darels

Hi all,
I haven't posted before (don't know enough to really help anyone), but I've learned a huge amount from other posts.

I drive a 91 D250, 2WD, 350K+ miles, essentially stock. A couple days ago, it seemed to be cranking a couple turns before starting. I thought it might be the battery (3 yrs old) or alternator (original, I think). I popped the hood with it running today to check with a meter, and was alarmed to see a serious fuel leak from the injection pump. It was dripping steadily, almost a stream. I wasn't able to see exactly where it was coming from, but it was not from the injector lines. It was dripping from the lowest rear corner of the pump. It seemed to be dry on top, and there was nothing on the side of the engine block. I got underneath, but couldn't really see anything past the power steering pump. It stopped when I shut the truck off.

It hasn't been doing it long, because I changed the fuel filter a couple weeks ago and everything was fine then. I haven't noticed any big puddles of fuel in the driveway (well, until today). Once started, the truck runs fine, no power problems or anything else.

I've searched forum posts, and haven't seen this addressed exactly, although I admit I may have missed or misunderstood.

This is my first diesel, so I don't have a lot of experience, I've just done basic maintenance since I got it a couple years ago, but I've done lots of work on gassers, so I'm not afraid of rebuilding the injection pump, if needed. I am afraid of the prices for a new one, so any advice would be greatly appreciated.

Thanks,
Darel

Junk Yard Dog

Check the return line (between the inj. pump and motor).

Rick

wannadiesel

Yeah, if it's not that return line it's probably the seal between the pump head and body. Really not a DIY job.

darels

I'm sorry to seem ignorant, but it's dark and cold outside (no enclosed garage at this house), so I'm looking at the manual instead of the engine itself. Is the "return line" what the manual calls the "fuel drain manifold"? If not, I guess I'm just missing it (although it's hard to tell from these illustrations; I've got the Chilton manual, not the actual shop manual).

Thanks,
Darel

wannadiesel

No such thing as a dumb question.

No, the fuel drain manifold is on the other side of the engine. This return line starts at the back of the pump in a banjo fitting and runs towards the back of the engine. The banjo fitting is a possible leak source, but I've heard of the line cracking in a couple of cases. The fitting is not likely to leak unless it has been disturbed.

Leadfoot

Sounds like the distributor head o-ring. I have had two go out. Do not try to fix it yourself. I learned on the first one.

The longer crank time is from the case having to refill with fuel before the injectors have adequate pressure to open.

A very good shop in San Antonio, TX charged me $648 for a complete rebuild.

Good luck.

darels

It's not the return line (rats), it seems to be between the distributor head and body, so I assume it's that o-ring. Dave, I assume this is the same place you were talking about.

I understand the advice to take it to a pro. OTOH, since I'm pulling it off anyway, is there any harm in trying to fix it myself? I know, I'll be wasting time and effort putting it on and pulling it back off if it doesn't work, but I've got more time and effort than money right now. Leadfoot, you apparently tried at least once to do this yourself, can you tell me about what all is involved?

wannadiesel

Yes, that was the seal I was afraid would be leaking.

You can get a reseal kit from a pump shop. If you feel comfortable tearing it apart that's your call. Professionals often raise their prices when broken stuff comes in already disassembled - it's a lot more work to fix a box of parts than a pump that just has a leak.

boiler-rat

[IMG][/IMG]Dave, is this where the seal is? I was waiting on my pics approval when I read Darels thread. Mine has a very small leak, like one drop per minute. Its coming from the bottom side so I cant see for sure. Could it maybe be tightened?

darels

Dave must be busy, but that's where my leak is. Mine originally started out as just a drop every few minutes, now it's almost a stream. You might want to keep an eye on it.

When I picked up the seal kit today at Mid-South Diesel Services, I talked to Steve there about the problem. He said the theory is that, on these older trucks, the rubber in the seals kind of "set" on the previous fuel blend, and since the ultra-low sulfur stuff started being sold in the fall, the different aromatic blend in the new fuel is degrading the older seals. He thinks that if we replace seals now, while using the new fuel, we shouldn't have further trouble (Steve, if you're reading, I hope I'm paraphrasing correctly). At any rate, he says they're starting to see lots of this kind of leak in older trucks (like mine).

John Faughn

Except for the extra cylinders that pump is the same [ close ] as the VWs , I was into a few of those when I had my own auto repair buis.
I was the only shop in the area working on diesels at the time [ mid-late 80s ]
Through some research , it seemed that the head body assembly is put into a press that allowed you to get the right [ preload ] torqu to the fasteners .
So this is where you need to let the shop thats set up for it ,

boiler-rat

Thanks for the info Darel. I will definately keep an eye on it. Keep us updated on yours! You know, I was using fuel additive but kinda fell out of the habit. I Wonder if that may have contributed to it?

darels

OK, so either way, I'm going to have to pull the pump. Right now, I have everything either disconnected or loose, except for the gear, and I CAN'T PULL IT! (Yes, I've removed the nut and washer). I've got my gear puller on and cranked so hard I literally can't turn it any more. I've read the instructions in the manual back and forth a dozen times, and can't see where I'm doing anything wrong. Is there some kind of trick to pulling this gear?

John Faughn

The gear is on a tapered shaft , the only thing that keeps it from spinning on that shaft is the tightness binding on the tapper .
You need to be careful with the gear puller , leave the nut on for a couple turns , put some tension on the gear , tap with a med. hammer on the puller bolt , then a little more tension [ maybe 1/8-1/4 turn ] , you should feal a losening each time you tighten / hammer .

wannadiesel

Not quite true, the 1st gens have a keyway as well. Don't drop the key in the engine.