Injector Pump Question

[TruChaos]

Since my Jinma 284 was new it's had a slight miss. Sometime it would go away then it would come back. I've done everything imaginable to fix it. Bled and bled everything again. tightened fittings, checked compression, checked injection timing, drained and replaced fuel, cleaned or replaced all the filters, took the top off the injection pump and checked for sticking parts, adjusted the valves and checked for proper movement, etc, etc.

It's sat unused over the winter and I just fired it up over the weekend. I noticed a puddle of diesel under the injection pump, theres a steady drip and I also noticed oil leaking out of the breather on top of the pump. The oil level was correct when I replaced it last fall and there was no fuel drip when I parked it last December.

The diesel is leaking from the bottom of the pump.

Any suggestions? Has anyone else experienced this?

I didn't have the time to play with it but will probably check it out this weekend.

[greg_g]

I don't believe that's oil coming outa the breather. Diesel fuel is lighter than engine oil. Good chance that your pump is drowning in a mix of fuel and lube oil. It's not a good thing, but it's not necessarily catastrophic.

I take it yours is the style that doesn't have it's own dipstick, so remove the drain plug on the side of the pump housing. Collect what flows out, odds are that it's 100% diesel fuel. If so, remove the bottom drain too. Let the pump empty itself completely, then replace the bottom plug. Pour fresh oil through the fill/vent until it starts to run out the side drain. Replace the side drain plug, replace the vent/fill plug.

From that point, watch the level as best you can. If it was a one time deal, you're good to go. If it happens with regularity, it's time to rebuild/replace the pump.

//greg//

[Soundguy]

That's why i like fuel lubed pumps...

soundguy

[greg_g]

Originally Posted by Soundguy

That's why i like fuel lubed pumps...

soundguy

Never heard of a "fuel-lubed" injection pump. The ones that share engine oil are quite common. But to rely solely on the fuel for lubrication.....? That doesn't compute (especially in the face of this new ULSD).

//greg//

[Bob Rooks]

The only lubrication the barrel & plunger get is with fuel oil, that's one of the reasons the tolerances are so close (because there are no seals), and one of the reasons there have been issues with using the ULSD. The lube oil in the injection pump lubes the rack, cam, and governor.

[doxford jim]

Originally Posted by greg_g

Never heard of a "fuel-lubed" injection pump. The ones that share engine oil are quite common. But to rely solely on the fuel for lubrication.....? That doesn't compute (especially in the face of this new ULSD).

//greg//

Greg,

There are a lot of fuel lubricated injection pumps around on engines these days - hence the need to use either fuel additives or a bit of two stroke oil with each tank full of oil.

On the F250 and F350 diesels (6.9 and 7.3) the fuel injection pumps were Stanadyne and ran only with diesel lubrication.
The VP44 fuel injection pump on the newer Cummins 5.9L turbo diesel engines has only diesel fuel as a lubricant - again a fuel additive or two stroke oil use is strongly recommended for long life.

This is just a couple that come to mind without any further research. I think you will find that most diesel engines (tractors or pickups) are lubed with diesel fuel.

Hope this helps

Jim

[greg_g]

Originally Posted by doxford jim

This is just a couple that come to mind without any further research. I think you will find that most diesel engines (tractors or pickups) are lubed with diesel fuel.

Interesting. Both diesel cars I've owned had injection pumps that share engine oil. I had a Yanmar and a John Deere (Yanmar engine) before migrating to the . They too had injection pumps that shared engine oil. Then I migrated to the Chinese tractors (four of them) each with the sump-type injection pump. Eight diesels, none of them fuel lubed. Figure the odds.

//greg//

[Bob Rooks]

Greg,
The only part that is lubricated by the fuel is the barrel & plunger, the actual parts that do the metering and pumping because lube oil is too viscous, and besides, would cross-contaminate with the diesel fuel (hence the tight-lapped tolerances). Think of them as a cylinder with a piston that rotates as well as going up and down. The remaining components are lube-oil lubricated.
You are not wrong at all in your statements, just needed a little more depth.

[greg_g]

That's a relief, thanks. I've had no formal diesel training, but I figured owning/operating/maintaining eight different diesels from five different countries in the last 18 years - counted for something. Having said that, I had a early 1972 Alfa Romeo (gasoline) with mechanical fuel injection. It shared engine oil too.

Obviously what I've done wrong here - was interpret Chris (fuel-lubed) and Jim (fuel-lubricated) too literally. Even at that, doesn't it seem something of a misnomer?

//greg//

[Soundguy]

I hate to break it to you guys.. but there are injector pumps that are solely fuel lubed.. no share oil line.. and no oil sump. Rotary distribution pumps on some fords and new hollands use this method. ( others use inline pumps that have an oil sump, or share engine oil ).

Soundguy