901 diesel timing

[sandhill rancher]

Having trouble with timing on a 172 C.I. engine.
Have checked front timing gears and with it at 23 degrees before top dead center the drive gear slot lines up with the two bolts like the book says, but the injection pump marks will not line up.
About 10 to 15 degrees off.
Can turn the drive gear one tooth either way but still will not time.
Injection pump is rebuilt.
Any ideas would be appreciated.

 

[john_Bud]

Front timing gears??

I'm confused. You mean the gears under the water pump?

First off, if you are messing with the fuel injection pump, you need to make sure that the engine is on the compression stroke of the #1 piston. Easy to not be there. The timing gears that connect the crankshaft to the camshaft under the water pump don't correlate with the #1 piston being in the correct spot.

If you are on the correct compression stroke for the #1 cylinder (closest to the radiator) and you followed the book instruction exactly, you should be ok.

When you say "drive gear", what do you mean?

 

[sandhill rancher]

drive gear is the gear that runs off the camshaft
and drives the injection pump and the oil pump.
And when everything is in time the book says that
the slot aligns with the two studs that holds the
injection pump.

 

[john_Bud]

(quoted from post at 21:21:47 09/09/10) drive gear is the gear that runs off the camshaft
and drives the injection pump and the oil pump.
And when everything is in time the book says that
the slot aligns with the two studs that holds the
injection pump.

Thanks for clearing that up. We don't all call things by the same names - which can lead to "bad advice".

I'm not sure about the "line up with the studs" part. In fact, my memory is that the drive shaft in the block has a slot that is off center. The slot needs to be on one side or the other -- I don't have the book in front of me -- but [i:8a580913c7]I think[/i:8a580913c7] it needs to have the slot farthest from the block. Read the book carefully and go by the book not my failing memory! It's not as simple as lining up the slot with the studs.

[b:8a580913c7]From memory[/b:8a580913c7] again, there are 4 things that need to be done to correctly time the 172 diesel.
1) put the #1 cylinder on the compression stroke
2) "time" the crankshaft to 23 degrees BTDC
3) Insert the drive shaft into the block with the slot offset big half moon to the block (from memory!! check the book here)!
4) Line up the 2 lines on the pump

It shouldn't be hard, but it is easy to get wrong, if you can follow that thought!

 

[JDemaris]

You said you just had the pump repaired (they are rarely actually rebuilt).

Are you 100% sure the timing marks were installed? The most common wear item in a failed pump is a piece of the governor with one of the timing marks. The new replacement part has NO mark on it, i.e. it is blank. Whoever is fixing the pump has to install a new timing mark with an etcher.

When you got the pump back, did you check to make sure that pump has two timing marks to line up?

If by chance, they are missing you can still install and static time by "air timing" via the #1 injection port.