Rebuild straight truck with 400K miles or cut my losses?

That's about all you'll get out of a medium duty motor.
The question now is what condition the rest of the truck is in. Clean box, straight body, good suspension, not wore out, good trans, rear end etc, you've taken care of it, I'd would consider a new engine. But if its gonna need a bunch of trans or chassis work and is just utterly beat to #### and rusted out just buy a new one.

As for the motor swap make sure the replacement engine is the same MY or newer, and that it will play well with your truck. There is a lot of integration nowadays where the body and trans is programmed and made specifically to play well with that motor, its not like the 90s where you hooked up a couple cables, bolted it down and sent it.

 

Why not just rebuild the engine?

Your dumping $14k for a rebuild that should cost maybe $6k.

If it is a Cummins, then it could be easy to do, the isc is a wet sleeve engine and as long as the block is good, it can be rebuild.

I have two trucks with isc Cummins in them, one had 600k and the other is pushing 800k miles.

 

We bought a ‘99 Freightliner FL60 straight truck with a 3126B Cat new for $52,000.
Went to 471,000 in ‘07 to need overhaul. Crate motor was $25,000. New truck $87,000.
Went another 525,000 on second engine to almost 1 million on truck and dropped valve in 2015.
New crate engine was $25,000. New truck was $102,000.
Ran another 63,000 miles and retired it in 2016. Replaced it with cheap $96,000 junk Hiney I mean Hino.
In those million plus miles no transmission or rearend work had to be done. Just 2 clutches. Still has its original driveline and brake system. Nothing needed replacement. Got it’s 3rd set of shoes about 80,000 miles ago. Still has original front end parts, king pins, tie rods, with only a steering box and springs changed.
Still have that FL. Waiting for it to turn 25 years old so I can register it antique and drive it as a play toy. Should last forever that way.
In the 17 years of use We coulda spent $200,000 on new trucks but instead we spent $60,000. Money in the bank.
Not bragging just trying to show that there is no need to throw something away if it can be repaired cheaper than new. Old and well kept is always gonna be cheaper to run than new anyday. Specially if there is no bank payment to stress about every month.
There are however those that believe that always having new means that their status level in life is higher than everyone else's. Lol!

 

Stay with Cummins. Cheaper in long run and it is an exact plug in for the truck. I can’t help you on the lowest cost of rebuild but I can tell you honestly that with parts and labor $25,000 is reasonable for a complete engine block swap.

 

My post is based on the past rebuilds I've had done, Cummins is the cheapest and it isn't difficult to do.

So start with this ...

Go ask Cummins how much a oh kit is for the engine, the last I looked it wasn't bad at all.

This is an 8.3 Cummins, it is a cheap rebuild. The 3126 (that was mentioned) isn't a cheap rebuild.

The 3126 really is a throw away engine, once the cylinders are scored, it is scrape unless you sleeve it. The Cummins is a wet sleeve engine so they can get replaced easily.

So let's go back to see what really is needed ...

You had coolant in engine, so are you assuming everything is bad or did someone pull the pan and look at the bearings to see if the crank is trashed?

Maybe it is just a head gasket?

400k isn't all that much with that engine.

Don't try to put anything other than a Cummins in the frame.

 

Listen to Ridgeline. And FFS take it to Cummins themselves and see what they say.