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Engine Will Not Build Air Pressure

March 19, 2016, 09:26:56 am

I started the engine to leave an RV Park yesterday. Air pressure would not build beyond the 60 pounds registering on the air tank gauges. I raised the pressure to 88 pounds pressure using the 12 volt air compressor. The engine would not build the pressure beyond the 88 pounds pressure on the air tank gauges. I then tapped the brake peddle to decrease the pressure to 60 pounds. The engine running would not build the pressure beyond the 60 pounds pressure. A mobile service provided by Coach-Net is supposed to arrive this morning. I called FOT and was told that the problem is probably the air dryer pop off valve or the governor. The Air dryer was serviced at FOT in August of 2015. Any one have an idea as to the cause. Thanks.

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Re: Engine Will Not Build Air Pressure

Reply #1 – March 19, 2016, 09:38:22 am

Start by building all the air pressure you can.  Turn off the engine. Walk around the coach and listen for an air leak.  If a leak massive enough to not permit building full cut-out PSI, it WILL be audible.

If no audible air leak, start the engine.  Go to the back of the coach and listen for the air dryer purging. If you do not hear the air dryer purging constantly, replace the governor-- around $25 for the part. The "most likely suspect".

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Re: Engine Will Not Build Air Pressure

Reply #2 – March 19, 2016, 09:45:59 am

Thanks Brett, I have done those things. There are no audible air leaks, and the air dryer does not purge at all. We do not have a toad and no spare governor. There is a leak somewhere though. We are on air level at this park, and the 12 volt air compressor is running ever few hours (about 6 to 12). Thanks for the reply.
Larry

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Re: Engine Will Not Build Air Pressure

Reply #3 – March 19, 2016, 09:49:56 am

(Edit: since you don't hear a leak, probably doesn't apply)  If you have manual air tank bleed valves, check that they are closed.  I've heard of cases where the valves got "accidentally" bumped open, either by some animal or by kids pulling a prank on the owner.

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Re: Engine Will Not Build Air Pressure

Reply #4 – March 19, 2016, 10:05:03 am

Thanks Chuck, I opened and closed all the air tank bleed valves yesterday. They do not appear to be leaking.
Larry

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Reply #5 – March 19, 2016, 10:15:34 am

Brett is right on as usual. Mine did the same thing and it was a defective new governor that Bern'd installed. Replaced the old one problem solved. I now carry a spare and hope that it is not bad.

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Re: Engine Will Not Build Air Pressure

Reply #6 – March 19, 2016, 11:57:06 am

I had trouble getting pressure once- thought it was the D2 and I was right, at least partially.  I bought another D2 and was going to start taking the old one off and I discovered that the bolts holding it on were not tight.  I tightened them up and have great air pressure.  I kept the new D2 for a spare.  Check your connections to make sure they are tight- maybe you will get lucky like I did.

Best of luck getting on the road Larry

 

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Re: Engine Will Not Build Air Pressure

Reply #7 – March 19, 2016, 01:09:11 pm

Thanks Ted, before I had a chance to read your post the mobile service guy had already determined that the problem was the governor and was putting on a new one.  I don't know if he checked the fittings, but he said the governor was leaking. He also said the governor appeared to be the original part and I am glad to have a new one. Now that I know where the governor is located and how to change it, I will purchase a spare and carry it with me.
Larry

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Reply #8 – March 19, 2016, 01:10:41 pm

The problem turned out to be the governor. Thanks to everyone for the replies and very good advise.
Larry

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