Series 60 - setting the rack

[merle&louise]

I have heard people talk about setting the rack on diesel engines. What does this mean? How often should it be done, every 100,000 miles? Does this improve the fuel economy?

[Jon Wehrenberg]

Tuga,

I believe this has been discussed previously, but I believe the concensus was that if the engine is burning clean and giving good mileage (or at least the MPG hasn't changed beyond what is caused by the current fuels) leave it alone.

Those of us with the XL body style find that good news because to remove the valve cover on our coaches in a lot of cases it involves the disassembly of our cabinetry in the bedroom.

I am a firm believer in PM, but in this case until my engine tells me the valve cover needs to come off that is going to be deferred maintenance

[dale farley]

Jon,

Just think how nice it would be if you owned a Country Coach and could just flip a switch and raise the bed for easy access to the engine!!!

[merle&louise]

My mileage is the same; 7.5 mpg pulling a toad so I guess it doesn't need to have the rack set. What does setting the rack do? Is it like timing?

Dale, mine is easily accessed also but I don't want to spend any money that is unnecessary. I still have 6 more air bags to pay for and mount!:D I watched the mechanic change them and I think I am going to try to do it myself or maybe I'll get Louise to do it!:eek:

There are 2 chances of that happening: slim & none!

[dale farley]

Tuga, When I had the 93 Marathon, I put it in the Detroit Diesel shop and asked them to perform a tune-up if needed. They told me the same thing Jon stated. Unless, I really had a problem, leave it alone. I had 150,000 miles on it, but they said there was no reason to mess with the engine.

[tdelorme]

Tuga, what is referenced as "setting the rack" is adjusting the valves so that they are opening and closing in proper timing with the fuel injection pump. If your at 7.5 mpg pulling your towed I would leave things alone.

[merle&louise]

Thanks for the explanation Ted, now I know what setting the rack is. So it is not done like an oil change - it is simply done on an "as needed basis".

Is there any other maintenance that needs to be done on a series 60?

[Joe Cannarozzi]

Tuga I went 550,000 before I did that on our Peterbilt engine and they put the "new and improved injectors" in at the same time. It was running completly normally when I did. I experienced absolutely no difference in performance or mileage. Felt it was just prudent after that amount of miles if for no other reason but to take a peek at things. As it turned out it was not needed.

[Jerry Winchester]

I think we have a bunch of terms all mixed up here. First, I don't think you can classify either the Series 60 or the 8V92 as having "injection pumps". They both use "unit injectors" thus eliminating the need for an injection pump like you see on most of the generators.

Next, I think the term "running or setting the rack" originally referred to the adjustment of the mechanical fuel injectors in the old 92's. the injectors had a rack and pinion arrangement that throttled the amount of fuel injected and had a fairly elaborate linkage that was fairly complicated with respect to setting all the injectors in the same place and then setting both sides of the engine to match. Lots of feel and mostly it was an art.

The other term you hear is "running the overhead" which is more inline with adjusting the valves. I don't know anything about setting the valves on a Series 60, but I do know that if you properly adjust the valves in the 92, you can impact the performance of the engine. Some times a lot.

However, with the advent of DDEC controls, a lot of the injector timing and adjustments required of the old engines are not the same.

[merle&louise]

I checked DD website and found that a "valve lash adjustment" is done @ the first 60,000 miles. I presently have 107,000 on my engine & I am sure that it has never been done. I am going to discuss this with the local DD dealer.

Check out the oil change interval suggested by DD!!! 30,000 miles - I don't think so.

http://www.detroitdiesel.com/supportnetwork/maintenanceintervals.aspx

Thanks for the input guys.

[Kevin Erion]

All engine manufactures have a recommended mileage for the first setting, I believe all are before 100,000 miles. This gives the tech a chance to "look" things over and make sure that nothing was put together wrong. It's my opinion that because it's so difficult to get at the valve cover on the motorhomes, it never gets done. I think the odds are in our favor that if the motor is performing well, everything is fine. If you ever have the bedroom apart for whatever reason, it would be a good thing to do.

[0533]

I think we have a bunch of terms all mixed up here. First, I don't think you can classify either the Series 60 or the 8V92 as having "injection pumps". They both use "unit injectors" thus eliminating the need for an injection pump like you see on most of the generators.

Next, I think the term "running or setting the rack" originally referred to the adjustment of the mechanical fuel injectors in the old 92's. the injectors had a rack and pinion arrangement that throttled the amount of fuel injected and had a fairly elaborate linkage that was fairly complicated with respect to setting all the injectors in the same place and then setting both sides of the engine to match. Lots of feel and mostly it was an art.

The other term you hear is "running the overhead" which is more inline with adjusting the valves. I don't know anything about setting the valves on a Series 60, but I do know that if you properly adjust the valves in the 92, you can impact the performance of the engine. Some times a lot.

However, with the advent of DDEC controls, a lot of the injector timing and adjustments required of the old engines are not the same.
Jerry, although your response is quite eloquent, it is incorrect. Setting the Rack refers to either preparing pool balls for play or a female term referring to the same with a girl friend or possibly ones wife.

[Jerry Winchester]

Bruce,

I can't wait for your technical presentation at POG 8 on "setting the rack". I think we'll like your version better.

[0533]

There are some technical procedures that are best left a secret. I do however agree that I might well be best suited to deliver the workshop on "Setting The Rack" but I am not certain our group is ready for this level of technical difficulty.

As JDUB Said, and I quote: "fairly complicated with respect to setting both sides to match. Lots of feel and mostly it's an art".

[dale farley]

This is really getting deep (or maybe shallow). I to get off this computer and get ready for church.

[Will Garner]

Tuga,

I get my coach serviced at a nearby tour bus outfit. Last time I was there I was looking at an oil change at 12,000 mile interval. They said they would do it but to consider they use 25,000 miles as their oil/filter change interval. I consider it, then went to Florida and had Parliament do it at the same time I was getting a pair of shocks changed out. There is more to that story but I won't post it here.

Oh yeah, the tour bus company has been in business for over 30 years. They started with Eagles and now are 100% Prevost.