The Fordson Tractor Pages Forum

Hello Rob, Yes the timing for Dextas i easy, Do as Bensdexta say,s remove the litle cover in front of the engine, (where the fuelpump is to adj). when you turn the engine untill the smallmarks appear (on booth wheels) in right side for the "opening" you can check the timingmark on the flywheel too. This two places of "marks" tell,s you that the timing is right (and you then have found the right turn...consideres the 18 turn,s of engine too) then you can safely take out your fuelpump, becouse you have the litle "smallmark" on wheel at the pump too, who will fit the right timingmark for the rest timingwheel,s insides the big cover in front of engine.

So I want you to try to start your engine without the rubberhose between your airfilter and intak on the right side of engine. This happens with a farmer from my region, and he tould me that his Dexta was running very bad...only up to 1200 u rm. The first I did was to remove this hose, and his tractor run up to full range with once. What was happen was that he never had cleaned the upper part of his airfilter, but only the lowerpart with oil in.

So at the end you should also check your valves for grinding-job?? it is often some problems here in the enginehead too, aspecially on the exosvalves.

Blue32

Blue 32
I think I'm happy with the timing and marks now. I have removed and cleaned the air cleaner and it has new oil. A great deal of grain and grass came out of the metal gauze when washed in petrol. It also draws well through the primary cleaner - the cap - so I don't think we lack air.

But we didn't grind in the valves - looked and tapped each. The expectation was that the known poor compression was the problem. Proved not to be the answer but there is no pressure in the injector pump - it will not open the injectors to spray properly. We can lift the head again and regrind pretty easily but time was against us on the first strip down. It may be done whilst the pump's away - but then we'll not know what the problem was.
Rob

For information, I have just found my notes regarding the fuel injection equipment on the Dexta and Super Dextas, details are as follows.

Dexta Mechanically governed pump type P4588, 6mm dia. Plunger and 7 mm stroke, max'm RPM 2,200. Spill timing 26 degrees before TDC.
Injector nozzles have 2 x 0.35 holes.


Super Dexta pump type P4696, 6.5 mm dia. Plunger and 7mm stroke, max'm RPM 2,450.
Spill timing 20 degrees before TDC.
Injector nozzles have 2 x 0.32 holes.

In the catalogue which I have to hand the same nozzle is specified for both the Dexta and Super Dexta.

Gerald

Gerald
This tractor has Super nosecone 4588 mechanical pump. That should make it an F3.152 enigine. Do I assume that the timing is 20BTDC because it's a Super or 26BTDC because it's a 4588 pump?
Rob

If the engine number starts with 14**** it is a Dexta, if it starts with 16***** it is a Super Dexta.

Once you have established which engine you have, set the timing accordingly.

Gerald

It's a 16 engine which confirms it as a Super Dexta so with timing based on engine bore rather than pump type it should be 20 deg BTDC. I think.
Rob

Well now, I'd planned to take the pump off early this week and left myself what I though was enought time. The manual says remove the 5 nuts and spring washers. I've seen on this board comments about difficult access. How about impossible access? It looks like the pump is bolted to an adapting plate which in turn is bolted to the timing cover. However i can't see how the pump can be removed without the adaptor plate bolts being removed anyway
Is the manual wrong or referring to a different pump? How did anyone on this board access the two 7/16 and two 1/2 inch heads at the bottom and back, close in to the block? The speed control lever is in the way for two and the access at the bottom for the other two is too limited.
What am I missing? Even my thin-armed son couldn't succeed!
Rob

Rob,
Suggest you remove the fuel filter to improove access and allow pump to be withdrawn backwards.
Getting at the bolts is a bit fiddley but not difficult. You will need a half moon spanner (got mine off ebay for a few ££) to get at the bolts behind the pump and also an extension bar.
See also
http://www.fordsontractorpages.nl/phpbb ... pump#p3703
All the best,

Wait until you refit the pump and have to fit the nuts and washers to the studs behind the pump.

I use a piece of wire or a welding rod to place the washers over the studs, I then use a long extension on a 1/4" drive socket to screw the nuts on. You will find that a universal drive used in conjunction with a socket is useful.

Gerald

Thanks Gerald - I'll look forward to that.
Why do I leave it until Friday to find a 3/8 drive socket set with universal coupling and 1/4" extension bar for the correct length?
I'm sure, Ben, Ford could have found a more awkward position for bolts but it would have been difficult.
Rob

I removed the oil filter to inprove access to those back bolts and to ease the removal.
Good Luck
Mervyn Spencer

Tubal Cain wrote earlier:
Dexta Mechanically governed pump type P4588, 6mm dia. Plunger and 7 mm stroke, max'm RPM 2,200. Spill timing 26 degrees before TDC.
Injector nozzles have 2 x 0.35 holes.

Super Dexta pump type P4696, 6.5 mm dia. Plunger and 7mm stroke, max'm RPM 2,450.
Spill timing 20 degrees before TDC.
Injector nozzles have 2 x 0.32 holes.

I thought the 4696 pump was for the New Power Super Dexta only. I'm trying to confirm the timing on a SD with 4588 pump. I'm not sure from this what the timing should be as the bore is 152 cu in but the pump remains the same as a Dexta.

Rob

Does the injector pump need oil in, on a normal Dexta? I have had mine rebuilt, and it came with a label on it 'No Oil'....

The 4696 does but i don't know about the 4588. I think it does and I think I had to top up this one - hence the probable reason for wear. The pneumatically governed ones I believe use diesel in the system but I wouldn't swear to it.

The pneumatic ones are also oil filled.

Hi,
I had always understood the pneumatic governors to be lubricated by diesel fuel but I have seen 2 over here that had a little oil pot drilled into and added to the side of the pump to put oil into.
It was added by 2 different dealers and looked to be more of a dust collector than really helpful!?
Don't know where the instructions or gossip to add it came from.

Les

Certainly the service manual states to fill them with oil (there are also, fill, drain and level plugs).

Quite how long it takes before the oil is diluted with diesel is anybodies guess (and I suspect down to the state of the pump).!

pnumatic pumps dont need oiling

But I'm still none the wiser on whether the timing is per pump or per bore!

Hi,

Timing is per pump.

Mechanical pump 4588 (for Dexta and Super Dexta) and 4696 (for New Perfomance S. Dexta) are all 20 degrees.
Earlier pneumatic pump is at 26 degrees.

(Got this from both ITT and Fordson workshop manuals.)

Les

An update to the saga:
I have now removed the 4588 injector pump. Even with a 3/8 drive u/j it was difficult. Now I know why - the speed regulator lever, attached to the pump between it and the block was loose on its splines and had slipped in the past. I think too it was the wrong way around so access past it was very fiddly.
Anyway, I left it outside Peter Strong's workshop in Reading, in a bag, in the dark. He found it, looked at it, took it apart and phoned me "was it running at all?"
Well it had finally stopped in August when it ran out of fuel and wouldn't restart even after bleeding.
I have some pictures of the result of water in the pump - presumably happened sometime in the last 5 years - I topped up but didn't drain!
I'll attempt to load them after I've read up on how.
The pump will be rebuilt and I have high hopes of an instant fire up.
Rob

http://www.flickr.com/photos/68578276@N04/6236786581/

Ok why can't I post the image directly? I've put the picture code between but it doesn't show

roromac wrote:Ok why can't I post the image directly? I've put the picture code between but it doesn't show

You have to ref the individual .jpg for each pic, not just the stream.

Aha. TKU Ben, this should work
And it does

The first photo shows the carriage of the mechanical governor with rusty wheels and the cam shaft from the pump which although rusty, is OK on the bearing surface and "is fine for light work".
The 2nd pic is the collection of 3 cam followers and three of each individual fuel delivering pistons. Stupidly I haven't photographed the scored surfaced that caused the trouble at the top of each of the slim pistons.

I now have back the rebuilt pump from Peter Strong. And I have all the old bits. I will photograph and post in due course.