Diesel injection pump question

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Diesel injection pump question

Post by the_weaver »

Is is ok to turn the diesel injection pump on a ZX 1.9D when the cambelt is removed? I understand that you normally lock the position of the cam sprocket and pump sprocket with bolts when changing the belt. However if I wanted to turn the pump sprocket once or twice is there any reason why I shouldn't do this? Provided I refit the bolts in the pump sprocket before I refit the cambelt I should be ok, shouldn't I? I assume that the pump repeats it's pumping cycle on every turn of it's sprocket, so there's no synchronisation to anything else other than the need to use the two alignment bolts.

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Post by CitroJim »

Absolutely correct Paul and no problem at all, just line up the holes and all will be well.

A second proof check is that when properly timed, the driveshaft keyway is at about 9 o'clock or pointing towards the engine block.
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Post by the_weaver »

Thanks for the reply Jim. Which driveshaft keyway are your referring to? Is it the one in the diesel pump sprocket? I've been looking at the pump to see if I can see a keyway or Woodruff key but I can't see anything. The Woodruff key and keyway seem to be hidden under the nut on the sprocket. Is there anywhere else that shows the position of the keyway without having to remove the nut?

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Post by CitroJim »

The keyway is hidden under the nut Paul and even with the nut off, it's not clearly visible. once the sprocket is off it it then becomes clear and the 9 o'clock position is useful when refitting a pump to know the timing is more or less close.
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Post by the_weaver »

Jim

Is the Woodruff key visible when the nut is off?

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Post by spider »

I don't think you'll be able to see it with the nut off, the sprocket would have to come off I think.

There is no 'upside down' with the injection pump sprocket (unlike the cam) if that's the concern ?
Andy.

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Post by jgra1 »

alluding to what Andyand Jim say, Paul, if those 2 M8 bolts go in, the pump is ready for TDC :D they are offset from each other, or unsymmetrical, so they only go in when pump is ready to have belt attached and rest of engine is at TDC.. don't worry :twisted:

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Post by the_weaver »

Andy and Jim

No, I'm not worried about the pump sprocket being on upside down. I was concerned that somebody might have removed the Woodruff key to make the sprocket "adjustable". I've been having another look at the pump today and I think I've worked out what's happened. The Woodruff key is probably still there. It's a bit of a long story. Here goes...

I took my car to a garage for a new cambelt some some ago. When I got the car back it was running really badly. I took it back to the garage and they adjusted it. After that, the performance was ok when hot, but the starting was bad, and the performance was bad with a cold engine.

I checked the cambelt timing myself with an 8mm rod and three bolts in the sprockets. The cam was ok but the pump was out by one tooth. I decided to move the sprocket one notch myself but ended up taking the cambelt off and putting it back on again. When I rotated the engine by hand a few times I noticed that the belt was running off the edge of the pump sprocket by about 1mm. It was on the cam sprocket by about 1 or 2 mm. So, I decided to change the tensioner and idler. It's still running 1mm off the pump sprocket. So, I haven't started the car yet because of that and some other work I'm doing for the MOT.

The chap in the garage said something about adjusting the pump timing but I wasn't sure what he was on about. At first I assumed that he meant that he was moving the cambelt one tooth on the pump sprocket. Now I think I know what's happened. They put the cambelt on with the pump one tooth out. When looking from the offside wing, the pump sprocket is out by one tooth in an anti-clockwise direction. I think that will retard the pump timing. That was their first mistake. Now looking at the pump mounting nuts I can see that they are all the way to the clockwise end of the slot (when viewed from the offside wing). It looks like they've compounded the problem by turning the pump clockwise to compensate for the cambelt being one tooth out anticlockwise. I bet they never adjusted the pump timing with a dial gauge either. I expect they just turned the pump and tried the car until it was ok.

I'm wondering how best to recover from this situation. I can put the cambelt on correctly, that's no problem. When I do, however, the car is probably going to run very badly because the pump is turned fully clockwise. Should I try it with the pump clockwise or should I set the pump to the middle of the slot? It's a Bosch pump, on a ZX 1.9D, 1993. Is it possible to get reasonable results by trial and error, turning the pump and trying the car out? The official method is to use a dial gauge and probe. I haven't got either at the moment. I have got a digital vernier gauge (with a long rod that comes out of the ruler part) but that might be too big to fit in the space and it might not be light enough for the pump to move, or accurate enough. I can probably obtain a dial gauge if necessary but what about the probe? Are they available or expensive? Can I make one? I heard something about using a spoke from a bicycle wheel as a probe.

I'm wondering whether the problem of the cambelt running 1mm off the edge of the pump sprocket is related to the garage having rotated the pump. As the pump has been rotated all the way to the clockwise end of the slot, do you think that this could cause the pump and sprocket to move backwards a bit, in the direction of the nearside wing?

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Post by the_weaver »

John

Thanks for the reply. I'm starting to understand the operation of the pump better now.

One more question:-

On the Bosch pump, does the dial gauge screw into the hole at the back of the pump which is in the centre of a group of four fuel pipes. It looks like the shape of a "five" on a dice. Does the centre nut of the "five" undo to allow the gauge to screw in? The only other possible place I can see has a screw head for a flat bladed screwdriver. I expect that might be an adjustment screw.

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Post by jgra1 »

Paul Paul...

I think your doing the right thinking here but maybe paying a tad too much concern re: pump timing and dial gauges.. I really doubt the majority of us on here have ever timed a pump by a dial gauge.. set yours in the middle, get the teeth ok, and run it..

keep 3 of the 4 pump nuts loose-ish and one a little tighter.. with engine running loosen that last nut, rotate the pump a bit in either direction and listen to either too quiet or too loud/knocking.. I think (citro)Jim will concur that a tiny amount of knock is what you want... and with revs rising that should dissipate..

I remember reading my BOL a fair few years ago, and reading about the dial gauge and becoming very scared :twisted:
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Post by the_weaver »

John

Thanks for your advice. It sounds like a good method. I'm not sure I'm brave enough to turn the pump with the engine running though. This is my first cambelt change and I wasn't expecting the belt to run off the sprockets. It's got me worried. Maybe I'll start off by turning the engine off, turning the pump a bit, restarting the engine. At least until I get more confidence that the belt isn't going to come off. I think setting the pump to the centre to start with is a very good idea. I'm going to try that and then see if the cambelt moves back onto the sprocket when then engine is turned over by hand. Is there any way of adjusting the back to front position of the pump? By that I mean the position of the pump between the two wings.

One thing I've noticed is that every time I put the cambelt on (about five times in the last few days) I set up the pump pulley with the two bolts going into the threads correctly, but once I've removed the bolts, turned the engine over twice etc as per the Haynes manual I always find that only one bolt goes back into the thread properly on the pump sprocket. The other bolt is very slightly misaligned, only goes in one thread and catches on the side of the hole in the sprocket. For some reason I always get this slight misalignment. I wonder if this is related to the pump being turned too far clockwise. Maybe the pump is sitting up on some rust or something.

Are there any fuel lines to loosen or disconnect when turning the pump? What about the four metal pipes that come out of the back of the pump?

I've been inspecting the cambelt, tensioners, idlers etc to try to work out why the belt is running off the pump by 1mm. One thing I've noticed is that the highest point of the water pump casting (the nearest point to the top of the engine) is very close to the bottom edge of the cam cover backplate. It looks like it might just be touching or sitting a bit high on it. My car has got the old style cambelt covers with a metal backplate on which the tensioner, idler, engine mount etc sit. The backplate is about 1.5mm thick. I'm going to have another look at it tomorrow and I might have to remove the water pump if it looks like a problem. The water pump was fitted by the same garage that did the cambelt, at the same time.

I'm also wondering whether too much cambelt tension will tend to pull the cambelt off the edge of the sprockets. I suppose it might do if it makes the idler and tensioner pulleys lean over a bit more. I've just replaced my tensioner and idler. The ones I fitted were made by INA (LuK). The new ones have got a bit of play in them. Is this normal? The old ones I took off have got play in them too. The ones I took off were an SKF tensioner and an INA idler. I was thinking about trying an SKF tensioner and idler instead of the INA ones. However I haven't found anybody who supplies SKF ones. Do the SKF ones have a bit of play in them when new? Is turning the cambelt through 45 degrees a good way of getting the right tension? Are XUD auto-tensioners known for putting on too much tension on the belt? I've got a method of measuring the frequency of the cambelt when "plucked" using my MP3 recorder and some software on my computer. However it's not much use because I don't know what the frequency is supposed to be for a XUD. If anybody has got a table of correct frequencies for the XUD maybe they can tell me what it should be.

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Post by CitroJim »

Paul,

This is an interesting thread.

The INA tensioners should be fine. I've used them. Now, the jump you see when removing the pins is common and what I've done is to put the belt on and put tension on by releasing the tensioner before removing the pins. Then rotating the engine and carefully checking it is still in time, then tighten the tensioner pivot and clamp and rechecking. A jump is usually because the belt is not pulled tightly when fitting between the crank, pump and cam sprockets; you need to get this run tight so that any slack is only in the run between cam tensioner, waterpump and crank run. The tensioner can then take up the slack without disturbing the timing.

If, however careful you are, the timing still jumps when the pins come out then there is an alignment problem 'twixt crank, pump and cam. Almost as if something is bent.

Worried about the belt running off. Is the tensioner "sat" correctly on the block and not at an angle due to bad fitting?

As the "garage" claimed they moved the timing, I wonder if the pump is sat nice and square on it's flange in the cradle? If it was a bit cocked up or, the sprocket was bent then that could account for it too. If, for unknown reasons, they removed the sprocket without using the correct puller then it may have ended up bent or warped. They can be shocked off with a hammer but it's not at all a god idea as the sprocket is not the strongest of components.

I reckon you may be onto something with a missing key but there should have been no reason to disturb it. The pump should not be sitting on one end of its slots. It's designed to be roughly in the middle when in correct time.

As John says, no need for dial gauges. Your ears will do the job. In any case, you need a special machined adapter. It's not just a case of removing the bolt and slipping a gauge in. Also, if you remove the bolt, you'll have a diesel flood of biblical proportions to mop up!

As said, adjust for a slight "tinkle" on idle that disappears as soon as you rev. If timing is right, the response to even a tiny rev will be immediate, quick and clean with the tinkling disappearing immediately. Set it to be a tad over-advanced, evidenced by knocking as it revs and then back off until it disappears.

Don't try to move the pump with the engine running. It is difficult and not a good way to hear the subtleties of what you're listening for. Move, test and move again.

Also, every time you move the pump, the HP delivery pipes to the injectors must be loosened and retightened to relieve any stress in them. If not you risk them cracking in service.

I'm rather interested to know the cause of all of this Paul, so keep us in the picture!

And, all the best for nailing this issue once and for all...
Jim

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Post by the_weaver »

Jim

I'm going to inspect the pump and pump sprocket. I'll turn the nut with a spanner and see if I can see any wobble. The starter is currently out so I can't use that to turn the engine over. I wonder if I can spin the pump sprocket with a drill or something to make it easier to see if it's wobbling. I've got the sprockets with holes in rather than the ones with spokes. I think they're a bit stronger. I'm hoping the garage haven't bent the pump sprocket, but I do suspect that they levered the crankshaft pulley off with a crowbar, by the looks of it. There's a dent on the outer edge of the crankshaft pulley, on the side nearest the engine, just the right size for a crowbar. The metal in the dent is shiny as well, so it looks like it's been done recently. There's only one dent, so it wasn't a puller. The dent has pushed metal into one of the grooves where the alternator belt runs, so I'm going to have to file it back down. When I removed the crankshaft pulley, about a week after the garage had put it on, it came off easily in my hand. I hope that's not a bad sign. There was no evidence of Loctite on the bolt threads either. I hope they haven't bent the crankshaft. The pulley is a bit worn by the looks of it. I can see some wear in the keyway in the pulley and in the Woodruff key. However, I replaced the Woodruff key and it feels a bit better now.

I'll move the pump back to the middle of the slot and see if the sprocket moves back towards the engine a bit. I didn't make a note of where the belt was running on the sprockets before I took the car to the garage. However by looking at the clean bits on the sprockets and pulleys it looks like the belt has always run very close to the edge of the pump sprocket (the edge nearest the offside wing). For some reason the belt seems to have now moved an extra millimetre or two, so it's now slightly over the edge of the pump sprocket intead of slightly inside the edge of the sprocket.

When I got the car back from the garage the belt was running about 0.5mm to 1 mm inside the edge of the pump sprocket. The bolt in the tensioner adjustment slot was about two thirds of the way across the slot. There was an extra one third of tension I could have added if required. There was slot visible on both side of the bolt head. I then took the belt off and refitted it, to fix the problem with the pump being one tooth out. I used the method in the Haynes manual. After I'd finished, the bolt in the tensioner slot is almost all the way over to the "tight" end of the slot. There is a bit more tightness adjustment left if required, but the slot is now obscured by the bolt head on one side. I can only see the slot on one side of the bolt head. The auto-adjuster sets the tension tighter than the garage left it. I got the feeling that the garage might have left the belt a bit slack because of the belt running slightly over the edge of the pump sprocket. I thought at the time that the problem got worse as I increased the tension. All this was with the original tensioner and idler that had been on the car for 17 years. I then decided to replace the tensioner and idler with new ones. The problem of the belt running slightly off the edge of the pump sprocket is still there. It's now running slighly more off the edge, if anything. There's only a millimetre or two between the belt being completely on the pump sprocket and running slightly off the sprocket. I can accept that changing the idler and tensioner leads to the belt running a millimetre or two different to what it did before. It may just be manufacturing tolerances. Unfortunately, everything seems to have added up to make the belt run slighly off the sprocket.

When I fitted the new tensioner and idler I spent ages scrubbing the backplate clean with a Scotchbrite pad and a bit of WD40. Then I cleaned the backplate with meths and kitchen towels as well, to get rid of any bits of the pad. I put a bit of copper grease (hardly enything) on the back of the tensioner and idler. The tensioner and idler do appear to be sitting flat on the backplate. The old tensioner felt gritty when it was sliding and there was some dirt on the back. The new tensioner slides smoothly. The tension on the belt due to the auto-tensioner is now greater than it was before. I wonder if the dirt under the old tensioner was making the belt run in a certain position. Once I've got rid of the dirt the belt runs in a different position, but not a better position.

I can see that one side of the cambelt "system" seems to run further out from the engine than the other side. One side being the diesel pump sprocket and idler, the other side being the cam sprocket and tensioner. The pump sprocket seems to be about 1mm further from the engine than the cam sprocket. Looking at the clean area on the old tensioner and idler I can see that the belt has been running a bit further out from centre on the tensioner. However on the idler the belt is running further out from the engine. The edge of the belt is close to where the INA pulley starts to curve over at the outside edge. I've got the old style cambelt covers with the metal backplate. The idlers etc sit on top of the backplate. I wonder whether this might make one side different to the other. The backplate is the same on both sides, but I don't know what's behind the backplate.

I would have taken the pump sprocket off a while ago if it wasn't so awkward. I was wondering if the sprocket was closer to the engine than it should be because the garage had overtightened the nut, after messing about with the Woodruff key or something. The problems with me removing the sprocket are that I haven't got a sprocket holding tool (I could make one), I haven't got any long M7 bolts to make a puller (only short ones), I can't get a torque wrench in there (no space) to torque the nut back up properly. I could tighten it back up with a ring spanner but I would be a bit concerned that I was overtightening it. I was thinking about buying a crow's foot type spanner end/socket so I could tighten it back up with a torque wrench.

With regards to putting the belt on. You release the tension with the bolts still in. Do you then turn the engine over with the tensioner bolts loose, or do you tighten the tensioner bolts, turn the engine twice, then slacken and retighten the bolts. I found some play in the crankshaft sprocket and Woodruff key. I thought that might be the cause of the slight misalignment. I replaced the sprocket and Woodruff key and it seemed easier to put the belt on afterwards. I get less problems with the teeth of the belt not wanting to sit down and mesh properly with the teeth of the cam sprocket when you first pull the belt on.

I wonder if the garage turned the pump without loosening the HP delivery pipes. Would those pipes be able to pull the pump off it's axis?

Paul
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Post by spider »

Regarding tension:

Tighten tensioner bolts up, remove pins etc, turn engine twice (two turns of crank pulley)

Refit pins (just before you approach the flywheel timing pin, its easier to get someone else to wiggle it it, do NOT turn back if you miss it, go around twice again) but I can do it on my own on the floor, so you should be ok)

Andy's tip: Make a mark on the crank pulley, so you know when you are 'near' the correct place for the flywheel locking pin to go in. ;) , then turn very very slowly so you do not miss it. You can sort of reach with one hand to hold the tool in the casting and another hand to slowly turn the crank pulley nut

When pins are refitted, slacken tensioner bolts a few turns, then retighten.

Remove pins

Build up rest of engine etc

Done :)

Short explanation: yes, fit the pins back before slackening and re-tightening the tensioner bolts.

Extra note: I cannot fit both of my inj pump bolts, one goes in normally the other half in but its never ever been a problem. Without the belt you can obviously, but when its tensioned up one fully in as normal and the other is halfway. Do not worry too much about this, as I say its not caused me any issues and I've done about 80K or so with it like this (two belt changes) and I must of done about 100 belt changes for other people too, no one ever complained.
Andy.

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Post by the_weaver »

Andy - That's interesting that one of your pump alignment bolts doesn't quite go in properly. It must be a common thing. I've got the hang of putting the 8 mm rod in the flywheel whilst turning the crankshaft pulley bolt. I've also worked out which of the holes in the crankshaft pulley marks the approximate position of TDC.

I've been wondering about the dent in my crankshaft pulley. If the garage did lever the crankshaft pulley off with a crowbar could they possibly have pulled the crankshaft out of the engine by 1 or 2 mm? Is this possible? Is there a measurement I can take to see if the protrusion of the crankshaft is correct?

I had a look at the pump and sprocket, with the cambelt removed. I thought it felt very sloppy to start with but maybe it's supposed to be like that. I'm not sure what's normal or what to check for. The pump has got quite a bit of endfloat. I can pull the sprocket in and out from the pump by about 2mm (estimate). There seems to be a spring in the pump which pushes the shaft outwards towards the offside wing.

I can feel a bit of rotational play in the pump sprocket. Probably about 1mm of movement on the outside edge of the sprocket. It's easy to move the sprocket by hand for this 1mm of play and then the pump starts moving and you need a spanner. It feels like a keyway moving on a Woodruff key with a loose nut. I can't see the pump shaft though, so I can't work out whether the play is in the sprocket or inside the pump.

When I turned the pump over with a spanner on the nut I thought the sprocket might be moving a bit towards the engine. I think this was probably just me pushing the sprocket inwards against the spring. It's the 2mm endfloat. I was using an adjustable spanner. I'll have another go tomorrow with a proper spanner. It's difficult to turn the pump sprocket smoothly because the pump fights against you one minute and then changes direction and helps you rotate the spanner.

I thought the pump might have some play when you try to rock the sprocket at, say, 3 o'clock and 9 o'clock. It seems to be similar to the 2mm endfloat with the spring pushing outwards. I can probably move the sprocket quite a bit. I suppose this could cause the sprocket to lean over when the cambelt is tensioned. Especially if the cambelt is on the outer edge of the sprocket.

I thought that the sprocket looked like it might be closer to the backplate on the sprocket's lower edge than on the sprockets upper edge. It could be an optical illusion as the backplate and sprocket are curved. I'll see if I can measure a difference tomorrow. This could be the pump alignment or the shaft leaning a bit on a worn bearing.

I didn't attempt to undo the fuel pipes at the back of the pump or turn the pump. The pipes don't look like they've been disturbed by the garage. They look fairly rusty. What's the best method of getting them undone? Wire brush followed by Plus Gas? Do I need a special spanner? Is the pipe likely to break like with a brake pipe on a rear wheel cylinder? Do I have to undo the nut completely? Should I pull the unions or pipes out?

I said previously that the pump mounting nuts are turned all the way in a clockwise direction when viewed from the offside wing. Well they are, but this means that the pump itself is turned anticlockwise when viewed from the offside wing. This would add to the error created by the cambelt being one tooth out, not compensate for it. I'm confused a bit now. My theory was not quite right. I'll have to have another look at it all. Also, I've looked in the Haynes manual and there's a picture of a Bosch pump on a car and the position of the mounting nut in the groove looks similar to mine. It's not in the centre, it's over to one side. Maybe, they're supposed to be like this. I can't tell if the mounting nuts are all the way over in the groove on my car because the nut and washer obscures the slot on one side. All I can say is, it looks most of the way over to one side. The garage said that they adjusted the timing. They said it was slightly out. Maybe they just turned the pump a bit.

I had a look on the websites of SKF and INA. One of the reasons that INA give for tensioners/idlers leaning over (in general terms, for all belt and pulley systems, not specifically cars) is the belt not running in the centre of the sprocket. Well, I've certainly got the belt not running in the centre of the sprocket problem, especially on the idler side. I'm wondering whether the cambelt system on the ZX is designed to work perfectly when the car is new but suffers from problems in real life when things start wearing. A bit of play here, a bit too much endfloat there, and before you know it the cambelt is all over the place. I think I saw a diagram somewhere which showed a typical tensioner with a dual-row bearing and an idler with a single-row bearing. If this is the case then it might be the reason why the belt is out more on the idler side than on the tensioner side.

I think the sloppyness in the pump might be why the problem is on that side. The camshaft bearing is probably very tight compared to the pump bearing. It might be that the pump sprocket is leaning over once the belt is tensioned. If the pump has got too much endfloat/play then it's only the spring in the pump that's going to be fighting the cambelt tension. As the tension increases, the pump sprocket leans over, as the cambelt always runs nearer to one edge on XUD's. This is my current theory. Only a theory though. What is the bearing in a new pump like?

Paul
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