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Stock Grand Cherokee Tech. All ZJ/WJ/WK Non-modified/stock questions go here!ZJ (93-98), WJ (99-04), WK (05+)
All ZJ/WJ/WK specific tech questions asked here!
Couple of questions. I just changed out the crank sensor two weeks ago, engine had cut out a couple of times which is either old sensor or heat soak. Did not use a Mopar sensor and it quit again with the new sensor and the engine felt hot to the touch. More than I think is usual. It runs about 196* according to the gauge.
So my next question is does the 4.0 use an electric fan AND a clutched fan? I bought it with just an electric fan and I have the Service Manual and it mentions the 4.0 as having both. I don't have the towing package.
Yes, the 4.0 only came with an electric fan unless it had the tow package. 195*-210* is the normal operating range. The thermostat is a 195*. On cold startup, the fan won't run until the engine gets up to 210* then it kicks on high until the temp drops to 195*, dropping to low speed at 195* and running as long as the engine is. If it gets back up to 210*, it kicks on high until it drops down again.
A clutch fan is a good addition in case the fan relay fails. Without either fan, it should stay at 195* as long as you have sufficient forward motion to cool the engine. My relay failed and I had to drive quickly someplace to get some wire to hot-wire the fan on high until I got a new relay. A clutchfan would have prevented that panic trip!
About the coolest fan setup I've ever seen was my dad's 62 Peugot. It had a freewheeling fan with an electric clutch on it like an A/C clutch. It only engaged in heavy traffic, but when it did, that poor little 90 hp engine fell flat on it's face for power! I always thought it would be a good thing on any engine. That way it wouldn't be pulling hp until it's needed.
Thank you both for answering the question on dual fans. Good idea on having both just incase. It had a new radiator, water pump and thermostat installed by the PO and he had the head magna fluxed for cracks. The head is not the 0331, it's a different casting number, a replacement head. It had overheated and a garage did the work for the PO. I found all the spark plugs in bad shape when I got it (bent or over gapped) plus the electric fan was shot (reason for overheats). As far as I was concerned the garage did a crappy job of diagnosing the problem. It has new gaskets all around and a new intake. I replaced the fan relay along with the fan just to nix that fault. I'll have to double check the thermostat and it has the long life coolant (yellow) so I think I'll replace the coolant with green after a really good flush. The block feels way hotter than the temp gauge says and I can't rely on the Jeep running right until I can figure out the heat soaking killing off of the crank sensors. Really enjoyed changing that beauty!
You might check with a dealer for active recalls. Mine was recalled for a PCM reflash, a heat shield on the intake manifold, and seat belt shoulder bolts.
I can't understand a heat soak of the CPS. It sits right above the dual cats and I've not had a problem with it, although I used a Mopar sensor. These are more expensive because they use a neodymium magnet where aftermarket ones don't. Those cats can get up to 600* or higher. The intake heat shield is to protect the injectors from exhaust manifold heat. It's just an aluminum wafer blanket that sits on top of the manifold and closes off the gaps where the injectors are.
I wouldn't mind getting the PCM reflashed, it's a Canadian model with DRL, want the headlights turned off as well. What are you two getting for average fuel mileage? I'm getting a solid 16 mpg average with half city and half highway driving per day. I just need mileage comparisons to know what tune condition the motor is in, has 200k+ on it.
I'm going to buy the Mopar CkPS but I want to get the cooling system/block flow ironed out first. I had the Jeep towed home when it wouldn't start, it sat for an hour in 30* outdoor temp and started right up when in the driveway. That tells me it's heat and not the crank sensor since it's happened same same between two different sensors. The Jeep has been running in very cold weather all winter (I bought the Jeep in November) and it's just getting above freezing now, not super warm but the motor is getting warmer because of the temp, doesn't take as long to warm up in the morning. Before the valve cover gasket was replaced it covered the block and trans tunnel with oil so naturally it's covered in oil and dirt so that can be cleaned off to help dissipate some heat. Replacing coolant would help too because it will be at the right mixture and fresh, not a big fan of long life coolant for the sediment it creates. I'll drill a hole in the thermostat flange at the top, that's an old trick for allowing some coolant to pass by until it opens. I had a Land Rover Discovery before the Jeep and those thermostats had a factory hole and jiggle pin to alleviate air bubbles.
The IR gun sounds like a good idea, I've put it off long enough. It would confirm what I believe, my hand can't display temps.....
You're loosing sight of the fact that the full flow heater creates a thermostat bypass by it's design. Until the thermostat opens, all the coolant flows thru the heater. This eliminates hot spots and steam pockets from forming. Drill the hole of you want to, but that's to release air.
Didn't loose sight. Chrysler part #53028 186 thermostat found installed, 195*F. https://www.moparpart.com/oem-parts/...tat-52028186ac The thermostat is probably original and looks every bit of it, does not seal completely when closed either, warped. Found a piece of water pump impeller (aluminum) in the head right behind the thermostat so I'll be peeling the water pump off to inspect/replace. Found allot of rust debris in the coolant, covered the bucket bottom, radiator petcock wouldn't drain until I removed it. The coolant was very dark. Didn't test it since it's obviously shot. I think the cooling system efficiency is kaput, might even be partial blockage somewhere in the block so I'll flush it really well. Once that's done I'll get the block grime cleaned off.
Oh...That will do it! Shattered water pump impeller! When I bought my 97 ZJ, I got a lesson on 4.0 water pumps. The pump started rattling soon after I bought it and I found I could move the fan tips about 1/2" back to front. I went to NAPA and bought a Premium pump with an aluminum impeller. The standard ones were plastic. There was a circular wear groove in the #1 cylinder barrel where the impeller had been rubbing on it! When I mounted the new one finger tight, it wouldn't turn freely. In my hand, it did spin. I took it back to NAPA and we compared it with another one and found the impeller hadn't been put on the shaft far enough by about 1/16". That tells me the impeller spins about 1/16" from the cylinder barrel normally! Any wear in the bearing will cause a strike! Plastic ones will disintegrate! It's near impossible to get all the pieces out of the block and they will cause flow problems.
Another thing about 4.0 water pumps. The ones for the serpentine belt and the ones for the v-belts drive in opposite directions! Be sure you get the right one! That's why some of the newer ones come with the pulley attached.
I've used Stant Superstats most of my life and always had good luck with them. They are only about $4. It's easier to remove the lower rad hose to drain the system. It can be messy if you're not careful, but quick. Those petcocks don't always seal after using them.
Don't know if the fin is from the water pump installed or a previous one. The outside faucets here aren't turned on yet, too cold. I'm gonna keep it together to take up to my heated shop at work with new parts and flush it out there and then put it all together. I'm getting the Dorman fan with the Carquest clutch from my local Advanced Auto along with a new thermostat. I bought the Jeep for less than a grand so it's worth putting a few bucks into it but they don't have to be big bucks. The Chrysler thermostat uses a check ball in a pinched brass housing to allow air passage, wasn't even installed correctly at the 12:00 clock positing and it has an arrow pointing UP...... I'll tell ya, hard to find things done right any more. I removed the front skid and the flapper deal under the oil pan to allow more airflow to the pan, no auxiliary oil cooler. If I keep the Jeep I'll be making many changes to it. Reliable and fun.
Just a small update. Fan clutch and fan installed. I used a spare fan from my 97 Land Rover Discovery which is CCW and same diameter. No mods needed. Replaced the thermostat and coolant. Have not had one issue with the crank sensor yet and temp is steady, several ticks below the 100*C mark (Canadian spec). The electric fan hasn't come on since, prior it was every day when pulling into the drive. I can feel the difference when I open the hood, not roasting hot. It's not a complete r&r of the cooling system but enough to get by. Winter hasn't given up here and really need the Jeep. Almost three weeks without issue so far. I'll say one thing about this Jeep, it has responded well to anything I do to it. All in all very dependable. Kinda spooky....... probably just killed my luck.
I bought my 2000 WJ Laredo in 2012 with 125K miles on it. It was a pampered garage queen and had maintenance records to prove it. Zero rust from western PA.
Since then I've put another 108K miles on her as a DD and delivering newspapers, which is similar to city taxi service. I go thru a set of brakes and tires every year. She's gone thru a cracked head, a blown rear axle, several sets of front calipers until I switched to Akebono, a heater core, radiator, a couple of water pumps, wheel bearings, ball joints, and control arm bushings. The engine has been acting kinda tired so I ran a converter cleaner thru it, changed the timing chain, and put a Flowmaster 50 muffler on it. It seems to have given it new life!
This is a keeper. She'll be headed for the shredder when I'm done with her.
03-22-2018, 06:20 PM
01 WJ crank sensor and cooling
