View Full Version : New owners getting thru th learning curve

11-13-2017, 12:30 PM
Hello fellow owners and enthusiasts. We are Russ and Gwen, new owners, first coach ever,,,,exciting learning curve.

(All this is in the introduction as new owners but I realized the topic specific stuff ought to be posted correctly so two air system items below.)

New coach is 91 Le Mirage XL, 92 Marathon Conversion #9178 with 202K mi and a lovely DDEC II 8v92 Silver. I like it! We are fourth owners and bought it in a somewhat 'used hard and put away wet' condition but it has good bones to build on and so the fun began a couple of months ago. None of the challenges we face will be news to those who came before, having all graduated from the same curve, but as newbies we will have questions and will appreciate the educated responses that seem to result as we have noted while reading various posts as lurkers prior to registering as owners. We have owned, refit and maintained several yachts and sailed 50 thousand sea miles offshore in the past five years with all maintenance performed ourselves. The last yacht was a complicated 60 footer, go fast dream with lots of similar systems to the XL so we have some basic skills and can work out most things. With a little help from you'all!

Our first move was to zero out the maintenance items, coolant triple flush, rad steam and new filters, same with oil, diff and fuel systems, flushed, changed, flushed changed etc. until we had everything clean and current. The trani is next in a week or so. All this went well, lubed everything twice, new tag brakes, etc. etc. Many many things have been repaired, replaced, updated and serviced. Going pretty good so far.

1- Recently fast idle stopped working but we did not go near that system as far as I can tell. Any advice hints there very much appreciated. It is the Prevost/Detroit system with the RPM rocker switch on the far left knee dash. It worked great till.....? I know it is air dependant but can only stare into the compartment for now. I am working thru posts on the topic and I am sure the answers are here.

2- The level low (the basic 4 solenoid [with one extra on a control valve near by] by Prevost) has issues, I am about to remove the manifold which does not appear to have leaks at all, all coils have tested and have resistance, left rear works as it should, right did work but has quit, front never worked. Will check for sticking valves once manifold is out then see where that goes. I have the switch exposed now and it seems to show resistance on all settings on the relevant posts with the key on so should be good, not sure how to see if there is power to all coils short of feeling when someone cycles the switch or using very fine pins on the meter? Any help there also appreciated.

Enough of that for now, the bunks have been removed and the restoration of the original bedroom is underway and calling for the next push. Previous owner was a Christian Rock band, is that an oxymoron? They gutted the bed etc. and installed six bunks and she went down hill from there cosmetically and interior condition wise. On the positive side they HAD to get to the next gig and so spent a fortune at Prevost giving us the base to build upon.

Lastly, we totally Get It as to why Prevost owners are so enthusiastic about their rides. It's the ride! They are really really fun to go down the road. Thanks in advance for any guidance.

Russ 91 XL 40 Marathon

11-13-2017, 07:03 PM
Hi Russ and Gwen. I'd like to help you, but I'm a newbie too and you seem to know much more about the operations than I do!

dale farley
11-13-2017, 08:50 PM
Welcome to the site Russ and Gwen. We have some excellent technical people, so just hang on and you will get some responses.

11-14-2017, 01:01 PM

I'm not sure how the fast idle works on an 8V. On a 60, the parking brake must be on and the transmission in neutral. If you have a dash light for parking brake, it will be a good indicator of the operation of the parking brake switch. If you don't have the electrical drawing, I recommend you download it from PrevostCar.com.

Sometimes the easiest way to test the level low solenoids without having someone to toggle the inside switches is to just disconnect the connector to the solenoid coils and power them with a jumper at the solenoid. Be sure you are using the correct voltage. Prevost coils are 24V but Liberty and possibly others changed some of them to 12V. If you have a spare coil, testing is even easier. Power the spare coil and use it on each solenoid. The C clip is the only thing holding the coil on. If some positions work up and down, that rules out the up/down switch. If the coil and solenoid operation is good, then it may be time to check the position selector switch. Let me warn you, there's a lot of wires on the switch.

11-15-2017, 01:00 AM
Thanks for the greeting, a lot of friendly folks with heaps of experience here. The initial learning curve is steep but not insurmountable. Looking forward to getting the coach finished and trying her out. Saw some of your videos, nice job.

11-15-2017, 01:01 AM
Thanks Dale, the assistance is always appreciated and is already flowing in. What a great bunch of enthusiasts.

11-15-2017, 01:38 AM
Update on things. After installing a bleeder vent on the aft exchanger, there was marginal flow -to- that exchanger, but no exit flow yet, on hold until bedroom complete. Probably just create a new loop after psyching up for the access struggle.

Fast idle, No progress on the fast idle yet but there are good discussions here that I am trying to get my head around before going after that gremlin. DC circuits are black majic for me sometimes but grounds appear to be the thing to keep in mind the way these are designed. I will try not to let the magic smoke out of any electronics.

Level low,,,Removed the valve body and stack. Disassembled, cleaned, really cleaned, inspected with a magnifying glass, reassembled and installed, front now works perfectly, passenger side appears slow but otherwise that one might be resolved. She seems to be sitting high and proud now as well. Knocking off leaks really helps. Removing, cleaning up and testing the switches was worthwhile too. I know they work, how they work and that they are current,,pun intended. Listening with a small hose, home made stethoscope, I can't find any leaks and I could hear a faint one before. It appears the only way is to have zero air loss in any system and keep it that way. Thanks to all those who have been posting about air systems, Hectors stuff is saved for obvious reasons and Jon's responses and guidance to others on the same quest and others, provided confidence to get in there and get after it. I intend to fully maintain the coach myself and with the level of experience and willingness to help out found here, hopefully others will find confidence to do more themselves. It's pretty satisfying to be at least a little self reliant.

11-15-2017, 02:26 AM
Thanks Gill, you are correct about that switch and the up down one. Not to mention actually getting your hands on them, mapping and removing then reinstalling them. It all makes good sense now having gone over them as well as the re and re of the manifold. Confirmed the four coil stack on this 91 chassis 92 Marathon, are all 24 volt. I bought two new coils and started out testing and reaching up thru the window and flipping the switchs and finally accepted reality and just removed the works. I did replace the coil for the front circuit as it was definately not functioning. The valves are quite easy to go thru and they were obviously suffering. They are clean and functional now though. Living out at the lake with only a small town nearby resulted in having to reuse the valve O rings as those sizes are rare here abouts, but magnified inspection revealed them to be lacking any flaws so back in they went. No issue at all to swap em later if they act up. I will get a new set of O rings to toss into the parts bin, the size and location of the parts bin are yet to be determined.

As for fast idle thanks again, confirm park break dash light functions, it always has. To see if this was an intermittent problem I tried various combinations of moving the coach ahead and back, park brake cycling on and off, engine on or off etc,,, confess, I even tried a couple cruise control combinations after reading some are set up that way although I knew I was grasping there. Next I guess have a look at the park brake solenoid, access the fast idle and parking brake switchs and work though it. I did save the electrical drawing from an earlier post which requires some effort to fully grasp yet but it will come.

11-15-2017, 10:07 AM
Welcome to the madness Russ and Gwen. Good luck with the new to You ride. Wow , 50K Sea miles logged, You are My hero’s ! Be safe out there.