2940 engine mystery

My 2940 will sometimes knock for 2 seconds after a cold start-up. Sounds like a compression knock with extra exhaust. Also, my crankcase oil level increases even after installing a new transfer pump. The coolant is never low and the engine does not overheat. It has 9500 hours and runs great in the field. I will greatly appreciate any experiences you can tell me about that are similar. Thank you very much in advance!!
Deereford

Install new injectors. Not much more $$$ than rebuilding the old units.

You can also get fuel in the crankcase past the injection pump drive shaft seals,but that would not make it knock.Change the injectors first.

I agree on possible injector problem but rather than replaced all 6 I suggest pressure/spray test and replace faulty ones. Below is JD price for reman inj. both from JD & A&I

I've yet to see a pencil injector that can be truly rebuilt. We regarded them as 'throw-aways" at the shops I worked at. They can be cleaned when plugged but no new parts are available to renew them (valve and seat area.

When an injector wears - it's the valve face and seat that gets hammered. On rebuildable injectors - you can buy a new "tip" an install it. On a pencil injector - no such thing available.

New ones are around for $50 each. I have no idea what some places are selling as "rebuilt" and what has actually been done to them.

I already asked that question on another tractor forum and was more-or-less asked to leave the forum. That was Lavoy's forum. He sells "rebuilt" pencil injectors and took offense when I asked him technical questions about what process was used to renew them.

Maybe somebody somewhere has found a way to actually regrind and narrow the valve and seat in a pencil injector - but I doubt it. Considering that the Chinese putting brand new ones on market for $50 - I can't see how trying to rebuild can be cost effective.

You can buy brand new pencil injectors for $30 each, more-or-less. I cannot come up with a valid reason to mess with used injectors that are cleaned up and sold as "rebuilt."

A bad injector can cause one heck of an engine knock. Worst part about working on injectors in a 2940 is they are pencil injectors. With some it's an awful job trying to get them out without ruining them. Even with with the OTC slide-hammer puller.

I assume you've got the Rotodiesel injection pump. It is likely leaking at the internal shaft seals and putting diesel into your crankcase.

New (not "rebuilt") pencil injectors.

$29 http://www.griggslawnandtractor.com/servlet/the-2541/John-Deere-Pencil-Injector/Detail

$35 http://www.powerequipmentmart.com/herschel-part-har89564-jd-new-injector-ar89564/?utm_source=googlepepla&utm_medium=adwords&id=58098359590&utm_content=pla

$39 http://www.buyautoparts.com/no-ymm-oembuynow.asp?partnumber=35-01697&gclid=COCyuM2-87oCFUzxOgodLGcAuQ

$28 http://www.ebay.com/itm/AR89564-New-John-Deere-Fuel-Injector-1020-1520-1530-2020-2030-1140-1350-1420-/230804463157

The reason I posted JD's price on rebuilt injectors is because that's what I'm familiar with looking up parts on JDparts.com. I agree on replacing bad injectors with new injectors.

I want to add that I am not current on all new
technologies. When I worked in a pump and
injector shop and a Deere dealership - there was
no known way to "rebuild" a pencil injector. So,
I do not know what is being done to the pencil
injectors sold now as "rebuilt."

I DO know this. The meaning of the word "rebuilt"
has been messed around with a bit by many sellers.

I see it this way. To "rebuild" anything is to
return it back to it's original projected service
life it had when brand new.

When we "rebuild" an engine - we renew all moving
parts subject to wear and movement. Cylinder
walls, pistons, rings, bearings, valves, valve
guides, seals, oil pump etc.

But . . many pump shops sell injection pumps as
"rebuilt" when often - major moving metal parts
are NOT renewed in any way and sometimes have near
1,000,000 miles on them or 25,000 hours of use.
They get resealed, recalibrated and often just
minor new small parts installed.

With fuel injectors? We used to clean some up and
recalibrate and sell as "good used", "used and
checked" or maybe "reconditioned." We never had
the nerve to call any injector "rebuilt" unless it
actually had a brand new nozzle assembly
installed. There IS no such thing for a pencil
injector. But to be fair - maybe somebody has come
up with a way to remachine them and renew their
service life. If so - I'd like to hear more about
it. A process might exist but I've yet to see any
evidence. When I ask sellers - I often get an
angry response like I got from Lavoy from JD
Crawlers.

Considering there are brand new pencil injectors
available for Case and Deere and Oliver for less
then $30 each -it seems to me that high dollar
attempts to "rebuild" would not be cost effective.

Thank you very much to all of you that responded to my question regarding my 2940. I hope sometime I can assist you also. Thanks again!!
Deereford

While it is a different injector, I put JD Reman injectors in my 4240 , ran it 300 hrs, ok a first then problems, took them to a quality shop and they replaced many parts. The old ones showed way more wear than I put on them. They were a poor investment. More like cleaned up and still work, definitely far from remanufactured.
Ken

I've used reman pencils for over 30 years with no ill effects. They seemed to last as long as new ones. The pintles and seats were reground.
However since new ones have gotten so cheap I have been using them.
Wonder if they are being made in China since they are cheaper than forty years ago.

I'd like to see some tech data on how pencil injectors are "reground." That would entail recutting the seat, recutting the valve face and then narrowing the seat back to factory specs. I'm not saying it now can't be done. I just have not seen any verifiable info on it. When we "reconditioned them" years back - we reamed out the orifices and used lapping compound on the needle and seat. It worked OK on injectors that were not all that bad to start with.

I don't have any data. I just bought them and they worked very well.
I know what you're talking about though. Regular authentic Roosa-master diesel shops could not do the job.