Question about 4.7L V8 in the WJ/WK/XK — need advice

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lfhoward

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Hi KJ & KK peeps,

Don’t worry, I am not selling or engine swapping my Liberty! :p

Now that we’ve gotten that out of the way, I would like to ask some advice from people here on the forum who own anything with the 4.7L V8. I am looking at adding a second vehicle to the stable, and the 05-10 WK Grand Cherokee or the XK Commander fit the budget. Our family has grown by 2 teenagers and we now need to be able to go more than one place simultaneously. We also need a bigger Jeep for long trips. I would consider WJ’s too but from 02-04, ABS was not required, but I want ABS brakes on anything my teenagers drive. Some of them have it as an option.

We have been seriously looking at Commanders today and it is like a grown up version of our KK Liberty. We like them. We’re looking at the 4.7L V8 engine because the V6 would probably struggle with such a large vehicle, especially towing. The V8 models come with 4-Low also, which is nice. All commanders have full time 4WD-High. Since Commanders were only built from 05-10, finding a nice used one can be challenging. We looked at three today and two of them had issues that immediately took them out of the running. The third was very nice and we like it very much.

It is a Rocky Mountain Edition, a silver 07. It has about 150,000 miles and a 4.7L V8, but the previous owners took really good care of it. The interior is in good shape and the engine purrs. The AC is cold and the heat is hot. Everything works as it should. There are no funny smells, either inside or out. After our test drive I hooked up my OBDII scanner and there were no codes or pending codes. Engine temperature was 204-206, which is normal (and relevant to my question coming up). It does have a few cosmetic issues of course, but I can either ignore or fix those and they aren’t really a factor.

There are a couple of things I wanted to run by y’all, which could be significant enough issues to rule this particular Jeep out. I am looking for advice. What would you do?

1) The coolant reservoir was empty. This makes me wonder where it went. There were no apparent leaks from the front end, and no steam from the exhaust and the engine was as smooth as could be. If it has a head gasket problem it is well disguised. This could be as expensive as a head gasket or a new radiator, or as inexpensive as a hose fitting or a weeping water pump. Not sure what is going on and the seller didn’t know either because he got the Jeep at auction. There was coolant in the radiator (yay!), but it was the green stuff. Definitely not HOAT. I am thinking at the very least this would be a complete coolant flush, water pump, and thermostat job if we bought it.

2) Perhaps this is a quirk of the V8 and the 545RFE, but there seemed to be a slight resonant hum in the driveline somewhere when getting on the gas and accelerating to pass or merge. There did not seem to be any noticeable transmission slip, and the noise lasts only a second or two before disappearing. I could feel it a little as well as hear it. Any ideas what that could be? I have on my list to check the transmission fluid after I let it warm up the next time we go back to see the vehicle, which could be tomorrow. I’ll make sure it’s at the right level and doesn’t smell burnt.

Thank you if you’ve made it to this point and you’re still reading. The price is $3500. I’m interested in any feedback. Thanks in advance.

Lauren
 
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u2slow

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IMHO, the 3.7/4.7 engine suffer from the 'luggy' programming of the auto trans. These engines cool and oil best with some revs - which is what happens with a manual trans.

I would find one with a 5.7L hemi instead.

A friend's ram 1500 (hemi) wasn't drinking anymore fuel that our 3.7L Jeep, when driven at conservative highway speeds. The cylinder cutout feature seems to work.
 

KKinTexas

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Hi KJ & KK peeps,

Don’t worry, I am not selling or engine swapping my Liberty! :p

Now that we’ve gotten that out of the way, I would like to ask some advice from people here on the forum who own anything with the 4.7L V8. I am looking at adding a second vehicle to the stable, and the 05-10 WK Grand Cherokee or the XK Commander fit the budget. Our family has grown by 2 teenagers and we now need to be able to go more than one place simultaneously. We also need a bigger Jeep for long trips. I would consider WJ’s too but from 02-04, ABS was not required, but I want ABS brakes on anything my teenagers drive. Some of them have it as an option.

We have been seriously looking at Commanders today and it is like a grown up version of our KK Liberty. We like them. We’re looking at the 4.7L V8 engine because the V6 would probably struggle with such a large vehicle, especially towing. The V8 models come with 4-Low also, which is nice. All commanders have full time 4WD-High. Since Commanders were only built from 05-10, finding a nice used one can be challenging. We looked at three today and two of them had issues that immediately took them out of the running. The third was very nice and we like it very much.

It is a Rocky Mountain Edition, a silver 07. It has about 150,000 miles and a 4.7L V8, but the previous owners took really good care of it. The interior is in good shape and the engine purrs. The AC is cold and the heat is hot. Everything works as it should. There are no funny smells, either inside or out. After our test drive I hooked up my OBDII scanner and there were no codes or pending codes. Engine temperature was 204-206, which is normal (and relevant to my question coming up). It does have a few cosmetic issues of course, but I can either ignore or fix those and they aren’t really a factor.

There are a couple of things I wanted to run by y’all, which could be significant enough issues to rule this particular Jeep out. I am looking for advice. What would you do?

1) The coolant reservoir was empty. This makes me wonder where it went. There were no apparent leaks from the front end, and no steam from the exhaust and the engine was as smooth as could be. If it has a head gasket problem it is well disguised. This could be as expensive as a head gasket or a new radiator, or as inexpensive as a hose fitting or a weeping water pump. Not sure what is going on and the seller didn’t know either because he got the Jeep at auction. There was coolant in the radiator (yay!), but it was the green stuff. Definitely not HOAT. I am thinking at the very least this would be a complete coolant flush, water pump, and thermostat job if we bought it.

2) Perhaps this is a quirk of the V8 and the 545RFE, but there seemed to be a slight resonant hum in the driveline somewhere when getting on the gas and accelerating to pass or merge. There did not seem to be any noticeable transmission slip, and the noise lasts only a second or two before disappearing. I could feel it a little as well as hear it. Any ideas what that could be? I have on my list to check the transmission fluid after I let it warm up the next time we go back to see the vehicle, which could be tomorrow. I’ll make sure it’s at the right level and doesn’t smell burnt.

Thank you if you’ve made it to this point and you’re still reading. The price is $3500. I’m interested in any feedback. Thanks in advance.

Lauren
Hi, we had a grand cherokee with the 4.7. It threw a rod and blew up on the highway. I would steer clear of them. Back two cylinders do not get enough oil and water circulation back to there is also not the best.
It gave us problems ever since we bought it used till it exploded. Body and trim were excellent and comfy. Just not that motor!

This appears to be a common issue as it is the 3.7 with two extra cylinders which was a Daimler influenced, modular approach.
Look for the V6 or hemi 5.7. steer clear of the 4.7.

My friend had a 3.7 commander. It was great In all conditions and very capable. Watch out for worn front end issues, which can easily be repaired, just something else to keep an eye for.
The v8 models typically have nicer trim levels. Not all are 4wd btw.
 

The gov

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Hi, we had a grand cherokee with the 4.7. It threw a rod and blew up on the highway. I would steer clear of them. Back two cylinders do not get enough oil and water circulation back to there is also not the best.
It gave us problems ever since we bought it used till it exploded. Body and trim were excellent and comfy. Just not that motor!

This appears to be a common issue as it is the 3.7 with two extra cylinders which was a Daimler influenced, modular approach.
Look for the V6 or hemi 5.7. steer clear of the 4.7.

My friend had a 3.7 commander. It was great In all conditions and very capable. Watch out for worn front end issues, which can easily be repaired, just something else to keep an eye for.
The v8 models typically have nicer trim levels. Not all are 4wd btw.
Good call on the 4.7, they need better oil pumps to accomplish properly lubrication of the back main journal, my Durango had a low pressure issue that required a few modifications!
 

MuckSavage

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I've had an '07 Commander Limited, 4.7 for around 10 years. I call it "the vehicle I hate to love & love to hate" . I purchased it with 120k miles, now has around 188k. It's currently parked in my shop because the oil pan rotted out. (I've done this job on 4 different customers 3.7 & 4.7's.)
During my time of ownership, I've replaced the ECM (last ditch effort after it left me stranded multiple times). These motors eat crank position sensors of not Mopar. I've had to cut/solder/relocate relays in the PCM.
When the Commander runs right. I love it. Comfortable, 4wd system (Quadra Track 2) is amazing, putting many modded Jeeps to shame off road.
I guess in closing, beware. I'm grateful to own mine. This may sound odd but it's really honed my mechanical skills.
 

u2slow

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I'd avoid a 4.7 with anything suspect in the cooling system as they overheat in a very short time, often leading to dropped valve seats. Why 3,7's do not seem to suffer in the same way I've never understood.

I dropped a 3.7L valve seat. Never been overheated. 305k and it got cold overnight - apparently all it takes.

On a spare engine, PO had a water pump failure... which he was sure he caught in time. Nope. Head warped and gasket blown.
 

lfhoward

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Thank you all for the info about the 4.7 and the Commander. It was too good a deal to pass up and is in really nice condition. I have actually owned it since Saturday afternoon (before I read most of your replies) and put a few hundred miles on it since. It is a really nice truck. I can see why MuckSavage is fond of his even though it has had its issues.

I think I have a good idea about the coolant loss. The level in the bottle is still creeping down slowly. It was filled on Friday and today it is 1/3 full. The two lowest bolts on the water pump look rusty and wet, when none of the others are. I think the water pump needs replacing. The drips never make it to the ground (or the cardboard I put there), meaning it only leaks when it runs and builds up pressure. Also I think the drips hit the main crank pulley and fan and get dispersed and evaporated. That crank pulley has a little rust while none of the other pulleys do.

I have to do a coolant flush anyway to rid the engine of the green coolant, so doing a water pump and thermostat at the same time should not add too much more expense. Hopefully that’s the only leak. The engine runs flawlessly. No misfires, no steam in the exhaust, no coolant in the oil that I can see.
 
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lfhoward

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Good call on the 4.7, they need better oil pumps to accomplish properly lubrication of the back main journal, my Durango had a low pressure issue that required a few modifications!
What modifications were you able to do to improve oil access to the rear main journal? I imagine keeping on top of oil changes to avoid sludge is key here. I plan to use Mobil-1 which keeps things really clean and change every 3000 miles. I’ve been using that in my Liberty for the last 50,000 miles or so and it runs very smoothly.
 

u2slow

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The water pump is 0-ring sealed. Its a quick change in your driveway. Haven't tackled a thermostat yet.

Watch for any codes. P03xx are misfire type... what i ran into with the blown head gasket.

IMHO, the brand of oil is never as important as the regular changes. You can start good practices, but you can't undo history either.
 

KJowner

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Get one with a proper engine! ;-)
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KJowner

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No good in London though, 'cos if it's new enough to be Ultralow Emissions Zone compliant, you get stung by being in the higher tax bracket.
True, but I avoid old London town like the plague!
 

lfhoward

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Get one with a proper engine! ;-)
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That’s a gorgeous CRD Commander. Those are unobtainium over here. I suppose once it becomes 25 years old it can be imported and driven legally here and exempt from emissions requirements.
 

lfhoward

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The Silver 07 Commander is in the shop for some work and its PA state inspection. I wish I had the time to do some of the work myself (water pumps are pretty easy), but we need this second vehicle to be inspected and reliable more quickly than I would be able to do it working by myself out on the side of the street.

On the list:
- Replace the green stuff with HOAT coolant. The shop is doing a proper coolant flush. They reported back that someone had put stop leak in it at one point too. Ugh. Jeep vandalism. Best to replace the leaky part whatever it is than rely on a band-aid solution that could fail at any time. The cooling system held pressure but the pressure test will get re-done after the coolant flush.
- The transmission gasket was leaking so we’re dropping the pan and fixing that. Hopefully also a new filter since we are in there anyways. I will check in with my mechanic about that tomorrow.
- Still figuring out the driveline hum. I don’t think they have gotten to that yet. I am pretty sure it is a bad CV on the transfer case side of the front driveshaft. Just like on our liberties.
- On the way to the shop the check engine light came on, wouldn’t you know it! The DTC is P0171, a lean condition in bank 1. Not sure what is causing that yet. The seller mentioned replacing an oxygen sensor and maybe he used a cheap one. The condition that caused the check engine light to come on will need to be fixed before it will pass inspection.
 

lfhoward

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I have some answers and some things are still being worked on.

- The vibration / hum at 35 mph is because the bushing at the top of the front differential is deteriorated so that the diff can move up and down and resonate when it receives torque from the front drive shaft. This explains the lack of noise while coasting too. I have looked into replacing this bushing and it is a hard job. I’m going to wait on it for a while and save up for this one. There is a ton of labor involved. Or I can do it next summer myself when the Jeep can be on jack stands for a week and I actually have the time. It is not a critical safety issue right now. And now I know the ring and pinion gears are not destroying themselves.

- The DTC P0171 turned out to be because of a bad MAP sensor. The sensor had been replaced with a cheap one at some point and it was sending false readings to the computer that led the computer to believe it had to change the air/fuel ratio. We are going MOPAR with the replacement sensor. This will help the Jeep pass inspection and emissions.

- We’re changing the fluid and filter on the transmission. Good to start fresh.

- The stop leak crap is still being flushed out of the cooling system. I will know more tomorrow.

- The matching 5th wheel came today from a junkyard in Texas. It is an exact match to my truck, having also been from a silver Rocky Mountain Edition XK. Going to get a matching tire mounted on that tomorrow and then I will have a spare.

This new Jeep acquisition is a bit more expensive than planned but it is a really cool ride. And it meets our needs as a family right now.
 

HoosierJeeper

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Post pics when you can! Those are awesome vehicles. Almost bought one when we got LR3 all those years ago, have always wanted one.
 
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