Dear RV.net family, I am planning to take my RV into Freightliner tomorrow. Just wondering if any of you have experienced the below before, advice or guesses? I promise to keep you posted on what service center says. With warm regards, James2008 Gulfstream Tourmaster RV, 64,000 milesFreightlinerCummins ISC 3601.) RV not able to keep steady 55 mph on the freeway, even with pedal to the metal. Low engine power, slow to no acceleration on uphills, could not go past 45 mph on uphills. 2.) Sometimes whistling, hissing, rattling noise during acceleration. 3.) Exhaust brake also very weak. 4.) Fluid leak on passenger-side of engine around fuel lift pump & air compressor?Freightliner Help Line says to check turbo, CAC, air filter, clamps, etc.

I'd bet a dollar to a doughnut that: If you open the engine compartment, run your hand around the 1" rubber hose on the passenger side of the engine from the bottom of the intake manifold to the air compressor, you will find a hold big enough to stick your finger in it. And It will probably be right next to where it connects to the air compressor. I had the same symptoms, whistleing noise, lack of power and threw a lot of parts at it until someone on this forum gave me the above advice. $40 later and a new hose all is good.

Also, look for signs of an exhaust leak (black/soot) between head and exhaust manifold, the manifold itself and exhaust manifold to turbo. Any leak between the engine and turbo will diminish power as will any leak upstream of the exhaust brake lessen braking HP.

Open engine compartment an the banjo fittings on the fuel transfer pump might be leaking so carefully tightnem them.Have you replaced the first fuel filter an cut it apart an if full of black goo you have bacteria in fuel.Do not be in rush to change final filter as you must be VERY CAREFUL NOT TO GET DIRT IN IT! Also NEVER check for leakks with fingers an engine running as high pressure spray entering your skin will give you blood poisoning

Please let us know what you find out! Good luck, I am hoping for the $40 fix for you!

Have you located the problem yet?????

Cummins ISC low power problem | Good Sam Community

univmd
Explorer
Jun 09, 2015
I dropped the coach off at Cummins in Glen Burnie, MD yesterday morning. They said they would get to it in a day or two. No word yet. Will definitely keep you all posted! Thanks for all the advice!
deandec
Explorer
Jun 09, 2015
Stuck butterfly valve in the exhaust brake. Been there, done that.
hershey
Explorer
Jun 09, 2015
Have you located the problem yet?????
robertbenita
Explorer
Jun 08, 2015
Please let us know what you find out! Good luck, I am hoping for the $40 fix for you!
charlie_good_ti
Explorer
Jun 08, 2015
Open engine compartment an the banjo fittings on the fuel transfer pump might be leaking so carefully tightnem them.Have you replaced the first fuel filter an cut it apart an if full of black goo you have bacteria in fuel.Do not be in rush to change final filter as you must be VERY CAREFUL NOT TO GET DIRT IN IT! Also NEVER check for leakks with fingers an engine running as high pressure spray entering your skin will give you blood poisoning
wolfe10
Explorer
Jun 08, 2015
Also, look for signs of an exhaust leak (black/soot) between head and exhaust manifold, the manifold itself and exhaust manifold to turbo. Any leak between the engine and turbo will diminish power as will any leak upstream of the exhaust brake lessen braking HP.
hershey
Explorer
Jun 08, 2015
I'd bet a dollar to a doughnut that: If you open the engine compartment, run your hand around the 1" rubber hose on the passenger side of the engine from the bottom of the intake manifold to the air compressor, you will find a hold big enough to stick your finger in it. And It will probably be right next to where it connects to the air compressor.
I had the same symptoms, whistleing noise, lack of power and threw a lot of parts at it until someone on this forum gave me the above advice. $40 later and a new hose all is good.

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