1996 MACK E7 350 all mechanical pump

[Thomastractorsvc2]

Had a guy bring in a truck with a bad miss. 3 injectors were bad, so replaced 6 injectors and 6 lines.  Checked pump and had to send out for repair.  Fly wheel is aftermarket and only has TDC.  No AB light available anywhere under $2k.  There has to be a way to check static time any idea?

[Joey Mack]

2 grand for the timing tool, holy crap.. ive been told that you can look in the hole and line up the 2 indicators, but i have never done it, i have the timing tool in my shop. Although, it makes sense because the tools contacts are opposite each other.

[Vladislav]

You need a portion of an injector line, actually an old line of any kind suitable to be installed onto the pump in place of the stock line. You need to cut that "donor" line into halves and bend one half the shape like what you have in your kitchen sunk. Just to not drain water but fuel.

Than you install the crank shaft to the desirable timing point and do the follow: remove #1 injection line from the pump, remove the top section of what seems as the plunger housing. That nipple is a so called "delivery valve housing". The idea is there's a kind of check valve above the plunger which doesn't allow pressurized fuel to drain back into the plunger barrel when injection stroke is finished. That valve is also spring loaded to operate faster. All in all you need to unscrew its housing, remove the valve stem and its spring from there (precision parts) than install the housing back and attach the bent pipe to it.

Than you check the timing point. You start pumping low pressure side with a had prime pump (or find another was if you dont have it). Low pressure travels inside the pump housing gallery filling up the plunger barrels, actually those in which plungers are in their low position. But fuel can't go any further since there's that delivery valve on its way (and further an injection line blocked by a injector. You have #1 valve removed and the line disconnected from the injector (and attached that portion of a free line). Ok, you pump, fuel comes into the #1 plunger barrel... And in a case the plunger is low the fuel goes up to the free pipe and drains outside into a can you put there to not have it on the ground. IF the plunger is upper at a certain point it closes a hole in the barrel wall low pressure fuel fills the barrel through. And nothing drains from the pipe. Actually at the time the plunger on its way up closes that hole you have initiation of injection (on the normal operation) since the fuel can't go back into the gallery and is forsed to go up to the injector (opening the delivery valve and a needle valve in the injector). 

So when you check the injection point you play with position of the pump and observe the fuel draining from the free pipe or not draining. That's because the plunger closes or opens the supply hole in its barrel.The point where the fuel flow shuts down is the begining of injection of #1 plunger.

Worth to add two points. First this is the method an injection pump is calibrated on a bench. So much sharper and truer than any test light and so on. Second, you better look into some older book where all that is described to get better figuring. And you also need to check out the way of removing delivery valve in a Bosch pump I can't recall particulary at the moment.

Good luck!

[Geoff Weeks]

Spill timing, been there done that.

[Vladislav]

I calibrated a pump that way. And when it happened to put it on a bench later for another reason the guy was veeery surprized.

[fjh]

Are there any degrees marked on the flywheel? Can you post a picture of the side of the pump?

[JoeH]

Get a Degree Wheel.

[fjh]

6 hours ago, Joey Mack said:

2 grand for the timing tool, holy crap.. ive been told that you can look in the hole and line up the 2 indicators, but i have never done it, i have the timing tool in my shop. Although, it makes sense because the tools contacts are opposite each other.

If he has marks on the fly wheel  he can just centre the spade in the hole.the key is having marks on the flywheel!

[Joey Mack]

FJH,?  I'm really rusty, but is it possible he has the timing pointers on the front of the engine?  and his degrees are on the balancer?  '96 E-7... 

[fjh]

23 minutes ago, Joey Mack said:

FJH,?  I'm really rusty, but is it possible he has the timing pointers on the front of the engine?  and his degrees are on the balancer?  '96 E-7... 

yup you are likley correct joe !  Un less the damper has been changed there should be something one place or the other!

[Joey Mack]

of course I i dont know if its full mechanical or has the electric gov. housing..  I may have missed that.. we will see..

[thomastractorsvc]

I bought this tool from a local turbo shop for $20 it fits the Bosch p7100 pump same as on truck.  Took some time but its back running.  Aftermarket flywheel had tdc indicator but that was all so we just marked fly wheel and removed pump gear rotated engine remarked and moved the engine until it was running good.

 

[fjh]

All good thanks for posting the fix! Appox 11/2 inch from tdc will be close! Good job! The spade centre in the hole is the same as that jig give or take a degree or two!👍good on you taking the bull by the horns!Its not a hard job just a bit hard to explain!

[Joey Mack]

yep, I missed it.. it's full mechanical..

[thomastractorsvc]

I am disappointed the AB light is so expensive I don't really mess with pumps a lot but that pin for $20 was simple enough it should come with a rebuild.

 

[Joey Mack]

Bud, That is awesome ! I never used one, but would like to see it in action..  I have the Kent Moore tool, but I really like that there is a cost effective way to get the same resullts..   

[fjh]

3 hours ago, thomastractorsvc said:

I am disappointed the AB light is so expensive I don't really mess with pumps a lot but that pin for $20 was simple enough it should come with a rebuild.

 

Most pump shops build it into the price the rebuild and come spiked on tdc!