Tickety Tickety tick

[dhirocz]

Got a nice tick going on. Sounds to be from the top of the head, only after the oil warms up, and mostly at or off idle.

Can't pull the valve cover off, it's raining like hell right now.

Oil was just changed before I went out, maybe 2k miles ago, with gear oil.

I noticed a similar sound yesterday, in FL 500 miles away. Now it's definitely more pronounced. Not a knock, but an RPM dependant tick when warm. I'm going to pull the top end apart when it stops raining (at my house now), and inspect the valve train. Sounds like maybe a rocker backed off or a roller is on its way out.

Anything else, or am I missing something? I'm trying to keep her chugging along until after this covid goes away so I can inframe it, it's about time. CM871 880k on the stock engine, @m*m^2 @ 685k.

[Mattman]

Maybe one of the Jake rockers??

[dhirocz]

No...cylinder 1 valve cam has a lobe starting to go on it. I replaced this cam 200k ago, oil has run clean since, regular overheads, cleaned out the rocker oil passages, etc...best I can think is metal fatigue.

[dhirocz]

CORRECTION: I ran it with the cover off, that particular lobe has no oil supply at idle. I'll be taking it off tomorrow to see if it's plugged. Why it would be, I don't know.

[Signature620]

Exhaust leaks make ticking and tapping sounds.
Check if any turbo nuts or exh manifold bolts are missing. Look for black patches around any of the gaskets. Spray soapy water around the area including the manifold expansion joints with the engine idling.

EDIT - We both posted at the same time.


See if you can find the part number rockers you used during the last repair. A couple of years ago Cummins was using rocker levers with no oil supply drilling to the roller. It was a major recall in Australia. We were replacing full sets of rockers and cams in brand new trucks and engines on shipping skids.

[dhirocz]

I'll check it out in the morning. That would make sense, all the other rockers have a good supply of oil...even that one to the tip, but nothing at the roller at all.

[dhirocz]

So the failed rocker had a hollow roller axle and is not retained by a roll pin, so I pushed it out on my press. Lo and behold, no oil supply to the roller. I can see in the diagram of this rocker, however, that it is supposed to be there.

From what I can tell, the older, narrow roller rocker arms had a solid brass or bronze axle with an integrated oil supply channel from what photos I can find. I'm trying to confirm this, as I don't have a roll pin puller to disassemble one without damage. It does appear that the hollow axle roller shaft is among the group that was recalled. Waiting on a call back from Cummins on this one.

What I do know for sure is there is no oil supply to that lobe and the rocker is date stamped 2/17. I also checked the oil supply. Let's just say my windshield is a mess.

Sig, do you have a tsb number to this? It's starting to look as if I somehow got one of these flawed rocker arms, nothing shows under my ESN.

[Signature620]

These might be applicable but judging by the terms used, I don't think they'll will cover any of your costs.

https://quickserve.cummins.com/qs3/pubsy...60088.html

https://quickserve.cummins.com/qs3/pubsy...80045.html

The campaign for the rocker lever replacements I'm sure was C1991. When you look it up on Quickserve, it has been removed/wiped as the campaign is over.

[dhirocz]

No surprise. I dont think Cummins would do anything either, but if it saves someone from flattening a camshaft because it was not machined correctly then it's worth it.