Hi Bradley. Thanks for the reply, I am hoping to find someone reputable here to try and diagnose this issue properly, so gonna take your advice on that.
Just to be clear, the example that I posted that you replied to was the "worst case" I have heard of this noise (on my car). Its usually quite a bit shorter and quieter. Matches 100% with the other reports of this issue. View post 1 of this thread, the other 2 examples there are an identical match to what others are reporting.
Back home from vacation have most of august to deal with this before I leave for business so hopefully over the next couple of weeks will have a solution.
Quote:
Originally Posted by bradleyland
Anom3, the sound you're hearing is completely different than what most of the guys in this thread are addressing. They're addressing the single "clank" sound that is (apparently) addressed by their brake pedal procedure. The problem you're having here is that most of the people in this thread wouldn't know a valve lifter from a check valve if you laid them out in front of them.
Unfortunately, your thread is full of useless clutter now. The sound in your post #258 is not the same sound that they're addressing, so you'd be well advised to ignore those comments. They're not going to get you anywhere.
The sound in the video in #258 sounds very much to me like lifter knock, or possibly cam chain slap. Listen to the lifter knock in this video:
That is the sound of a lifter knocking on a single cylinder, which is why the rate of the knock is so slow. Notice how similar the sound is to your car though. Keep in mind that this is a truck engine, so there is only one cam lifter actuated per intake/exhaust event. In the S65, you have four valves per cylinder, so there are two cam lifters per intake/exhaust event.
The rate of knocking in your engine definitely sounds like it's once per cylinder ignition event, which would also correspond with a single cam rotation. In my opinion, your knocking is coming from one of a handful of sources:
1) Lifter knock. The lifters in the S65 are hydraulic. Low oil pressure can cause lifter knock, and you mentioned earlier that you're seeing a dip in oil pressure during startup.
2) Knock related to engine vibration. During startup, your engine spins up a large mass of metal, which takes a minute to settle in to a cycle of equilibrium. During this startup, each cylinder firing event causes a lot of shockwaves that go through the entire engine. This can cause objects that are attached to the engine and reciprocating assembly to "slap".
IMO, you need to find someone local with the talent to diagnose it. Using those stethoscopes effectively is a real trick. They also make them with metal rods attached to them, instead of the sound membrane. It allows a technician to touch it to part of an engine and pick up sounds transmitted through the material instead of the air. That is, IMO, the only way you're going to get to the bottom of this. |