I have a tick...

[JeepSJ]

Now that the timing is set and it does not sound like a PSD any more, I can focus on other things. Like this darn ticking or rapping. Sounds almost like an exhaust leak - not quite deep enough to sound like a piston. When I had the heads off there were some scratches in #8, but nothing that I thought was out of the ordinary. The sound is louder under load, and goes away when I lift off the throttle. I do not have the sound at idle. It is worse when cold, and goes away some when it warms up. I listened and felt for exhaust leaks under the hood and could not find any.
I'm hoping that it is not a piston - those scratches in #8 now have me concerned that the motor may have been overheated before I got it and the sound is that piston slapping around.

Thoughts? Ideas?

[JohnC]

Piston slap is most noticable under light load and decreases under heavy load. Keep lookin'...

Make sure the injector lines aren't touching anything, like heater hoses...

[neo]

My 6.2 has done something that sounds very similar two or three different times. It was nearly imperceivable at idle and would increase in amplitude and frequency with the addition lf throttle. Each time this has happened, once I opened the trottle up, revving the engine up, it has stopped. Mine was kinda loud when I opened the hood and was distinctly coming from the even bank towards the front. Did you notice any roughness in the engine? Mine seemed to run rough when it happend.

[JeepSJ]

No, engine seems pretty smooth. Occasionally I can get it to go away if I get on it hard. Is it possible that the noise is coming from an injector? Can an injector be bad/noisy without causing excess smoke, etc...?

[jdc]

My G30 does this, too.

I've never been able to replicate it on demand.

The noise has puzzled me for at least 30,000 miles, but in the absence of catastropic failure and obvious phyiscal clues, my anxiety bleached out and resembles a non-descript shade of acceptance.

[GSE2SCHMIDT]

Vacuum Pump? seems like when they wear they get noisy with the little plunger bouncing off of the cam lobe. Easy to check, just pop of the belt and if it goes away........

[JeepSJ]

I have no vacuum pump, so it rules that out. I did finally get to take a good freeway run and after about 15 min on the freeway the sound just about went away. But after it sat for a while, it was there again when drove it. But again, after about 15-20 min it nearly went away. It is driving me nuts because it is so loud.

[a5150nut]

Exaust leak? Ater it warms up the metal expands and seals. Try using a lenth of hose and listen arround your exaust manifolds, down pipe and crossover.

[john8662]

Can you upload a recording?

[JeepSJ]

I thought maybe exhaust leak, and got excited when I found that things had settled a bit and the exhaust band clamp at the back of the turbo was a little loose - not like rattling loose, but well below torque. Didn't help. The drive to CA over the weekend the sound came and went.

It is back at the body shop for a couple weeks while they touch up some blems in the body work and paint. I'll dig back into it when I get it back. I'll try to get a recording then.

Question - could it be an injector? Can injectors be noisy/broken/bad without causing excess exhaust smoke?

Thanks for all the help everyone!

[Robyn]

OK grasshopper

Try this little gig.

With the engine sitting idling and ticking away, get your self a good heavy leather glove on your left hand and place your hand firmly on the back slope of the turbo heat shield.

If my guess is correct your noise is the one thats common to many 6.5 TD's
The heat shield amplifies the injector closing/opening sound and makes a very audible clicking noise.

Back in 93 I passed on one new GMC crew cab that did that and it was a brand new truck.

My 94 Burb does it really loud since the overhaul and the rebuilt injectors and such.
If the hand on the shield trick does it your set.

A 1/4" thick piece of lead sheet bolted to the shield will kill the noise.

Had to do this on a Dodge Cummins for a fellow. He had a similar noise that was driving him and the dealer to drink.

Took a listen while the techies were all standing there looking lost and stuffed my hand wrapped in a shop rag onto the shield and poof no more noise.

Give it a go

Robyn

[JeepSJ]

Thanks Robin! I will give that a shot. I will report back when the Waggy is back from the body shop.