premirrider

The truck makes a weird almost diesel sound on start up, then when at a constant throttle (above 2 grand) The truck makes a definate dieseling sound.

From what I've heard from the locals, It could be a number of things. My buddie said to first just chekc the timing, cold be advanced to far, also cross the X&Y's under the diagnossis cap, then turn your key on and the Check engine light and depending on how many times it flashes, depends on the code its throwing. Then check the valves/ adjust if needed. He also said it takes alot to break the timing chain. He said it would grind through before it breaks.

I've also bought the timing chain set from engbldr so Im going to replace that anyways. But just want to try to diagnos the problem before.

If you guys have any other advice on what it could be I'd appricate it.

thook

Your buddy's right on every point. When was your last major tune-up?

Matt16

Valve cover on too tight perhaps?

85TurboRunner

Sounds like the timing chain guides have broken causing your chain to rattle on the timing cover.

DanStew

I have the same issue. I changed my timnig change and it still happens. I did have my timing off and have found out my TPS needs to be cleaned. I set my timnig to 14 degrees with diagnosis plug "Not" jumpered and it quieted it a touch at the higher RPMS but i get the rattle at startup still. I am gonig to get to the TPS to clean it and maybe it will somehow fix the situation I feel your pain, it is an annoying sound.

MMA_Alex

pull the valve cover and check the condition of the chain & guides