POG OCHO Detroit Diesel / Allison Questions

[Jerry Winchester]

On the retarder temp thread, Jon asked a fleet of questions about temps and other operating parameters on the Allison transmission.

I think the best way to not be disappointed from the technical session in OKC with the Detroit Diesel and Allison tech guys is to perhaps give them some of the questions in advance. That way if they need any technical aids or to research this a little more, we will benefit from getting the answers based on the facts rather than the best available information.

So if we can get everyone to post their questions here, I will see that they get forwarded to the right folks.

Note To Krakman - I won't ask them the brake horsepower reduction per sheep attached to your bus question.

[garyde]

My temp guage will climb upto 230 or so on long down hill grades. What temps should we expect to see. What would be considered too high of a temperature.
Can we get some operating instructions on how best to use the retarder.

[Gary & Peggy Stevens]

Can we get some operating instructions on how best to use the retarder.

If ONLY I had a Retarder instead of a Jake....:( :)

Gary S.

[michaeldterry]

If ONLY I had a Retarder instead of a Jake....:( :)

Gary S.

I'll once again risk displaying my ignorance for all to see without reservation:
Why would one prefer a retarder over a Jacobs brake? I've never had a retarder (although many would say that would be redundant since I am brain damaged), but I've had a Jake brake system on both of my coaches - a single stage Jake on my 1981 vintage Eagle 10 and a two stage Jake on my current Prevost XL45. I love my Jake, so what might I be missing? :o

[rfoster]

Michael: As posted previously - I have had both retarder and now a 2 stage Jake. I prefer the Jake. No worry about overheating with the jake. I even had the tranny oil changed to syntrend to help on temps on the coach with the retarder.

The retarder is more effective in city traffic/driving - but I am mostly on the interstates and the jake works best for me.

It maybe like chocolate or vanilla, just which one suits your taste and pocketbook.

[JIM CHALOUPKA]

So far I like the retarder. I find that there are many communities that do not allow jake brake usage. With the retarder I do not have to worry about that.

JIM

[jack14r]

The retarder has 500 brake horse power compared to about one half that for the 2 stage jake.

[Gary & Peggy Stevens]

Micahel, I only had one driving experience with the transmission retarder, and that was when we were test driving a 98 Liberty Classic, 2 1/2 years ago.

I really liked the more positive braking response I got when I used the various 6 speeds of the Retarder to bring the bus to a stop, vs the stopping power of the Jake I currently have.

But BOTTOM line, I really love our bus and the fun we have in it.

What is the Old saying " Love the one your in " or "with", something like that? :D

Gary S.

[ajducote]

Questions for the seminars:

Show us the location of all the sensors that Jon recommends we carry for on the road fix. 60 series and 8V
What do we need to be able to replace them?
How to lock the fan clutch.

[GDeen]

My questions are:

** what is proper protocol for using the Jake with the transmission, eg, how much manual downshifting combined with Jake application...

I have read some threads on that but am curious what Allison and DD have to say about proper use to optimize the Jake only system combined with the 6 speed Allison.

[Jon Wehrenberg]

The picture below tell the story.

Rotate the fan and clutch until the tabs on the fan line up with the holes in the clutch housing There are two, 180 degrees apart.

The screws are located in the end of the pulley.

The screws are all shown loose so you can identify them easier.

[ajducote]

Jon,

Thanks for the great pictures. I have now meet my quota of " learn 1 new thing everyday". Don't like to overdue it, so I guess I will go goof off now.

[lonesome george]

Jerry:
This is a REAL good idea you have come up with.
This may be old business but here it goes.
A friend mentioned that DD has redesigned some of the valve train components and that the early Series 60's should be updated with the new components. Question is since most of our units are low milage compared to trucks and such is this update something we should be concerned about? It is a project on our bus to get the engine compartment closing panel out to gain access to the valve cover and rocker box, which will be required to do this update. Would be nice to know if this is something that needs to be addressed.

[Jerry Winchester]

WTF?

I go work in Louisiana for a day and Spongebob hijacks the thread and it degrades into a Jake Brake / Retarder pissing match?

Take the flipping Jake / Retarder debate to one of the ten other threads started on this topic.

Okay, any more constructive questions or thoughts we need to pass on to the gurus?

[truk4u]

Yep, I'll add one that relates to the 8V and 5 speed. This will bore the crap out of you series 60 guys, so you may want to switch over to the Retarder/Jake thread!:rolleyes:

My Liberty, like most other 8V's out there freewheel in 1st, 2nd and part of 3rd gear when when the throttle is retarded. This all happens with no jake brake action, because under about 30 mph, it's like putting the tranny into neutral. You can manually select 1st or 2nd gear and as soon as you retard the throttle, away you go freewheeling. I understand from Allison that there is no adjustment for the lock up function of 1st and 2nd gear. I would like a little more information if possible at OKC.

Here's the issue... Your on a steep grade and need to be holding that 20 - 30 mph speed. With mine, I'lll be on the brakes all the way down to the bottom with no engine hold back or jake function. I look at this as a safety issue.

OK 8V guys, what say you?

[Joe Cannarozzi]

Everything they have learned so far about the new exhaust systems and then their opinions. What to expect with power, mileage, cost, characteristics, service.

An explanation of exactly what the components are and what is taking place.

Any comments or info on weather clean air rules of the future will require them installed on all diesel engines new and used, being used for the highway.

Where will most of the Caterpillar customers end up?

My Alison really shifts hard into lock-up I was told once it was characteristic while another suggested a recent rebuild greatly eliminated the hard lock-up.

[Jerry Winchester]

Joe,

I can hit a couple of these. The man said they were going to discontinue the Series 60 and the replacement engine is a MTU design which is their JV with Mercedes. I think it is a DD15. The new engines may end up using urea to meet the emissions requirements.

He also said the trend is for vertical integration - Volvo truck w/ Volvo engine, so he thinks the truck mfg's will end up with engines of their own (Paccar has an engine for their Peterbuilts) and this moves the traditional engine makers to a different place.

The CEO of United Engines is slated to spend an evening with us and he is a virtual cornucopia of engine and truck knowledge. We can get him to tell us the same story he told me when we had lunch. Pretty interesting.

[Jon Wehrenberg]

I'll reiterate my questions. My interest is in data, not theory from a mechanic. Specifically, what is the Transynd temperature limit? I know what the limit is on the trannie, but I want to kniow how close that 300 degrees (the trannie limit) relates to the Transynd limit. I ask it that way because I limit my trannie temp to 230, a number I arbitrarily picked to be conservative. The Allison maintenance schedule halves the interval if we have a retarder. I presume this is based on temperatures and would like to know if we never reach the retarder to cooler limit of 300 degrees can maintenance intervals be extended.

What is the engine temp limit? What is the set point on DDEC?

What is the maximum RPMs for the engine. We can let our coach drift downhill and push our RPMs up beyond any RPM we can get with the engine driving the coach.

What is the minimum voltage? Maximum voltage?

Using the engine power curve is there a specific speed or RPM that is most efficient?

I run the hills balls to the wall. I anticipate a hill, downshiift and smash the throttle. I do not let up unless my speed exceeds what I want or I crest the hill. Others have posted that they back out of it a little going up hills. What does DD say about this? Since the S60 has no pyrometer we have no measure of engine output. If necessary I will run at max engine RPM (around 2150) in whatever gear will hold the desired or best speed for the entire length of a hill.

What is the limit of turbo boost? Does it vary based on engine model? What lax boost should we expect to see as a measure of engine and turbo health?

[JIM CHALOUPKA]

This links to a page that has Transynd and Amsoil specifications listed in a comparison chart at it's bottom.

http://www.thebestsyntheticatfamstorquedrive.com/

JIM

[Jon Wehrenberg]

All the answers to my Transmission related questions are here if anyone wants to read them:

http://www.allisontransmission.com/servlet/DownloadFile?Dir=publications/pubs&FileToGet=OM3349EN.pdf

These are highly detailed manuals and for those that want to really learn about the transmissions this is the pertinent poop.

No fair studying this and then sandbagging the techs in OKC that are trying to teach us.:D

[BrianE]

Tom, You're describing a situation that you can remedy every time (IMLE). True a downshift will produce an out of lockup, freewheeling, scary condition with throttle retarded. However if you downshift when engine speed will allow it, applying throttle with the shift will result in a positive downshift and lockup. The trick is of course to downshift early, like I know you did for millions of miles using an Eaton. Or did I miss something? :confused:

[Jon Wehrenberg]

On my 87 which was DDEC I and which may not be like Tom's it would drop out at about 20 MPH regardless of gear.

I think Tom points out a significant difference between a Jake and a retarder (apart from braking forces being 50% or 100% of engine HP respectively). That is a Jake is effective at highway speeds, but as it approaches city speeds it drops out. The retarder works all the way down, and is especially effective since it is proportional to braking force. If the output temperature could be tightly controlled it would be no contest between the two.

I would trade even for a Jake because I liked it, but the two systems are as different as night and day.

[Petervs]

Why the heck is Tom worried about braking when going down a steep hill. Geez, there is not even a mild hill within 1000 miles of where he lives in the Southeasy USA. Come to Montana or Idaho for some real hills!

And Jon, I do have a pyrometer on my series 60. Mine was the first coach converted to have the series 60 and I guess they were used to installing them and were not ready to leave it out just yet. I too drive flat out going up what we out west call hills. The EGT has never risen to more than about 800 degrees which by airplane standards is next to nothing.

I do not think you can judge engine power produced by the pyro gauge either.You can judge it from RPM and manifold ( or boost) pressure. Mine will boost to 28 psi all out ( that would be like 90 inches of manifold pressure on your airplane! and would have been called WAR EMERGENCY POWER in the good old days).

[Jon Wehrenberg]

I kind of agree with you Peter. The EGT doesn't tell HP produced, but in the 8V92, with pyros and boost gauges you know what peak is, and if any of the three fell off you knew you had lost some power.

MP and RPM is only a way to define horsepower if you have the charts AND if the coach is not set up lean of peak, at which case HP produced is fuel flow in gallons per hour X some factor (13.75 on turbocharged gasoline powered engines for example).

What we need are perfomance charts.

[Petervs]

Jon,
"lean of peak"? We are talking Detroit Diesel Series 60 here not airplanes. For crying out loud, the DDEC computer controls all the engine parameters and the ProDriver could have easily been programmed to display horsepower output if the Detroit engineers had been allowed to do so. I bet the DDEC controls fuel flow to maximize power when the throttle position is all the way down, and if it is not, the computer controls engine operation to maximize efficiency. It is all automatic, just like FADEC on some modern airplanes. Gee, can I get an STC for a DDEC on my Cessna?

You certainly can not get horsepower directly from EGT on an 8V engine, but you certainly can get it from RPM and manifold pressure on both engines. And yes, you need the performance chart if you want an actual number for the horsepower. But you can get a general idea of where you are on the power output curve by seeing the rpm and manifold pressure on the gauge. Watching the pyrometer will not tell you much immediately but if you watch it for a while it will tell you if things are heating up or cooling off. It is the most useless instrument on my dashboard.

[truk4u]

Brian - True, you can add rpm's and get into lockup, but it happens at a time when you want less throttle and not more. As soon as you let up even a little, your off to the races and I know I'm not telling you something new, you put a lot of miles on the green machine. If it had Jake action in 1st and 2nd, that would be a big help and you could possibly hold some speed with high rpm's. This is one time that a retarder would out shine the jake for sure.

Peter - I doubt the folks with 8V's that have cooked an engine will agree with your assessment that the pyro's are a useless instrument. Engine temperature and pyro's are the focus of my scan! As for comparing mountains in the east vs the west, I have been to both many times and can assure you, there are some mole hills in the east that will get your complete undivided attention!:rolleyes:

[Jon Wehrenberg]

Truk,

You are wasting your breath talking about mountains to those from the left side.

What those folks don't want to recognize is that our roads that cross the mountains go to the very top of the mountains while their roads go through mountain passes. Roger can lead a few westerners down I-26 so they can see we do have hills.

When we were in CO which has more 14,000 foot hills than any other state I was amused to see their hills are like ours. Colorado Springs near Pike's Peak is about 7000 foot elevation, and Pike's Peak is about 14000 feet high for a rise of about 7000 feet. We live at a 900 foot elevation and Mt. Leconte in the Smokies is about 6500 feet for a rise of about 5600 feet. That's a 1400 foot difference between their "mountains" and our "hills".

[garyde]

Jon. I hate to say this but, your making a mountain out of a mole hill. Sorry, it was just too easy.

[jack14r]

Jerry,I would like someone to ask the Allison rep a question,on my 07 shell the shift points with the cruise control on are very agressive and can they be changed in the ECU.For instance with the cruise on and in hilly country the trans will shift down to fifth around 71 Mph and shift back up to sixth at 75,IMO this is a waste of fuel and really does not enhance performance very much.I called Allison several months ago and they said that this could not be changed.

[Jon Wehrenberg]

Jack, is your default performance mode or economy? I have the reverse situation in that mine will hang in the gear until the RPMs get so low that even downshifting will not get me back up to speed. My default is economy mode.

My resolution to that is to punch it down a gear manually when I anticipate the hill and only upshift when I know the next gear up can hold my speed.

[jack14r]

Jon,The default is economy,the interesting thing is that if I am in the performance mode at some speeds without the cruise on it will not downshift but if I then resume the cruise it will immediately downshift.The settings with the cruise control on are much more aggressive than the performance mode without the cruise on.There is another setting in the trans that is activated when the cruise is turned on,I would like to have it adjusted to a more conservative mode if possible.

[lewpopp]

I entered a question and I want to thank Jack14r for over riding me. I might as well ask it here so some doesn't do the same, at least right away.

I have a very rusty cap on the reservoir to the cooling system. It looks like the oraface takes a pressure cap. The cap that is on there is not a pressure cap. Does anyone know what pressure cap should go on there. Hopefully someone will read this and answer before Jack 14r gets to it.

[JIM CHALOUPKA]

Lew, this is where the questions that one wants answered at the rally in OKC are asked. You will have to wait until then to get the answer. By the way what is an "oraface" that you are referencing, :cool::D that sure has me flummoxed. Answer now please don't make me wait until OKC.

JIM

[phorner]

Uhhhh.....

Could it be "orifice" ???

:D

[Jon Wehrenberg]

I can't be sure about your vintage coach Lew, but I think our reservoir tanks have two caps. One behind the door and one on top of the tank. The two caps might be the same and interchangeable. There is no reason why the cap won't come off. Press hard on it while turning. The cap seal is a rubber gasket held against its seat with a spring. When you push down on the cap you are pushing against the spring and that should enable it to easily turn. I had a cap that got a little grungy (a highly technical term I hesitate to use here) and I just wire brushed it and it was good to reuse.

Once you have it off the pressure rating should be on the top of the cap. I would guess any auto parts store could have one in stock.

[lewpopp]

I stand totally corrected with the orifice.

Now, my cap has no spring and nopressure # on the cap. I think roger gave it to me when he removed it from Jim's coach

The cap has a rubber piece sandwiched between a small metal disk (the size of a half dollar) and the cap itself. No spring. I have seen hundred of caps in my lifetime in the auto service business and haven't seen one like this since we put the old fashioned antifreeze in a non or much lower pressur system. I'm sure I can find a cap to fit, but what pressure should I settle on?

[dalej]

Lew,

Mine takes a 7 pound cap. It's a guess, but I would think it would be the same.

[phorner]

FWIW, my reservoir tank takes 2 caps, one on the top (which you cannot access to fill) and one on the filler tube.

The cap on the top of the tank is spring-loaded, but I could find no indication of pressure rating.

The cap on the filler tube is not spring-loaded, and simply turns to tighten, also with no information to further identify it.

Perhaps the best resource is a call to Prevost Parts.

[PLSNTVLE2]

I just replaced both of my coolant system caps. The one for the pressurized side was a standard 14 psi cap and the one on the surge tank is just a plain cap with no pressure requirements.
Both are available at NAPA auto parts.

[lewpopp]

Thanks, I noticed the Webasto fill tube is presurized and the other is not. I will get a better cap for the coolant fill.