what milage do cummins and detroit engines usually need an overhaul on average?

Each engine has its fans. Id look for maintanence records and submit oil for anylsis if your really leaning to purchasing it. If you find good records it may be a million miler. If you dont Id put the money away for an inframe instantly with those numbers.

 

Overhauls are not an exact science. It all depends on how the motor is treated. Parts wear out over time, but quicker if the truck has been over-rev'd, over-torqued or just run too darn hard.

The typical time frame for a Series 60 Detroit (which is the go-to standard among 13L pre-emission diesel motors) to need an overhaul is somewhere between 750,000-1,000,000 miles. There are a lot of factors that lead to someone wanting to do an overhaul on their motor. Some do it as a preventative to bigger problems later (they might be noticing a new quirk). Some do it "in time". While others wait too long, have something blow, and now have to do an overhaul and replace whatever blew.

My first advice is head on over to the Trucks [Eighteen Wheelers] board and ask this question there. Second advice is stay VERY far away from used emissions trucks. Even if you find a gem, you are still going to be dealing with SCR/DPF system issues down the road whether you want to or not. Go pre-emissions (unless you want to run Cali) and avoid the headache.

Look into 2000-2004 CAT's, 1998-2004 Cummins (N14 specifically) and any and all Series 60 Detroit's. Those motors, with the right driver and right maintenance care, will have already run 1.5-2 million miles relatively trouble free, and will be ready to run a million more at the drop of a hat.

Beyond that, you'll need advice from people who work with these motors on a regular basis as to what to look for when looking to buy.

 

You can look up the B50 life for most major truck motors, it's a manufacturers rating that basically indicates an expected lifespan for 50% of the motors they have built. From memory a ISX has a B50 of 1.2million, meaning they expect half of the motors to make it to 1.2million miles without a rebuild.

The flip side of it is they don't expect the remaining 50% to make it, which is not great odds...

 

I had a 2012 isx that got overhauled around 425,000 due to oil consumption. 1 gallon every 1500 miles. Liners glazed. Two buddies has theirs rebuilt before 500k

 

Great post.

Personally - 1st truck - N14 at 963,000, now 1,156,000. Never inframed. Oil samples showed copper and lead rising, so I rolled in rods and mains at 1 million - uses 1 gallon every 10,000.

Bypass filtration and oil samples. I typically change oil at 35-50,000 miles, only because of increased base, lowered viscosity and sheer paranoia.

I'm still not onboard with the new engines, or California.

 

Well if you want a good answer, here is one.
An engine coming off the assembly line is different than that of its brother sitting behind it or in front of it. That means an engine can last a million miles or just 300k, it is a crap shoot in reality.

Now that said, most truck engines last a long time, taken care of with the minimal amount of maintainance like oil changes, I expect most will last 750k without a major overhaul but ...

How do you tell?

First the most important test.

There is a test out there that is done often, it is called a Dyno with blowby. This test tells you two important things, one is what is the precentage of RATED horse power is being produced (that's the Dyno part) but more importantly is the blow by that is produced by the engine >>>> under load <<<<. The blow by tells you the overall conditions of the rings and cylinders, and with that, you can determine when it needs to be overhauled.

Each manufacuture has a limit for the amount of blowby that their engine is allowed to produce before a overhaul takes place, I don't have those numbers here but the tech will tell you what they are and what the condition the engine is in.

Now there is a second test but it needs to be done regularly, that is an oil analysis which tells you what is in the oil when the engine is runnning, some bad things can be like high copper (that indicates bad bearings) or coolant in the oil that you can't see, this goes along with the Dyno with blowby to tell you what's going on and when to overhaul.

I like Cummings, I have Cummings in my ws trucks, my macks have macks. I have a few trucks that are close to 750k and one sitting at over a million, all of the high mileage trucks get tested annually for blow by and the million miler one still does 80% of its rated hp with low blow by, so that engine will not get an overhaul any time soon it at all - may sell it if it isn't cost effective.

Hope that answers your question.

 

How does one do blowby on newer engines?

 

The same way they do it in a used engine, they have an adapter for it they will put on it.

 

1.1 million on my 2009 ISX ... regular oil test and routine maintenance on the emissions system.