1.9 XUD9TE idle, starting and smoke problems

[Flynn2]

I am uninclined to suspect the head gasket. The reason being is because today I have been out and replaced all of the fire washers and then started it. It seems to run clean for awhile and with more power. I took it for a test drive and the power delivery seemed back to normal as well as the steering feeling lighter due to the increased power of the engine. It was idling better as well, before it was very difficult to get it to a consistant idle and the revs would hunt dramatically. However, after awhile it started pulsing smoke again and does the juddering when it is in gear and the revs go low. Towards the end of my test drive it seemed to be running quite smoothly again. So ruling out the injectors it is almost as though there is some contaminent in the system which will not go away. I have run it on vegetable oil mostly and not had more than 10 litres in the tank at a time. I am almost tempted to run a full tank of diesel through and see if that would cure it, but that is wishful thinking more than anything. I am really quite tempted to suspect a single injector is playing silly buggers but it doesn't make sense since I tried the old Lucas injectors in and if I remember correctly they did the same thing. I need to get those valve clearances checked anyway.

[nametooshort]

Lucas and Bosch systems use different injectors, they pop at a different pressure and are not interchangeable. Maybe your Bosch injector is faulty and those symptoms are caused by it popping at the incorrect pressure, which of course would not be rectified by substituting Lucas injectors, since they also pop at the incorrect pressure for this system.

When I run stuff on veg oil, I usually run two fuel filters, like some agricultural machinery does, and also of course a fuel per-heater. The two filters are somewhat of a paranoid thing I guess, but filters are cheap.

Injector pumps are VERY sensitive to dirt and water, so you can't be too careful. Strangely enough, it seems that I hear more and more often that genuine Lucas/Cav filters are actually BETTER filters, because Lucas/Cav systems are so much weaker then Bosch systems, they need much better filtering. Bosch systems are much tougher and therefore don't need such fine filtering. It seems a genuine Lucas/Cav filter (one actually made by them, not a pattern copy) has finer filtering media then most other fuel filters on the market for this reason. So when running on questionable stuff like raw veg oil, it would actually make sense to retrofit a Lucas/Cav style filter head onto a Bosch system.An added bonus is that Lucas XUD systems (early ones, like 205 etc) had a coolant-heated remote mounted filter, which is always a good idea when running on oil. You can't have enough pre-heating.

I am not 100% sure on the validity of this myself, but I HAVE heard it reasonably often from various people. The coolant-heated remote filter is certainly a massive bonus. Some later XUDs have the filter in the thermostat housing, which is also a good design, but it seems that the early Lucas style filters were the most effective, because back then diesel was dirtier, and they were designed for the Lucas system which is really REALLY fussy.

As a side note, I always wanted to retrofit a Bosch inline-style pump from something really old/agricultural to a more modern diesel like the XUD. Those pumps can pump pretty much ANYTHING, and are super rugged, from what I gather you physically can't kill them. \Usually they are too agricultural (very low redline and etc, basically for fixed-speed applications) but there are a few fitted to Unimogs and other things which are suitable for vehicle type conditions. Would be the ultimate oil burner.

[Flynn2]

The lower break pressure of the Lucas injectors would just make the injection timing more advanced, not cause the pulse of smoke that happens on both sets of injectors. I can assure you that this never used to happen when running on vegy oil. There is something going on with the injection of the fuel, why was one injector carboned up for instance? And fuel on the nozzles of the other ones? It doesn't make sense. Why is the smoke coming out of the exhaust? It's crazy.

[Peter.N.]

Could be that the compression is low on that cylinder and you have incomplete combustion.

Peter

[Flynn2]

Glowplugs are tight, injectors are tight, new fire washers. Also the problem sometimes gets worse. How do you explain that when I pull the injectors and put them back that for a few minutes it runs as it should then? And the carbon build up on one of the injectors? If the compression was down it would be like that all the time.

[Peter.N.]

Well, it definitly looks as though its missing on one cylinder and the puff of blue smoke indicates that fuel is being injected but not burned, low compression is the most likely cause its probably also the easiest to check, untill you have eliminated or otherwise that problem its difficult to find where else to look.

Peter

[Flynn2]

Right, valve clearances have been measured:



The inlet is supposed to be 0.15 cm, + or - 0.05mm;
the exhaust is supposed to be 0.30cm, + or - 0.05mm

These are the measurements I got:

Inlet 1 .004
Exhaust 1 .011
Exhaust 2 .011
Inlet 2 .006
Inlet 3 .006
Exhaust 3 .011
Inlet 4 .006
Exhaust 4 .011

So they are all reasonably close to each other, but very far out of their tolerances. But due to their close proximity in tolerances I don't think they would be causing an issue.

[Peter.N.]

You are probably right, as long as there is some clearance the valves are actually closing, I have come across them with no clearance at all - and the engine has still been running although not as well as it should be. Does it always miss just on one cylinder?

Peter

[Foggyoutcome]

You could try running a steamer like the ones you use for wallpaper up the air intake. Make sure it's after the turbo. It would give it a good clean out.
You would need to get the engine hot then leave it steaming for about half an hour.

[Flynn2]

You are probably right, as long as there is some clearance the valves are actually closing, I have come across them with no clearance at all - and the engine has still been running although not as well as it should be. Does it always miss just on one cylinder?

Peter

Yeah, always it seems to be one cylinder. And normally once it's warmed up. There is little smoke on a cold lump. Once it's warm the missfire is there again. And if I take my foot off the throttle in a high gear with the revs lower than about 1500 it starts juddering violently. That could be due to fuel pump setup though as I have modified the pump but I don't know so worth a mention anyway.

You could try running a steamer like the ones you use for wallpaper up the air intake. Make sure it's after the turbo. It would give it a good clean out.
You would need to get the engine hot then leave it steaming for about half an hour.

What to clear out the inlet manifold? I don't think that's a problem. Could a leaky manifold gasket cause this? I can't see how it could since it's after the combustion chambers unless theres something I've missed.

[spider]

Not sure I'd want to run steam in the air intake / manifold at all, although in theory may clean it out I'd not want any moisture / water in the combustion chamber (its bound to cool and won't come out) that sounds like it could be a recipe for hydraulic lock...

[Flynn2]

Well if it's not the valve clearances, not the injectors, not air getting into the fuel lines then it must be the head gasket, even though there are no symptoms. I'll have to get a compression test done, the spending never stops

[Peter.N.]

The only thing left is the pump, I can't really see how unless there is uneven wear in the distribution section, but there is an easy way to tell, once the engine has warmed up and is missing empty a bucket of water over the pump and see if the fault goes, not freezing water though or you might break something.

Peter

[Flynn2]

How would the water thing help? I'm not questioning the practice, just genuinely interested to know the theory behind it. But bear in mind that I have had this problem across two pumps; the first one I rebuilt and suspected of being the cause which I replaced with one that had not been opened. The only thing the two pumps share is the ground lda pin taken from my old pump and the governor modification, neither of which would cause an injection problem like this.

[Peter.N.]

The reasoning behind it is that it cools the pump, was a well known way of testing old tractor pumps. Didn't realise you had this problem with two pumps, I'm afraid I have rather lost track of the thread. If its the pump at fault its got to be that the pressure delivered to one injector is low and as the fault worsens as the temperature increases this could be clearance increasing with expansion. If its not the pump the only other logical solution is compression down on one cylinder, but even that is not logical as the compression normally improves as the temperature increases. You may be able to find out which injector it is by raising the tickover speed and slackening off one pipe at a time, if its still only missing on one it must be another, when you get it missing on two, you have found it, you will need quite a few revs though to stop the engine jumping out. I have been running diesels since 1959 and have rebuilt a fair few so I have had most problems but these one seems to defy logic .

Peter