Mechanics

TRANSMISSION NOISE

1997 Honda Civic

Transmission problem
1997 Honda Civic 4 cyl Front Wheel Drive Manual 119Km miles

There is an intermittent noise coming from the transmission. The noise is a clunka. Clunka. Clunka type which is in synchronism with the engine RPM ONLY WHEN the clutch is out. The noise occurs in neutral, 1, 2, 3, 4, 5 and reverse. It seems to get quieter in the higher gears. The interesting part is that the noise can stop altogether - and transmission noises sound normal - until the engine RPM reaches about 3000, then the noise restarts.
I have checked the transmission oil level - OK.
Looking into the the bell housing where the release fork is I've noticed what looks like a scoring mark on the pressure plate. With the clutch engaged (pedal pushed in) the noise stops. The pressure plate is still rotating of course but I'm wondering if the plate is loose somehow and pressure on it from the release bearing is pushing it up against the flywheel moving it away from whatever is touching and scoring it.
I hope it is a loose pressure plate and not something internal in the gearbox.
Any ideas?
Jeff.
Avatar
Jeff_Y
October 6, 2009.




Hi Jeff,

Seems smething is loose or has dropped into the bell housing and might require the trans to be removed to verify.

Remove the splash shield under trans and engine to check if you can see anything.

KHLow2008
Oct 10, 2009.
I took the splash shield off. It only revealed the flywheel. However nothing fell out. There is a bit of oil in this area. Looks like its coming from the main bearing seal. The engine oil level has never been a problem though. See pic.
I had another look at the pressure plate. The marks on the plate I mentioned before look more like tool marks not scoring marks.

The only thing I can think of that may have damaged the trans. is driving though flood water. What usually happens is after a few hours is the clutch plate and flywheel become stuck together. After the car is started it sometimes won't go into gear. So I turn the engine off, put it in first, push the clutch in and then start it. The car of course lurches forward until the clutch is unstuck. I cant see the starter generating enough torque to brake trans. parts. I don't remember any trans. noise straight away though.


http://www.2carpros.com/forum/automotive_pictures/418118_Civic_flywheel_2.jpg

AD

Tiny
Jeff_Y
Oct 27, 2009.
Intermittent noise is not likely to be due to trans internal components failing.

From the symptom description, it should be external. Does depressing the clutch slightly cause the noise pevel or pitch to change?

KHLow2008
Oct 27, 2009.
No. Only beyond the clutch take up position does the noise stop. You can hear the noise decrease in pitch to nothing as the momentum of the clutch plate and main shaft spin down. Takes about 1 second. I could make a recording of it and send it to you if you like.

Jeff.

Tiny
Jeff_Y
Oct 28, 2009.
So we can conclude that the noise is present when the main shaft is turning.

Worn trans internal bearings would produce whining noises instead of what you have described. The only possibllity of the described noise is a bad bearing, one of the balls is cracked or rough thus causing the noise.

Looks like you would have to at least drop the trans to check out.

The problem of the clutch sticking after going through floods should not be the cause of the problem. However water getting into the trans or any external bearings would.

KHLow2008
Oct 28, 2009.
Yes, I guess one of the main shaft bearings is the problem. However if I push the clutch in while the car is moving the noise diminishes. Only under load does the noise increase in volume. Looks like I'm in for an expensive repair anyway.
Thank you very much for your time and expertise.

Jeff.

Tiny
Jeff_Y
Oct 29, 2009.
You are welcomed and too bad this is something that cannot be avoided.

Thank you for using 2carpros.

KHLow2008
Oct 29, 2009.

AD