Simms pump on Nuffield

Hi all,
I have posted this on the MF site but it has been suggested that the same pump may be on a Fordson and someone here may be able to help.
I have a Nuffield DM4 with BMC engine and Simms injector pump with pneumatic (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

Did you take the pump off the tractor to do the
repair? If so, it is possible you got it back on
the tractor 180 degrees out, all the marks line up
correctly but you are on Number 4 cylinder rather
than Number 1.

The symptoms you describe are just what you would
get. I own a Nuffield and a Major and the diaphram
is the same.

I did not remove the injection pump, and as the marks are all correct under the timing cover I have also ruled out sheared keys (if that is possible)
Thanks
Bill

Hi Bill,
Try asking this question on the Peatland Export
Parts forum for Nuffield tractors. The chaps there
are excellent and very helpful.

http://leyland.conforums.com/
Untitled URL Link

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.
Bill