Onan L 423D-M Timing

[mykim]

Happy New Year to all,

Had to have the injection pump on my Onan L-423D rebuilt. Very easy to reinstall, EXCEPT, my book doesn't tell me if #1 cylinder is on the flywheel side or in front of the motor.
I know one of you guys knows the answer.
Thanks in advance.
Gary

[Captain Ralph]

If you put it back in, with the gear in the same position, and your marks line up (that you made before you removed it), you will be near spot on. Repairs to the pump usually do not change it's timing characteristics.

Next, there are marks on the gears (like cam gears) you can align to them, then study the paint on the pump to case or under the mounting nuts.

Usually, later cranks had the marks on both ends (flywheel and balancer/pulley).

You can find #1 ignition TDC by watching the #1 valve rockers and looking for the TDC mark on the balancer/pulley.

[mykim]

Unfortunately on my unit, there are no marks on the gears as is normally found on every engine I've ever worked on.
The pump itself has a pair of timing marks accessible thru a small cover plate. So thats very easy to set. After I took it apart I was doing other work on it and rotated the crank without thinking about the settings I'd marked. So that was lost.
Book says bring #1 up to TDC, Align marks on the pump and reinstall the gear.
Book does not say if the aft cylinder at the flywheel end is #1 or if it is on front.

Thats my delima, which is #1?

[Captain Ralph]

Unfortunately on my unit, there are no marks on the gears as is normally found on every engine I've ever worked on.
The pump itself has a pair of timing marks accessible thru a small cover plate. So thats very easy to set. After I took it apart I was doing other work on it and rotated the crank without thinking about the settings I'd marked. So that was lost.
Book says bring #1 up to TDC, Align marks on the pump and reinstall the gear.
Book does not say if the aft cylinder at the flywheel end is #1 or if it is on front.

Thats my delima, which is #1?

Oh, I understand that question.
Usually, on small diesels, #1 is on the fly wheel end.
However, Cummins/OhNo has used so many engines, with out hands on, I can not say.
What is the gen-set model and maybe I can find some more info that way..
Luv all lots bot not going to purchase a manual on that engine today.
You will have to look at the valve rockers to determine TDC of that cylinder and see if any marks line up.

[mykim]

It's an L423D-M, Onan.

Thanks for your help Ralph

[Captain Ralph]

Oh, A Cummins MDL4. Standyne injector pump. Usually the rotatory pump. Think I have a manual on that OhNo 20 in my archives.
Be back in a few. Have to plug in & boot up that old XP monster.
I've been replacing (and trashing) many these last few years.

[Captain Ralph]

As I'm scratching my brain, was there a gear cover in front of the engine? I think thru here is where you can see the marks on the gears.

[Captain Ralph]

Seems ole XP/Dell server is down for the count. Out in the scrap tomorrow morning. I found a folder in another box that did not have more to offer.

If I remember, a square-ish plate is on the front you can remove and further look for gear timing marks. Past that, it's up to the tech that took it apart..

[mykim]

Ralph, sorry for my delay.Been in the mountains and no signal.
Yes, there is a gear cover. But no marks on the gears.

[Avenger]

It would be very unusual for an engine like that to be numbered from the flywheel end. There must be a TDC mark somewhere either on the damper or the flywheel. Make sure the rockers are free on the front cylinder with the mark lined up and time the pump accordingly. If you can't get it to run then try timing to the rear cylinder. You can't hurt it by mis-timing that far out. It just won't run. At least not easily.

I'm @$$uming you had the pump drive gear out, otherwise we probably wouldn't be having this conversation, right?