Diesel injection pump question

the_weaver · Post by **the_weaver** » 26 Sep 2010, 00:03

I've discovered another problem. When I turn the engine over by hand, the cambelt is moving slightly from side to side, on the diesel pump sprocket. Is it called a shimmy? I wouldn't have noticed it, when turning by hand, apart from the fact that the cambelt is running right on the very edge of the diesel pump sprocket. When I checked it, it kept alternating between being slightly off the sprocket, and slightly on the sprocket.

I will do some more investigation tomorrow. I don't know whether it's the sprocket or the belt at this stage. I'm thinking of measuring the distance between the points at which the belt is at it's maximum outward position and seeing if this matches up to the circumference of a sprocket. I suppose it could be the pump sprocket itself. I'm also wondering whether it could be the crankshaft pulley. Maybe it's not sitting straight and is putting oscillations down the cambelt.

Is it ok to turn the engine over via the cambelt from the diesel pump sprocket nut, or the camshaft sprocket nut? It would make diagnosis easier. The starter motor is out at the moment. I might put it back in, and use it to turn the engine over. Is is possible to rig up a remote switch or something, to operate the starter from the engine bay?

It looks like the ZX has got bolts and spacers holding the diesel pump bracket on. I can't see any dowels (although I haven't dismantled it yet). Does the lack of dowels mean that it will be sloppy when I reassemble it, and will I have to realign the pump sprocket to the cam sprocket, using a straight edge or something? I'm wondering if I'm going to have a bigger alignment problem caused by disassembling it. Can I rely on the bolts to locate it correctly, once the rust is cleared, or does it require alignment by me?

Paul

spider · Post by **spider** » 26 Sep 2010, 10:46

Do not attempt to turn the engine via the cam or injection pump bolts

Only turn via crank pulley bolt.

Yes, you can rig up a simple test switch to operate the starter, a piece of (fused!) wire with a momentary switch in.

Fit one end to starter (the thin feed wire obviously) , then the switch, then the fuse and finally to the battery positive.

Ensure ignition is off (ideally unplug stop solenoid really) and more importantly gearbox is in neutral

Obviously, don't leave any timing pins in.

the_weaver · Post by **the_weaver** » 27 Sep 2010, 01:35

I had a go at checking the runout of the diesel injector pump sprocket today. I used a plunge type dial gauge, with a ball bearing in the end, and I angled it at 45 degrees onto the outer edge of the sprocket (cambelt still fitted). The runout was 0.6 mm. As it seemed quite a lot, I decided to investigate further.

I watched the dial gauge, as I turned the engine over, using the front road wheel. It seems that the runout is linked to the operation of the pump. As the pump sprocket turns, the runout increases gradually to 0.6 mm, and then it jumps back to nothing suddenly. It does this four times, for every rotation of the pump sprocket. This must be the pump pumping up the pressure in each injector pipe, in turn. I can hear a release of pressure from somewhere, at the same time as the dial gauge goes back to zero. As the pressure builds up, the sprocket seems to be pushed outwards more, towards the offside wing.

I think this is probably related to the fact that I could feel endfloat in the diesel pump sprocket, when the cambelt was off. I didn't measure it but it could have been 0.6 mm, or more. The sprocket was being pushed outwards by a spring, towards the offside wing, but I could push the sprocket in.

What I'd like to know is whether this is normal. Maybe it is. On the other hand, I might have a worn bearing in the pump which is creating the endfloat, and allowing the sprocket to move in and out.

I don't know if the problem with the cambelt moving slightly on and off, right at the edge of the pump sprocket, is related to this at all. I think the cambelt might be following the pump sprocket, as it's too tight to slide along the sprocket. So when the pump sprocket moves, the cambelt moves. I think the cambelt weaving might be due to something else though, but I suppose it could be related to this.

I checked the runout of the crankshaft pulley, on the outer edge of the pulley, on the side nearest to the offside wing (wrong side really). It was 0.1 mm. Is this ok? The surface of the pulley was rusty. I didn't have time to clean it up. I could probably have another go after cleaning it.

Paul

the_weaver · Post by **the_weaver** » 07 Oct 2010, 02:07

After putting the cambelt on properly, and setting the timing to the middle of the slot on the injection pump, the car started first time. I've been for a test drive in it and it runs ok. The smoke that used to appear under the bonnet when the car was cold seems to have gone. The cambelt is running straight. I can't see any wobble at idle. The cambelt is still right on the edge of the injection pump sprocket, but it seems to be where it wants to run, so I'll leave it for now. It may move onto the sprocket a bit more when the belt stretches and loosens up a bit. I've still got to do the timing properly, but I think I'll put the car in for the MOT first, as it's due in a few days.

Paul

spider · Post by **spider** » 07 Oct 2010, 08:41

Thought it might be OK with the pump in the middle and the sprocket set properly.

You may find when you come to do the timing its not that far out.

, you can tell with practise by ear anyway (to a certain degree at least)

the_weaver · Post by **the_weaver** » 09 Nov 2010, 23:43

As the car was starting first time and running well I decided to just leave the timing in the middle. Unfortunately the car is now failing to start first time, first thing in the morning. It seems to be due to the onset of the cold weather. It usually takes quite a few attempts to start it now. It looks like I will need to adjust the timing a bit better than I have done. It starts ok during the day, it's just the first start in the morning that's the problem.

I tried pumping the priming bulb and that doesn't improve the starting, so I don't think it's an air leak. It could be a glow plug, but as I've only adjusted the timing very roughly I think it's probably the timing. I haven't got much time to work on the car as I need to do some traveling. I was thinking about moving the timing a bit to see if the starting improves. My question is: which direction do I move the timing? The timing seems to be not quite right at the moment. Would poor starting (say six attempts) be due to retarded timing or to advanced timing? If it's due to retarded timing then I'll advance it a bit. If it's due to advanced timing then I'll retard it a bit.

Would leaking leak-off pipes cause poor starting and could this be temporarily cured by pumping the priming bulb? I'm wondering if the priming bulb can "cure" all air leak problems or whether an air leak could cause poor starting even after I've pumped the priming bulb?

Paul

spider · Post by **spider** » 10 Nov 2010, 11:29

I'm not sure regarding which way will 'improve' I would suggest if you are going to do that a fraction one way then if no better a fraction the other way a couple of days later. Usually you can tell by ear if its out, although you do need to hear a few of them to know, its not something I can explain really.

I was thinking of valve clearances *gulp* although its rare for these to go out and if they do it tends to not start when hot rather than cold.

I would be more inclined to say its pre heating or air ingress.

When it does start (from cold) is it really lumping / running on 3 cylinders for a few seconds , smoke ?

Priming the bulb will fix 'most' (but not all) air leaks for a few seconds, long enough to start it usually.

I'd be more inclined to suspect you have one or two glow plugs down. With one down it will start usually without any trauma but will be a bit rough until that cold cylinder chimes in

, with two down it will be difficult to start. This is less apparent when warm if at all.

One quick test you can try: Wait for glow plug light to go out. Do not attempt to start. Turn ignition fully off then back on again, wait for glow plug light again. Now try to start it. Tip: Don't 'glow' them more than two or three times or you risk burning them. If there's any improvement, suspect glow plugs (this does not always work but its a 'free' and easy test)

Do you have a clear pipe on the pump inlet ? , you should be able to see any air bubbles...

the_weaver · Post by **the_weaver** » 10 Nov 2010, 18:43

Andy

I tried giving it two goes on the glow plug heating before starting and it didn't improve the situation. Yes, it does emit a cloud of smoke from the exhaust and runs lumpy for a few seconds after starting. The smoke soon clears and then there's hardly any smoke. It also emits smoke under the bonnet when first started. That problem went away during the warm weather but has now come back. It's not as bad as when the garage had the timing miles out though. I haven't got a clear pipe on the inlet but it's a good idea.

Paul

the_weaver · Post by **the_weaver** » 15 Nov 2010, 23:38

I checked the glowplugs with a meter and two of them were open-circuit. I've replaced them and the car started first time. I've only started it once, but I expect that will be the problem fixed. I thought I could see some smoke under the bonnet, just on starting, but it was dark so I couldn't be sure. I'll check again tomorrow.

Paul

spider · Post by **spider** » 16 Nov 2010, 10:07

Excellent.

Yes it will start with three usually without any concern apart from a bit of smoke. With just two you start to get problems, more so the colder it is.

The N/A units seem to need little preheating if they are warm anyway, compared to turbo models (no doubt due to the differences in compression, turbo engines have slightly lower compression)

Not sure what this smoke under bonnet is, difficult to guess. Could be something like clutch dust coming up out of the tdc sensor aperture area or something.

I would suggest replacing all four glowplugs though to be honest, but if you are happy with just the two you know were dead that's fine. They can read reasonably well with a meter but have faults you cannot see, such as glowing in the middle etc.

Anyway let us know how you get on in the morning, especially now its started to turn cold too.

the_weaver · Post by **the_weaver** » 16 Nov 2010, 23:37

Andy

I started the car today, but it was dark, so I couldn't see the smoke properly again.

I bought four Beru glowplugs a while ago but only replaced one at the time. Now I've replaced two more. So there's one left as a spare. I don't like replacing the glowplugs until I know they've gone. The reason is that I stripped the thread on a sparkplug on a Puegeot 405 years ago and had to get a helicoil insert fitted. Ever since then I've hated changing glowplugs and sparkplugs.

Paul

spider · Post by **spider** » 17 Nov 2010, 10:19

Good to hear it started well.

The smoke could be anything really its difficult to say, possibly even some oil that's ran on the exhaust or maybe some clutch dust coming out of the bellhousing.