What not to do to a diesel

Post by **CitroJim** » 12 Nov 2009, 20:13

I very much suspect that in reassembling the head to the body, either the fast idle or boost compensation levers are fouling the delivery valve collar operating plate (governor plate) and effectively keeping the governor plate hard back. When reassembling, just before finally dropping the head into place, check that the throttle spring does pull on the plate and freely moves it forward against the governor plunger. If you have disturbed the triangular bolts that act as bearings for the governor plate, check these are correctly located in the plate.

Before final assembly, check the plate is properly engaged in the delivery collar and that the plate bias springs (the ones that are located on the end of the distributor head) are correctly placed; they can drop out of place so easily. Also check the governor weights are free to swing and correctly assembled.

Mike, I agree that the serrations on the throttle arm offer many permutations for adjustment and a pen mark is not really adequate. I scribe a fine line deep enough to survive cleaning.

When all is back and running, it is vital to very carefully adjust the fuel screw (maximum delivery adjustment) to ensure the engine will just rev to the red-line off load (snap idle test as done by the MOT station) as one very important purpose of this screw is to set the maximum RPM of the
engine. It effectively sets maximum fuel delivery.

Colin, a have a PDF that explains in great detail how these pumps work and it may help you. It's far too big to post here but if you'd like a copy I can email it to you.

colinxm · Post by **colinxm** » 13 Nov 2009, 04:35

Hi Gents, thanks for all the moral support and suggestions, I was back late today so didn't get chance to play with the pump.

Mike and Geoff, I did actually time the pump with a test indicator before I fitted everything else so we can rule that one out although I've since moved it just to see if it would help. I did indeed remove the distributor head, this was the only part that I didn't strip down further but the pump/engine ran great before the stripdown except for a small leak.

Jim, I think I'll pull the head off first as I can do this without removing the pump from the car, then I'll be able to see what's going on (or not in there), yes please would love the pdf. My email is: citxm(at)online.no

Thnks again all, Colin.P

Geoff Lebowski · Post by **Geoff Lebowski** » 13 Nov 2009, 09:57

colinxm wrote:.... Mike and Geoff, I did actually time the pump with a test indicator.....

So did I! That's what I don't quite understand about what happened on mine. As I did no further dismantling but only adjustments, I can only assume it was a mixture of getting fuelling/governing adjustments sorted and getting rid of trapped air......

My only explanation for the pump running initially better with advanced timing than correct timing is that air trapped within the pump prevented correct pressure transfer within it, thus causing retarded timing on the timing ring.

The reason I think trapped air would cause retarded timing would be due to compression of the air taking 'time' to compress to a value equal to the internal hydraulic pressure and thus delay (retard) any transfer of hydaulic pressure to timing events.

The timing ring is controlled by hydraulic pressure and is responsible for the advancement of timing at higher engine speeds. With the exception of the KSB cold timing advance device, there is no advance at idle timing - hence yours ticking over ok. In the event of revs above idle, the timing ring advances the timing, but due to the trapped air, the timing occurs too late and hence poor running.

All the above is just my theory and understanding of the pump after reading many times the Germanic pdf file that Jim is going to send you. It makes sense, but I could very well be wrong! The fact that I had to advance my timing initially supports my theory but doesn't necessarily prove it.

Eventually, my pump ran/runs best at the scribe mark I made with the DTI at the recommended timing, presumably after all the air was out.

I'm not at all trying to say I'm right or that Mike or Jim and others are wrong, but if it saves you stripping things down it may be worth considering.

I'm perfectly happy to be 'ripped to shreds' if I've spouted a load of rubbish btw, I'd rather be proved wrong in the interest of correct info.

Also, continually running with advanced/retarded timing isn't good, especially advanced!

Good luck!

MikeT · Post by **MikeT** » 13 Nov 2009, 12:52

It's all good sound advice and useful suggestions as far as I can tell and keeping an open mind is the way forward without concrete evidence of the problem.

If the timing was set and has since been moved, I would suggest you reset it again as, true to most adjustments within these pumps, just the finest of alterations can make a substantial difference.

It is possible, without removing the governor cover to see if the governor lever is mobile and free to move by removing the LDA top and diaphragm with concentric cone pin. Looking down the hole you should see the fuelling pin. Push it back in then operate the accelerator and it should pop out again. That will confirm the accelerator linkage is still connected to the governor and the governor is not trapped by the parts mentioned by Jim. What it won't tell us is if the governor lever is properly connected to the control collar but we'll cross that bridge if/when we come to it.

colinxm · Post by **colinxm** » 13 Nov 2009, 19:13

Hello again Gents, I managed to get to poke around with the pump a bit today

I removed the LDA and pin/diaphragm, the fuelling pin was nowhere to be seen but duly popped into sight when I operated the accelerator, I tried this several times proving that this is ok. I then pulled off the whole top, to me everything looks in order but have taken a few pics for more knowledgable people to take a peek at if you'd be so kind

Thanks once again for all your helpful suggestions, Colin.P

MikeT · Post by **MikeT** » 13 Nov 2009, 20:43

Helpful as they are I can't see any obvious problem in those pictures. Can you see if the governor lever is correctly fitted into the control collar below or is it impossible?

Also, can you move the lever assembly towards and up against the governor shaft tip freely though with strong spring resistance?

Geoff Lebowski · Post by **Geoff Lebowski** » 13 Nov 2009, 21:14

MikeT wrote:Helpful as they are I can't see any obvious problem in those pictures. Can you see if the governor lever is correctly fitted into the control collar below or is it impossible?

That's a very good point as I assumed mine was ok and only noticed by chance that it wasn't! Also, it's hard enough to tell when it's on the bench but try to ascertain if the control collar is mounted the correct way round! There is a chamfered/lipped edge that should face the driving pulley.

Only other thing I can think of is the timing piston at the bottom. Did you fit it the correct way round and include all the springs?

colinxm · Post by **colinxm** » 14 Nov 2009, 08:00

I refitted the top last evening and tried for over an hour to get the motor to run correctly without success, I think the only thing to do now is pull the pump off again and do another rebuild carefully taking into account all the the points you guys have mentioned and especially following Mike's fantastic rebuild thread.

Mike, the lever assembly does move toward and against the govenor shaft tip as it should with spring resistance, it's impossible to see what's going on down below but I'm sure that the tip of the lever is installed in the collar as it was before I refitted the distributor head.

Geoff, thanks for the tip about the controll collar, I didn't particularly notice the way round I fitted it

, the timing piston though was fitted correctly with all springs and collars - I was very proud not to have any 'spares' left over

When (if) I find what I've done wrong I'll put up some pics for all to see.

Cheers Colin.P

MikeT · Post by **MikeT** » 14 Nov 2009, 11:21

Unfortunately it does appear removal is required to delve deeper as the governor end appears all good unless you want to assess the internal pressure first? I'm thinking sticking vanes (which, come to think of it, may have been Geoff's problem).

Otherwise, the plunger shim may have slipped out of position and it is possible to fit the camplate 180 degrees out if it was removed.

Geoff Lebowski · Post by **Geoff Lebowski** » 14 Nov 2009, 11:49

MikeT wrote: Otherwise, the plunger shim may have slipped out of position and it is possible to fit the camplate 180 degrees out if it was removed.

Good thinking about the camplate being 180 deg out - another easy oversight - although would it run at all?

Never thought of sticky vanes, what would cause that?

Sorry to hear your woes Colin, you'll get there!

colinxm · Post by **colinxm** » 14 Nov 2009, 12:15

Ok, i've got the pump off again, I'll pull it apart this evening once my "fast-fingered" four year old has gone to bed and all is safe

The camplate was fitted with the drive dog inline with the shaft keyways and the vanes were free to move so unless something has 'nipped up' after being reassembled I don't think it'll be that but you never know, I hope the vanes are interchangable as I didn't make a note of which slots they came from, I'll put the micrometer on them and see if they're all ground to the same width but I would think this to be the case.

Thanks for the encouragement, it'll be great to get it going again.

Colin.P

MikeT · Post by **MikeT** » 14 Nov 2009, 13:03

Vanes can stick when there's goo build up as in the case of the pump I just dismantled and I now wonder if that was your problem Geoff - eventually freeing themselves up due to centrifugal force.

It's simple to test in-situ - just measure how much fuel is returned to the tank at idle over 90 seconds. There should be well over half a litre.

Someone said the vanes should not be swapped around but I've yet to have that confirmed and I tested mine for resistance changes but couldn't detect any.

Colin, if you're sure the camplate is correct then we can also rule that out. After checking the shim and spring placement, I'm pretty much out of ideas though I'm still not fully convinced you had the accelerator lever on the right spline.

colinxm · Post by **colinxm** » 14 Nov 2009, 16:22

Hi Mike, would putting the accelerator lever a spline or two out really make such a difference ? after all, operating the lever has the same effect as repositioning it a spline or two but the engine still runs terrible.
I can see that it could be positioned 180 degrees out though - I used the slot in the shaft as a ref point.

More daft questions to follow

Colin.P

Post by **CitroJim** » 14 Nov 2009, 16:38

Hi Colin,

Just emailed you the PDF I spoke of

Sorry for the delay, been a pit pre-occupied just recently...

MikeT · Post by **MikeT** » 14 Nov 2009, 17:07

Hi Colin, I understand what you're saying and we may well discover yours could be out by who-knows how many notches but I don't think it's wise to make big changes IMHO - is it not better to use the small increments as given? Bear in mind that the control collar only has to move a few mm to make the difference between idle and full power.

On the other hand, as long as you understand and are prepared for the consequences, by all means make larger changes. For instance, I would also suggest you screw the max fuel screw all the way in to begin with as there's obviously not enough flow even with the accelerator lever at full travel.

AFAIC, there are no such things as questions.