hosrom_951

Say you took off the intake manifold to replace the vacuum hoses, lines, injector sleals and a whole bunch of "while you are in there" brag.

You covered the ports of each intake on the cylinder head with tissue paper, you took off the intake gaskets and some debris fell in (sand grains and dirt, no "big" debris).

You then re-install everything, start the car and she idles smoothly. Once you reved thje car (only 1,200-1,500rpms) a major knocking noise appears. Sounds like a bolt came loose and fell into the cylinders, quite loud but then quiets down. You switch off the car, visually inspeact for any missing bolts, washers etc.....nothing.

You crank the car, but don't start it, and listen for any "unusual" sounds. Nothing, sounds fine. You start up the car, the noise is gone. You rev the car, the noise is gone.

No smoke from the exhaust, good oil pressure, good idle. Everything runs fine, car runs smooth and good.

Now, could someone explain to me what the heck that pinging sound was for? some sand got into the exhaust from the combustion chambre or something? why did it knock? was it a knock? sounded like a ball in a tin can for a moment and the car was cold and barely reved up! maybe a lose spark plug cap on a plug? couldn't fire properly???

Toolmaster

If the noise was there - and isn't now - then either one of the following may have happened...

1 - a Bolt or washer dropped in - that in some way blew out of the exhaust valve. This would be VERY rare - but is a potential.

2 - a large piece of debris was in there that got burned up.

3 - The bolt or washer that fell in is now embedded in either the top of a piston or the head. That's bad news....

When I rebuilt an engine back when I was a youngin' - I dropped a washer into combustion chamber. I tried starting the car - but heard the loud noise and shut her down. I removed the head AGAIN - and there was the washer - now smashed - embedded on top of my piston.

You can try a boroscope to look into the combustion chamber and you MIGHT get lucky and see something. But - if you're the same sorta person as I am - the head would come off to be SURE.

Sorry- but HTH!

hosrom_951

Toolmaster: Since that sound, the car had been driven for a while without ANY problems.

Like i said, all the bolts, washers and any hardware wasn't missing from the intake, fuel rail, hoses etc.

I believe it could be some debris that got caught up somehow, since the noise completely stopped. But i wanted to see if such debris (sand mostly) could be possible to cause such a sound (but remember, very small quantities in each port really).

But if any hardware (washer, bolt etc) is embedded in the piston or cylinder head, wouldn't the sound still be there? maybe slightly?

Toolmaster

If the part did embed - then potentially no - as it's not moving around anymore. Sand won't make that much a racket (take a look sometime under your air filter.. ICK!)

If it breaks loose - then you're in for some damage - especially if you happen to be at 5k RPM, etc.

See if any of the local shops have a boroscope - and take a gander in there. If there is something there - the small charge for the boroscope will potentially save an engine. If nothing's there - then you paid a little for peace of mind.

HTH!

hosrom_951

My "assistant" who helped me re-install everything just informed me that when standing at the rear of the engine, looking at the exhaust. Some small ***** of sand shooted out..........

I guess i found out what the problem was then.......

Campeck

um....sand.
wouldn't that like destroy your cylinder walls.

hosrom_951

Campeck: We are talking about just very VERY minor grains of sand, nothing close to a tablespoon of sand or any kind.

It was just one ball that shooted out, and i remember just a couple of grains of sand got into the intake ports.

But yes, if we are talking about a lot, the we are looking at some bore damage. Next time, i would get a vaccum mcleaner and suck those grains out

Campeck

haha!
crazy desert!

iloveporsches

A small amount of ceramic powder was enough to signifigantly damage the cylinder walls in the CBR600 motor for our FSAE team.

hosrom_951

Campek: It is extremely hard to keep things clean here, really. I used to get all pumped up and pissed off whenever i see a clean engine bay, untill i realized that there is NO point in cleaning the engine, since the next day sand is going to cover the thing.

Brandon: Yes, i am aware on how small debris came completely damage an engine. But do remember, that on extremely high revs, the effects could be worse. In my case, since yesterday till today, the car never saw 3,000rpms. Luck also plays a big role here, guess i was lucky, VERY lucky