2.5l cold start injection timing advance mechanism retrofit

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weelsey
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2.5l cold start injection timing advance mechanism retrofit

Postby weelsey » Sun Feb 18, 2018 11:40 am

Hello everyone, I'm hoping to accomplish a modification to a 2.5l injection pump that will allow for easier cold weather starting. The idea is to have a cable leading to the cab to activate the diesel equivalent of the gas engine choke.

Adding a mechanism to the injector pump that advances the timing of fuel injection ~5 degrees, thereby allowing more time for fuel to burn, involves one of two common methods (that I know of);

1) Levered cam acting on the roller ring directly,
2) Levered screw acting on the timing piston to advance the roller.

Anyone done a retrofit using the second method? Perhaps there is a l300/l400 4d56 pump that includes such a thing already (in which case I'd love the pump number). So far in my search, tho, it looks like there was no advance mechanism on the Astron diesels using the timing pistion.

My preference would be to use the second method as is done on older mkII VW diesels because of its mechanical simplicity and apparent robustness. The 4m40 units came equipped with pumps using the first method as did the 4d55 and many other pumps including my old Mazda diesel, and I have a suspicion that it will be challenging to achieve the proper spring pressures on the timing piston using the VW equipment. Perhaps not. May be this system is prone to leaking, and I'm not sure how hard it will be to find the parts that will alow for the retrofit like the piston and screw/timer caps but may be its as easy as swapping parts from a VW bosch pump, which someone here suggests is being done.

The first method involves machining the existing mount cut-out in the pump body to allow the ball on the cam to act on the roller (or just getting an American 4d55 pump body and swapping internals, if that's even necessary). This method shouldn't interfere with timing, but I hear of these breaking and doing damage to the pump internals. May be my fears are unfounded.

Does anyone have some feedback/thoughts for me on the advantages/disadvantages of one or another method? I'd be pleased to be able to glean from others experiences and I realize this is pretty technical so if there is a forum I might go to for this kind of discussion I'd love to hear about that, too.

Cheers, Vern

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Growlerbearnz
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2.5l cold start injection timing advance mechanism retrofit

Postby Growlerbearnz » Sun Feb 18, 2018 3:20 pm

Righto. Download the Bosch VE fuel pump manual from here: https://drive.google.com/open?id=1N-0nAEGDdZJ2l0CVEL09aQjovFBGhDJV

Pages 41-43 cover the two kinds of cold-start devices. Your option 1 is what Bosch call "mechanical cold-start" and option 2 is "hydraulic".

Since your pump isn't drilled for mechanical, I'd go for option 2. It would be a bolt-on mod, and easily reversed if needed.

VW and Cummins (and some Ford/Mazda) injector pumps commonly have the electrically heated hydraulic cold start devices. You could probably go to a wrecking yard and find one, then bolt it to your pump, and see what happens.
DSCF2346_zps04ea4d0c.jpg
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The Isuzu cold-start device does the same job, but I think it does it every time the engine is started regardless of how warm the engine is. I don't like that idea.
Nothing says "poor workmanship" more than wrinkles in the duct tape.

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weelsey
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2.5l cold start injection timing advance mechanism retrofit

Postby weelsey » Tue Feb 20, 2018 12:00 pm

Hiya.
Growlerbearnz wrote:Download the Bosch VE fuel pump manual

Done. Thank-you.
in the manual, Bosch includes my option 1 and two in the "mechanical cold-start". number two is included parenthetically.
I'd forgotten about the third, hydraulic, option. This is what the isuzu, cummins, Volvo, and many other automated ve pump automated cold-start mechanisms use. It advances the timing by temporarily increasing pump body pressures to hydraulically advance the timing piston that way it would under normal acceleration.
I'm not interested in that clap-trap!
A disadvantage or two: It will not be immediate that is it requires the engine to crank and build up pressure before it does the advancing which is why the curve of the advance vs temperature graph shows the arc starting at 0 (how long does that take?). Also, the pressure regulator valve then becomes complicated. and so does the temperature automated thing a ma doodle wax solenoid.

I learned from the manual that the roller ring in the cam-type has a spot machined in it for the cam tab. More reason to go the other mechanical way, perhaps, if I also need a new roller ring.

A Isuzu pup solution to leaking was to get rid of the hydraulic advance mechanism and put in the VW/bosch screw sort.
Frank's Finished Pump for Printing w cap.jpg
http://www.isuzupup.com/viewtopic.php?t=7773
Frank's Finished Pump for Printing w cap.jpg (105.75 KiB) Viewed 791 times
This option should not require drilling the pump body or replacing the roller ring.
Growlerbearnz wrote:bolt-on mod, and easily reversed if needed.

My number two, pictured, won't be so easily reversed, since it requires replacing internals. I can't find a zexel 20mm pump that has this type. I pick up a VW mkII bosch pump this week and will see what I can make of it and will share what I find.

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weelsey
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2.5l cold start injection timing advance mechanism retrofit

Postby weelsey » Tue Mar 06, 2018 6:44 pm

Well, didn't the source pump I acquired come devoid of the advance lever/timer cover I need to do this! At least I got the timing piston and cable mounting plated. I'm hoping to share the difference in my cold starts before/after, that is, before the cold weather lifts entirely. We'll start to see more Delica's posted for sale once the temps climb up, won't we :)
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weelsey
Posts: 64
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2.5l cold start injection timing advance mechanism retrofit

Postby weelsey » Mon Mar 12, 2018 10:34 am

Looks like Pump MD307497 is shown here to include the cold start advance mechanism that acts on the roller ring using coolant to control a wax motor. So it looks like this pump came on the Jasper and or Chamonix editions.
Another option would be to acquire one of these pumps.
It would be unlucky to have this happen: https://www.youtube.com/watch?v=weQt4pdf14o

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Growlerbearnz
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2.5l cold start injection timing advance mechanism retrofit

Postby Growlerbearnz » Mon Mar 12, 2018 2:27 pm

Ah, the mysterious "Cold... sensor... thing... IdunnoWhatItIs". Yes, you need one of those. Without the snapped off bit.

Interesting that it's from a 4M40. More options! Though it would be neat if the Chamonix had the cold start advance, since they're a bit more common.
Nothing says "poor workmanship" more than wrinkles in the duct tape.

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weelsey
Posts: 64
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Vehicle: '90 2.5l high roof exceed
Location: edmonton

2.5l cold start injection timing advance mechanism retrofit

Postby weelsey » Tue Mar 13, 2018 4:12 pm

Growlerbearnz wrote:Ah, the mysterious "Cold... sensor... thing... IdunnoWhatItIs". Yes, you need one of those. Without the snapped off bit.

Interesting that it's from a 4M40. More options! Though it would be neat if the Chamonix had the cold start advance, since they're a bit more common.


Hehe. Gotta wonder if the guy got it back together on his Paj.

I learned about the l300 pump w/CSD on PartSouq. Then looked up the pump diagram on the dieselinject page for the diagram.

ChuckBlack who is in Edmonton ab Canader also says his Jasper has one. Don't know about all of them or any of the Chamonix from experience. PartSouq said so. Apparently the pump is a higher-pressure pump at 150kg/cm2

I bet you could take the neccissary internals from the 4m40 (pre-electronic) pump or even the pump body and use it on the 4d56. Guy at the pump shop said I could take roller ring out of a 17mm pump and use it in a 20mm, even.


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