Hi Idle Air Cylinder Rebuild

[DW SD]

Originally Posted by sfedeli

Doug-- if you loosen the keeper nut and screw the solenoid into the governor housing a little further, it will increase the RPM's. Take the air hose off and loosen the clamp a little. Then the whole solenoid should rotate. I'd experiment with moving it in 5 turns, then fine-tune for around 1000-1100 RPM's.

Shane,
thank you. My assembly is a bit different. I think it is due to the air throttle which is installed, maybe aftermarket. I have a switch on the assembly which hangs off from the side and doesn't allow the cylinder to thread deeper into the fueling body. My cylinder only spins about 180 degrees before it makes contact. I'll have to figure out a way to gain clearance I need. I'll attach a photo. I know a picture is worth 1000 words.

Doug

[Turbokitty]

Doug,

Is a picture or two possible?

[DW SD]

Originally Posted by Turbokitty

Doug,

Is a picture or two possible?

Hi Ryan,
As you can see, the bracket is too big to thread in further and hangs up at the top and bottom. The switch is hanging off of that bracket extension - see the red wires.

Doug

[DW SD]

In looking at this further, there is a large adjustment nut on the bracket body. It is my impression that doesn't spin freely of the bracket itself, but I will take a closer look. This whole setup looks intended for the application, so I would assume it is intended to be adjusted.

Thank you,

Doug

[Randy Dupree]

the switch is for the jake brake,it makes sure the jake is not engaged until the engine is at idle.
Also,that screw is called the buffer screw,screw it in too far and that engine will idle up to about 2400RPMs,with no idle down until you un-screw the screw.
Caution needed here!

[DW SD]

Originally Posted by Randy Dupree

the switch is for the jake brake,it makes sure the jake is not engaged until the engine is at idle.
Also,that screw is called the buffer screw,screw it in too far and that engine will idle up to about 2400RPMs,with no idle down until you un-screw the screw.
Caution needed here!

Randy,
Gulp - don't want to blow this puppy up.

Thanks for your input.

How do I turn the screw in when the bracket makes contact in several locations as I tighten? Is there a trick?

Doug

[Randy Dupree]

its been years since i adjusted the idle on a jake equiped 92 engine,it didnt seem bad to do,but thats all i remember.

[96 Deluxe]

This thread just saved me a lot of time!
So it bears being put forward to the group's attention again.
I just completed the removal of the old Bendix Cruise Control which has as one of it's functions the throttle. In it's place I installed a Williams Air Throttle and a Cruise King.
While testing my work I snapped the "High Idle" switch and the engine went WTO. Quickly snapping the switch to the off position the engine went back to normal idle. There was a "What just happened?" moment so I did it again with the same result.
Somewhat sobered I decide to try out the new "Engine Stop" cable...perfect and easy to use.
Amazing for a cable 45 feet long.
Going thru my mental WOG Rolodex I remembered this thread. Once I got to my computer I found the answer in reply #3. Failure on my part to install the throttle return springs. I had taken it off because one was missing and I was going to find a match for it. In testing with air supplied by a "Shore Compressor" the throttle seemed to return just fine using the spring inside the governor. But it isn't enough for the function of the High Idle Cylinder.
Thanks to Shane and others who contributed to this thread!

[Dog Leg Bill]

My buffer / high idle switch incorporates the Jacobs brake idle cut off switch but neither of these systems are currently working. Having gone over both systems extensively I conclude that this unit is the problem with both. After reading warnings of runaway engines with much trepidation I pulled the unit to rebuild as Shane described so well in this thread. The O-rings are worn, nothing serious but I will replace them and lube the unit. The problem I see is that the plunger rod is not long enough to engage the jakes, nor is it long enough to produce high idle. How this could happen is beyond me it does not appear to have been broken. Remarkably the part is available from MUT (DD and Jacobs part #3224) so I guess ordering one up is the next idea. Has anyone here taken one of these apart and can concur with my thinking? Anybody have one of these lying around?