Uneven run, low revs, white smoke

This forum is about the Fordson Dexta, Super Dexta and Petrol Dexta.
chrism0dwk
Not Quite Blue Yet
Posts: 36
Joined: Thu Feb 28, 2013 7:27 am
Location: Near Palmerston North, New Zealand

Uneven run, low revs, white smoke

Post by chrism0dwk »

Hi All,

Dex, my 1963 Super Dexta is poorly! The other day when I fired her up, she suddenly stopped. Out of fuel, I thought, but apparently not. Having restarted her with a completely full tank, she ran well for a bit but then developed an unevenness in her revs and started producing quite a bit of white smoke. Then the revs dropped and the white smoke got a lot worse, so I took her back into the garage.

I've tried bleeding the fuel -- fuel seems to be flowing fast out of the bleed screws when I open them. This is without pumping the lift pump arm, presumably it's under pressure from the head of fuel in the full tank. I unscrewed the injector pipes at the injector end, and turned the engine over as suggested in the service manual. All three pipes delivered a bleb of fuel as I would expect. The only thing I can see is a tiny little bubbling coming from under the bolt flange on injector 2. Before I go out and spend lots on a new set of injectors, does this sound like the most likely issue, or should I be doing something to make sure the injector pump isn't kaput (I hope it's not for the sake of my paddocks!).

Cheers,

Chris


[edit 06/02/14] Problem solved: check that it's diesel in the tank and not petrol![/edit]
Last edited by chrism0dwk on Thu Feb 06, 2014 4:14 am, edited 1 time in total.

Bensdexta
True Blue
Posts: 2666
Joined: Mon Sep 15, 2008 12:59 pm
Location: N Wales

Re: Uneven run, low revs, white smoke

Post by Bensdexta »

Bensdexta - 1961 working for a living!

chrism0dwk
Not Quite Blue Yet
Posts: 36
Joined: Thu Feb 28, 2013 7:27 am
Location: Near Palmerston North, New Zealand

Re: Uneven run, low revs, white smoke

Post by chrism0dwk »

Thanks for that. Just looking at the Sparex catalogue for new injectors. Their offering (http://v2.nz.sparex.com/ItemDetails/Ite ... ility#Tabs) doesn't look like my injectors. What gives?

Cheers,

Chris

Bensdexta
True Blue
Posts: 2666
Joined: Mon Sep 15, 2008 12:59 pm
Location: N Wales

Re: Uneven run, low revs, white smoke

Post by Bensdexta »

Just take them to your local diesel shop, may just need cleaning. And fit new seals. :wink:
Bensdexta - 1961 working for a living!

PghBill
True Blue
Posts: 166
Joined: Wed Nov 23, 2011 12:24 pm
Location: Pittsburgh,PA.

Re: Uneven run, low revs, white smoke

Post by PghBill »

Also check that your primer is not leaking fuel into the manifold. Could create the same symptoms.

chrism0dwk
Not Quite Blue Yet
Posts: 36
Joined: Thu Feb 28, 2013 7:27 am
Location: Near Palmerston North, New Zealand

Re: Uneven run, low revs, white smoke

Post by chrism0dwk »

Thanks, all!

I phoned my local diesel shop today who suggested that I should be thorough about making sure my fuel system isn't blocked. I have a fuel pump repair kit, so I figured I might as well use it.

Does anyone know if there's an online manual for the later mechanical-governor type fuel pump that I have? Unless I've missed something, Stephan's manual only covers the older pneumatic type.

Cheers,

Chris

JC
Site Governance Team & Expert Team
Site Governance Team & Expert Team
Posts: 1092
Joined: Thu Apr 17, 2008 3:48 am
Location: Montague Calif. USA

Re: Uneven run, low revs, white smoke

Post by JC »

There really aren't any repairs, to the injector pump, that you can do yourself. The kit that you have is probably for the lift pump.
I would also check for water in the tank and the filter and make sure that the air cleaner is not blocked. Also check the screen on the valve in the fuel tank.

chrism0dwk
Not Quite Blue Yet
Posts: 36
Joined: Thu Feb 28, 2013 7:27 am
Location: Near Palmerston North, New Zealand

Re: Uneven run, low revs, white smoke

Post by chrism0dwk »

Hi guys,

An update on my fault finding process:

1) I took the air cleaner apart -- dirty, yes! In the garage (clean air), I started her up without the air cleaner attached. Problem not solved!

2) With the bonnet off, I could get a much clearer picture of the injector side of the cylinder head. With the engine idling, I loosened each injector pipe in turn, allowing the fuel to spill onto a rag, rather than enter the injector. Not much change in engine revs for any of the injectors, but possibly a little less white smoke. However, as well as the bubbling from just below the bolt flange on injector #2, I noticed that the combustion chamber gasket on cylinder #3 was bubbling where fuel had spilt on it.

I guess, then, it's a good opportunity to change the combustion chamber gaskets and see if this alleviates the problem partially. If it does, then I'll see to my injectors.

3) I'm beginning to worry about the cylinder head gasket. I'm used to things like pressurised coolant and heavy breathing from the rocker cover. I have neither of these things. Before I embark on compression testing, etc, does anyone have any pearls of wisdom for diagnosing head gasket faults in these tractors?

Cheers,

Chris

chrism0dwk
Not Quite Blue Yet
Posts: 36
Joined: Thu Feb 28, 2013 7:27 am
Location: Near Palmerston North, New Zealand

Re: Uneven run, low revs, white smoke

Post by chrism0dwk »

Hi all,

Just a quick update. I took my injectors out and had new nozzles fitted to each of them by a professional tractor mechanic. He verifies them as good. I refitted them and took my SD out of the shed today. Though the engine now sounds much crisper, the unevenness is still present, as is the white/blue smoke pouring out of the exhaust. I managed to do about 10 minutes mowing, before the revs dropped to idle (irrespective of the throttle setting) and I had to limp back into the shed, with the engine threatening to cut out at several points. I found that I could bring the revs back up and improve things a little by pumping the hand primer on the lift pump.

To recap, I have:

1) Checked the fuel line from the tank for blockages -- okay
2) replaced the lift pump diaphragm -- okay
3) cleaned out the fuel filter -- a little sediment, but very clean on the pump side.
4) checked that a jet of fuel is sent out of each injector line when the engine (and hence fuel pump) is cranked
5) renewed the injector nozzles
6) looked closely at the cylinder head gasket to see any leaks -- no oil in water, water in oil, bubbles in water, signs of leaking on the exterior of the block, etc.

I'm wondering what to look at next. Can anyone offer any advice on further diagnostics before I call in the pros? Short on cash currently, so this is a last resort...

Cheers,

Chris

fenhayman
True Blue
Posts: 114
Joined: Tue May 19, 2009 11:18 am
Location: United Kingdom
Contact:

Re: Uneven run, low revs, white smoke

Post by fenhayman »

Chris if the revs pick up when you pump the hand pump you must have a fuel shortage caused by a blockage.
Have you taken out/cleaned the outlet filter in the tank. Accessed by unscrewing the tap.
A lazy but effective check is to take off the pipe where it exits the tap and blow some air up it. I use a hand cycle pump with about 1/2 inch of rubber connector. The blasts of air will clear the filter and you should get a stronger flow of fuel. If you do you need to take out the tap, let the rubbish flow out of the tank and clear the filter. 2 man job, the second man has to put his finger over the tap hole in the tank until you have cleaned the filter!
I think that if you had a pump or injector issue the problem would be consistent and not alter as your does.
Best of luck.

tom lad
True Blue
Posts: 443
Joined: Tue Oct 05, 2010 2:53 pm
Location: Preston, Lancashire. UK.

Re: Uneven run, low revs, white smoke

Post by tom lad »

hi
my instinct is fuel starvation also , mine had the same prob .

the solution for me was to remove the tank to clean it properly , and check that filter on the tap as advised .had to do it twice.
with respect blowing on the line will confirm the problem but not solve it . my filter was a metal tube with holes drilled in , stuffed with wire wool ? not a plastic tube + gauze ? mine would run fine then revs fade away and stall ..... wait a bit re- bleed then run .. fade away as it ran out of fuel .. no fun.

all fine now tho , my tap wouldn't un screw with tank still fitted , only get half a turn .

all the best
Some mornings I wake up grumpy, but most mornings I let her sleep in.

PghBill
True Blue
Posts: 166
Joined: Wed Nov 23, 2011 12:24 pm
Location: Pittsburgh,PA.

Re: Uneven run, low revs, white smoke

Post by PghBill »

chrism0dwk wrote: I found that I could bring the revs back up and improve things a little by pumping the hand primer on the lift pump.
If revs pick up when working the handle on the lift pump. And you've relaced the diaphram. Seems to me that not enough fuel is getting to the lift pump. Or not passing thru the fuel filter to the injector pump.
I'm agreeing with Tom.
The filter in the tank on the tap is very fine.
Tractor sits and dirt falls off the filter. Tractor starts moving dirt gets sucked back onto the filter.
Why not try putting some clean fuel in a clean container. Remove the fuel line from the primer and run a hose from the container and slip it over the end of the fuel line. Might need a hose clamp. Make sure the container is higher than the injector pump. Prime the lift pump and see if she'll run. Should give you an idea as to if the tap filter is dirty.

chrism0dwk
Not Quite Blue Yet
Posts: 36
Joined: Thu Feb 28, 2013 7:27 am
Location: Near Palmerston North, New Zealand

Re: Uneven run, low revs, white smoke

Post by chrism0dwk »

Thanks for all the info! I attacked the fuel tank, and took out the tap. Here is the likely source of my problem, I think! Time to order a new gauze, and have a look at the tap diaphragm (there was a small leak before).

Image

Chris

PghBill
True Blue
Posts: 166
Joined: Wed Nov 23, 2011 12:24 pm
Location: Pittsburgh,PA.

Re: Uneven run, low revs, white smoke

Post by PghBill »

Hopefully that will solve your problem. Keep us posted.

Bensdexta
True Blue
Posts: 2666
Joined: Mon Sep 15, 2008 12:59 pm
Location: N Wales

Re: Uneven run, low revs, white smoke

Post by Bensdexta »

chrism0dwk wrote:Thanks for all the info! I attacked the fuel tank, and took out the tap. Here is the likely source of my problem, I think! Time to order a new gauze, and have a look at the tap diaphragm (there was a small leak before).
Those taps are hard to repair as it's a pressed steel cover.

An alternative quick fix to stop the primer leaking into the inlet manifold would be to fit one of the small shut-off taps that later Dextas/Supers were fitted with as standard. Turn tap on to start, then turn off. A bit of a fiddle when starting, but hopefully when the weather is warm, you won't need the primer at all. My Dexta starts with no heat or primer, so long as it's above freezing.
Bensdexta - 1961 working for a living!

Mark
True Blue
Posts: 530
Joined: Thu Apr 17, 2008 2:13 am
Location: Eastern Kentucky

Re: Uneven run, low revs, white smoke

Post by Mark »

My Dexta did the same exact thing as yours, and it was the fuel tap. You said you were going to get a new gauze filter? Where can you get these at. I've looked for many years without finding one. You can go onto Stephen's tractor site that he let us put on this forum and see how he made his.
See ya
Mark
See ya
Mark

When all else fails, get a bigger hammer

PghBill
True Blue
Posts: 166
Joined: Wed Nov 23, 2011 12:24 pm
Location: Pittsburgh,PA.

Re: Uneven run, low revs, white smoke

Post by PghBill »


chrism0dwk
Not Quite Blue Yet
Posts: 36
Joined: Thu Feb 28, 2013 7:27 am
Location: Near Palmerston North, New Zealand

Re: Uneven run, low revs, white smoke

Post by chrism0dwk »

Hi Mark,

Sparex do replacement gauze filters, P/N S.65287

Chris

Mark
True Blue
Posts: 530
Joined: Thu Apr 17, 2008 2:13 am
Location: Eastern Kentucky

Re: Uneven run, low revs, white smoke

Post by Mark »

Thanks guys I'll order me one. :clap:
See ya
Mark
See ya
Mark

When all else fails, get a bigger hammer

chrism0dwk
Not Quite Blue Yet
Posts: 36
Joined: Thu Feb 28, 2013 7:27 am
Location: Near Palmerston North, New Zealand

Re: Uneven run, low revs, white smoke

Post by chrism0dwk »

A quick update on my quest to fix my low revs and white smoke problem. Sorry I've taken so long to re-post: I took the fuel tank off my SD to remove the fuel tap and replace the gauze (see previous picture). I took the opportunity to strip and repaint it while I was at it, replacing dash lights and giving her a new steering wheel. Very pleased with the results aesthetically.

However, having re-filled her with fuel and bled the fuel system I took her out into the paddock to do a bit of mowing. She was reluctant at first -- a refusal to increase revs when I opened the throttle, and quite a bit of the white smoke. Suddenly, however, the revs came up and she ran really well for about 10 minutes. After this, the revs became uneven again and she lost power to the point that I had to stop mowing and limp back into the shed. All the while the revs were eratic -- up and down randomly. I took the fuel filter and lift pump apart and made sure there were no blockages in either unit. In fact, the fuel system appeared extremely clean (no crud in the fuel filter either).

I'm suspecting the pipe from the fuel tank to the fuel lift pump -- the right angled bends seem like prime candidates for constrictions and crud plugs, even though I can blow air through it and squirt degreaser through, I'm not convinced its flowing freely. Also, I'm not convinced that the compression fitting at the pump end is air-tight. The compression nut is shorter than the nut on the pump-to-filter pipe, and the thread disappears all the way into the pump housing, only tightening when the hex head comes into contact with the pump casing. Could this be allowing air into the system I wonder?

Anyway, unless anyone has any further suggestions, I'll renew said pipe (if I can source one in NZ!) and see how I go.

Cheers,

Chris

fenhayman
True Blue
Posts: 114
Joined: Tue May 19, 2009 11:18 am
Location: United Kingdom
Contact:

Re: Uneven run, low revs, white smoke

Post by fenhayman »

Chris I think your problem is the pipe.
Why not see if a car/motor engineer can make one for you. They might have a kit to flare open the pipe ends and a selection of fittings. If you are making up a new pipe get the angles right. If you try and bend it yourself you will probable kink it and leave it restricted. Best of luck.

Mark
True Blue
Posts: 530
Joined: Thu Apr 17, 2008 2:13 am
Location: Eastern Kentucky

Re: Uneven run, low revs, white smoke

Post by Mark »

Chris, another thing I did whilst my Dexta was doing this same thing. It's really the reason I found out what was wrong.
While it's running and doing the low rpm thingy reach down and turn your fuel tap off and on several times to see if she opens up. The reason to try this is, on mine it made a difference. You might and I say might still have some crud in the fuel tap. It worked for me, maybe yours will do the same thing. I had to take my fuel tap completely apart and my problem went away.
I hope this helps in some way.
Mark
See ya
Mark

When all else fails, get a bigger hammer

islander
Not Quite Blue Yet
Posts: 35
Joined: Fri Jul 19, 2013 1:22 am
Location: Magdalen Islands, QC CANADA

Re: Uneven run, low revs, white smoke

Post by islander »

Take a compression test...could be head gasket.

chrism0dwk
Not Quite Blue Yet
Posts: 36
Joined: Thu Feb 28, 2013 7:27 am
Location: Near Palmerston North, New Zealand

Re: Uneven run, low revs, white smoke

Post by chrism0dwk »

islander wrote:Take a compression test...could be head gasket.
If it was the head gasket, I'd expect the problem to not be so intermittent. Wouldn't you agree?

Chris

chrism0dwk
Not Quite Blue Yet
Posts: 36
Joined: Thu Feb 28, 2013 7:27 am
Location: Near Palmerston North, New Zealand

Re: Uneven run, low revs, white smoke

Post by chrism0dwk »

Hi All,

Well, I'm now at my wits end. I've ruled out a blocked tap (by by-passing it), blown compressed air through the tank-to-lift-pump pipe which seems free, and cleaned out the lift pump and fuel filter heads and associated pipes. Still the same old white smoke, loss of revs, and general uneven running. I guess the only things left are:

1) a worn lift pump cam/follower
2) a defective fuel pump
3) the head gasket.

As I don't have things like a compression tester, I think it's probably time to call in the pros...

Cheers all and thanks for your suggestions. Will keep you posted!

Chris

Post Reply