The Fordson Tractor Pages Forum

Hi All

Can anyone tell me how much fuel should come through the manifold heater when you push the primer button, tractor has recently become difficult to start from cold and I'm not hearing the usual "whoosh" after pushing the primer button. I took the heater out of the manifold today and can see the coil heating when I push the heater button but not much fuel comes through when pushing the primer, does it rely on heat from the coil to allow fuel to spray onto the coil or is it just the pressure from the primer.
Had a look at agriline products but their heater doesn't look like the one in my manifold. Any info appreciated.

Bob.

You may have a blocked jet Bob, it should be a squirt onto the coil when you operate the primer. Later heater units only open when the heater is operated but not the original ones. Later build tractors had a small tap on the manifold because the engine could draw fuel in past the primer and flood the intake manifold.

The Agriline unit works well as it does away with the primer, there have been many cases of leaky and faulty after market primers and their system means you can use a normal (leaky after market) fuel tap instead.

OK, thanks Brian.

Is the jet simply like a carburettor jet with a small hole in a brass bush or is it a spring loaded ball valve arrangement, will be having a look later on today sometime.

Bob

Brian wrote:You may have a blocked jet Bob, it should be a squirt onto the coil when you operate the primer. Later heater units only open when the heater is operated but not the original ones. Later build tractors had a small tap on the manifold because the engine could draw fuel in past the primer and flood the intake manifold.

The Agriline unit works well as it does away with the primer, there have been many cases of leaky and faulty after market primers and their system means you can use a normal (leaky after market) fuel tap instead.

Glad to have found this, thanks.

My 1964 Superdexta has a manifold heater which has never been wired up in my ownership.

Thinking it might be nice to have it working I wired it up this morning with a test bulb in circuit. Now when I hold the button type switch down the bulb lights up nicely so something's going on.

If I hold the button type switch down for a count of twenty elephants the engine does start, but with no less reluctance than usual.

The manifold heater is a big fat fellow, to look at it's nothing much like the slimline item pictured in the Agriline Catalogue.

If there's a tap involved I have yet to find it.

Question One: Can the manifold heater draw current without actually heating up?

Question Two: If I remove the manifold heater for inspection and cleaning do I need to bleed the fuel system once I have put it back in the manifold?

TIA

Richard,
Is your test bulb in series with the heater? Or does it have a seperate ground? If it is in series, it shows that current is passing thru the heater.
Question One: Can the manifold heater draw current without actually heating up?
Yes it can, but is highly unlikely. If your heater is thermally operated, it's possible the element is heating up but the fuel valve isn't opening.
You can remove the heater from the manifold and ground the base.Then hit your button and see if it is heating up and fuel valve is opening.
[Question Two: If I remove the manifold heater for inspection and cleaning do I need to bleed the fuel system once I have put it back in the manifold?
No need to bleed your fuel system after servicing the heater
No fuel tap required if it is thermally activated
Bill

Thanks Bill

I'll do just that.

So, I did that and here are a few pics, the link is to my personal motorcycle blog, hope that's o.k.




I’m obliged to Pgh Bill of the Fordson Tractor Pages Forum for “talking” me through this and hope to repay his generosity a little by adding images to his words.


Full story here - http://thebridgeclubfive.blogspot.co.uk ... c-for.html

My new manifold heater from Forge Services arrived this morning, excellent.

Out of interest I tested it on the bench, the coil began to glow almost as soon as I hooked it up to a spare battery.

Then out into the yard to fit VPF3701 while the rain persisted down.

Result - much easier starting, lovely, I'm almost looking forward to our next frost.

Richard,

Does your tractor have the primer pump arrangement to supply the heater, I haven't yet got back to have a look at my heater, but the part you quote looks identical to the one on my tractor but it is a 1958 dexta with primer pump. If it turns out to be the same then I would buy a new heater like you did to save hassle with the old one.

Bob

bobfaecullen wrote:Richard,

Does your tractor have the primer pump arrangement to supply the heater, I haven't yet got back to have a look at my heater, but the part you quote looks identical to the one on my tractor but it is a 1958 dexta with primer pump. If it turns out to be the same then I would buy a new heater like you did to save hassle with the old one.

Bob

Sad to say Bob I'm so innocent of the workings of diesels that I don't really know the answer to your question.

The following may help - the part VPF3701 has an electrical feed controlled by a manual switch which I hold down for a count of "twenty elephants" before using the starter motor. What I know happens during the count of twenty is that the coil within VPF3701 glows orange, what I assume, or imagine, happens during this count (as a product of the heating up) is that a metal component within VPF3701 expands to allow diesel oil from the fuel feed to pass into the manifold via VPF3701's internals giving a nice spray of warm diesel.

The diesel feed to VPF3701 can be traced back to a smallish red metal cylinder which is fed by an "overflow" pipe from the injector nozzles. Also proceeding from this red cylinder is a fuel pipe which seems to be connected to a point high in the fuel tank, as if to feed surplus fuel back into the tank. So I think my manifold heater is fed its fuel by the general action of the fuel pump.

Best I can do, except to say two things

a) the tractor starts really willingly now, as if we were in mid-summer and I'd just started it again after lunch during haymaking, and

b) when I removed the manifold heater (having bent the tang for the electrical connection so it didn't foul anything) the part number was stamped into one of its flats which was very instructive.

Hope this helps.

Thanks for update Richard, your's is the later version with a small reservoir filled from the injector spill pipes and I think the heater allows the fuel to pass after the heater has been operated for a certain length of time. Older tractors were fitted with a push button type primer pump which is part of the fuel shut off tap under the fuel tank. These operate by holding the heater button for approx 40 seconds and then pushing the primer button to introduce fuel to the heater element, whereupon you hear a "whoosh" as the fuel ignites within the manifold, this is where my problem lies in that my "whoosh" has disappeared The heating element is working but the fuel is obviously not getting to where it needs to be - further investigation required but am busy installing a new bathroom at the moment

Bob

"Whoosh", that's a Lucas part I think.

Its a thermostart, dead common and used right up until the early 90's one industrial diesels

If you have the seperate fuel jet fitted just before the heater, There is a tiny spring in the nozzle which holds a ball to seal it . When you press the primer the pressure lifts the ball off the seat aagainst the spring and fule is then sprayed onto the heater.
If over time water may get into the spring/ball part and cause it to rust. Removing the nozzle and unscrewing the tip will reveal the ball and spring. Or you could get a fine needle and push back up in the nozzle to loosen the ball.
Worth a try IMHO.

Hi All,

Update on progress with manifold heater.

I now have my "whoosh" back - well almost. I ordered up a VPF3701 as suggested by NVNL because it looked similar to the heater fitted to my Dexta and connected it up before fitting it in the manifold, held the heater button for 20 seconds, saw the coil glowing red hot, pushed the primer button once and nearly set the tractor alight . You get a very big flame for not much of a squirt. Went to fit it in the manifold only to find the diameter of the threads is smaller than the old one, I have contacted the seller to see if a VPF3703 might be the size that I require - anyway good news in that I now have the answer to my problem.

The heater fitted to my tractor was one that needs the coil to be hot to open the valve in the heater before allowing fuel to pass, this was obviously my problem in that no fuel was passing through the heater valve. I took the old heater apart and the connexion to the actual heater coil had broken inside the device, had to break it to get it apart so non salvageable.

Bob