Perkins 4.108 Leaking Throttle on CAV DPS

[AirApparent 1]

Our Perkins 4.108 has a CAV DPS fuel injection pump that is leaking 1 drop per 5 to 12 seconds from the bottom of the throttle lever. It continues to leak after shutting the engine off. Checked all the fuel lines and none are leaking, so we think it is an o ring or something on the throttle shaft. Does anyone have a parts manual or repair manual that would show us how to fix this?. I'd like not to remove the entire pump if possible.

[boatrips]

AirApparent 1:

My past experience with this engine was that we had to remove the diesel fuel pump and have it rebuilt.

We had quite a job removing it because of the placement of the engine in the boat, but with a little patience it came off quite nicely.

We took it to the local people who rebuild injectors and they gave us a price on rebuilding it. Alternativley they gave us a price on a rebuilt pump they alraady had in stock at about the same price, so we bought it and kept ours as a spare, just in case we had another problem later.

Good News: Fortunately, we've never had to use the "spare" in 10 years since that incident.

By the way: It really wasn't that hard to remove the pump or to replace it and the 4-108 is a great engine.

Good Luck,

Jim

[Pappy]

I tried to attach a perkins shop manual but the file s too large; If you have a email I could try that



damn, I've been here 2yrs and that's my 1st post ???

[jordyz]

Hi there,
I just fixed my leak. While I was back home, I went to a shop that specialized in rebuilding perkins and got a rebuild package for that particular leaking problem. It consisted of 3 o-rings, a small gasket and two small bolt rubber washers. That was the easy part. Eeven though my engine is easy access, getting the throttle control mechanism out was the hard part as it is under the exhaust manifold. I did not remove the injector pump.

[jenny2]

Originally Posted by jordyz

Hi there,
I just fixed my leak. While I was back home, I went to a shop that specialized in rebuilding perkins and got a rebuild package for that particular leaking problem. It consisted of 3 o-rings, a small gasket and two small bolt rubber washers. That was the easy part. Eeven though my engine is easy access, getting the throttle control mechanism out was the hard part as it is under the exhaust manifold. I did not remove the injector pump.

they can be a pain to get to and to prime one that has ran out of fule I use to leave a wrench tied to a string that I was moving with alge infected fule tanks even with a 2 micron racor before the primary filter they are very sensitive to trash verses a plunger type pump

[Kaitsu]

Originally Posted by jordyz

Hi there,
I just fixed my leak. While I was back home, I went to a shop that specialized in rebuilding perkins and got a rebuild package for that particular leaking problem. It consisted of 3 o-rings, a small gasket and two small bolt rubber washers. That was the easy part. Eeven though my engine is easy access, getting the throttle control mechanism out was the hard part as it is under the exhaust manifold. I did not remove the injector pump.

Greetings from Finland! I have the same problem with my good old Perkins 4108M '76. I searched the web and noticed your post.
Where did you get that service kit, does it have a code? How much that costs? Would that seal kit fit in to all models? I know there are variations on the pumps.

Regards,

Kai

[Hillbillyfunk]

before you go out and spend a bunch of money replacing an injector pump let me relay this event:

A friend of mine showed up in the Bahamas with a leaking injector pump on a Perkins 108, at some shop in KW he was quoted $3,000 to rebuild it despite the fact that it didn't need to be rebuilt (rip-off shop) I took a look at it and was able to replace the rubber "O" rings in the throttle control, I have a set of O rings that I picked up from Harbor Freight tools for $3, darn near every size needed contained therein. A pair of 12pt head bolts that mate to a 7mm socket easily remove this part without pulling the injector pump the trottle controls just snap into place without any nuts or bolts holding them in, remove from pump and pull the shaft the throttle lever is connected to out

There was still fuel leaking from the copper crush rings (smash gaskets) from the injection lines being loosened too many times for bleeding the system, without a good parts store anywhere nearby I was forced to make new copper crush rings. I took a few bits of copper pipe (that I always have around) and cut thin slices off the end with a pipe cutter, then filed them smooth, viola! no more leaks, $3,000 saved.

hope someone else can benefit from this trick

[Unicorn Dreams]

Go to the Sricky's on this forum and you can download shop manuals for your 4-108

[Kaitsu]

Thanks for the tips and already fixed the problem, but forgot to put it here.

I got the the rebuild seal package which included all necessary seals and O-rings (5 pcs) to fix the governator and throttle arm leak.
The task itself was not that simple because I needed to remove the exhaust manifold and 1 fuel pipe before able to access the 2 mounting bolts of the governator and able to pull it off the pump.

Of course one of the manifold retaining nuts (4th cylinder) was in place where you cannot reach with common tool and also needed loosen another fuel pipe from atomizer and bend it a little to be able to reach the nut. Need to use swivel and extension with small ratchet and it took quite a while to open.

As I needed to remove the exhaust manifold from the block and off the heat exchanger, I pulled also the coolant reservoir and renewed some water hoses between those units. (needed new paper seals as well for the joints).

The attached photos; 1st shows the governator unit and how it's under the exhaust manifold and fuel pipe. 2nd one shows the governator unit tear down and the 2 axels where the leaking o-rings were. On the right old o-rings and the mounting bolt seals as well the seal between the pump chassy and governator.

I cleaned all parts with petrol and air (compressor). The new O-rings need some force to put in place and you need to stretch them with e.g. small screwdriver. Before that, I did coat them with some engine oil.

Kaitsu

[Stormshag]

Originally Posted by Hillbillyfunk

before you go out and spend a bunch of money replacing an injector pump let me relay this event:

A friend of mine showed up in the Bahamas with a leaking injector pump on a Perkins 108, at some shop in KW he was quoted $3,000 to rebuild it despite the fact that it didn't need to be rebuilt (rip-off shop) I took a look at it and was able to replace the rubber "O" rings in the throttle control, I have a set of O rings that I picked up from Harbor Freight tools for $3, darn near every size needed contained therein. A pair of 12pt head bolts that mate to a 7mm socket easily remove this part without pulling the injector pump the trottle controls just snap into place without any nuts or bolts holding them in, remove from pump and pull the shaft the throttle lever is connected to out

There was still fuel leaking from the copper crush rings (smash gaskets) from the injection lines being loosened too many times for bleeding the system, without a good parts store anywhere nearby I was forced to make new copper crush rings. I took a few bits of copper pipe (that I always have around) and cut thin slices off the end with a pipe cutter, then filed them smooth, viola! no more leaks, $3,000 saved.

hope someone else can benefit from this trick

Hi Hillbillyfunk! I'm facing this exact same repair I think. Noticed a small drip of fuel from my throttle on my lucas cav pump. I don't normally try to anything mechanical but have tackled small stuff on my engine. Do you have any cautions or insights on how to do this repair? I'm thinking I should be able to just disconnect the throttle cable and spring from the arm and then the nut from the front and just pull it and swap the o-rings. Is this correct? Will fuel just be coming out a lot? Should I cut it off upstream first? Will the pump need bleeding after? Sorry for the novice questions but I just dont know. Would love to save some $$'s and just pull the throttle shaft and replace those rings but dont know what else may be involved or what I might mess up in the process. Picture of the throttle linkage included.

[Stormshag]

Hi,

As my previous reply indicated, I'm also in the same predicament. Have a small leak from the throttle on my lucas cav dpa hydraulic injection pump. I'm hoping that there might be a way to simply pull the throttle shaft straight out and replace the o-rings and stick back in. The think is I don't know if that's possible or advisable. I'm concerned since I don't know the internals, would pulling the shaft out un-link things inside? I dont have a diagram or anything for the pump.

I'm assuming I'd need to bleed after the process. Would tons of diesel come out or just a bit? Sorry very new to this and just don't know. Any help appreciated.

Pic attached of the throttle on the pump

Thanks for any help!

[Kaitsu]

Hi, seems that no one answered yet, so let me try. I also found this thread years ago when had the problem, you can see my post there too.

What I can recall is that there is not much leak when pulling the governator top off, but I would still pack some rags round the pump to catch any spillage. I recall you need to pull the top off in order to dismantle the shafts where the O-rings locate. At least that's what I did and cleaned all parts in petrol and compressed air.

And yes, you need to bleed, as I recall Perkins is very touchy for any air in the system when it's disturbed. You may of course try to crank over and see what happens. If it runs and then stops, you need to bleed. Also, you may want to prepare for the job with 5 seals (see my pics). The paper/mass seal for the governator top, 2 O-rings and also 2 seals for the bolts. The last two might be reusable if in good order. Mine were not.

When dismantling the axle/shaft, take pics, as I think I had some puzzle to put back together after couple of days parts on the table, however I think it might be that when you put your mind to it, you see the only right way to put them back together. All in all quite straight forward job.

[Kaitsu]

Addition to "all in all quite straight forward job" is if it's accessible, unlike mine as I needed to take off the exhaust manifold etc. which was pig of a job and bigger effort with unreachabel fixings using standard tools, if you look my earlier post in this chain.

If you need to do the same and take that off, you need new manifold seals too. I have also heat exchanger attached to it as I dont have raw seawater cooling.

[Stormshag]

Hi Kaitsu!

Edit... Thanks for the reply! Do you happen to know what sort of injector pump you have on there? They do look similar actually. One thing I'm still wondering is if its possible to pull only the throttle shaft out. I may have similar access issues to you and I'm hoping to avoid taking all that stuff off.

[Kaitsu]

It's CAV DPA type (engine is year 1976 model). There are earlier and later type, which have small difference in governator. The difference according Perkins service manual: On some hydraulically governed fuel pumps a reversible governor is fitter. The bleed screw position has been moved from above the anti-stall device on the top of the housing to a position of the side of the housing.
There are also 2 illustrations of the pump versions.

I did the job back in 2011, so I have bit vague memory of it, but I think to take the shafts out requires to pull the governator out. I remember trying to do it in situ also, but found it non-doable. If I recall right, the antistall device needed to come out too, as you can see in the pics, there are 3 pieces (shafts) and I recall they all needed to come out.