4108 Perkins Running Erratically when Hot

[Seman]

Re: Problem with Perkins 4.108 Governor

Would anybody know how the plunger in the governor should be adjusted?
The large washer below the springs has a 2.5mm gap to the seat. I wonder if the Springs above the washer need stretching or replacing?
I've the manual, but can't find any info on the internals of the governor.

The motor runs erratically when hot, on low revs, at around 1200rpm.
Could the incorrect adjustment of these springs cause my problem?

I've replaces all the "o" rings, no change.

[cburger]

I just went through this problem a week ago, the throttle shaft was leaking from the body of the hydroulic governor. Purchased the pump rebuild kit and replaced the o rings on the throttle and kill shafts, reassembled the govenor and reinstalled on the pump. No leaks motor running fine.

What was the reason for you taking the govenor off the pump? Thto measerue plunger you are referring to is the anti stall valve. The valve needed to be replaced in the govenor body at the same adjustment it came out at. I used a set of calipers to measure the height of the valve out of the govenor body.
If the anti stall valve is reassembled wrong or the adjustment is off slightly the motor will run erraticly.

By the picture you have posted it appears that your govenor is identical to the one I just worked on, and it appears that the anti stall valve is screwed into the govenor way to far. The Perkins shop manual goes into adjustment of the valve or as an alternative I still have the caliper set for the proper adjustment and could get this info to you.

[Seman]

Thanks Cburger,
I removed the anti stall device because of erratic running at low speed when the motor is hot.
Just running out of idears.
The slack on the springs of the plunger doesn't make any sense to me.
I have a spare old anti stall device, it is the same, slack springs.
I be tempted to stretch the springs & try it again, but it is such a bitch to remove & re-install the unit.
Some info or specs on the anti stall device would help. I have no problem adjusting the unit as per manual, but that is not what I need right now.
I have to try to get info on the plunger (valve) first.
Thanks again,
Walter

[cburger]

Not sure what you are calling the anti stall valve. The anti stall valve sits on top of the govenor body and was set and wired in position at by the factory. I am pretty sure no adjustment of the anti stall should be required unless it was disassembled...

The part with the slack spring I believe is the govenor, my govenor spring was slack and I would resist any attempt at stretching the spring. Unfortunately these CAV hydroulic govenors are no longer made and engineering diagrams for this unit are impossible to locate.

I am under the understanding that the purpose of the anti stall valve is to prevent the motor from stalling when throttling back from high rpm.

If this was not you symptom cause of the rough running may be something else, maybe a fuel delivery issue.