1985 PT40 Cruise Problems, better than a roller coaster ride

[GARY MINKER]

If you have a pre 1988 Bendix Cruise and you are driving along and suddenly notice that your cruise is stuck at full throttle, you are not alone. Your seat will pucker when you realize the on/off switch will not disengage your cruise throttle body and you are hurtling down the highway. In the 5 times it happened I was able to diagnose that when you apply the brakes, the pressure over rides a safety valve dump on the cruise throttle body and you can bring the coach to a stop and shut down the engine. Once the air pressure is alleviated, the valve snaps back to place for another scare at an unknown interval. It is pretty exciting to let go of the brake and see the engine come back to full 20 pound boost pressure. The culprit turned out to be sticking valves on the Bendix back board. The maintenance manual states that these valves should be cleaned at regular intervals. They are not kidding. I recommend at least every 20 years or 100,000 miles. Florida Detroit Diesel in Fort Pierce, Florida is the place to go. Mike the Svc Mgr and Gordy the Tech are kings. If anyone knows who is re-habbing the Bendix Controllers, please let me know. Thanks Gary

[Ryan Wright]

Gary,

Wow - that doesn't sound like fun! Thanks for the heads up here. Can
you tell us where to find the board in question, and provide a quick
explanation of how to clean the valves? A runaway coach is my worst
nightmare.

Here's a story:

My previous RV (1966 Travco) had the throttle linkage jam on the
freeway due to a loose air cleaner cover. At freeway speeds, I was
still having to apply throttle to maintain speed and thus had no idea
this was going on until I came across a helicopter logging crew, on a
steep downgrade, with a flagger standing in the middle of the road
holding a big read "STOP" sign. I had just picked the vehicle up not
half an hour earlier. I got her down to 40mph and she wouldn't slow
any further! Pulled the e-brake, didn't help, and the poor woman with
the stop sign was getting closer and closer. Unbuckled my seat belt
and STOOD on the brake with all my weight... got the speed down to
~30mph but still moving and about to hit this lady. Laid on the horn;
it didn't make a sound! Hit the aftermarket air horns - they didn't
work, either! My passenger stood up and made "get out of the way"
motions with his arms. She scooted over, but not enough to avoid
hitting her with the driver's side mirror... with seconds to spare I
stuck my head out the window and threaded the coach between her and
her brother's old pickup parked on the shoulder immediately opposite
of her. Missed her by mere inches but my awning bracket took out the
pickup's side mirror. Well, better that than her.

We flew past her and down into the logging zone with a large,
log-laden chopper hovering overhead... couldn't get the bus any slower
and still didn't know the throttle was jammed open because RPMs were
low, but I had the bright idea to pop it into neutral as we continued
down the grade, just to be sure and take the engine out of the
equation. While I was still standing on the brake. Boy, she stopped
fast! Almost sent me through the windshield. Then I heard the engine
perk up and RPMs climbed high. Turned the engine off, brakes smelled
like liquid rubber but she stayed put, so we trekked the couple
hundred feet back up the grade to have the discussion. All the above
happened in about a 30 second time frame... real quick.

We were on an Indian reservation and the Indian brother was torqued
off to no end about his pickup's mirror. Demanding police come, etc.
Didn't care it wasn't my fault, he wanted me jailed. Only after I got
in his face about his sister not moving out of the way in time, and
made him understand that my choice was either his truck or his sister,
did he calm down enough to have a rational discussion. A $200 bribe
for a $20 mirror and he called off the reservation police. Opened up
the engine compartment, found the problem, secured the air cleaner and
we were on our way.

Lesson learned... never drive a vehicle without a thorough inspection.
The non-functional horns and the loose air cleaner would have been
discovered had I paid more attention when I bought it.

-Ryan
'86 PT-40 8V92

On Mon, Dec 22, 2008 at 3:33 AM, GARY MINKER wrote:
> If you have a pre 1988 Bendix Cruise and you are driving along and suddenly
> notice that your cruise is stuck at full throttle, you are not alone. Your
> seat will pucker when you realize the on/off switch will not disengage your
> cruise throttle body and you are hurtling down the highway.
>
> In the 5 times it happened I was able to diagnose that when you apply the
> brakes, the pressure over rides a safety valve dump on the cruise throttle
> body and you can bring the coach to a stop and shut down the engine. Once
> the air pressure is alleviated, the valve snaps back to place for another
> scare at an unknown interval.
>
> It is pretty exciting to let go of the brake and see the engine come back to
> full 20 pound boost pressure.
>
> The culprit turned out to be sticking valves on the Bendix back board. The
> maintenance manual states that these valves should be cleaned at regular
> intervals. They are not kidding. I recommend at least every 20 years or
> 100,000 miles. Florida Detroit Diesel in Fort Pierce, Florida is the place
> to go. Mike the Svc Mgr and Gordy the Tech are kings.
>
> If anyone knows who is re-habbing the Bendix Controllers, please let me
> know.
> Thanks
> Gary
>

[GARY MINKER]

Hi, Sorry for the delay, All the valves should be discected completely and polished internally and cleaned. Lubrication should be sparse. Unfortunately the only board guy has 24 volt boards and none of the 12 volt models left. I would like to find a source myself. I have a manual on the system also. The manual is pretty helpful but does leave a lot to be desired. You can contact me directly at gary@... --- On Tue, 12/23/08, Ryan Wright wrote: From: Ryan Wright Subject: Re: [WanderlodgeForum] 1985 PT40 Cruise Problems, better than a roller coaster ride To: WanderlodgeForum@yahoogroups.com Date: Tuesday, December 23, 2008, 6:04 PM Gary, Wow - that doesn't sound like fun! Thanks for the heads up here. Can you tell us where to find the board in question, and provide a quick explanation of how to clean the valves? A runaway coach is my worst nightmare. Here's a story: My previous RV (1966 Travco) had the throttle linkage jam on the freeway due to a loose air cleaner cover. At freeway speeds, I was still having to apply throttle to maintain speed and thus had no idea this was going on until I came across a helicopter logging crew, on a steep downgrade, with a flagger standing in the middle of the road holding a big read "STOP" sign. I had just picked the vehicle up not half an hour earlier. I got her down to 40mph and she wouldn't slow any further! Pulled the e-brake, didn't help, and the poor woman with the stop sign was getting closer and closer. Unbuckled my seat belt and STOOD on the brake with all my weight... got the speed down to ~30mph but still moving and about to hit this lady. Laid on the horn; it didn't make a sound! Hit the aftermarket air horns - they didn't work, either! My passenger stood up and made "get out of the way" motions with his arms. She scooted over, but not enough to avoid hitting her with the driver's side mirror... with seconds to spare I stuck my head out the window and threaded the coach between her and her brother's old pickup parked on the shoulder immediately opposite of her. Missed her by mere inches but my awning bracket took out the pickup's side mirror. Well, better that than her. We flew past her and down into the logging zone with a large, log-laden chopper hovering overhead... couldn't get the bus any slower and still didn't know the throttle was jammed open because RPMs were low, but I had the bright idea to pop it into neutral as we continued down the grade, just to be sure and take the engine out of the equation. While I was still standing on the brake. Boy, she stopped fast! Almost sent me through the windshield. Then I heard the engine perk up and RPMs climbed high. Turned the engine off, brakes smelled like liquid rubber but she stayed put, so we trekked the couple hundred feet back up the grade to have the discussion. All the above happened in about a 30 second time frame... real quick. We were on an Indian reservation and the Indian brother was torqued off to no end about his pickup's mirror. Demanding police come, etc. Didn't care it wasn't my fault, he wanted me jailed. Only after I got in his face about his sister not moving out of the way in time, and made him understand that my choice was either his truck or his sister, did he calm down enough to have a rational discussion. A $200 bribe for a $20 mirror and he called off the reservation police. Opened up the engine compartment, found the problem, secured the air cleaner and we were on our way. Lesson learned... never drive a vehicle without a thorough inspection. The non-functional horns and the loose air cleaner would have been discovered had I paid more attention when I bought it. -Ryan '86 PT-40 8V92 On Mon, Dec 22, 2008 at 3:33 AM, GARY MINKER <"garym33407%40yahoo.com"> wrote: > If you have a pre 1988 Bendix Cruise and you are driving along and suddenly > notice that your cruise is stuck at full throttle, you are not alone. Your > seat will pucker when you realize the on/off switch will not disengage your > cruise throttle body and you are hurtling down the highway. > > In the 5 times it happened I was able to diagnose that when you apply the > brakes, the pressure over rides a safety valve dump on the cruise throttle > body and you can bring the coach to a stop and shut down the engine. Once > the air pressure is alleviated, the valve snaps back to place for another > scare at an unknown interval. > > It is pretty exciting to let go of the brake and see the engine come back to > full 20 pound boost pressure. > > The culprit turned out to be sticking valves on the Bendix back board. The > maintenance manual states that these valves should be cleaned at regular > intervals. They are not kidding. I recommend at least every 20 years or > 100,000 miles. Florida Detroit Diesel in Fort Pierce, Florida is the place > to go. Mike the Svc Mgr and Gordy the Tech are kings. > > If anyone knows who is re-habbing the Bendix Controllers, please let me > know. > Thanks > Gary >

[Hugh Turner]

On the 2 stokers there is an emergency shut down cable that you can pull to shut down a runaway mine is just to the left of the steering wheel. May be a good idea to get out the PB Blaster and get working just in case since it has more than likely not been moved since installed. Hugh & Lexie Turner 1984 Wanderlodge PT 40 “PAPA'S MAGIC BUS” FMCA F393612 Bluebird Chapter Good Sam Life Member 057729600 Thomaston, Ga 30286 hturner12@... / ford10076@...