David P on Nuffields?

[MF Pain]

Hi all and David P
Given your location David I thought you may have had something to do with Nuffields! I hope someone may be able to point me in the right direction.
I have a Nuffield DM4 with BMC engine and Simms injector pump with diaphragm governor. The other day the motor revved ungoverned for a short time - probably 20 seconds but seemed much longer until I was able to shut it down! Traced the problem to a fractured diaphragm in the governor and replaced same. The diaphragm that came out was shaped like an open tin can but replaced it with a convoluted shaped one (a Nuffield/Simms replacement part) that a diesel repair centre would be fine. The rack operates freely and the cold start button sets OK.
Problem is that when attempting to start it pours white smoke out the exhaust without any detectable firing in any cylinder.Can hear the injectors creaking when turning over by hand and each cylinder appears to have the same amount of compression -(by unscrewing the decompression bolts in the head). I thought maybe the timing may have changed with the over revving so pulled the timing cover off today to check. It appears to be OK according to the manual I have - 30 chain pitches between Injector pump drive and camshaft and 34 pitches between camshaft and crankshaft sprocket marks.I am thinking perhaps next step may be to remove the injectors to make sure they are atomising OK. When the over revving event occurred I had the exhaust off as I had been working on solenoid/battery and amongst the panic was aware of a lot of flame from the open exhaust.
Thanks for any help
Regards
Bill

 

[farmer 76]

Hi
I am not a expert but did you reconnect the vacum lines back in their orginal places? also check for blockages in the lines
Stephen

 

[MF Pain]

Good comment Stephen - when I went to reconnect the vacuum lines I realised they can fit in more than one place! I looked at photos in the owners manual and am pretty sure I have them right. Also looked at how it operates and fitted the first line to the port in the inlet manifold on the engine side of the throttle butterfly to behind the governor diaphragm. When I push the rack back against the governor spring air vents out of the port on the engine side of the throttle butterfly so think this sounds right? The vacuum tubes and ports are clear.
Bill

 

[Bob N.Y.]

Is this the same setup that was used on the Fordson Major? Maybe someone on that forum could help you.

 

[Roy in UK]

Hi Bill,
Why not try The "Lesser Known Classics" forum? I often see questions about Nuffields and indeed Leylands asked (and more often than not answered!) on there.
Regards,
Roy.
Orphans

 

[DavidP, South Wales]

Hi, sorry, can't add much to what has been said. Not done much with Simms.

DavidP

 

[Roy in UK]

Or you could try a dedicated Nuffield forum.
Nuffield / Leyland Forum

 

[mattwillson]

i would guess that the rack setting is out of
adjustment due to the different diaphram, or a
return spring is misplaced. there s not much inside
those pumps, but they are fussy. i ll bring my
manual up from the shop and scan it if you like.

 

[MF Pain]

It would be great if you would scan that for me, I have not been able to find information on that pump
Thanks
Bill

 

[mattwillson]

here s the 1st bit. its just an over view. more to
follow shortly

 

[mattwillson]

Here s the 1st 20 pages, it s in english english so it s a read and re-read. detailed though.

 

[MF Pain]

Hi all,
Well I think I have found the problem - it looks as though the coupling on the injector pump drive slipped when the engine over revved. Apart from resetting the timing I have not as yet reassembled and tested. A pic of the timing cover removed to remind me how much more work I have done than was needed. Photo 1 (if I get them in the right order) shows the fresher paint on the coupling that alerted me to it when I finally saw it. Photo 2 shows the position of the pump timing when the crankshaft is at 28deg BTDC (correct position when marks on pump and drive should be aligned). Before resetting the pump timing I aligned the marks on the pump and the drive and checked the crankshaft position - it was about 10deg past TDC - no wonder it wasn't firing and only pouring out white smoke.
Thanks for all the help offered especially Matt - many thanks for your efforts in scanning the manual.
Bill

 

[Roy in UK]

Hi Bill,
That brought back a few memories! I worked on a Perkins P3 engine (fitted in a Fergie TE20) that was running very erratically. It had an injector pump coupling just like that one that was badly worn and not only that, the two bolts would not remain tight as the threads were shot. once this was replaced the engine ran far better.

 

[mattwillson]

glad you got her figured out, while your at it
bump the timing up a little bit further. it ll
start easier and won t smoke as much at idle

 

[MF Pain]

Hi Matt,
The pump timing is as advanced as the slotted coupling will allow just to get the marks lined up so cannot advance any further unless it is possible to move the coupling on the drive side.
Also with regard to the pages you have scanned I am having trouble reading the print - if your original scan is a higher quality is it possible to somehow get a better quality copy? I hope I don't sound ungrateful for the work you have done already.
Thanks
Bill

 

[mattwillson]

Hi Bill. When next i'm home, I'll see if the scanner will enlarge the pages with clarity. If you need to advance it a bit more, you'll have to clock the drive hub 1 or 2 teeth(splines) on the accesory drive. I was lucky with mine as it was already clocked advavanced and the coupler was almost fully retarded. I also gave the buffer screw a bit extra for revs. Mine will rev almost instantly, like the newer simms set up on our Leyland 270. I do get a fair bit of fuel knock, if I floor it though.
I should get a few pics of this in complete form, the exhaust is funky as I didn't feel the love of hacking a new hole in the hood.
BTW, if you want to install a block heater, get a 1500 watt for a cummins and tun it down to fit in the back of the head. You have to drill and tap a hole for a retaining bolt, when done it'll work good. 140 degree engine temp in less than hour.