Detroit Diesel Series 60 MPG

[W5CI]

I don't have a motor coach with a Series 60 Detroit but I did have a 2000 Kenworth I bought new and put a Million 500 thousand miles on it before I retired and only put one water pump and one turbo on it well after the million mile mark. It was the best engine ever put in a truck or bus IMHO

[corprimo]

I drove a lot of MCI tour buses in Alaska with Detroit engines. We usually got 6-7mpg, but if you have a ZF 12 speed tranny, you will get better mileage. It’s very different from the Allison and takes some getting used to with it’s free wheeling, seemingly random shifting and lurching at low speeds.

[Chargerman]

Not to pull this thread off track but I do with the Allison had 2 more gears. It would help keep the engine in the sweet spot and provide more power. At times on long hills it feels like it needs a gear or two in between

[vito.a]

Actually, a part of the problem with lower mpg is the Allison 4000 takes a tremendous amount of power just to rotate.
The manual transmissions in class 8 trucks have a lot less drag.

[RVRon]

‘07 DDEC V 515 hp in 54k dry weight coach pulling 5K Ford Explorer; best 6.4. Worst 5.9 ave.
Used to own OTR fleet trucks. 12.7’s would get 7 mpg regularly at 80k. Our 14 liters could only muster 6 mpg. Mack engines almost broke us due to 250,000- 300,000 rebuild. Cycle. DDEC’s turned it around. Definitely a million mile engine.

[Smitty77]

I've appreciated the continued info sharing on this engine, and MPG by those who have one.

I was walking an RV Sales area in Arizona earlier this year, and a salesman was walking a gent thru one coach after another - always having some comment about the coach on the way out. I knew a tech at this facility, and he was walking thru, we stopped and talked awhile. The salesman was coming out of yet another coach nearby, and the gent he was showing around said 'Well, I'd like to keep it between $140-160K range.' The salesman adjusted his belt, and steered him off to another coach...

The tech said 'At that price point, the only coach he should be looking at in inventory now is the Holiday Rambler with the DD60 in it.' (Which, was in a different building, so doubt the gent ever saw it...).

I thought that unsolicited comment from a tech I respect, was worth sharing in this thread!

Best to all,
Smitty

[RichardE]

Back to the OP's question.

99 Newell with 12.7 DD S60. Subaru Outback toad. Avg mileage 8.3 for last 20000 miles. I drive 64 to 65 MPH. We weigh 52000 lbs fully wet.

The coach has 225,000 miles, and the VMSPc indicates that it's lifetime mileage is closer to 7.3 MPG.

The mileage improved significantly when I ran the overhead to set clearances on valves, injectors, and jakes.

[Chargerman]

The mileage improved significantly when I ran the overhead to set clearances on valves, injectors, and jakes.

Richard

Can you explain what you did here. I average only 6.3

[RichardE]

Yes, running the overhead involves pulling the valve cover, and adjusting the valve clearances, adjusting the clearances on the injectors, and setting the clearances on the jake brakes. Detroit calls for this maintenance around 100k miles. I did not have the service records to see that it had been done by a PO. Many motorhomes do not get this maintenance because it is a PITA to remove the flooring hatch over the engine. Getting access to remove the valve cover is way more work than actually adjusting the clearances. I set the clearances to specifications. I did not use any "special magic" settings. Other Newell owners that I am familiar with report similar 0.5 MPG increases after running the overhead.

I also have a low restriction exhaust on the coach. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 not too loud at full bore or on the jakes

[grldst]

Have an inlaw that is in the trucking business. He mostly does speciality loads like over sized loads.

His had bought a tractor unit brand new with a Detroit 60 series. The last time I visited with him he was telling me that it had just turned 1,000,000 miles. Still running well and in them miles has only required normal servicing and a starter.

He had nothing good to say about Cummins motors ( my preference) but did say the Cat engines were his favorite and the best for power/torque. The Detroit was better with regards to fuel economy.

Running similar loads he said when they came to a grade the cat would run away from the Detroit but the Detroit required less maintenance and less fuel.

[Chargerman]

Thanks Richard. I was aware of the valve adjustment but I didn’t know it also included injector and Jake brake adjustment.