RPM rises to 3500 to shift from 4th to 5th

[ricelake922]

Hello
I have a 1996 Monaco Dynasty. I am currently at a RV camp 3 hours from home to see fall colors. While driving at first the RV was driving just fine. An hour into the trip, I noticed that the RPM was running at 2800 rpm at 5th shift. Got to a red light and when I went to shift from 4th to 5th, the RPM went to 3500 before shifting. So painful. It got to the point where I kept the speed to under 80 km so that the RPM would stay around 2800. No changes to any of the gauges while the strong increases in RPM. No changes in sound of engine when driving with high RPM. Last week the RV was in the shop when the fuel solenoid was replaced, line from oil to turbo boost replaced, cooler and fuel filters changed, and turbo boost was repaired as it was not working. I will be going home Wednesday and would really appreciate any thoughts. Thank you in advance.

[oldave]

I'm almost certain it's the tach .
The mechanical engines, those not computer controled like
I'm thinking yours is used the alternator pulses as a
signal for the tach .
The tach acting up is often a sign you may have alternator trouble .
You might want to get it checked out before putting it in storage .

[11178adm]

regardless if this is a 3126 Cat or a 8.3 Cummins it would have had a cast iron hemorrhage by the time it got to 3500 rpm. as stated in other posts the most likely cause is a tachometer issue

[ricelake922]

All other instruments were just fine. A friend at a RV shop in FL told her that you can’t blow the engine as the governor in the fuel pump will not allow the engine to blow. So now it appears that it is the tachometer and could be the sensor which is a line attached to the alternator. I was told by freightliner that most new RV do not have a tach but people rely on the other instruments for issues. I am going to ignore the tach, crawl home, put the RV into storage for the season and deal with it when the RV comes out in the spring. There is always something but having fun learning.

[wolfe10]

d 1 - - means no codes.

What engine-- that RPM would have most diesels spitting parts out (IF really that RPM rather than a tach issue).

Were speed and gear indicated what you normally see for that speed? Power OK?

[ricelake922]

I got - -. No codes

[wolfe10]

And, with the second push of the up and down when d-1 came up, WHAT FOLLOWED THAT.

If - -, you have no diagnostic codes.

If diagnostic codes they will be pairs of two digits each.

[ricelake922]

I did the up and down arrows again and got 0 L and then d1.

[ricelake922]

I did as you said regarding key pad codes and at first it said “0 L”. Then it beeped either an 8 or 0 and then “Mode in service”. I checked the transmission fluid on cold engine and it is full up to the top of stick. The transmission fluid was changed in August 2016.

[bjbear]

ricelake922 wrote:
.....An hour into the trip, I noticed that the RPM was running at 2800 rpm at 5th shift. Got to a red light and when I went to shift from 4th to 5th, the RPM went to 3500 before shifting. ........ No changes to any of the gauges while the strong increases in RPM. No changes in sound of engine when driving with high RPM.

Based on your comment that there was no changes in sound when driving with the high RPM, before I started thinking it was a transmission problem, I would strongly suspect a tachometer problem. I have trouble imagining a diesel engine at 3500 RPM. It would be noisy....

Hope it is as simple a problem as it first appears to be..........

[ISBRAM]

You didn’t post what engine you have but I can’t think of a diesel from 1996 that had a governed speed that would allow 3500 Rpm’s.
If the engine doesn’t sound like it absolutely screaming maybe it’s just a tachometer problem.

[wolfe10]

Will be out running errands, so here is the "how to":

Ignition on, engine off

Push up and down arrows on the Allison shift pad at the same time. Your transmission was right at the time that added "check fluid level from the shift pad), so you will either see O L or d-1. If O L, hit the up and down arrows again at the same time to get to diagnostic codes (d 1).

If there is a diagnostic code stored, it will flash d 1 and then the two digit codes. Copy it down. If no codes, it will show d 1 - -.

If you get a diagnostic code, push the mode button to go to the next diagnostic code. when you get a - -. you are finished. Just turn off the ignition.

Allison's website and the Allison owners manuals that come with your coach will have the list of codes.

[wolfe10]

Use the Allison shift pad to check for diagnostic codes.

If you need instructions on doing it, let us know.

Let us know what you find.

[donn0128]

Tranamiasion fluid of course. Trans fluid can make a hugh impact on how the trans works. Mainly slippage of the clutches. Which if you allow it to go on for very long could result in a very very expensive rebuild.

[ricelake922]

Which fluid(s) were you thinking of and how would that impact the issue?