Hydraulic Fluid Leak - Stranded, Update

July 09, 2012, 01:25:26 am

Dean, C Marshall, Bo, Jim Veen and others,

Update and final results report.

Thank you all for your concern and immediate assistance in spite of a couple of bits of misinformation I initially reported. Sorry I confused the issue:

1. The oily substance leaking was coolant, not hydraulic fluid. The hydraulic fan motor is all ok. I jumped to this conclusion as I had the fan motor fail on another engine. I should have been more discerning regarding the color of the fluid rather than only the oily feel on my fingers.
2. I reported a small amount of coolant lost. I was off a little on that. Cummins shop added about 3 gallons! I probably decorated I-50 beautifully.
3. I reported that the engine did not seem hot. I was wrong. It was hot enough to alarm and derate to save itself from catastrophic failure. The tech's readout confirmed that event. Thank you, Cummins electronic engineers for auto shut down feature designed for guys like me who do not watch the gauges often enough. You can bet I will be more attentive in the future.

Bottom line: All of you guys were right. The so called"School Bus" circulation pump was the offending component. It took the Cummins tech 10 minutes to agree with the diagnosis of the posters on this forum; the failure of that pump. I asked him to bypass it with hose, nipples and clamps as was suggested here. This was done and our coach was ready as promised. Only two days lost from my planned itinerary. Cost was $500. Seemed a bit high but, tolerable when I think of all the other things that high heat can cause. BTW, Cummins West in West Sacramento appears to be a very professional and well managed shop. One night in even a very nice hotel is about all I can stand. I was rudely reminded as to the reason that I always travel coach...Country coach.
That said, I wish I had been a little more patient, because with all the good advice that I received, this could have been a DIY project. I could have completed the job to bypass the pump with a few simple parts within a few hours. Instead, I ended up with a $500 repair bill! On the other hand, the outside temp was just under 100 degrees with very high humidity. At that temperature my patience runs rather thin.

This group is great! Thanks again.

Daron

PS: Did anyone determine the reason that CC installed two redundant pumps?

Re: Hydraulic Fluid Leak - Stranded, Update

Reply #1 – July 10, 2012, 06:29:49 pm

Yahoo Message Number: 80809

Daron,

Glad that you were able to get everything taken care of and back on the road. As to your P.S., I suspect that lift capacity of the pumps may be the reason for there being two of them. Not sure of the specs of the pumps or the system design requirements. There is a long run to the front of the coach. Although there should be constant pressure when at operating temperatures, there may be occasions when there is no coolant on the supply side of forward pump to ensure prime. Much like the fuel lift pump and main fuel pump.

Just my two cents worth.....

Jim Hughes

2000 Allure #30511

Re: Hydraulic Fluid Leak - Stranded, Update

Reply #2 – July 11, 2012, 08:33:04 am

Yahoo Message Number: 80825

FWIW, per CC schematics, and my own inspection, my coach has only one coolant pump feeding the dash heat. I do have another pump up front, but it circulates coolant from the independant Hurricane heater coolant system. I have a 36' coach, so that might be the diiifernce?

Larry, 03 Allure 30856

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