The first thing I did when I bought this '96 EX Coupe was take it in and have a guy I know at the local dealership perform a timing belt replacement job on it, which included the water pump and seals and the whole nine yards. I also had him adjust the valves and replace the valve cover gasket while he was in there. At the time I took it in, the car needed a new muffler and when I got it back I noticed it was very loud in the 1750 to 1850 RPM range when accelerating. I just figured the muffler was the source of the noise. Well, a few weeks ago I had the muffler and resonator replaced, but the rattle and/or vibration is still there. The guy at the muffler shop worked with me for nearly an hour and a half to try and isolate the source of the rattle, but could not find a definitive source. His best guess was that there is a slight crack in the manifold somewhere because when the car gets hot on a real warm day it almost completely disappears. When you first crank it up in the morning (when cold) it is very noticeable. The cat is solid and all the heat shields have been removed... so they can't be the cause. I'm almost inclined to think that it IS the manifold, however, I don't want to go spend the money on a new set of headers right now if I can get away with it. I called the guy at the dealership and talked to him about it, and he said that it could be piston slap... that all the Accords and Integras do it when cold... basically that the piston rattles around inside the cylinder when you first crank it up because the components haven't had time to heat up yet. Well, I've been around a few Accords and I've never heard of that before, and with the manufacturing tolerances Honda has with their engines, I'm inclined to call BS on this one. I'm wondering if there's anything that could have been done wrong with the timing belt replacement that could cause this. When the car was up on the lift at the muffler shop, you could visually see the vibration in the downpipe when the vibration set in... I'm just at a loss... any ideas?

Thanks!

 

Do you think the noise/vibration is originating from the engine? If it started after the timing belt job, the balance shafts may not be properly aligned and that could cause some vibrations.

 

most likely your heat shield is loose on your cat. The dealer can fix it by placing a strap around it. Check that out first. the 94-97 cars are notorious for this problem.

 

It might just be a resonant sound. The entire exhaust system vibrates all the time and it vibrates at a certain frequency. If you are hitting this frequenc at the 1800RPM range, then you will hear a sound and there isn't much you can do about it unless you are an engineer.

 

yea i bet it is the cat too. its tough to say though without hearing it.

 

 

I was wondering about that... the noise DOES sound like it's coming from the engine, but with someone holding the throttle open to that RPM it doesn't sound like it's originating from any one given spot... and to describe the sound a little better... imagine if you left the hard plastic handle of a screwdriver INSIDE the plastic timing belt cover (I would seriously doubt that is what it would be... just trying to describe the sound)...

 

Hondas put out a couple fixes for it over the years but nthey dont seem to last very long if they do anything at all. The noise originates from the short section of pipe between the a-pipe and the cat. We just tell customers it's a normal characteristic of the cars.

 

Well... if that's the case when I put headers on it the problem should be eliminated, correct? I just don't want to go throw money at something when I don't know what the problem is.

 

bulletin # 94-041,, effects 94-96 accords,,

it says to replace gaskets, bolts, nuts and springs on the mid pipe ,,, ( the small exh pipe between frt pipe and cat )

Now i do not know if that is exactly the noise you hear , i would have to listen to it to confirm it , but it sounds like the same symptom