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Hydraulic Booster Pump -stuck? Ford 460 OshKosh

Mrsmoos
Explorer
Explorer
Went for a 45 minute drive yesterday in the new-to-us 92 Southwind. We stopped at a park for apx 45 minutes-motor off, generator running and then started up and drove home in 100 degree + weather. When we got home and shut the MH off, there was a buzzing/humming sound coming from the front end of the MH. At first my husband assumed it was some sort of cooling fan but 30 minutes later the same noise was there. He disconnected the battery which stopped the noise. It was so dang hot (and our anniversary) that he didn't want to mess with it right then. After doing a little research he thinks it is brake booster pump and somehow it is stuck on. Does this sound familiar to anyone? He said everything seemed normal yesterday-steering, brakes etc except for a slight squeak from rear brakes which he attributed to dust/rust etc from it sitting for possibly years. When we bought the MH he drove it apx 90 minute drive back to our town. No sounds then except for squeaking from idler pulleys which have been adjusted. This is the first time we have heard this sound-it was also the longest its been driven at one time since we brought it home.
So has anyone else experienced this sound/issue? It sure would be nice
So--hopefully someone else had this issue and can give us some info on this. Always nice to know a little about the issue before talking to a mechanic...
4 REPLIES 4

johnhicks
Explorer
Explorer
Your brake pedal/master cylinder is stuck down a little. You have hydroboost and there's an electric booster for hydro failure or engine stop; that's what you're hearing.
-jbh-

wolfe10
Explorer
Explorer
Sounds like the electric booster pump for brakes-- runs when engine off/brakes on.

Pull UP on the brake pedal. The pedal may be sticking a little and/or master cylinder plunger may be a little long and need adjustment.

Again, it should run if engine off and brakes on.
Brett Wolfe
Ex: 2003 Alpine 38'FDDS
Ex: 1997 Safari 35'
Ex: 1993 Foretravel U240

Diesel RV Club:http://www.dieselrvclub.org/

RLS7201
Explorer II
Explorer II
Oshkosh was purchased by Freightliner. So Freightliner may be your best source for information.

Richard
95 Bounder 32H F53 460
2013 CRV Toad
2 Segways in Toad
First brake job
1941 Hudson

K_Charles
Explorer
Explorer
It may be run by a switch on the drake pedal.