Dexta Engine/Fuel help!

[Dexta Guy]

Hi. This is my first post but I have been reading the old blogs a lot over the last couple of months and found them very useful.

A month ago i bought a 1960 Dexta which has spent most of its life on a golf course and caravan site. It started with a bump and I had a drive around the village on it and a deal was done. It was delivered and put into my garage where it is still sat. The first job was to rewire it and sort the starting system out as well as the oil and filter change. That done, a problem has developed; Ive read on here that dextas pulse or hunt but mine now revs up and down by about 500-1500 revs and i wondered if anyone could sugest a reason for this before I throw any more money at it. I suspect air in the fuel and have checked all the unions etc and all look good. My next thought would be lift pump? And I've bled it a hundred times.

Another complication is that the fuel line between the lift pump and filter has a t-joint in it and a fuel line goes right over the top of the engine and into the heater plug. Is this standard? I cant find any reference to it and it doesn't make any sense as surley its just pumping fuel in all the time. And could it be affecting the rev problem?

Also there is a little back pressure when it warms up and when i put my finger over the end of the breather pipe it seems to calm the revs down and it doesnt hunt.

I'm sure someone will know the reason for this and help me get it running right. Then I've just got everything else to sort out!

Cheers!
Guy

[JC]

Welcome to the forum, Guy.
The first thing that I would do is make sure that the filter on the governor housing isn't plugged.

[john.n]

Is there a valve on the inlet manifold? if there is, close it after starting. Other things to check are the vacume pipe connections, and the diaphram, may have a hole in it. Simple to check, remove the pipe out the back of the pump, and remove the 4 small bolts that hold the round part of the pump on. There is a large spring in there, behind that the diaphram.

hope this helps
Regards,
John

[GERRY]

Hi , the pipe which is tee off the between the pump and the filter is probley inthe wrong place
as this if memory serves me right is under pressure , ihad done the same afew years back with adexta
as it was hard to start, it worked for awhile but was going through alot of heater plugs, brian put me right on this. and explined that the best place to tee off was the injector leak off to fuel tank pipe, the other post have told you how to test the difram as this probley the cause of the haunting up and down. it can also be caused by a hole in the pipe between the injector pump and air inlet manifold, good luck Gerry

[Dexta Guy]

Thanks for the advice lads, I'm back at uni for the week so wont get chance to investigate until the weekend but i'll know where to start looking now. Are the diaphrams the same as the ones in a tef fergie? As ive got a spare pump with a good one in which i could use. And with regards to the heater plug fuel feed, if i moved it to run from the leak off pipe then would i need to put a valve on it? (it doesnt have a valve on it now by the way) And what sort of pipe do i need to use? The injector leak off pipe looks like it'll collapse when i try to cut it so will probably end up replacing it with some new.

[GERRY]

You could put a valve on the pipe to heater plug just in case the heater plug fails
but if heater plug is working as it should in may not be needed, when you are connecting up the pipe
put acouple of coils on it to act as a resvoir before it goes into heater plug. the other way to go
would be to get the market type set up with the pump under tank with the orignal after market heater plug and pipes to suit
although this can be expensive , good luck gerry

[Dexta Guy]

She's running!

I went through the fuel system, from tank to injection pump, checking all joints. I put a new diaphram in the lift pump as it looked a bit suspect and i had it apart to sort the manual lift lever out. Then i took the cover of the govener diaphram which revealed a rusty mess. I was going to order a new one but thought i'd check it as it says in the manual, by putting your finger over the pipe and pulling the stop cable, and there was pressure there so I left it in. I took the inlet manifold off next and cleaned it out and checked the heater plug, put a new gasket on and bolted it back on. Bled it and with a few turns she fired up! The rain stopped so i took her for a spin, Then everyone wanted a go! (they werent so keen to help me with the diesel problem!) I'll put a picture off her on to prove it if someone could tell me how.

So thank you chaps for your help and advice. Very useful but there were a few other things i was wondering.....

I've got a diesel te20 which has got a worn engine but sits at top revs all day and will climb most steep roads with no loss of speed at all in top gear. I cant say the same for the dexta, It slow down on the slightest gradient and even need to change down a peg on a steep bit. As i considered the dexta engine to be in better condition i was surprised at this. Is it normal? I havent driven another one so i dont know.

And a slightly simpler question... Am i right in thinking that the heater plug only lets fuel through when its hot?

[russelm]

It sounds like you dont have a standard Dexta heater setup and that you might have a Thermostart

[Dexta Guy]

Ah yes you're right Russel. I've just been reading an old post and its all become clear. The original attomiser inlet has been retapped to take the thermostart and the heater plug hole has what looks like a sump plug in it. Is the original heater plug the same as the one in a diesel fergie? I'd like to try and get it back to original but want it to work for the time being.

[john.n]

i would suspect the diaphram in your dexta, mine was showing similar symptoms (lack of power) few months ago then the diaphram gave up and ripped. runs much smoother now after replacement, and pulls up hills well.

Regards,
John

[Dexta Guy]

Cheers John. Do you mean the diaphram in the lift pump or governer diaphram?

[john.n]

governer diaphram.

[Dexta Guy]

Cheers. The more expensive one! Typical!

[john.n]

think i got one for £26 from old 20. personally i dont think i would ever risk a 50 year old govener diaphram again. Fortuantely i had hooked up the stop cable a few days before.

Regards,
John

[russelm]

Ah yes you're right Russel. I've just been reading an old post and its all become clear. The original attomiser inlet has been retapped to take the thermostart and the heater plug hole has what looks like a sump plug in it. Is the original heater plug the same as the one in a diesel fergie? I'd like to try and get it back to original but want it to work for the time being.

Pretty sure its the same as the P3 engine (I have a new one in the garage which fits which is a P3 one).

I might fit a thermostart though as they do work very well!

[Dexta Guy]

Yeah good point John, It was tricky enough to drive when the revs were going up and down. I wouldn't fancy being on it when it gave up!

The heater plug from my standard diesel fergie fits too so for the time being I was going to install it as well as the thermostart, until i sort an atomiser out. Anyone got any ideas on this? I figure every little helps with starting from cold.

[russelm]

The atromiser is nothing more than drilled jet type insert which is fed from a branch on the fuel tap on the base of the tank. The tap has a bulb on it that you press which in turn squirts fuel through the atomiser which ignites on the heater element.

The issues are that its a many hands job to start the thing as a result and the bulbs on the taps fail.

Hence a thermostart is ideal as it controls the supply of fuel automaticaly.

[Jerry Coles]

Many Dexta owners may be unaware that at the junction of the fuel pipe with the atomiser there is a tiny spring loaded valve which the Fuel Tap pump pressure has to overcome before fuel can be squirted into the manifold. It's purpose is to prevent fuel leaking into the manifold when the engine is stopped or not being sucked in when running.
As this is a tiny steel spring and ball they can rust/clog/seize with the passage of time/water etc so it might be worth bearing in mind when trying to sort out any cold start problems.
An alternative method I reported on under the topic 'Cold Starting a Dexta - A novel solution!'
And the picture is here:
http://i307.photobucket.com/albums/nn28 ... CF0871.jpg
Regards

Jerry
Bath
UK

[Dexta Guy]

Hi, just a quick update on my Dexta and to say a massive thanks for all the advise I've had.

As soon as my student grant came in I bought a new govener diaphram and fitted it and she goes like a rocket up hill and down dale so very happy with that and I never would have suspected it.

I haven't changed the cold start system yet but have put the original glow plug in next to the thermostart and wired it up. Seems to work as the tractor now starts with out easy start.

So after a 40 mile road trip the other day I thought I'd better check the back end oil level and it looks like the seal has gone between the box and back axle as the gearbox is nearly full and I could see nearly all of the diff.

Has anyone had experience of changing these seals? I assume it needs splitting somewhere. For the time being I'll just keep draining the box and put it back the right place.

And the tractor has got 1 PUH lift arm on it with the hole in and swinging bracket. I bought a non PUH one off ebay to replace it as it looked a bit odd and rattles like hell. But I cant get the old one off. It looks like someone has not put it on right as there is a 7mm gap between it and the hyd top and the end plate has become mishapen when they've tightened the bolt up. Anyone got any top tips for getting it off?

[kiwiland dexta]

As soon as my student grant came in I bought a new govener diaphram

Sorry, Guy, not an answer to your question but I couldn't help but congratulate you on your use of money...who needs textbooks anyway! You'll learn a sight more from workin on the old girl!
Good on yer mate!
Derek.