Yanmar 4JH2E injection pump removal

[kilmaine]

Further to the kind responses to my runaway scenario with the above engine it’s now clear that I need to remove the injection pump. There is an access plate on the engine timing cover behind which there is a very large plug, illustration 20 on the parts manual. This is proving to be extremely tight having defeated an air impact wrench and causing a 1/2 industrial socket bar to bend! Would someone please confirm that this is a normal right hand thread? And advice appreciated!

[kilmaine]

Parts book image.

[kilmaine]

Improved image!

[skipperpete]

Hi Kilmaine
That big hex nut is only a blanking plug and the timing mechanism is held on the pump drive taper by a long nut(boxnut in the parts diagram) down the hole that the blanking plug covers. You will probably need a special puller to thread into the auto advance hub, the only time I’ve done a pump removal with auto advance was with the timing cover off and it actually wasn’t very tight so no struggle.........unlike the bare gear that is more common and is generally quite tight. As far as I remember, it’s a RH thread on the plug and it should only be about 8 or 10 ft lbs torque max.
The gear is floating and the housing in your pic is attached to the injector pump drive taper.
Pete.

[seaescape]

Hi.
Old thread but hoping to get answer.
I am pulling my injector pump. I like you am unable to loosen the large gear nut.
I was wondering does the gear stay on the pump when removing?
Cheers
Kevin J

[skipperpete]

Originally Posted by seaescape

Hi.
Old thread but hoping to get answer.
I am pulling my injector pump. I like you am unable to loosen the large gear nut.
I was wondering does the gear stay on the pump when removing?
Cheers
Kevin J

Nope, the gear stays where it is, under the timing cover, preferably with the keyway at the top. Its wise to put a mark on the gear and the housing with a white paint pen as a reference point and disconnect the battery throughout the entire procedure. Do not under any circumstances try and move that gear, if you manage to jostle it over a tooth ( practically impossible to do) you still have the white reference marks to warn you if this happens.

[seaescape]

Hi Skipperpete
Thanks for your reply.
Just to get this straight in my head.
1. Remove large nut. Very tight.
2. Remove box nut from shaft after setting tdc. Check key at top as not to lose in case. The gear teeth are not in view.
3. Remove 3 flange nuts from pump and slide out. I have marked pump flange and gear case for realignment

I take it that the gear and compensator will stay in place. Won't fall into case.

The reason for removal is after 7 years on the hard she wouldnt start. I found no fuel at injector 4 and that the pump piston is not moving.

Cheers
Kevin J

[skipperpete]

Yes, mostly correct but you need a harmonic balancer puller to get the pump shaft out of the gear hub, that son of a gun is tight, usually lets go with a bang. The key is a tight fit in the shaft keyway, it won’t fall out. Yes, as in step 3 make a mark on the pump flange and a matching mark on the engine, I don’t usually bother with this and prefer to either spill time or strobe time the pump but a pair of marks before loosening the 3 nuts allows you to find the original timing again without the ordeal of learning spill timing. You’re lucky to have just a no start, often a stuck plunger can cause an engine overspeed.

[seaescape]

Hi Skipperpete

With the lack of a puller. (in the back blocks of asia) would it be possible to insert a socket after removing the box nut then install the big nut to the compensator and tighten given there is a gap to be able to push the pump shaft.
Will applying pressure to the big nut damage the spring set-up inside the compensator.?

Cheers
Kevin J

[seaescape]

Hi Skipperpete

There is also nothing to attach the puller to. Do I need to remove the timing cover?
Just wondering how Kilmaine removed his.
Have you got contact with him.
I have looked through Google and there is nothing about how to remove the pump.
I have the service manual there is nothing in there.
Is there a Yanmar workshop manual?

Thankyou very much for your info on this.

Cheers
Kevin J

[skipperpete]

Originally Posted by seaescape

Hi Skipperpete

With the lack of a puller. (in the back blocks of asia) would it be possible to insert a socket after removing the box nut then install the big nut to the compensator and tighten given there is a gap to be able to push the pump shaft.
Will applying pressure to the big nut damage the spring set-up inside the compensator.?

Cheers
Kevin J

Technically… no, here’s what the hub looks like in a cross section view…. but in practice, not really, the risk of stripping the threads on the plug kinda outweighs any advantage, I even made up a puller for this purpose and at a later time, successfully managed to do what you suggest with the plug. These timers are quite rare and there’s more than one design, some have threaded holes for a puller but they can only be used with the timing cover off, others have access to the puller holes. not a really big deal BUT if the front of the engine is up against a bulkhead (Hunter and some Cat’s) , ya have to pull the damned engine out to either get the timing cover off or to even get a puller in there if you luck in with the accessible threaded timer hub.

[skipperpete]

Oh, those two little angled holes in the pic are drillings for grease from the cavity formed by the big plug.

[seaescape]

Hi Skipperpete

Well looking more like having to remove the timing cover. As per kilmaines photo above there is nothing to attach a puller to.

Do you know if there is a Workshop manual NOT the Service manual

Cheers
Kevin J

[skipperpete]

I wish. Maybe someone wrote a better service manual but I haven’t seen it. Try a search for the 4TNV 78.
Yanmar gave us false hope by showing the injector pump off the engine with the timer still attached ….. like the pump was removed complete with the timing gear. Which part of Asia are you in?
Oops , ignore the reference to the 4TNV 78, I did a search for the workshop manual but couldn’t find a hit.

[seaescape]

Hi Skippermate.
Kudat Sabah.
Update. I found on a fb comment. This is what I did.
1. Unscrew box nut 1/2 a turn
2. install plug nut without copper washer. Turn to tighten.
No real force needed, gear just released easy.
One thing I near lost was the spring washer under the box nut when I reinstalled. It was still in the gear.

I also set timing marks prior to removing.

Cheers
Kevin J