mine's still stuck somewhere in the same area, but i can't see or reach it. Unfortunately, I can always hear it.

 

I just got back and it's sooooooooooooooooooo nice not having this rattle anymore!!!!!! I can actually enjoy the beautiful sound of the motor!

 

there is a replaceable rubber gasket on the oem oil cap, when it wears out the cap can loosen while driving if it isn't snugged down enough. If your cap has come loose on it's own check to see if the rubber gasket is still visible, if not replace the gasket or get a new cap. When I bought my car the rubber gasket was worn away and the cap never felt right when it mated up to the valvecover, I put on a new cap and it snugs down nicely now.

 

Do you have the part number for that ?

 

I see it listed on majestichonda.com , check the oil cap part on their parts diagram for the valvecover menu and you will see the gasket identified. It might be just as easy to get a new cap but they do list the gasket as a part.

 

Been there, done that. It feel on top of the transmission and i went to knock it out with something and i knocked it down on top of the header under the car... it was a PAIN IN THE ASS.

 

Well I too am in the same boat now. Made the rookie mistake of working late at night in a hurry. All finished up with the oil change and carelessly dropped the oil cap. It was wedged between the back of the engine and firewall as others have described. I had it in my hand and bumped a wire while pulling it out. I watched it fall down out of my hand, bounce off the top of the tranny, and shoot under the firewall. I cannot see it whatsoever.

I got a replacement oil cap for $5, realizing that it's just the tranny housing and exhaust pipes down there. It shouldn't hurt anything. I was driving and I can hear it rattling around under the dash in front of my shifter; it's such a ridiculous noise (somewhat amusing when not reminding me of so much fail). Part way though my drive to work, I hear it shift positions. I hoped it had fallen out, but it seems to have just shifted to more confined location. It is not making the outright rattle in front of my shifter, but it seems to be reacting with the vibration of the tranny and probably against the exhaust. It sounds as if the car is running rough, just some added vibration at idle and extra noise while driving.

I went to my mechanic to get the car up on the lift. We couldn't find the cap, even with a mirror and light looking around. But he confirmed that it's not interfering with anything. The added noise makes me think the car is running very rough when I'm trying to tell myself it's just the oil cap. If I can't find the cap today I suppose I'll go back to the mechanic, have him drive it, and see if it's worth it to pursue a more involved method of removing the cap. Possibly lowering one of the tranny mounts as someone here has stated. I do not have the means to do that myself.

If anyone has any other suggestions for attempting to locate the oil cap. Please let me know. It was likely on top of the tranny, under the firewall. It sounds like it changed positions during driving. It probably fell to one side of the tranny and likely got wedged between the tranny and exhaust pipes.

 

you could lower the rear of the trans 3" or so...no more. That cap will not come out until you remove it.

It is between the transmission and the firewall/car body/transmission tunnel.

 

Thanks Billman, quick and helpful as always!

 

Recovered my oil cap last night.

I had bought a $5 one from Autozone and been driving to work. I knew the cap wouldn't interfere with anything important, but the noise was driving me absolutely nuts. Idle sounded rough. Car vibrated at idle. Exhaust sounded loud.

Yesterday I lifted the car to unbolt the transmission brace to drop it down a couple of inches. I had some s2ki threads as a reference, they were mostly for replacing clutch, or one was to replace motor and tranny mounts. As stated in the tranny mount replacement thread, it is necessary to move the catalytic converter. I was concerned with unbolting the spring bolts because I wasn't sure if I would be able to reseal it properly. So I decided to put it off until I had proper materials/tools.

So I did some more prodding around under the car as I have been doing, attempting to locate the cap. I finally saw it, just barely, looking from the top under the hood from the front driver side wheel. I put the flashlight at my nose so it points in the view of my eyes. I looked at just the right angle to bring a small part of the cap into view. I found the cap lodged on the transmission, as everyone here has described, but maybe 4" inches behind the firewall on its side lodged in a crevice between the side of the tranny bell housing and the exhaust pipes. I knew it was there, but I could never see it until now.

I bent a coat hanger to be straight with a little hook at the end. I managed to hook in one the cavities formed on the underside of the ergonomics around the oil cap. I yanked the hanger firmly to pop the cap out of its crevice and closer to the driver side of the car, away from the obtrusive exhaust. From there it was just 10 minutes of tediously reeling it in. It seemed possible to pull it from under the car at that point, but I fished it out of the top with two wire hangers.

Everything is back to normal now. All irregular noises have ceased. I am surprised how many different sounds I heard while that cap was down there. I heard rattles, felt extra vibrations, louder exhaust. it was hard to believe that so many different sounds were just a product of a vibrating oil cap.