Mystery Chirp / Squeak noise.

[cbriggs]

I have an 08 apart right now that has a weird chirp, sqeal noise under light to moderate accel, but not hard accel. I can rarely duplicate it, as it is temperature sensitive, does it worse cool, or after a long downhill coast. I have heard it with customer driving. Sounded kindof like an exhaust leak, but kind of like a boost leak as well, I couldnt find any soot anywhere, smoke test revealed nothing. I dove in and pulled the trans thinking it must be the rh up-pipe leaking. ( and posibly the cleanest running 6.4 ever- hence the no soot?) As i was about to re- install the rh uppipe i noticed a tiny, tiny trace of soot at the rh manifold, just at the top rear corner of the back cylinder. On closer inspection i saw the top rear bolt appered loose. Ah-ha, i'll just tighten it up..... The bolt appeared loose because it had broken off and was held in by rust. So now i am pulling a rh manifold and extracting a broken bolt.

 

 

Anyone ever have one of these out? or seen this yet?

[Mikill]

I have seen this 4 times all on ambulance which were not fun to work on. It is actually a known concern. They break flush with the head and I only had luck getting one of them out. Those bolts are a pain to drill out. Two we sent to a machine shop to remove and the other ended up getting the head replaced because neither us or the machine shop could remove it without damage.

[joshbuys]

Seen several on the left hand side (lower rear bolt), and 1 on the right hand side (upper rear bolt) was able to extract a couple on the left, and heli coiled one with no issues, customer couldn't leave us the one on the right, so never got to try that side.....looked alot harder to get at though!!

[cbriggs]

Got it done. No luck extracting it. Drilled it oversize and helicoiled it. Not to bad to do, but if it was a lower bolt the engine would have to be lifted up for access.