#1 cyl at TDC. Valves closed. Cam pulley 180deg off... HOW?! Lombardini LDW 903 Dsl

[777funk]

Well good news and bad news.

Bad news first... It will white smoke a bit and catch once in a while, but it won't start even with starting fluid (a little risky I know). If is 32F (0C) today. So the cold isn't helping, but my TDI starts fine as does my 7.3 Powerstroke.

Good news, the compression on all 3 cylinders is 405 to 415 psi. So I don't think i have any bent valves or bottom end issues. The glow plugs all glow.

So next stop is injection I believe.

[Wotname]

Thanks for the update - looking forward to hearing more.

[777funk]

Tried again today with a little warmer weather and no fire. When I crank by hand, I can hear the injectors start to squirt far before TDC.


It's about to get more complicated if I have to adjust those. Guess that's how it goes.


It may also be flooded with diesel.

[Capt Gill]

Originally Posted by 777funk

Tried again today with a little warmer weather and no fire. When I crank by hand, I can hear the injectors start to squirt far before TDC.


It's about to get more complicated if I have to adjust those. Guess that's how it goes.


It may also be flooded with diesel.

Good story, thanks for contributing!
I feel for you on the manual issues, when I had an auto repair shop I sometimes had to resort up to three different manuals. When manuals went digital I recall the first entry to this market, I think it was ALLDATA, saying that the print manuals were published when they got to 90% accuracy and then would send out supplements as complaints came in, now that's in a v. large market so, in a relatively smaller market I would think there'd be more error as there are fewer techs to review the manuals. The take away: read with a large grain of salt.
A personal opinion: Don't buy/ take too seriously any book titled The Bible of *******.

[777funk]

I can see that the manual has its flaws and needs to be known in and out (plus some hands on and maybe dealer knowledge) in order to be used as the big picture.

In my earlier post I meant to say far AFTER TDC. The injectors squirt (can hear them when hand cranking) a good 15 degrees After TDC. Spec says 12 to 13 Before TDC. So I'm missing something here. The cam operated plunger isn't even moving yet at 13 degrees bTDC. But with a little experimentation, I can see that the injector timing was good right where it was (even with the apparent late timing). It seemed to run a little better with 2.5 degrees further advanced than how I received the engine. But obviously i am missing something on the timing here since 15 degrees ATDC shouldnt run.

Last note... All the cam to crank mismatch came from an oversight. Lombardini has a dot on the crank timing belt pulley and a dot on the accessory belt pulley. When i put the acc belt pulley back on after removing the timing cover, the acc belt pulley covers the timing belt pulley. I figured the cyl one dot was in the same place on both pulleys. NOT so... This is where my error was coming from. The cranks acc belt pulley is off by about 15 degrees vs the dot on the cranks timing belt pulley. I found this by putting a vac gauge on the compression tester fitting and watching the needle for compression to go to zero then reverse to vacuum to find TDC.

Frustrating but now I know.

Cam is now in time once again (was to begin with). Engine runs.

Compression is good which is a relief. Something must be wrong with fuel to create the lack of power. Maybe dirty injector nozzles.

[Wotname]

^^ The joys of the DIY engine mechanic! The good news is that soon you will know your engine better than most professional mechanics who aren't familiar with our model.


I'm not familiar with the Lombardini injectors but if they are anything like small engine Yanmar injectors, they are pretty easy to pull apart and clean etc.
Also easy enough to observe the spray pattern although it isn't possible to DIY the pop off pressure. It is possible to check they don't drip (lose pressure) after popping. They never wear to a higher pop off pressure so if you like experimenting, you can always shim up a small amount to up the pressure. Note, this applies to older Yanmar injectors, I can't speak to the Lombardini ones.

If you haven't done it before, read up on the precautions!

[777funk]

Pretty familiar with pop testing. I think those little "Yanmar" diesels are Lombardini. They're Italian and not Japanese like the regular Yanmars. But who knows. Could really be Yanmars.

The injection is very similar and even timed similarly but with the one cyl air cooled Yanmar, there's an injector line. The Lombo has Bosch unit injectors. So it's a little harder to isolate the pump half. Have to have some special fittings. I'm going to pull one and see how difficult it is to work on/clean. I've experimented with the timing enough to know I can get it rezeroed by the sound of the injector popping. I ran it 7.5 degrees retarded from where it was set (no run) and 20 deg advanced from where it was (no run). It will run at 10 from the starting point. All interesting to play with. Can't do this easily on Bosch inline injection pumps.

[skipperpete]

Timing the camshaft is only the first step, timing the unit injectors is a little more difficult.

[777funk]

Originally Posted by skipperpete

Timing the camshaft is only the first step, timing the unit injectors is a little more difficult.

Cam turned out to be ok as it stood. It was just a matter of knowing:
1. Cam timed by the exhaust stroke. A bit unconventional.
2. The PMS mark on the timing belt cover is Italian for TDC.
3. The crank acc belt pulley cannot be used as a reference to the oil pump timing mark as its not at the same angle as the crank timing belt pulley mark that it obscures when mounted. I find this odd since it must be mounted to turn the engine over by hand.
4. The dots on the acc pulley DO line up with the timing covers PMS mark which is of course OFF when timing the cam to crank pulley. Again odd.

Now to time the injectors, special tools would be in order. It looks fairly straightforward in the manual. I have found that (with the fuel run solenoid energized) I can hear the squirt at a repeatable mark for each injector when the crank is turned over by hand. With this data I've been able to make changes and get back to the starting point just fine. I feel confident enough to pull the injectors, brush the deposits off of the nozzles, and reinstall. I suspect the engine had been possibly run on blended diesel and waste motor oil. This can foul the injector tips. I'm going to look at one to start with. I'm sure the fuel rail could use new o rings anyways so this is a good time to do it.

[NavPak ECS]

Is it possible that #1 cylinder is on the opposite end from the flywheel? It would not be the first time a manual was wrong. Just a wild guess; it has been decades since I rebuilt engines.

[Rumpi]

777 please please read the manual a few times over. You clearly have to adjust the injection, and it is described. Each dot on the acc pulley marks the TDC of one of the cylinders when aligned with one of the timing cover marks, then you adjust injection to the left mark.
This is not like any other engine you worked on, follow the manual to the letter, you can not wing it.

[Capt Gill]

Originally Posted by Rumpi

777 please please read the manual a few times over. You clearly have to adjust the injection, and it is described. Each dot on the acc pulley marks the TDC of one of the cylinders when aligned with one of the timing cover marks, then you adjust injection to the left mark.
This is not like any other engine you worked on, follow the manual to the letter, you can not wing it.

Yeah, looking at the manual, it appears that each injector incorporates its own high press. pump and is driven by the camshaft - new to me.

[777funk]

Originally Posted by Rumpi

777 please please read the manual a few times over. You clearly have to adjust the injection, and it is described. Each dot on the acc pulley marks the TDC of one of the cylinders when aligned with one of the timing cover marks, then you adjust injection to the left mark.
This is not like any other engine you worked on, follow the manual to the letter, you can not wing it.

I didn't miss that in the manual. My complaint was about the pulley to cover configuration. The two pulleys (crank acc and crank timing belt) do not align and match at the same zero. You have to have the acc pulley on to turn the engine. But if you have the acc pulley on, in order to see the cam timing mark, the timing belt cover has to be off. The acc pulley's timing mark matches the marks on the timing belt cover (which is now off). This is impractical! It doesn't make sense. I don't think this impractical poor design (I believe it's an oversight of some engineer at Lombo) is mentioned in the manual. Correct me if you think I'm wrong here. The timing mark on the timing belt pulley can be used to match to the oil pump cover... but how do you turn the engine over by hand without the acc pulley on the crank. Why do the zeros on each pulley not align to the same spot? IMO they should have had the embossed marks on the timing cover rotated to match the same zero as the oil pump zero. This way both pulleys would be at the same zero and could be used as a reference with the belt cover off (since this is the only way to see the cam pulley obviously).

On to injector timing. The first mark is 13 deg BTDC. What I'm unsure about is how to time without the apparatuses mentioned in the manual. What I did was mark the base squirt (it's consistent). This audible squirt is after TDC (more than 20 degrees after the 13 deg BTDC mark... and well after the TDC (i.e. PMS in Italian)). I moved the timing to squirt at the 13 BTDC mark on the cover (by the 3 dots spaced 120 degrees apart on the acc pulley) and it wouldn't run. 1/2 turn on the plunger timing adjust screws is ~5 deg according to the manual. It will run at 10 degrees advanced from the base timing (as I received the engine). It will not run at -7.5 degrees from where I received the engine. So how the used engine was received by me is close. Obviously, the audible squirt reference means something as I've tracked it and it's repeatable. However, it isn't possible to reference this sound to anything on the timing cover. Probably the special tools used would show that it was received timed where it should be (near 13 deg BTDC).

But again, it's not a matter of not understanding the manual... there are some things I'd call quirks about this engine that are not mentioned in the manual. I would call the oddity about the pulleys mentioned in more detail in my last post from 3rd of Nov 2019... quirks. You wouldn't find that kind of stuff in most mainstream diesel engines (Yanmar, Mercedes Benz, Cummins, etc). Not saying it's a bad engine... I'm sure it's fine engine. But this is an oversight or at least strange design. Now that I'm aware, it's a different story.

WORK UPDATE: Injectors pulled out and torn down, reassembled and back in the engine. The manual shows that fuel quantity should be readjusted after pulling the injectors. It looks like the rack lever has the adjusters in it and the actual fuel quantity levers that rotate the plungers for fuel bypass are not really adjustable. I did make a setup to measure where each plunger lever sat in reference to each injectors body with a dial indicator. I'm fairly confident that I can get them set very very close to 'as they were'. I did see some light rust in the injectors. Obviously someone has had water in fuel. However, the problem I was looking for is coked nozzles. These looked fine. There was a fine layer of soot, but no buildup. The copper washers had sealed just fine as well with no burn back. One more thing I can check is the fuel supply pressure. It seems fine since I'm getting a large quantity of fuel returned to the tank at idle. But it'd be worth checking under full load. The other thing I have not checked is the governor. Going to check that as well.

[Rumpi]

1. You are supposed to move the crank by reinserting the left handed screw after removing the pulley. The reasons for different mark positions have to do with different configurations, there are some where you simply line up the marks on the belt cover and change the belt.
2. It is not really possible to adjust timing without at least one of the tools. Timing is adjusted by observing fuel flow on the return line, when this stops the injector is ready to fire and the injection timing marks should be aligned. You need at least the tool in fig. 183. In theory you could rig something up, it would require you to connect fuel to the pump and a clear line to the return. I would investigate how much the tool costs, or if there is a service station near you that has one and can do the job.

[777funk]

One thing I observed yesterday when I had the rail off is that I could fill the injector's supply port via a spray bottle full of diesel before injection (fill, rotate back 90 degrees, then forward to injection, repeat procedure) and watch the spurt of return fuel. This was repeatable. It didn't match anything that made sense timing wise though (as in 13 deg BTDC as it should be). I do consider it useful data however to return the injector timing to 'as it was'.