Mechanical Cummins C8.3-High Idle

[FormerBoater]

At the end of our trip today the Eagle idle RPM was 1500.


Slowed down to 700 RPM as I pulled into the storage yard so I was able to get it into neutral.


The throttle on this vintage engine is a mechanical link which seemed to be "hanging up" this not allowing the engine to return to its normal idle of 600 RPM.


Hopefully someone on this board has experienced this and can give me some guidance.


(Engine was too hot to check it out this afternoon).


Thanks in advance!

[RKins]

I also have a mechanical engine but so far my cable is still moving freely. I have read on this site that you can spray lubricant into the end of the cable and that helps.

[FormerBoater]

Thanks for the lube tip! I have some Boeshield T-9 which would be perfect for this job.



A fellow vintage Eagle owner posted a pdf of the throttle linkage for these mechanical engines which I downloaded.


It may be that some of the springs in the assembly have gotten tired....anyone else that has experienced this I am all ears.


I will lube the cable while I am in there.

[RescueRamsey]

Back when I was a mechanic, I had a fire truck with a mechanical 8.3 do the same thing you describe. The governor in the pump broke. Had to remove the pump and send out for a rebuild. It's not a bad job if you have access. It's been a while, but if memory serves me, it's was over $1000 to rebuild.

[FormerBoater]

Lubricated the Rod Ends with Ball Studs thoroughly and as much as I could get into the cable itself.


24 hours later tested withy DW depressing the throttle. Throttle spring return appears to be very strong and the throttle lever returned to its normal idle position.


Started the engine, idles at normal idle RPM.


Lubricant used was Boeshield T-9. The OEM Rod Ends with Ball Stud has a zerk for lubrication, NAPA replacements do not.


Adding lubrication before operation to my pre-flight routine.

[RKins]