governor and idle of a perkins 4-108

[lastkahuna]

My perkins 4-108 needs the steady idle and governor set back to its original factory setting anyone know anything about this? or have any info? thanks Mike

[skipperpete]

There are two different injector pumps used on the 4-108 perkins, hydraulic governor and mechanical governor.
If you have the hydraulic governor its the easiest to do, there are two screws with locknuts, the one with the tube and wired lead seal is the hi speed adjuster and the other is the low idle adjuster.
The mechanical governor is harder to adjust because the two adjusting screws are under the heat exchanger on most configurations of the marine 4-108 and are really difficult to reach.
I’m not sure what you mean by “steady idle”, there is no idle buffer screw on DPA pumps to stop a surging or rolling idle.

[lastkahuna]

thank you for replying, mine is mechanical it ran well until I and others tried to bleed it after changing filters. Maybe you could answer this. at the top of the governor is a screw a body and a lock nut bolt dead in the center, on mine it was all loose all only finger tight, I didnt know this but the boat ran great? when I went under there to see what I can bleed I found it out. When I open the locking nut at the base open enough to let a small stream of diesel-run out the engine runs like a champ but when I tighten it down. no running? Even adjusting the center bolt or screw it is to secure 2 turns either way? Is it getting to much fuel? turning that center governor bolt down reduces fuel or increases it? thanks Mike

[rbk]

Sounds like you have a CAV hydraulic pump. That screw on top is the anti stall device. It should out about 1/4” and locked in position with the lock nut at the base. It is also a bleed point. Be very careful tightening it as they shear off rather easy.

[lastkahuna]

Ok thanks will try it tomorrow and see how it goes thanks again

[skipperpete]

Does your pump look like this one? Perkins 4-108 series have several different variations of the idle screw, one directly into the hydraulic governor and one type on the speed control arm

[lastkahuna]

it looks more like the first color picture but not exactly ? ?or example there is no nut on the far right idle screw on mine just a bolt sticking up but the center bolt with a nut in the middle a nut at the base and a screw or bolt at the top looks like mine except the center nut is not as wide and the bolt that goes throughs seems longer? We bleed it from there like I said it was just finger tight. and a lot of air came out that was the last bleed problem but the distance or relation of the top screw to the middle nut and the bottom seems off . as mentioned when it is opened at the base till diesel comes out by the locking nut it runs great? the middle nut and top nut and or bolt we can not seem to get right and I am not sure if the adjustments a half turn at a time either way are increasing or decreasing the fuel?

[skipperpete]

If you are doing a lot of dead cranking in an effort to get it to run properly, be careful not to flood the engine with seawater.... turn off the raw water intake until it actually starts.

[lastkahuna]

I am trying to get a mechanic that is familiar with a perkins 4-108 to come and adjust the governor and anti-stall and idle. It is not that easy here to find one even at the very very expensive hourly rate. I have another problem, not knowing the exact identity of my boat. the HIN Boat number is CABJ0517M79A. if anyone can tell me exactly what I have is ? It was sold to me as a 39 foot Catalina 1979? I do not think that is correct. I am in search of the engine serial number for the mechanic, before he hopefully eventually comes but I can not find it ? any advise is welcome thanks

[lastkahuna]

I still need help here in Cayman, my Perkins 4-108 has a Delphi hydraulic pump. The governor never should have been touched when bleeding but it was. Mechanics are 80 ci dollars an hour so it getting expensive. The second mechanic that has come to work on it says the spring is missing from the governor bleed assembly now? I have a replacement spring but have no idea if it is the right stiffness. no matter where the governor is adjusted up or down I can not get it to run except with the locking bolt so lose it drips diesel. dripping diesel it will run at a good fast idle and respond to the throttle. Where I am both of the diesel mechanics that have come have no previous experience or solutions for the Perkins 4 108. I do not know if it is the spring tension or getting to much fuel, or most puzzling to me why it will run well dripping a good flow of diesel from the governor locking nut? Any help would be appreciated.

[skipperpete]

Here's a picture of your Delphi from an old CF thread that might help out. Is the flow of fuel from the governor locknut smooth and free of air bubbles?

[lastkahuna]

yes, the fuel coming out is free of bubbles a steady stream but when I turn the lock nut down to stop the stream with the governor in any position so far it shuts down. I do not know if the spring is to weak or to strong or if to much fuel is getting to the engine and by letting it run out under the lock nut it becomes the right amount. I do not know really if turning the governor down decreases or increases the fuel supply. The sad part is it ran fine until I changed all the filters and introduced air to it.

[skipperpete]

Ok, why not try going to a steady 1500 rpm then tightening down the lock nut, or try adjusting the valve in or out but maintain the 1500rpm then reduce slowly to 800/900 and see if that works. If its the wrong spring I think it may be problematic.
Is the stop control fully in the “run” position.

[lastkahuna]

Yes, the stop control is fully in the run position. The first mechanic said there was no spring in there? The second mechanic say it could not have run without a spring that he must have lost it? neither has resolved this. I do not know how strong or weak the spring pressure should be, that is a problem too.any turning of the lock nut to keep fuel from escaping while holding the governor with a wrench causes a stall, In fact, holding the governor bolt and adjusting the lock nut an 8th of a turn tighter or looser acts just like a throttle that is with the governor bolt adjusted up and down so far. After the fact reading on the internet "Do Not Touch This " I can see why. My assumption from all my trying is that there is one magic spot and an 8th of a turn either way and it will not run..? From this I am guessing that way to much fuel is being given to the engine and by letting the xtra fuel dribble out at the lock nut it is relatively the right amount to run well. From looking at the schematic maybe you could tell me does turning the governor bolt down close to the lock nut increase or decrease the fuel. In the factory pictures of my style pump, it shows the governor bolt down with a small gap between it and the lock nut. There is a little plunger or actuator on the end of the governor bolt that the spring pushes against and I do not know if turning the governor down is reducing fuel or increasing it? thanks Mike

[rbk]

This your anti stall not your governed or idle adjustment. Easiest ways is to get someone with the same setup to measure the height off the pump housing simple height measurement and start from there. In believe the adjustments for that are in the manual but not the factory setting.