rough idle on a 2H diesel?

[mr_diesel60]

Over the last 3 weeks, the idle on my 60 series has slightly become rougher. It feels like the car is sort of bobbing up and down. It's due for its tappet adjustment (every 20,000km).

It's only done 62,000, but was involved with a head on about 2 weeks ago, and has a crack in the exhaust just after the manifold. I've also been using flash lube every diesel fill up, and it seems to gain more power and less smoke.

It's getting fixed in two weeks after the panel damage is fixed. I'm leaning towards tappet adjustment. It's not using oil, and there is no oil in the water or vice versa.

Any ideas would be great!!

[beast2h]

like it is missing????? is it blowing smoke???

[nilla60]

Missing a tappet adjustment by a few km is not going to give a sudden change in character like that. Just how much worse is the idle? Maybe the throttle linkage also took a shunt and you just need to re-adjust the idle?

My 60 rattled the flange off the exhaust right behind the manifold about 15 years ago and that made the truck sound like it had an exhaust brake.

[dakar61]

A couple of things can give the 2H a lopey idle. One can be a compression issue causing it, but more commonly loose delivery valve holders on the injection pump.

The delivery valves have a nylon seal that shrinks over time and allows high pressure fuel to bypass back into the supply gallery of the fuel pump. This effectively reduces the fuel going to that cylinder and will make it start to miss. In the early stages its not a full miss but will eventually become one. Let it go too long and the seal will break and the sealing surface on the plunger barrel and the delivery valve will become corroded by the fretting movement of the valve, meaning a pump repair.

A tell-tale sign of a loose delivery valve holder is black dusty deposit around the base of the holder, where it screws into the pump.
You may be able to tighten these yourself, but they do need to torqued correctly or you may nip up a plunger in the pump if you overtighten them. Torque is 30 to 35Nm force. You will have to remove the fuel lines and clamps from the holders to tighten them. Check them all anyway.

If you are not mechanically inclined, take it to your local diesel fuel injection guy. It`s a well known fault

[Tapage]

I would propose a simple other option .. just to check ..

Air in the line .. if you have the factory water separator on the frame down under the pass side ( Driver seat in RHD ) check it ..

The 2H is very sensitive to the air in the line ..

[mr_diesel60]

Nope, no smoke. No blow-by. I was leaning towards a problem in the pump or an ejector. I've actually had this issue before!! The feul line from the pump was leaking.

Thanks for your help guys. DAKAR61 - Sounds like you know what you are talking about!! The old girl is at the panel shop for the next week or so, and then goes in two weeks from today. I'll let you know what happens!!

[mike_l]

Another problem area is the rubber diaphragm controlling the pump govenor. Over time this can split causing hunting in the revs which can be mistaken for a missfire.
mike_l