved hills).

The radiator looked really new when I got the jeep about 2 years ago. Coolent looks excellent and im not losing it. Both fans seem to be working well. Replaced the thermostat and radiator cap.

I was thinking that an exhaust leak near the engine could superheat the engine bay. So i got under there, and I cant find any cracks (through all the mud), but I noticed a spot looks like it was smashed. It is just after the headers near a bend, I would call it the "downpipe" on a car (?). It looks like it might be bent in to about 1/2 its original size (maybe not quite that bad). Could this restriction be causing the engine to run hot? I obviously want to replace this anyway, but wondering if it should be my next move in trying to solve my cooling issues or if it is likely unrelated?

Any good places to get exhaust pipes, and are they all the same on the 4.0's (this is a 91 4.0 AW4)?

Thanks for any thoughts/tips!

Ben
 
Normal, that is how it is made on the XJ.

When is the last time the cooling system was flushed with a commercial product--the kind you put in and drive for 500 miles or so? How does the coolant test? Any obstructions in the airflow through the radiator--bugs, mud, bodies of small critters? How is your fan clutch? Considered an upgrade to the ZJ HD fan clutch, NAPA 272310, $44? Do you have an efan and if so, is it working?
 
Oh, really? That seems aweful. No, i havent put anything through to flush the radiator. How do you test coolant?? I pressure washed the radiator front and back after my last trip to Death Valley, which has kept me from entering the red again.

The efan is working fine. How do i test the clutch on the other fan? guess i will go search. How is the ZJ clutch an upgrade?

BTW, beginning to think you are the most helpful man on earth :)

Ben


joe_peters said:
Normal, that is how it is made on the XJ.

When is the last time the cooling system was flushed with a commercial product--the kind you put in and drive for 500 miles or so? How does the coolant test? Any obstructions in the airflow through the radiator--bugs, mud, bodies of small critters? How is your fan clutch? Considered an upgrade to the ZJ HD fan clutch, NAPA 272310, $44? Do you have an efan and if so, is it working?
Click to expand...
 
Found some info about the HD fan clutch, sounds like a pretty good idea. Is it normal for the efan to not switch on until ~230ish?
 
I've read the efan should come on about 215-220.

I'm not currently running an efan, but if I did I would consider getting a sensor that would have it come on earlier.

The HD ZJ fan, when engaged, runs at 80-90 percent of shaft speed. The standard clutch fan runs at 60-70 percent. It flat out moves a lot more air.

Lot of others on here been helping longer than I have, and I have learned quite a lot from them.
 
Do you know anything about how the efan sensor works? Im assuming it is tied into the same temp sensor that goes to the dash. Easiest to just hardwire it so its running when the engine is on and add a switch?

Is it a pretty good bet the water pump isnt failing?

Thanks!
Ben
 
pantherchams said:
Do you know anything about how the efan sensor works? Im assuming it is tied into the same temp sensor that goes to the dash. Easiest to just hardwire it so its running when the engine is on and add a switch?

Is it a pretty good bet the water pump isnt failing?

Thanks!
Ben
Click to expand...

Depends on what year/engine. Some fan sensor is in the radiator, some in the thermostat housing, and some it is just one sensor for the computer and the fan.

The temperature gauge/idiot light sender doesn't have anything to do with the fan.

Water pump failure is usually leaking through the weep hole or the shaft bearings give out and it wobbles.

Putting a command switch on the dash for the efan is a common fix, rather than hot wiring the fan to run all the time. Only downside is remembering to turn the fan on early enough to do some good, and if it runs all the time then warm up will be effected and I don't know how much that would shorten the efan's life.
 
winterbeater said:
C'mon, Joe's a good guy, but this is out of hand! Actually though, you can count on what he says. Just don't get carried away with lavish praises. LOL. :roll:
Click to expand...

I don't know--I felt obligated to put the disclaimer in my signature! LOL!

Really though, this whole forum is one big learning experience. Just about the time I think I have a good handle on a fix or upgrade, someone pops up with a better idea!
 
about 2 years back I had an overheating issue while running in the sand dunes.

If you do not run in the sand... to climb a big dune you normally have to blast at about 4000RPM for 30 seconds or so to get up...Do that a few times and you will find out just how good your cooling system is on a hot summer day.

I found an exhaust manifold crack that was blowing right back onto the side of the block. Once I got rid of my exhaust leak my overheating also got better. It did not go away completely but I do believe that dumping that amount of hot exhaust gas onto the side of the block was a contributing factor in my case
 
Install a new water pump and a new mechanical fan clutch and you won't need to put a switch on the E-fan. It is common for the vanes on the coolant pump to wear down over time and the coolant flow to steadily decrease as a result.
 
Any way to test for this? How do you test the water pump? Just pull it, and check the vanes?

I've just replaced my e-fan(it was making nasty noises), and the mechanical fan clutch(it was bad). I had a winch blocking air flow into the grill, so I pulled it (reciever hitch mount) for road use. System is flushed, new t-stat(195). Passed a compression test, and no bubbles/oil in the coolant. I haven't lost coolant. Bottom radiator hose does have the spring in it. Pretty much, I've replaced everything but the hoses, radiator, and water pump. Oh yeah, complete new exhaust, manifold and all. This stuff needed to be replaced, but I'm sick of throwing parts at the problem.

I've got lebaron hood louvers coming, and my e-fan is wired to run on command, or by sensor. When I didn't have the running hot issue, the switch was great for trail use. I've wanted the hood louvers for a while now.

I just want to know how to trouble shoot this to fix the issue. The fan switch is a pretty hack way of fixing this issue.

Thanks
 
mrrbby said:
Any way to test for this? How do you test the water pump? Just pull it, and check the vanes?

I've just replaced my e-fan(it was making nasty noises), and the mechanical fan clutch(it was bad). I had a winch blocking air flow into the grill, so I pulled it (reciever hitch mount) for road use. System is flushed, new t-stat(195). Passed a compression test, and no bubbles/oil in the coolant. I haven't lost coolant. Bottom radiator hose does have the spring in it. Pretty much, I've replaced everything but the hoses, radiator, and water pump. Oh yeah, complete new exhaust, manifold and all. This stuff needed to be replaced, but I'm sick of throwing parts at the problem.

I've got lebaron hood louvers coming, and my e-fan is wired to run on command, or by sensor. When I didn't have the running hot issue, the switch was great for trail use. I've wanted the hood louvers for a while now.

I just want to know how to trouble shoot this to fix the issue. The fan switch is a pretty hack way of fixing this issue.

Thanks
Click to expand...

When are you having overheating problems?
 
mrrbby said:
Any way to test for this? How do you test the water pump? Just pull it, and check the vanes?

I've got lebaron hood louvers coming, and my e-fan is wired to run on command, or by sensor. When I didn't have the running hot issue, the switch was great for trail use. I've wanted the hood louvers for a while now.

I just want to know how to trouble shoot this to fix the issue. The fan switch is a pretty hack way of fixing this issue.

Thanks
Click to expand...

My setup is similar to what you are working towards (lebaron vents, switch on dash). The vents are nice for reducing the underhood temps but I don't think they do alot for coolant temps. My thinking is that it would, but I just don't see it.

I like having a switch on the dash for the e-fan as it comes in handy when wheeling and the tranny cooler when towing. It's wired through the existing relay and comes on on its own when the A/C or defrost is on.

I haven't had many cooling problems until my last trip (last weekend) when I was towing a fairly light trailer (canoes), it was 105F and I was running the A/C all at highway speeds (60-70). I came close to red lining for the last climb up the hill. My tranny was at about 150-180F.

The key to troubleshooting this has also been elusive to me. I converted to an open system, have a HD tranny cooler, replaced hoses, t-stat (that also were due). I replaced the fan clutch last year and saw some improvement but did not get the torrent of air I expected. The water pump is about 3 yrs. old. Probably due, or weak.

My project this weekend is to replace the water pump AND the fan clutch with a ZJ HD NAPA fan clutch. I also need to completely flush, dump the coolant and change it out which involves getting the !#@$%^ block drain out.

I think the answer is to continually strive to improve air flow AND coolant flow acxross the board.
 
Going uphill during "normal" road driving. I can understand running hot running slow in low range for extended periods of time. It's the road driving. I should mention I'm running 34's w/4.56's.

Oddly enough, offroad, I'm fine.

Time will tell on the other stuff. I'm just looking for what to trouble shoot. I'll be daily driving my rig to give it a "shake down" so I don't break down on the trail over stupid stuff.

I'm just trying to eliminate the variables.
 
ParadiseXJ said:
My setup is similar to what you are working towards (lebaron vents, switch on dash). The vents are nice for reducing the underhood temps but I don't think they do alot for coolant temps. My thinking is that it would, but I just don't see it.

I like having a switch on the dash for the e-fan as it comes in handy when wheeling and the tranny cooler when towing. It's wired through the existing relay and comes on on its own when the A/C or defrost is on.

I haven't had many cooling problems until my last trip (last weekend) when I was towing a fairly light trailer (canoes), it was 105F and I was running the A/C all at highway speeds (60-70). I came close to red lining for the last climb up the hill. My tranny was at about 150-180F.

The key to troubleshooting this has also been elusive to me. I converted to an open system, have a HD tranny cooler, replaced hoses, t-stat (that also were due). I replaced the fan clutch last year and saw some improvement but did not get the torrent of air I expected. The water pump is about 3 yrs. old. Probably due, or weak.

My project this weekend is to replace the water pump AND the fan clutch with a ZJ HD NAPA fan clutch. I also need to completely flush, dump the coolant and change it out which involves getting the !#@$%^ block drain out.

I think the answer is to continually strive to improve air flow AND coolant flow acxross the board.
Click to expand...

I've always expected to replace the water pump every five years, maximum.

I have an idea brewing on water pumps--if you can find one with a cast impeller get it rather a pump with a sheet metal impeller. This idea is based on an known problem with some Chevrolet engines that when you use a water pump with the sheet metal impeller (new OEM at the dealership) cavitation results and overheating. The last one my Son had to deal with they had to go aftermarket to get a pump with the cast impeller.
 
joe_peters said:
I've always expected to replace the water pump every five years, maximum.

I have an idea brewing on water pumps--if you can find one with a cast impeller get it rather a pump with a sheet metal impeller. This idea is based on an known problem with some Chevrolet engines that when you use a water pump with the sheet metal impeller (new OEM at the dealership) cavitation results and overheating. The last one my Son had to deal with they had to go aftermarket to get a pump with the cast impeller.
Click to expand...

I am not buying this one, no way. Maybe the sheet metal impeller is slipping on the shaft, or the seals are bad on all those, or the cast impeller has more flow due to better curvature of the blades, real hard to believe it is causing cavitation. Unless there is real difference in the blade shape?
 
Ecomike said:
I am not buying this one, no way. Maybe the sheet metal impeller is slipping on the shaft, or the seals are bad on all those, or the cast impeller has more flow due to better curvature of the blades, real hard to believe it is causing cavitation. Unless there is real difference in the blade shape?
Click to expand...

Like I said, just an idea.

Please note though, Hesco claims their hi-flo water pumps with the CNC machined impellers reduce cavitation.

Just an idea.
 
joe_peters said:
Like I said, just an idea.

Please note though, Hesco claims their hi-flo water pumps with the CNC machined impellers reduce cavitation.

Just an idea.
Click to expand...

Well I guess a smooth curved blade, versus the abrupt sheet metal blade on the stock XJ pump could make a difference. It would be more of an issue at higher rpms, so maybe you are onto something.
 
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