High Mileage Cummins??

[1972K20]

Hey guys, what do y'all think about a 1995 12V Cummins with 350K miles? I found one for sale in a Dodge and was wondering what to expect for a Cummins engine with 350K miles.

[Dieselwrencher]

It really depends how it was taken care of during those miles. If it was maintained, it should be ok. We've got some at work that have 400-550k on them and are still going. Most if not all have a stock short block. The most work done to them is an injection pump, head gasket, and oil leak repairs. We have 2 12v's with over 23k hrs on them and are still going. They need mains rolled in as they are in gen sets and the thrust bearings are severly worn. I have a 90 12v in my 95 F350. It supposedly had 160k on it when i got it. We put 5k on it in the truck it came in, and then put another 150k on it in my Ford. It still runs great. Last year it finally had to have a head gasket put in it, but it runs stronger now than it did when i first got it. The engine in my Dad's 91 F350 had 142k on it when I put it in. He's put 145k on it since the swap, and he drives it everyday.

I've had plenty of customer trucks come in with over 250k on them, and we've done performance work to them and they all are alive except one. It blew the head gasket with compounds. When we pulled the head, #6 had scoring so it got a rebuild.

Moral of the story is, it could be fine and live for a long while. If you plan to buy it and reseal the whole thing, you might as well re-ring it and bearing it. The cost of the gaskets and seals would suck to do again in 6mo to a year if a problem would occur.

[1972K20]

Thanks, for the reply. What about blow-by or using oil? Is that something that's common on an engine with 350K?

Also, if I were to go with new rings, bearings and seals, what's the best place to get that from?

[HemiChallenger71]

As stated I'd ring and bearing it while its on the stand. Maybe rebuild or replace the oil pump.

My personal ppump 6bt has 355k and is turned up to 350-400hp. As far as I can tell its never been apart and still has the original turbo. With 15w-40 it will use a quart in 5k miles. When I switched over to 5w-40 rotella it doesnt burn a drop. My truck has lived a hard life. It was used as a farm truck in indiana before I got it (320k miles looks like it hauled a 5th wheel horse trailer), and Ive towed with it (heavy, like over 8k) at least once or more a week in the 35k Ive put on it. These engines are unbelieveable. Mine gets 17-23 consistently.

[Dieselwrencher]

Blow by could be high, it just depends on the engine. When you start it, remove the oil fill cap and see how much "smoke" comes out of the fill tube. 12v's also have a breather with a road draft tube. It is nornal for these to be wet and to have a little haze coming out at high mileage. If it's dripping oil out of their continuously, or smoking worse than the exhaust, it has an issue.