Swapping a Cummins 290 into a M939 series truck

[Vintage iron]

Ever since I bought my first 5 truck. I have always wanted to put in a more powerful engine. I bought a rebuilt Cummins 290 a few years back and put it on mothballs. Last year I sold a Cummins 400 big cam to Setvepala. Well now it is my time and I am biting the bullet and getting it done before the Sussex show at the end of this month.

1.I have already disconnected all of the lines, wires, and hoses.

2. pulled the engine with the help of my friends Greg smith, Pat McDonnel and Martin Cox. Martin loaned me his Wrecker to do the job.

3. I have been talking with my stevepala and he has been giving me insight into problems he came across.

 

[Vintage iron]

pictures

Here are some pictures to show the progress.

 

[davo727]

That is a handy engine hoist

 

[hklvette]

I'm curious what you're planning on using for a transmission.

 

[M35A2-AZ]

Looks like a cool job. Let use know how it goes.
Was the NHC250 bad or you just wanted more power?

 

[Vintage iron]

Reusing the Allison transmission and I blew a head gasket in the cold weather.

 

[mydingo]

Matt Any update on this project? Going to be ready for the Sussex show?

 

[Vintage iron]

I have been working 16 to 18 hour days working on the swap. The Cummins 290 is the same block as a Cummins 250 but they are different in just as many ways. I am replacing all of the rubber O-rings, hoses and doing all the hard work while the engine is on the stand. I have had to make some custom parts but I am happy with how it is coming. I won't have time to post pictures till after Sussex. I will get it in even if it kills me!

 

[Ord22]

Keep us updated on the progress, thanks

 

[Vintage iron]

Just a quick update. Of course I pulled the old Cummins 250, Pressure washed the Cummins 290 engine, changed the air compressor, replaced all o rings, replaced rear main seal, made new dual fuel feed lines, changed over all sensors and accessories, added grease fitting to water pump and idler pulley, added oil filter relocation. Tomorrow I change the oil pan and the bell housing over. Monday I cut the front crossmember. Everything about this engine looks good. I think it will be a good runner.

 

[Jeepsinker]

You may as well change the rear main seal while you are at it.

 

[Vintage iron]

Well, I won't be at the 2014 Sussex NJ show with my truck. I hit a wall with a few parts. I was making great progress but the odds were against me. I am doing a bunch of custom work to make everything fit like "the factory" did the work. I will be painting the front frame while the motor and transmission are out, relocating the coolant expansion tank, modifying the heater box to clear the turbo, putting in poly body bushings, beefing up the cab mounts for mounting my LWS and adding motor driven power steering

 

[hklvette]

Reusing the Allison transmission and I blew a head gasket in the cold weather.

I'm curious to see how well the MT654 does behind that motor. Its "only" rated for 850lb-ft of input torque if memory serves.

edit: double-checked, and its 950ft-lb.

 

[Vintage iron]

My customer Steve is running his 450hp Big Cam through the original M929's transmission. He said so far so good

 

[Hammer]

I am curious as to what mods to the truck you are going to have to do to get it to fit.
I know where a really nice 290 is that has low miles on a rebuild with lots of goodies. And this post really might answer a number of my questions.
Either way, good luck with the project!

 

[162tcat]

I've heard if you find an engine from a Western Star or Ford truck, it's a straight forward swap. They use the same front mount so no cutting and welding needed. This info was from Cummins NW when I had my truck in for service.

 

[Artisan]

Perhaps see if an MT654CR has any way to be beefed up?

I recently ran into a ALLISON repair shop that is old school, these
guys have decades of experience. Maybe they know?

Tell them I sent you. CLICK HERE

SubCribed!

 

[Vintage iron]

The engine is ready to go back in but, I have to put it on the back burner. I just got hired for a M931A2 bobber build and a M923A2 four door bobber build.

 

[machinist75]

Gots to make that money!

 

[Ord22]

Send some pics, thanks.