Friend has a 2000 prelude and he runs a 75 shot. After the track one night it starts making a horrible knocking noise. Now the motor has been running like this for a month and it has not gotten worse and there are no metal shavings in the oil. So I don't think it is a spun bearing.

The spark plug was destroyed on cylinder 4. Missing parts of the electrode and some of the porcelain. Compression tested out fine. consistent across all the cylinders (within 5psi of each otehr) and the number was pretty high 240's.

I inspected the valve train, valve adjsutment was ok and no rocker arm nuts were backed off. None of the retainers appear to be cracked.

The motor still runs ok but the knocking is pretty loud especially at idle. Sounds like it is coming from the middle of the motor where the head meets the block or under that.

Does anyone have any ideas.

TIA

 

That would most likely be rod knock, check your oil pressure at idle and 2500 rpm, checke it with the specs on ths service manual

 

it could also be a real bad piston slap.

 

How about tell him not to drive it until he can find out what's wrong with it.

I hate to say it, but I'll be the first to laugh when you come in here and say "my friend shot two rods and 7 1/2 valves halfway to Alaska last night."

Knocking isn't supposed to happen... ticking, clicking, clacking... maybe acceptable. Loud *** knocking? WTF is he thinking?? It's just gonna go away??

My vote is for a bearing. You squeeze... you gamble. He lost. Maybe he should read my thread about modding your lude.

 

I've worked on alot of cars with rod knock and this isn't rod knock. My thoughts were that the piston has a piece of the spark plug lodged into it and it is slapping the head. The sound is kinda hard to explain. I'm going to begin troubleshooting today so I'll tell you all how it goes.