Chrysler PowerTech 4.7L engine issue
 

I need some input from you engine guys, please. I have experience but I am not an engine expert.

I have a 2006 Jeep Commander Limited with the 4.7L PowerTech engine. The vehicle only has 65,000 miles and is bone stock except I swapped out the original five spoke OEM rims for the exact size six poke OEM rims . I took it in last week for some service, program the TPMS system, change the oil, replace the sway bar bushings and replace a broken manifold stud.

I have noticed over the past month a tap when the engine is cold. It slowly quiets as the engine warms, but does not go away. It just quiets down. Again, I am not an engine builder but I know enough that the sound is quieting because the gap between the block and manifold or head is closing as the engine warms.

I explain the tap to the mechanic and I think it may be a valve or lifter? My jeep was sitting at this point for some time and was more or less cold. We go to the vehicle and start it and you can hear the tap. The mechanic puts his head under the car, opens the hood and we go for a few mile test drive. He stands on the pedal several times. We get back and he goes through the expansion contraction engine getting warm. He doesn't think it is anything and once the stud is repaired it will be fine. OK fine but I hear a tap. I ask him to look into it any way to just to be sure.

Today I get a call from the shop manager that the Commander is on the lift and it needs an engine. I asked why does it need an engine? The reply was the sound is in the bottom of the engine and they believe the main bearings are going bad. Now again, I am not an engine builder but I do know that generally a bottom end rebuild could be performed. I asked why can't the bearings be replaced? The reply was I need to speak to the mechanic. I am going in the a.m. to get more information.

Am I missing something? Is there something about these engines that the bottom can not be rebuilt? The vehicle runs fine has plenty of power, to the best of my knowledge nothing has let go.

Any in put or questions to ask would be appreciated.

I've never heard a rod knock that sounded like a lifter.

Even if you'd never heard it before you'd know it's not a lifter.

I have heard exhaust manifold leaks that sound like lifters.

Pull the car and get a second opinion.

Thanks for the quick reply Stomachmonkey. It is definitely not a rod knock I know that sound. I intend on getting a second opinion.

Exhaust leaks and lifter slack gets quieter as engine warms up. Exhaust manifold will expand and tighten the leak and oil will eventually get to the lifter.

Rods on the other hand tend to knock louder when the engine warms up, as oil viscosity and pressure go down. It's a rather deep sound that differs from lifter noise.

The rods are "cracked " rods, and cannot really be machined back to spec. You have to replace them. The rest of it is simple engine rebuild 101. The heads are also garbage, and are known to have valve seats fall out when you overheat them

you could do a quick check,
pull the dipstick drip the oil onto a black piece of cardboard,
look at the oil in the sun with magnifying glass ,
if you see lots of metallic s then you have major engine wear happening

If you go full engine replacement what are the options for a 5.2l or 5.9l Magnum replacement on the Commander? They don't seem to have the issues the 4.7l has.

Let us know what the second opinion is.

Somebody noted that they've never heard a rod or main issue that sounds like a lifter. Neither have I.

Others have mentioned they have heard exhaust leaks that do sound like a lifter. So have I.

Have the stealership replace the broken stud, then just drive the car. If they're right and it needs a new engine anyway, you're out a tow (unless you're covered for that in which case you're out just the time).

What nkowi said. Drive it till it pukes. I doubt it will, because I doubt their diagnosis.

My 4.7 has over 230k miles. The valve train sounds like a bunch of marbles in a coffee can and it keeps right on running, day after day. For what it's worth, the 4.7 uses chain driven overhead cams. Instead of the cam acting directly on the valve, they have it acting on a rocker arm.

http://www.1962to1965mopar.ornocar.c...s/47valve1.jpg

Good luck! My Wife's 09 Town and Country burns 2-3 quarts of oil every 3000 miles and Chrysler told me that it was "normal consumption" My van only had 55K on it at the time. We have every record for the van from the first oil change on.

I would talk to a different dealership.

Isn't that the motor that tends to break rocker arms?

Are we sure it's not piston slap, like in all the GM Vortec engines that have had their piston skirts removed?

My '06 Altima developed this at 142k, sounded like a VW TDI when cold. After it warmed up everything went quiet, didn't use any oil either :)

If the main bearings are going bad make them show you. Simple drop of the pan, remove one main cap and inspect.

Flipper is onto something as well ;)

Thanks for all the posts.

Just to fill you in a little bit more. When my factory warranty was expiring I purchased an aftermarket warranty for $1,200.00. It covers 60 months or 100,000 miles which ever comes first for all engine, drive train, internally lubricated components and associated electrical items. That is 100,000 miles over the mileage at the time of purchase.

I spoke to the mechanic today who I trust and has done right by me so far on other vehicles. The shop manager that I spoke to yesterday I have had minimal interaction with in the past, but he just doesn't seem reputable to me. I think he smelled easy money. When I dropped it off I did not authorize any repairs, only diagnosis as the repair may be covered by the warranty.

So today when I met with the mechanic he stated he confirmed two broken studs on the back of the exhaust manifold which I knew. He further stated he used a mechanics stethoscope on the engine to see if he could locate the source of the tapping I explained. He stated when he used the stethoscope on the bottom of the engine

"he could hear an internal tapping noise"

I concur with you guys every rod knock I have ever heard sounded like a power stroke diesel, you didn't need a stethoscope to hear it.

The shop owner was in ear shot as the mechanic and I had our conversation and I questioned the shop managers explanation and statement the vehicle needed an engine. At this point the shop owner chimed in stating the manager most likely recommended the engine swap as it is often cheaper to buy a re-man than rebuild the original as the rest of the engine is still original and could potentially fail down the road.

I explained that is all well and good however, a swap would devalue the vehicle as 1. the numbers would no longer match. I wasn't all that concerned about that. But more importantly I would no longer be able to certify the mileage should I choose to sell or trade it in at some point. He didn't have much to stay after that. Again, my opinion is the shop manager smelled easy money counted on my not knowing or questioning his statement and lastly I think the mechanic and owner tried to cover for him.

So right now I haven't made any decisions but am leaning toward nkowi's suggestion and having the studs repaired. I will bring it home and see how it sounds, performs and see if anything changes, get a second or third opinion and I will also do the engine oil check as MrMerlin suggested.

I am open to any other suggestions you all may have.

Thanks again for all your in put thus far.

Flipper35 if by chance it did need a new engine I would most likely opt for the 3.0 Mercedes diesel that was installed in European export Commanders.

Get it the hell out of there. Everything about the situation sounds shady. There's a reason they call them stealerships.

I've owned 3 4.7 V8's and they have been amazing no matter how much I beat them!

I've also had that exact sound you're describing. It was from a broken stud on my manifold.

The stud actually backed off so easily I was shocked. It backed out by just turning with a vise grip and then by hand. Replaced the stud and knock was gone.

If you've done basic maintenance on schedule I would be surprised if the engine had any internal damage.

By chance do you know if you have single or twin plug heads?

Wait so the motor is under warranty?

Of course he wanted to replace it.

I hate thieves.

Took my 3000 GT in for inspection one day.

Manager calls me at lunch and tells me it failed, needs brakes.

Told him I was coming right over.

When I got there I asked if he'd even pulled the wheels.

He said "of course, how else would we have known?"

I responded as loudly as possible without yelling in the crowded waiting room that either he was a liar or the mechanic incompetent as I'd just done all four corners over the weekend.

He was not pleased.

Puppy- it will be out in short order.

Earlyporsche- it is single plug. I believe only twin plug engine for the Commander XK/Grand Cherokee JK was the Hemi. I chose the 4.7L over the Hemi for several reasons. Excessive moving parts, fuel economy, and 8 vs. 16 spark plugs.

Stomachmonkey- Yes, the entire drive line is under warranty. engine, transmission, 4 wheel drive, related electrical components, fuel delivery system. $1,200.00 dollars, 60 months or 100,000 miles. That equates to $250.00 per year or 25,000 miles per year. $100.00 deductible per claim.

I almost forgot the other issue that prompted me to take it in for service occurred a few weeks ago during one of our snow storms. I took the Commander to the store. I made a right hand turn out of my development onto the main road, as I allowed the steering wheel to slide through my hands to return to center, the vehicle abruptly turned left into the on coming lane. I had to fight the wheel to get the Commander back into my lane. Shortly after this incident the service four wheel drive notification came up on the screen. This is the first and only time this has ever occurred or the notification has come on.