Noisy D16Y7

Does anyone know what to do with a D16Y7 engine that is making noise similar to a diesel engine when its cold (-30C to 5 C). I ajusted the valve clearance (engine cold) to .008"(intake) and .010" (exhaust) but the engine kept making noise! Does anyone has any idea of what could be the problem. The engine is only 170 000 km and apart from that it has always been working properly?!?

Is it affecting the performance of the car at all? Does it hesitate when you start out when it is cold? Turn the car on, open the hood, and listen to about where it is coming from. Is it coming from the top, the side, the back, etc. Might be difficult to tell.

The performance of the engine doesn't seem to be affected by that. But the noise is so loud that you are not tempted to push hard on the accelerator!

Clearly the noise is syncronised with the opening of the valves. So the noise is clearly comming from the top of the engine. I tested that by putting a flat screwdriver on the valve cover with a piece of clothe and putting my ear on the screwdriver handle. That way you can hear clearly feel the vibration source.

I tried adjusting the valve clearance 2 times and the first time the noise disapear for a week and it came back. I think it is related with that mecanism altought the clearance hasn't change since the last adjustment.

Is there another part of the valve mecanism that can by wear out like the springs or anything you ever heard of?

Don't be affraid to get technical... I'm familiar with mecanical terms :biggrin:

I was thinking about this earlier and I thought of some things that might cause it.

If it is indeed coming from the valve train, you might want to remove the entire head of the engine and check to make sure the valve springs are still correctly installed, make sure that valves are properly seated on the valve rockers on the camshaft. One thing that I thought of that would be pretty disastrous is if the valves built up enough carbon deposits on them that it was grinding into the cylinder when the valves open and close(with 170,000 KM on the engine, that is a possibility. Run some of that concentrated Techron stuff from Chevron through it). Another thing that I thought of that might not be good is if the pistons are scraping the top of the valves when they open. That might be an engine timing issue. Of course, the piston would be very very lightly brushing against the valves. Usually having a piston hit a valve is catastrophic to the engine, as I'm sure you know :).
That's a tough one. There are a lot of things it could be! Gives you a GREAT excuse to tear apart your engine, though! :)

I'll think of more ideas and post them.

Thanks for your comments. Maybe it could be the timing issue! The odds of having carbon deposits that would be grinding into the cylinder are very low. I kept the engine very clean since the day I bought the car. Don't know how the other owner was maintaining the engine however?!?

The spring installation could also be a good thing to check.

Another fact is that the noise dissappear when the engine heats up. So it really seams to be a tolerance problem. Unfortunately, the mecanic who did the job after me wasn't able to get right!?! That surprises me because adjusting the tolerance is so simple to do... I don't see how a Honda certified technician wouldn't be able to do that!