is a rattle in the oil fill normal?

[sask3500]

With the cap off it rattles, I assume that is the timing chain, is this right?
Is a noisy chain an indicator of wear or do they sound rattly when new?
Or should I go to bed and stop wondering?
Also the haze that comes out of it, when hot, disappears when I hit the 1100 rpm switch. That's a good sign right?

[DmaxMaverick]

Timing chain "rattle" is normal. It's a chain, and that's what they do. A little vapor huffing at idle is normal. If it clears up at 1100 RPM's, no load, that's good. The "haze" you are seeing is mostly water vapor being steamed off. Oil absorbs water when cool, then dumps it as it gets hot. At higher RPM's, the vapor is pulled into the intake. 1100 RPM's is OK for crankcase vapor balance, but you should see a similar result around 800-900 RPM, ideally.

Don't lose sleep over any of this.

[Robyn]

As Maverick said, dont lose any sleep over these things.

The Rattle is due to the timing gears that are connected to the cam to drive the injection pump. As the pump pulses the gears set up a harmonic (NOISE).

The two gears in there are Helical Cut and are not the most quiet in the world. The cam is driven by a chain off the crank, but the pump is gear driven from a gear that bolts to the cam, just ahead of the timing spocket and this meshes with the pump gear.

These engines all do it, even when brand spanky new.

As far as the "haze" at the fill port when running. Some engines will have far less than others.

The last couple I have rebuilt had near zero vapor at an idle and nearly no oil pull over in the turbo inlet.

I have seen factory new trucks that really slopped up the air inlet with oil and had a lot of vapor at the fill port.

It depends on how good the rings have sealed mostly.

Overall, a small haze at idle that clears when the engine is brought above idle is just fine.

Missy

[sask3500]

Thanks, I think I'm getting more comfortable with this motor. You hear lots of crap about it and mine is a bit of a mongrel, 95 block & pan, 98 IP, 94 intake, 97 cooling system etc. I think I'll keep it though, seems healthy enough.
Justin