don0344 Report post Posted November 3, 2010 I have a 275 HP Cummins Diesel 5.9 Liter, 24 valve Ser# SBM81599 98 38 engine in my 1998 Monaco Diplomat motor home with an Allison transmission Model #MD3060. On the dash board, in addition to the Check Engine light, is a "Warning" light that comes on and goes out erratically. Sometimes I can go for days without the warning light coming on. Sometimes it will come on several times in an hour. Often, when I am idling, this warning light will come on and the engine will rev up by itself and then quit. When I am driving and the light comes on I seem to loose power. What general problems would cause the warning light to come? Any guesses as to the root problem? Share this post Link to post Share on other sites
Smosher Report post Posted November 3, 2010 I have the same problem. Cummins read the codes as to much blow-by. They put valve seals on it the first time. The second time they re-ringed it put a new head on it. Still didn't fix it. They now think that it is the turbo. The problems could be major or the could be as simple as fluid levels. Did you check the coolant, hydraulic, trans, hope that it is a simple as the pros can't seem to fix mine they have had it for three weeks now. Cummins can tell you what the codes says that it is if you can't find the problem. Mine is a new one with less than fifteen thousand miles. 2009 Camelot Monaco 425 ISL good luck Steve Mosher 2009 Camelot Monaco HHR toad Share this post Link to post Share on other sites
OldAsDirt Report post Posted January 31, 2012 I have a 1999 Monaco Diplomat M38A build date Jan.1998, same coler as yours. And we are also new to this RV business. We put 4,000 + miles on it, got 100ml. from home and our warning light came on. We also lost power just like you are talking about. We are going to have it looked at next week. There are a number of things that can make the warning light come on, low coolant is one of them. Our MH does not have a coolant probe in the expansion tank and it was 3.5 gal. low of coolant with a bad radiator cap, so that can't be it for us. Dirty fuel filter can be another thing. I am sorry this has happend I would like to keep track of what your problem is. Good Luck, OldAsDirt Share this post Link to post Share on other sites
dickandlois Report post Posted January 31, 2012 How many miles on the Engine? When where the fuel filters changed last? Does the check engine light stay on after you shut down the engine and turn on the ignition again? You could have picked up some bad fuel,if it started after a fill up. A number of issues could be causing the problem,need more information and then more able to address to your problem. 35 plus years driving Coaches, only a 2 year member of FMCA. Currently driving an AD unit. Share this post Link to post Share on other sites
don0344 Report post Posted March 2, 2012 I recently had an oil change and replaced the oil, fuel and air filters at that time, hoping the problem would be solved but, alas, it was not. In view of Cummins apparent inability to pinpoint the problem my next step will be to add Sea Foam to the fuel tank and, in addition, attempt to clean the injectors following Sea Foam's instructions which can be found here: http://www.seafoamsales.com/how-to-use-sea-foam-motor-treatment.html. I'm leaving on a road trip to Organ Pipe National Monument on Sunday and before I leave will add the Sea Foam to the fuel tank. Because of the procedure required to clean the injectors, I will do that as I leave the OPNM park and head back to Tucson where I am now located. I will post the results when I return. Share this post Link to post Share on other sites
dickandlois Report post Posted March 3, 2012 By chance when you had the filters changed, did they check the pressure in the fuel system? Lift pump pressure is important. Could you note the mileage on the Coach ? Rich. Share this post Link to post Share on other sites
Wendellbro Report post Posted March 4, 2012 It sounds like the exact cause of the "warning" light is unknown, impling it must not be labeled. If this is the case, it could be one of the retro installed warning lights for low fuel lift pump pressure. Detecting low pressure is critical because it leads to the high pressure pump failure- quite expensive to replace. A clue that the light was retro fitted would be the 12 volt power lead will not look the same under the dash as other 12 volt devices. This is the case with my 99 39Z Bounder, 275 Cummins. This retro warning light and presure sensor was added by the previous owner, a truck repair shop owner. Soon after 99 this warning light started to come as standard equipment. Hope this might help. Wendell 99 Bounder 39Z Share this post Link to post Share on other sites
don0344 Report post Posted April 26, 2012 On my return from Organ Pipe my coach seemed to run better. The warning light came on only once on the way out and the engine coughed only once on the way back. Last week I left on another road trip from Tucson to Seligman, AZ by way of Wickenburg. Before leaving I added another gallon of Seafoam. The two trips totaled about 600 miles. My coach ran well all the way to Seligman. No warning light, no stalling and I could sit at idle for long periods without the engine quitting. So the problem may have been with the injectors being fouled. It appears that Seafoam did the trick. At $60 per gallon, it seems a cheap way to maintain a clean engine by adding Seafoam to my 100 gallon tank every few thousand miles. Thanks for everyone's input. Share this post Link to post Share on other sites
