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Topic: Retarder and rear tank air pressure (Read 588 times) previous topic - next topic

Retarder and rear tank air pressure

Had an interesting thing happen on the way home from SC on Tuesday.  Retarder worked fine coming through the mountains in WV except--When I pulled into a rest area, I would stop and then realize the cooling fans were running.  I almost never hear the fans running when I stop and Monday it was below freezing out.  As the fans ran, the rear tank air pressure would drop below 60 psi.  One time it even dropped low enough that the low pressure alarm sounded.  As soon as the fans shutoff, the air pressure climbed back to 130 psi and everything was normal until my next stop.  Or maybe it was as soon as the air pressure started to build the fans shutoff.  This did not happen if I shutoff the retarder and did not use it coming into the rest area.  Any suggestions on what might be going on?

Thanks,

Rich
Rich and Peggy Bowman
2002 U270 3610 WTFS, build #5939--"Freedom"
2022 Jeep Grand Cherokee Summit 4xe
SMI AirForceOne brake system
PakCanoe 15

Re: Retarder and rear tank air pressure

Reply #1 –
Check the retarder for an air leak from the solenoid valve.  There are some good photos in the following 2 threads as well as Dick S' write up on how to replace the valve (eBay is likely the most reasonably priced place to buy one, by a couple hundred $):

Big Air Leak Hydraulic Accumulator

Replacing transmission retarder valve (split from What did you do to your coach)
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Retarder and rear tank air pressure

Reply #2 –
Thank you Michelle.  I'll go spelunking under the rear of the coach when we get a warm day here in Ohio.  No trips planned until Spring.

Rich
Rich and Peggy Bowman
2002 U270 3610 WTFS, build #5939--"Freedom"
2022 Jeep Grand Cherokee Summit 4xe
SMI AirForceOne brake system
PakCanoe 15

Re: Retarder and rear tank air pressure

Reply #3 –
Is the clutch on your fans air operated?
1998 Foretravel U320c
4200 RCFE  unit # G5341

Re: Retarder and rear tank air pressure

Reply #4 –
No, I believe they are hydraulic.  Although I may just be hearing the air leak from the retarder valve, it sure sounds like the fans to me.  I'm going to have to see if I can actually see the fans spinning.  I just went local (4 miles RT) to dump the tanks and everything was normal on the air pressure using the retarder.

Rich
Rich and Peggy Bowman
2002 U270 3610 WTFS, build #5939--"Freedom"
2022 Jeep Grand Cherokee Summit 4xe
SMI AirForceOne brake system
PakCanoe 15

Re: Retarder and rear tank air pressure

Reply #5 –
Quote from: Rich Bowman –
No, I believe they are hydraulic.  Although I may just be hearing the air leak from the retarder valve, it sure sounds like the fans to me.  I'm going to have to see if I can actually see the fans spinning.  I just went local (4 miles RT) to dump the tanks and everything was normal on the air pressure using the retarder.

Rich

Almost sounds like water in the air system.  Air dryer not good?
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Retarder and rear tank air pressure

Reply #6 –
Air dryer is fine although I will check for water or dust again.  I serviced it in June.

Rich
Rich and Peggy Bowman
2002 U270 3610 WTFS, build #5939--"Freedom"
2022 Jeep Grand Cherokee Summit 4xe
SMI AirForceOne brake system
PakCanoe 15