Strange vibration when wet...

[Julio Bro!]

Hello everyone!

I have a 93' 240SX SE, mannual transmission, with 2.5" tubing and Random Tech cat.

During the past 2 or 3 months everytime it rains a lot and I go over some puddles a rapid hitting, kind of hard bubbling, noise and vibration is felt directly under the driving seat.

At first this was very troubling to me because I thought it had something to do with the shaft, but that's located at the middle of the car and this thing is happening just under my seat. So then I noticed it happens only when going over some water, and I don't mean flood puddles, I mean very small patches.

I'm thinking it could be water evaporating rapidly over the cat, is that possible? Anyone have had this one?

[98TURBOKA]

Are you sure that it's not just water hitting the floor board underneath your feet?:D

[Julio Bro!]

Are you sure that it's not just water hitting the floor board underneath your feet?:D

Come on man, I've had the car for almost 10 years and I've drive through hurricanes and once I submerged the car almost entirely in a big pond. This is new.

[yellow_jacket]

If you are having a problem in the rain then it might actually be a run condition. Remember, things like spark plug wires can short out easier when it is humid or wet out. It may be causing a temporary misfire. Check for that first. Vibrations run though metal very easily.

[Julio Bro!]

Hmmm, my plug wires are a Magnecor set that I bought last year, fairly new; but it's a possibility.

How can I check if that's the case.

[undertaker]

have look for something loose under the car. i had a poorly mounted exhaust once and certain puddles would knock it onto the driveshaft bracket or rear swaybar transfering vibrations through the whole car. it took a while to track it down because it would mysteriously fix itself.

[p00t]

do u have abs?

[Julio Bro!]

do u have abs?

No ABS.

[Julio Bro!]

have look for something loose under the car. i had a poorly mounted exhaust once and certain puddles would knock it onto the driveshaft bracket or rear swaybar transfering vibrations through the whole car. it took a while to track it down because it would mysteriously fix itself.

I know I'm late answering this, but I need to thank this post because that was exactly what it was. I did a 2.5" exhaust tubing, eliminating the resonator. This part had a thin bar connected to a hanger attached to the under chassis of the car at the drivers side; this was eliminated along with the resonator.

Yesterday I went to the shop and explained the situation and asked to add a hanger there. First they made a wider gap between the tubing and the underside of my seating area, that's where the vibration and some banging felt more, then used a universal bar/hanger to weld and attach in the same area where the resonator used to be. The universal bar/hanger is a nifty thing that can be used for any place in the exhaust system.

And that was it, no more banging or vibration, thanks Mr. undertaker.

[undertaker]

no problem JB, glad i could help:)