View Full Version : 4.7 Durability

Windsors 03 Cobra
01-30-2008, 02:25 PM
I am looking at a 99 GC with a 4.7 and 135k on the clock, no clue on the vehicleshistory its at a corner dealer so they know nothing.
Do these engines last forever a LA engine or do they have sludge and other problems like some imports ?
I wish I could find a 318 GC or 2 to look at.

Thanks for any help. :headbang

Prince Valiant
01-30-2008, 02:47 PM
My parents GC with the 4.7 has over 175,000 with zero engine (or trans for that matter) issues.

I would believe that sludgeing could be an issue, but I haven't heard any specific complaints (I believe they are issues in OHC engines in which the cam is always keeping the oil toward the top of the engine while "sitrring" it. This is exacerbated in engines with poor drainback qualities....also keep the PCV system in good shape as poor venting can lead to break-down of the oil additives designed to prevent sludging from occuring.

The two best ways to prevent sludging in any event is to use mobil1 and change the oil every 5,000 miles as my parents do with their GC.

The engine itself seems utterly reliable. Both my brother and parents have 2000 GC, but the bro went with a 4.0...and he wishes he didn't. Niether is his jeep as fast, nor does it get as good a mileage as the parents in their GC (dad and brother drive approximately with the same style).

As far as 318 vs 4.7, the 4.7's is both stronger/faster and does much better on gas despite being in a slightly heavier platform. The 4.7 performs nearly as well as the old 360/5.9 GC's but again, with much better mileage.

Windsors 03 Cobra
01-30-2008, 05:38 PM
Thank you for that information, good to know.

02-01-2008, 10:56 AM
I rebuilt one in my shop, never again!!! But the lady who owned the Cherokee never changed her oil. It had a rod knock, when i pulled it apart the entire engine was full of both aluminum shavings, and bearing material. 7 of the eight main bearings were worn out of limits for turning so I had to get a new crank. The timing chains, there are 3 have painted timing links, so any time you take it apart you either have to repaint them or get a new chain if you forget to paint them as the engine oil takes the paint off most the time, they are very PIA to time if you never did one before. And when you rebuild them they are prone to oil leaks if you dont torque the heads right, in the steps using a torq degree tool, it has head bolts and front head sealing bolts. I dont know why they built this engine when they have had reliable 318 engines that are tried and true!!
The only reason I say never again is that my shop is a performance shop and I just did this engine as a favor as the dealer charges $8500 to install a new engine, and $5500 to install a used one!!!

02-01-2008, 06:43 PM
I happen to be a big dakota guy and I talk on forums all the time, and as far as I've read, engines are just as good and reliable as the magnums and LA's. I've heard only a few blown head gaskets that have lead to other problems but other than that I've heard great things. And the HO intake and cams I hear are a pretty easy 30 horse