So I asked about this over on the truck section and got some peekers but not much help. I’m looking at buying a 2007 Chrysler Aspen (Dodge Durango) with a 4.7 with 123,000 miles. I’ve been out of the game for a while but I seem to remember something about the 4.7’s having oiling system problems. Is this true? What exactly were the problems? What steps can I take on a used truck to guard against possible problems? Thanks for any help.

Go to the "search" feature, click on "truck, jeep, 4X4" section, click the button that says "in subject" and change the range to 1 year. Type "4.7" in the field, you'll have plenty to read.

They make than with a Hemi, right? I had a Ram 1500 with a 4.7, and a bunch on them with Hemis. The hemi gets much better mileage, and the 4.7 is so under powered. I'd recommend skip that 4.7 and find one with the hemi.

If the original owner didn't keep up with the oil changes, at 123K miles, the damage has probably already been done. Mopar originally expected a 150K life span on the 4.7.

That said, I've heard of some them going well over 200,000, but probably a lot more haven't made it to the 150K.

The 4.7 is unreliable and under powered in a heavy truck like that Aspen, but You may be lucky. Gene

I bought a 2001 durango with the 4.7 and it had 148k when I bought it.
Now it has 170k on it haven’t had any issues with it at all.
Just run synthetic oil in it and a good filter and change the oil every 5-7k miles.
That’s what I’ve been doing with mine and it’s been flawless.
The fuel mileage could be better, specially with a smaller v-8 I get about 12 city and about 18-20 highway depending on how fast I’m going.
I’ve noticed my 4.7 is very picky on the air filter, I change the air filter about once every six months cause mileage will start to fall off after about 6 months on a paper air filter.

I wish it had the hemi, but it don’t so this is what I may be getting. And after a test drive, it certainly doesn’t seem underpowered to me. Got plenty of get up and go. And the only thing it will likely ever haul is groceries and grandkids so I’m not really worried about towing abilities. This truck is in really nice condition and looks like it’s been well taken care of, but I have no way of knowing the maintenance history on it and if they did regular oil changes or not, or what kind of oil may have been used. I was basically just wondering if there was anything that could be done from this point forward to help prolong the life. I figured a synthetic oil would be a good start, but wasn’t sure if there was some kind of cleaner I should try first or if that would be advisable.

Check your local craigslist for trucks with blown up 4.7's. They are numerous. The 5.7's are starting to trend that way too although not as bad. Never saw blown up 5.2/5.9 trucks for sale.

I know this is a worthless anecdote, but a guy I work with was given his mother in law's durango. The 4.7 was changed after a rod went through the side of the block. He looked for a used 4.7 and couldn't find her one around for less than 2k so she took it to a shop who had one from an insurance write-off truck. Now it gets synthetic oil changes every 3 months.

I had an 01 Durango with the 4.7, we bought it with 170k miles. used about 4 quarts of oil in 1000 miles. It was very under powered, but ran as smooth as could be. I think it also cracked a cylinder head as well. We got rid of it with 195k miles.

I had a 2008 Ram with the 4.7L & loved it. Plenty of power & very dependable. That was from new however & never had any problems. Traded it in with about 19,000 miles.

I tend to stay away from cleaners, but the one cleaner I’ve had good success with in the oil pan and in the fuel tank is marvel mystery oil.
Put in a qt of marvel mystery oil and drive it for about 200-300 miles to let it soak in and clean thins up then drain the oil and re-fill with a synthetic and a good filter and put a good paper air filter in it at that time as well and I bet you’ll be fine and not have any issues.
Just change the oil every 5-7k with a good filter.
The 4.7 in my Durango has been a very good engine so far.
It’s a little noisy when it’s cold but I’ve been told it’s the valve lash adjusters making noise cause when it gets warm it’s quiet and it’s always been a smooth running engine as well.

http://www.enginebuildermag.com/2012/01/valve-seat-selection-finishing-materials/

Sample quote

Chrysler has reportedly had problems with the exhaust valve seats loosening up and dropping out in some of its late model 4.7L engines. Seat failures have typically occurred between 60,000 and 80,000 miles, often after an overheating episode in which the coolant got above 250 degrees F.

Some engine builders say Chrysler didn’t use enough interference fit for the seats in these engines and recommend using an additional .002" of interference when the seats are replaced. Cutting the seat recess slightly deeper can also improve seat retention.

Some vehicle manufacturers use only a couple thousandths of interference when they install valve seats in a new cylinder head. They can get by with minimal interference because the heads are brand new castings that have been freshly and accurately machined. There’s been no wear, corrosion or motion to loosen up or distort the valve seat recess as is often the case with high mileage cylinder heads.
End quote

The big "take away" I get from all of the 4.7 conversation I've read is this: All engines will require replacement at some point. The 4.7 is very expensive to replace and not easy to find. Thus, the vehicle becomes virtually a "throw away" vehicle when (not if) the motor gives up.

I met a guy a few years ago, worked as a mechanic for a buy here, pay here lot. They bought a lot of repos, high milers, etc at the auction because they were cheaper ...

He was complaining about the 4.7 he was currently working on, which conversation developed into a sort of rant on all 4.7s.

The current one he was working on had warped the head so badly he couldn't get the cam out of it.

Seems they have a lot of top end, head gasket, cam followers issues.

My buddy the Dodge dealer says he has no problems with them, but one of the things he makes sure to do with a used one is change/flush the coolant, factory fill stuff gets toxic.

As with any aluminum head (IMHO) overheating is a definite no no.

Member Hotrod Dave has a lot of insight on these.

Oh yeah, they have a reputation for building sludge in the oil drain back areas.

Can a dealer run a check on the VIN? It may bring up something useful. Carfax or its competitor can also look into histories by VIN. On my wife's new used car we found quite a bit of information using one of those services.

R.

This is right as I had a few drop valve seats in them. Many would come in with a rocker arm that fell off and laying in the head because the seat dropped and held the valve from closing all the way and the clearance let the rocker fall out. I also saw many that ran good for a long time but I would say our dealer would see a dropped valve seat maybe every 6 months as I know I did about 4 of them over a 2 year period one time. The other thing about them is they are overhead cam and they have a few timing chains on them going to each head and one to a dummy shaft where the in block cam would normally be. It has a gear on that shaft that makes it look like it has a cam in the block until you remember its overhead cams. But I know without the special tool to hold the chains in place on that gear on the dummy shaft its hard to do the chains on them. The tool holds the chains in place on that gear while you put the chains on. My point is it will cost alot more then a timing chain job would on say a 318 magnum eng would.
But I would want to look at the oil and coolant and drive the truck hard before I would consider buying it. If it looks to have been maintained right and runs fine then if the price is right I would buy it. But I can also do my own repairs if I had one and something did break. Good luck with it , Ron

Why does the 4.7 get those bad
"Above 250 degree coolant episodes" ?

Does the water pump seal go out earlier than normal,
or does the impellor corrode away if the antifreeze is not changed on schedule ?

Is another part of the cooling system plumbing prone to sudden large leaks?

Does the viscous fan clutch go bad and no longer lock up?

Some 4.7 equipped vehicles have electric fans, so does something malfunction there?

I remember early model year 4.7 V8s had " brown sludging" where crankcase air flow was not carrying away blowby gas moisture properly.