Lucas fuel pump leak from fuel control arm, Cures?

[doog]

So recently running my engine frequently to charge batteries, Ive discovered a drip, drip fuel leak from the arm of the speed control arm about one drop in eight to ten seconds, and it seems to continue after the engine is stopped. And it also seems to bleed off the fuel pressure so that the next start is hard after the engine has been sitting approximately 8 or ten hours.

The Perkins 4.108 starts at the mere touch of the starter when run within six or even eight hours but after about ten or twelve, it requires an extended cranking, then is rather hard to start. And I believe its due to the fuel pressure having bled off as a result of the leak.

Now of course it needs the seals replaced, and its in the schedule but I see mechanics stating that a little ethanol gasoline added to the diesel will rejuvenate the seals and reverse this condition. In this case regarding a VW diesel car...But any advice regarding additives which can get me by till summer and possibly eliminate the need for this project?

Thanks for reading and happy Sunday to all.

[SailingHarmonie]

Mixing gasoline into diesel fuel is a TERRIBLE idea.

The (rather bad) thinking here is that a bit of gasoline will cause the rubber seals to swell, and thereby cause them to "magically" reseal.

The problem is that even a little bit of gasoline lowers the cetane rating of the diesel dramatically, causing premature ignition and potentially damaging valves, pistons, rods, bearings,. etc, etc.

It can also cause the very seals you are trying to repair to soften to the point that they shred and totally fail.

Finally, adding gasoline will significantly reduce the lubricity of diesel fuel. Causing premature wear of your injection pump and injectors.

Maybe, MAYBE, if you got exactly the right amount of gasoline in, you could swell the seals, and not damage them or the engine. You also might not blow up your boat with a fuel mixture that has a much lower flash point that straight diesel. Do you KNOW what that magic amount of gasoline is? Does anybody?

Do not do it. Do NOT.

[doog]

Good to know SailingHarmonie. Thanks. And you know I used Standodyne fuel treatment when rejuvenating this engine, in a high concentration, and wondered if perhaps that caused the seals to wear, being a solvent type treatment, but highly recommended by TAD diesels. Running great except for the leak.

Ive had great results in restoring bad transmissions with redline seal saver but that's an entirely different sort of issue. For now the absorbent pads catch the drips but it really needs repaired.

[donradcliffe]

It took a trip to the injector pump rebuilder for new seals, but that solved the problem. I did hang a funnel below the drip to recycle the diesel until I got back to civilization. The biggest issue was the third cap screw holding the IP on. I used a drill extension and shaped it with a dremel tool.

[doog]

Thanks Donradcliffe,

Yes that third nut in my case, you had cap screws? Ive recently had the exhaust/heat exchanger off and I can get it. But its not a project I relish right now. I need the boat running for a couple months, in order to relocate. And just cannot risk pulling it apart and possibly being laid up in the near future.

[donradcliffe]

See if the funnel and plastic drink bottle will work. Its not elegant, but it should hold the leaked fuel for 24 hrs before you have to empty it.

[doog]

Yes, Ive just stuffed an oil absorbent pad under the drip, but the real issue is the hard starting after the engine has been not running for ten hours or so and must build pressure again before it starts. I just replaced the battery with a 900 AH gel cell which will do it, but one can burn up the starter with the cranking. And the real issue isnt the mess but risk of draining the battery and ending up dead in the water unable to start. The engine has always started very reliably but now with this FP leak its becoming very hard to start when cold. I just rebuilt the head but was unaware of this leak and its effect until I began running the engine daily and one thing leads to another...
But yeah a plastic bottle with a pad in the bottom would save the mess in the bilge and the drip pan. The fuel lost is only a few tablespoons per hr..

[Scubaseas]

Originally Posted by doog

...
Now of course it needs the seals replaced, and its in the schedule but I see mechanics stating that a little ethanol gasoline added to the diesel will rejuvenate the seals and reverse this condition. In this case regarding a VW diesel car...But any advice regarding additives which can get me by till summer and possibly eliminate the need for this project?

Thanks for reading and happy Sunday to all.

Excellent advice if you want to blow the head gasket, punch a hole in a piston or snap a connecting rod and punch a hole in the block.

You could try putting a drop or two of LUCAS Stop Leak or Power steering sealer on the rod from the outside but I doubt there is anything you can do to stop the leak short of replacing the seal.

Funnel and bottle are crude but effective.

[marcjsmith]

doog, my pump leaked at the same spot as well. the FI pump is in a horrible location on my boat. opposite the access side so I had to remove the bowman heat exchanger/manifold to get to the pump.


while I had it off also took the HE and cleaned out the tube and repainted and put new rubber endcaps on.


I removed the pump and rebuilt at home. I believe that you could probably do the work you need with out removing the pump. if you had good access. not sure if it could be done with the bowman HE in place though....

[doog]

Im looking foward to doing this project and just had the head off and all the exhaust and HE parts but did not have the leak issue then, now after about 20 hrs its leaking and Im planning to do it but must keep the boat in running condition right now because my marina has evicted the liveaboard tenants and requiring us to relocate. This will be my next task now with a new starter and rebuilt head, and the engine runs beautifully and starts with a touch of the starter.

I just introduced some leak repair for hydraulic systems and sucked into the lift pump and then opened the #1 injector to allow the fuel to circulate the sealer into the pump, and hopefully it will improve the function, mostly around the issue of next-day cold starts. What happens is the fuel pressure falls off after a long sit because of the leaking control shaft and then it takes excessive cranking to build up pressure again and start. And my main concern is running the battery down or burning up the starter with a long crank.

Anyway the sealer is in and Im giving very brief runs to work it through the pump slowly over a couple days. Its compatible with any hydraulic fluid or fuel so it hopefully can do no harm. And thanks so much for the great photos and support on this job! Great work!

If only I'd known this was needed when I had the engine out and pulled the transmission and changed the balance disc and then did the cylinder head..Anyway it can all come apart again if needed!

[doog]

So after adding the One Seal by bars leaks the dripping reduced by about half, after sucking a cup of equal parts fuel/stop leak into the fuel system with the lift pump. After an overnight sit...Still hard to start in the morning. It fires on #1 and then chugs and in a cloud of smoke the other cylinders kick in and it runs fine all day, once warm.
So I pulled the little bleed screw and injected about 5 cc full strength into the pump itself with a hypodermic which forces out the fuel around it and sends a concentrated shot. (Just wish we could still get that stuff they outlawed around 2017 and is no longer available)

[Scubaseas]

Originally Posted by doog

So after adding the One Seal by bars leaks the dripping reduced by about half, after sucking a cup of equal parts fuel/stop leak into the fuel system with the lift pump. After an overnight sit...Still hard to start in the morning. It fires on #1 and then chugs and in a cloud of smoke the other cylinders kick in and it runs fine all day, once warm.
So I pulled the little bleed screw and injected about 5 cc full strength into the pump itself with a hypodermic which forces out the fuel around it and sends a concentrated shot. (Just wish we could still get that stuff they outlawed around 2017 and is no longer available)

NOOOOO! Don't do this. You can clog up the injectors and ruin the pump. Never , ever ever do this,. On the shaft from the outside sure. Never use sealer on fuel injection internally! It usually breaks the pump. It almost always screws up the injectors AND the pump.

[doog]

the process is to introduce the sealer which is a softening agent, various solvents, nothing solid whatsoever. These work to restore the seals on transmissions which get hard and my old merz lost reverse gear and the seal-saver restored it beautifully to full function with a strong reverse. There is nothing to 'gum up' the injectors or shafts. And this is compatible with diesel which is a cousin to ATF, a diesel engine will run fine on ATF and similar oils. And I shared the idea with a diesel mechanic instruction professional who said, give it a try..And so far it seems to be partially effective.

I turned the engine over with the bleed screw out and woah! Powerful jet of solid fuel!! This is direct access to the High Pressure chamber.

This sealer is nothing like radiator leak sealer with the semi-solids that catch in the pores of leaks and build up to block the flow, but a chemical agent to swell and soften the rings that seal the shaft in the pump housing sleeve. And its a very high pressure we're working with so no wonder they leak when worn.

Anyway thanks for the concern.

[Scubaseas]

Originally Posted by doog

the process is to introduce the sealer which is a softening agent, various solvents, nothing solid whatsoever. These work to restore the seals on transmissions which get hard and my old merz lost reverse gear and the seal-saver restored it beautifully to full function with a strong reverse. There is nothing to 'gum up' the injectors or shafts. And this is compatible with diesel which is a cousin to ATF, a diesel engine will run fine on ATF and similar oils. And I shared the idea with a diesel mechanic instruction professional who said, give it a try..And so far it seems to be partially effective.

I turned the engine over with the bleed screw out and woah! Powerful jet of solid fuel!! This is direct access to the High Pressure chamber.

This sealer is nothing like radiator leak sealer with the semi-solids that catch in the pores of leaks and build up to block the flow, but a chemical agent to swell and soften the rings that seal the shaft in the pump housing sleeve. And its a very high pressure we're working with so no wonder they leak when worn.

Anyway thanks for the concern.

If your sealer is thick like Lucas Stop Slip or their Stop Leak Sealer you can easily snap the crank in the pump. Your boat, do as you wish. My warning is for others. Who am I? Retired ASE Master Mechanic, foreign car mechanic who ran a very busy 7800ft sq 5 guy shop for 48 years. Pushed a wrench for 52 years. I have seen an injection pump or two. And way more than two injectors.

[doog]

Ive not used or seen Lucas stop leak but the red line product that was recently outlawed but now still available in UK and Australia, and worked wonderfully, is quite thin. Solvents, no solids. Nor is it like the thick lucas oil additive or stop slip.
Now my friend in Thailand just did snap the crank in her identical Lucas cav pump and was faced with a rebuild so Ive followed the details.
I do see in various fuel chats that the newer diesel is less lubricating and there are suggestions to add a bit of two stroke oil or lubricating additive for these old style engines. And Ive followed lots of attempts to save old transmissions with additive and sometimes it doesnt work but in no instances Ive read did anyone snap a crank or a shaft as a result of the additive. No not Lucas.

Thanks for the expertise.