Thread: Doing some investigation to try and pin point knocking sound

It would be great if you could define "knocking sound" a little more. For me a knock is something drastic, like a run big end, everything else is a tap or a rattle. So, have you ever heard a big end knock? Is it like that? Is it higher in pitch, like someone tapping on a window?
Way too hard to pin down by a description. Put up a .wav file or something.

If your hearing isn't broken, like mine is, a screwdriver works fine, and I'll bet you already have one. Do what Wraithe said, and use it that way.

Wraithe also mentions gaskets. Given you have just done some work in this area, I'd be checking that. A leaking exhaust manifold gasket can sound like a knock.

Originally Posted by johntins

It would be great if you could define "knocking sound" a little more. For me a knock is something drastic, like a run big end, everything else is a tap or a rattle. So, have you ever heard a big end knock? Is it like that? Is it higher in pitch, like someone tapping on a window?
Way too hard to pin down by a description. Put up a .wav file or something.

If your hearing isn't broken, like mine is, a screwdriver works fine, and I'll bet you already have one. Do what Wraithe said, and use it that way.

Wraithe also mentions gaskets. Given you have just done some work in this area, I'd be checking that. A leaking exhaust manifold gasket can sound like a knock.

On the knock side, you can get a diesel knock just like a big end... Especially when you advance the pump way too much...

Example, timing on a Fordson diesel is 14 deg adv, was messing with one and it was way too far, started to loudly knock like a bigend does... Thought I'd killed my rake tractor, backed off, all fine... done spill test and was still 18 deg, but ran great, so left it there...

Some times on diesels, it can be deceptive as to what the problem is... Mind you, petrols are a lot harder to deal with compared to a diesel.

I HAVE DEVELOPED KNOCKING SOUND ON DECELERATION, PULLED OVER AND WITH SCREWDRIVER MOST EVEDENT AROUND IP, TIMING COVER/ AC COMP AREA.
GOT IT TOWED HOME LAST NIGHT (BIG STORM BRISSIE, FELT LIKE A THRILL SEEKER IN FRONT OF TOW TRUCK FLAT OUT)
ANY WAY SOUND BAD AFTER UNLOADING BUT SUBSEQUENTLY STOPPED TO MINOR INITIAL KNOCK ON START UP, FURTHER INVESTIGATION REQUIRED, SUSPECT TIMING BELT, IDLER PULLEY ? 30K OLD BELT

i had an expert say it didnt sound like big end. ive never heard big end knock myself so cant confirm it. it does sound louder at IP side of engine. when i did use screwdriver sounded almost like IP. i tightened all exhaust nuts again. they were all still nicely tight. could be possible i didnt do the gasket well enough.

basically is sounds like someone is tapping lightly with a hammer on hollowish bit of metal. sometimes its louder than other times. sometimes its hard to hear.

it sounds like its in time with a rotation of the engine rather than with a single piston. if you understand what i mean.

i have advanced the low boost fueling on IP. the cap with the torx screw under i mean. i have not changed the other two settings underneath the actual IP cover (starwheel and diaphragm) as i could not get the screws undone with the tools i have.

there is a video on one of my headgasket threads which has the sound. was actually the first time i was alerted to it because someone mentioned it and woke my paranoia. ill look for it and post link