transmission Noise

Post by **AHall** » Thu Nov 21, 2002 2:42 pm

I am hearing a metallic rattling type sound when I am sitting idle at say a stop light with my car in neutral and my foot off the clutch. When I press the clutch, the noise stops. Does anyone have any idea what could be causing this noise? The noise started more than a year ago. I recently replace the clutch master cylinder, however I believe this was unrelated, as the noise has persisted. My car shifts fine into and out of gear.

Also, periodically, when my car is in gear and I am coasting with the clutch pressed in, I hear a "wincing" noise. Sounds kind of like a dog whimpering. This noise also sometimes occurs when I am putting the car in gear or taking it out of gear while I am rolling, like a rolling stop. The problem seems to come and go with cold weather maybe.

I have a 93 240sx with approximately 170,000 miles. I purchase the car as a demo with 5,000 miles on it and it has been a pretty good car over the past 9 years. I have never had to replace the clutch or had anything done to the transmission. I am not a hard driver as I usually shift around 2500 rpm's.

Any help or comments would be appreciated!!!!!

Post by **PapaSmurf2k3** » Thu Nov 21, 2002 2:42 pm

This doesnt explain why it only happens in neutral but, maybe its your transmission to exhaust mount. Mine broke and would make a rattle noise pretty often. It seems to me its not a needed item, so i just cut mine off and no more rattle.

Post by **AHall** » Thu Nov 21, 2002 2:42 pm

Thanks for the response. Does anyone have any idea what the wincing noise could be. Perhaps something if loose in the transmission? Hence the rattling. The wincing may be caused by something loose getting turned until it is tight? Like when the car is out in gear? Not sure, what do you guys think???

Post by **QuinGarcia** » Thu Nov 21, 2002 2:42 pm

The first thing to look for with the rattling is stuff attached to the drivetrain, as the other fellow said, check the rattling mounts, check the heat shields for the exhaust system as well, these can become loose. Trying getting under the car and listening for where exactly the sound is coming from. If you determine that it is infact coming from the front of the transmission, I suspect that the input shaft bearing at the frnt of the transmission case is done for. I say this because when the engine is running with your foot off the clutch and transmission in neutral, the input shaft is still spinning. That could get expensive for you.The wincing: I am not sure what wincing is, but manual trannys often whine. When they whine, it is often just bearing noise in the transmission which doesnt necessarily mean bad things. The sychronizers will also whine when you make them work. My transmission in my 90 240sx whines quite often, and it is fine. Synchros will whine when you are putting the car into a different gear, and the engine speed is not perfectly matched to the tire speed. It doesnt mean something is broken. However, if the wincing or whining is very loud, I have a feeling you have some bearings going bad, or syncros going bad. But, bad syncros often cause the gears to grind when you switch gears. It is also a possiblity that this wincing is caused by the same culprit as the metallic rattling you mentioned earlier. Unless something is rattling, in the drivetrain, I have a good feeling you will have to replace that input shaft bearing, or even get a full rebuild. Take the car to a shop that rebuilds manual trannys and they'll tell you whats wrong. good luck

Post by **sxse** » Thu Nov 21, 2002 2:42 pm

I think I know what AHall is trying to say cause my transmission makes a funny noise only sometimes too

AHall, Is it kind of a warble/shudder noise? mine does it around 2000 RPMs but only sometimes...

Post by **Touchdown038** » Thu Nov 21, 2002 2:42 pm

Sorry to bring this thread back, but mine is making the same noise with the clutch engaged in neutral, a whirring sound. But it also makes the noise when I put it into first when I'm rolling to a stop with the clutch disengaged. Does this still sound like the input shaft? NISTECH?

Post by **NISTECH** » Thu Nov 21, 2002 2:42 pm

if its making the noise with the pedal down,throw out bearing. if its makeing the noise with the pedal released and it is all the time except 4th gear internal trans bearing.

Post by **taskertown** » Thu Nov 21, 2002 2:42 pm

My 89 240SX coupe with manual transmission makes a noise with the clutch pedal released in all gears except 4th. From the message above this would mean it is a bad "internal trans bearing"

I am assuming that the transmission would have to be rebuilt. Is that something I can do myself using the FSM?

Thanks

Post by **NISTECH** » Thu Nov 21, 2002 2:42 pm

you would need a hydrolic press to do it. but you may want to consider either a used trans or a new one from the dealer since by the time you replace all parts that appear damaged by the loose metal inside it may cost you more then a used one and quite possibly a new one. If you get a used one be sure to get a 30 day minimum guarentee on it so you can swap for another if that one has a problem.

Post by **taskertown** » Thu Nov 21, 2002 2:42 pm

Thanks for your response.

I am going to attempt rebuilding the transmission myself. I have had the car since October 1988 and plan on holding onto it indefinitely. So, I figured it would be a good idea to learn how to do it in case I have to do it again many years down the line.

Don't want to replace the transmission as I would like to keep the car original as much as possible.

Any pointers on what to watch out for? I coudn't find any service manuals specific to the transmission with a search on Google. I do have the FSM.

Thanks

Post by **NISTECH** » Thu Nov 21, 2002 2:42 pm

do you have a hydrolic press? get a factory service manual if you intend to do this. you must follow the steps and set up your spacing properly. pay close attention to the detents when you pull them out. they are different sizes and must go in exactly as they came out.

Post by **taskertown** » Thu Nov 21, 2002 2:42 pm

I have access to a hydaulic press.

I do have the Nissan Factory Service Manual for the 1989 240sx - with a chapter on manual transmissions - major overhaul, disassembly, inspection, and assembly.

When I disassemble the transmission, what exactly am I looking for? How do I know which parts need to be replaced?

Thanks

Post by **NISTECH** » Thu Nov 21, 2002 2:42 pm

the bearings for sure the rest will need to be inspected for chipped teeth and worn syncros.

Post by **taskertown** » Thu Nov 21, 2002 2:42 pm

Thanks for your help!

Post by **djtomr941** » Thu Nov 21, 2002 2:42 pm

I was thinking definitely a throwout bearing if it is a manual. If that is the case have them replace the whole clutch. You can find kits usually pretty reasonable. I bought a clutch kit on ebay for 90 dollars. I put it in and after 10K it is running GREAT!!

Got the Clutch, Pressure Plate, Bushing, Alignment tool and throwout bearing. But buy from someone with good feedback if you go the ebay route.

Post by **Touchdown038** » Thu Nov 21, 2002 2:42 pm

djtomr941 wrote:I was thinking definitely a throwout bearing if it is a manual. If that is the case have them replace the whole clutch. You can find kits usually pretty reasonable. I bought a clutch kit on ebay for 90 dollars. I put it in and after 10K it is running GREAT!!

First of all, it's not the throwout bearing making the sound if the sound is happening while the clutch is engaged. The throwout bearing isn't even touching the pressure plate.

And I think he's already decided about rebuilding the transmission.

Thanks for the input though.

Post by **djtomr941** » Thu Nov 21, 2002 2:42 pm

I Apologize I was replying to AHALL and someone else hijacked onto this thread. THis was not in response to them

And also the Tech says

Quote »if its making the noise with the pedal down,throw out bearing. if its makeing the noise with the pedal released and it is all the time except 4th gear internal trans bearing.[/quote]

You and him are saying 2 different things.

Post by **NISTECH** » Thu Nov 21, 2002 2:42 pm

actually now that you mention it djtomr941 it has been jacked twice. I didnt catch it the first time and the second time I let it go. but you make a valid point it should not have been jacked even if it was 2 months since the intial thread starter posted. I will leave all of it since there is useful info throughout the thread. Guys please try to create your own threads. it makes it easier for replying as he pointed out it added confusion.

Post by **taskertown** » Thu Nov 21, 2002 2:42 pm

Sorry. My mistake. Did not know the rules of the forum.

Actually it is a year and three months since the original post!

Post by **Touchdown038** » Thu Nov 21, 2002 2:42 pm

djtomr941 wrote:You and him are saying 2 different things.

No, we're not. We both said that pedal down, if it makes a noise, throwout bearing. taskertown said that his noise comes when the pedal is up, therefore eliminating the throwout bearing as the culprit.

Sorry, done hijacking thread now.

transmission Noise

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