thoughts on the M11 Cummins?

[Jas2153]

A friend of mine just bought a 97 Freightliner day cab that has an M11 in it that needs to be overhauled. He's looking for some opinions on just how much he would be able to haul with this motor. We're trying to decide if he just should take it out and go with a bigger motor or go with the overhaul. We're in southeast Texas where it's pretty much flat so he won't be going up an hills or mountains. All opinions would be appreciated.

[tree98]

1997?? You do realize that truck is 28 years old right? Personally I wouldn't put a single penny into a truck that old unless it was a hobby truck for parades or something.

[schISM]

(03-21-2025 )Jas2153 Wrote:  A friend of mine just bought a 97 Freightliner day cab that has an M11 in it that needs to be overhauled. He's looking for some opinions on just how much he would be able to haul with this motor. We're trying to decide if he just should take it out and go with a bigger motor or go with the overhaul. We're in southeast Texas where it's pretty much flat so he won't be going up an hills or mountains. All opinions would be appreciated.

I wouldn't be afraid of an M11. Though I never personally owned one they're a precursor to the ISM but more akin to the N14. The ISM was capable of grossing 80k with proper gearing and delivered respectable mpg's while still weighing 400 lbs. less than the large bore engines. If the parts are available, rebuild it and go trucking.

[amermextrucker]

I owned one once , it was very good to me , but they are an 11 liter engine.

I pulled 43k containers with it in illinois for years no problems.

I'd say geared properly they should be good , not a million mile engine but you'll get 750k out of it.

Major issues where injectors , fuel pump and gear housing leaking. Very , very reliable.

[amermextrucker]

Tree 98 is right , 28 yrs old and youre not only will be dealing with engine issues but also chassis and electical bugs , it can get expensive real quick , also availability of parts , and when you do find oem parts for it , theyve been on the shelf so long the part will not perform as it should.

[SFT21]

We have a M11 in an older IH truck that we use on our farm. Just had to do an in frame on it @775k but it is a good truck that’s had very few problems so we thought it was worth it.

OH here ran us right at 20k with a new head manifold and turbo.

Like others have said, as long as it is geared right they hold their own at 80k loads