engine knock

[archieb]

I have a 93 metro convertable that has a rather loud engine knock.
The rod and main bearings were replaced by the previous owner yet the noise continues. The vehicle runs and drives fine and has done so for the last year. The noise sounds like it may be coming from the top of the engine. I also notice that the noise seems to lessen during deceleration. Any suggestions as to what might be the cause? It has a couple of good mechanics that love metros stumped.

Thanks
archieb

[geozukigti]

Back the ignition timing off a couple degrees. A manual will tell you step by step how to do this. It's probably pre-detonating.

[MonsterZ71]

Originally Posted by geozukigti

Back the ignition timing off a couple degrees. A manual will tell you step by step how to do this. It's probably pre-detonating.

Too bad it's not that easy. I have had several of these, and my brother currently has 5 or more. The piston skirts like to break on these things, causing knocking and excessive oil consumption and Blowby.

[westsidex]

But wouldn't it suck to rip apart the engine to change the piston skirts only to find out the timing was off a couple of degrees?

[MonsterZ71]

Originally Posted by westsidex

But wouldn't it suck to rip apart the engine to change the piston skirts only to find out the timing was off a couple of degrees?

It would only knock when accelerating if it was timing. He said "the noise seems to lessen during deceleration". Besides, All you have to do is drop the pan.

[geozukigti]

Very true. Could also be a wasted thrust washer too. There's a lot of things that can knock. Pulling the oil pan and takin a look up her skirt might be your best bet if it's not electronic.

[brianneves]

if you have the 3 banger, check the valve clearances. keep your search simple at first. things like a clogged radiator or clogged fuel injector can cause overheating and lean fuel conditions..... thus detonation

[archieb]

Problem fixed, sort of, the flywheel was cracked. Unfortunately it failed catastrophically and threw a peice through the side of the block. I have found a new engine so it will be back on the road today or tomorrow.

thanks for all of your help

[geozukigti]

Woah. That really sucks. I've never seen a Metro crack a flywheel. My best guess is someone dropped it last time it was apart, or someone pounded on it with a hammer.