doof in idle

Submitted: Saturday, Oct 24, 2015 at 14:25
ThreadID: 130686 Views:2373 Replies:4 FollowUps:4
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recently we removed the timing gear of the front of a HJ60 2H engine to replace a leaking seal. We also replaced the rockers, they where worn with shallow pits. We left the valve tops, lifter, rods and cam as they where.
We had to remove the injection pump but it came out with it's adjusting plate intact. We didnt re-time the pump with the tube/timing marks method.
One injector line got a bit of punishment in the form of a twist. Further to the ip line twist (1st line), the first cap on top of the injector pump was loosened all the way. I carefully repositioned the spring and capped it down 3lb's short of torque spec because it was getting very tight. The other caps where also out of spec.

After bleeding it thru the glow plugs it started first pop.

But now there is a "doof" in the idle. Previous to the disassembly there was an almost unnoticeable "thun" in the idle until it warmed then it was smooth.

I don't want to think "valve" as to the cause but i need to ask, is there anything else in a diesel engine that would cause an idle doof very similar to that of a fouling plug in a pertrol engine?

Would pump timing make a difference on one cylinder
Would a fouled injector make a difference?

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