E36 Scrape/Squealing sound when coasting in gear

[xgeetx]

Hey guys, I'm having a really terrible sound coming out of my car and I'm hoping to get some info on what it could be. I've looked around on various sound threads, but this situation specifically hasn't been covered (at least not that I could find). The sound is a high pitched squeak/scrape oscillating noise that speeds up with higher speed. I can't really tell if it's the front or the back... or somewhere in between. With windows up it sounds like the back, but with windows down I can't honestly tell. The sound only happens when I'm in gear AND coasting.  I hear it most strongly in 3rd gear and reverse. At interstate speeds I don't hear it all. When I hear the sound it will go away if I either hit the gas pedal (disappears instantly), or push the clutch in.

A couple possibilities according to the forums:
- Something on the drive shaft?
- Throw out bearing?
- Other clutch issues
- E-brake scraping?

Does anything I said above rule out certain things and hint towards others?

Thanks for any help you can provide!

 

EDIT: It's a 1998 328i with ~180k miles on it. To my knowledge the clutch has never been replaced.

[patsbimmer1]

What your describing sounds like the throw out bearing.  Big hint is that it goes away when you hit the clutch

[B C]

Throwout bearing is certainly a possibility, though id expect noise while the clutch is pressed and the bearing is under load. 

Can you hear it while rolling at a low speed,  say 5mph? 
 

[xgeetx]

Thanks guys. Snap: that's why it puzzles me so much! But then again, I don't understand a clutch that well (except for seeing diagrams..) since I've never done work on mine. Yes, you can hear it at a low speed, but better in reverse. If i'm coasting in 1st gear at 5 mph it's pretty quiet.

[jc43089]

The most important question is whether it follows engine RPMs or MPH?

[xgeetx]

Hmmmm i will try to test that on my commute home and let you know. I'll listen to it in 3rd and shift down to second and see what happens.

[industrialsized]

i would guess trans output shaft bearing or cross shaft bushing but thats probably not what you wanted to hear

[B C]

 

the throwout bearing receives thrust loading when you press the clutch pedal and it sandwiches against the pressure plate. 

[xgeetx]

Does any part of the clutch take extra load right when acceleration stops but car remains in gear (and the car rapidly starts decellerating)?

 

It didn't sound like it mattered what RPM's were.... just speed. But it's hard to tell over all the engine noise when I mash the gas or downshift. Definitely increases frequency of the oscillation noise when i go faster. Can't tell if the sound is gone at interstate speeds or there are just too many other noises to notice .

[xgeetx]

i would guess trans output shaft bearing or cross shaft bushing but thats probably not what you wanted to hear

 

I would much rather know what it is, than not know what it is! How impossible is transmission work for a DIY'er?

[industrialsized]

a zf for your car can be had for around 200 + fluids +clutch +mount + center support bearing +time you can do it in your driveway in a day so song as you have some basic hand tools and an external torques set. Cracking open and rebuilding a zf is not the hardest thing but its tinkery and the parts cost mucho dollars plus the housing tends to wear maybe your lucky and it's the center support bearing or a u joint on the prop shaft any vibration when you give her full bean? i would say put it up on some jack stands and see if you can get it to make the sound in the air then set the cruse or find a friend and pinpoint the issue

[xgeetx]

a zf for your car can be had for around 200 + fluids +clutch +mount + center support bearing +time you can do it in your driveway in a day so song as you have some basic hand tools and an external torques set. Cracking open and rebuilding a zf is not the hardest thing but its tinkery and the parts cost mucho dollars plus the housing tends to wear maybe your lucky and it's the center support bearing or a u joint on the prop shaft any vibration when you give her full bean? i would say put it up on some jack stands and see if you can get it to make the sound in the air then set the cruse or find a friend and pinpoint the issue

 

Luckily I do currently have the money and time to repair if I want to, the question is whether or not it's going to be worth it. I've already sunk some money into it and I don't know how much more I want to put in . But I Love this car, so I'll probably go for it.

 

Is it safe to put it on jack stands and run the car? I've never done that, tbh....

 

By the way, noticed this morning that the sound is WORST in reverse. Also, in reverse it doesn't matter if I start to press the gas pedal -- the sound doesn't go away like it does in other gears.

 

Thanks for all the help!

[Rowleym]

Luckily I do currently have the money and time to repair if I want to, the question is whether or not it's going to be worth it. I've already sunk some money into it and I don't know how much more I want to put in . But I Love this car, so I'll probably go for it.

 

Is it safe to put it on jack stands and run the car? I've never done that, tbh....

 

By the way, noticed this morning that the sound is WORST in reverse. Also, in reverse it doesn't matter if I start to press the gas pedal -- the sound doesn't go away like it does in other gears.

 

Thanks for all the help!

How much cheaper could a transmission that is incredibly robust cost? My brother picked up 2 for 200$ from Dons sportcars. You should check them out. They will have everything you need. 

Wait a minute is your car clean? Its junk Sell it for cheap.

328's are the best. 

 

[xgeetx]

Haha, I actually deep cleaned it and threw in new floor mats 2 weeks ago I went without floor mats for a very long time. I'm ashamed.

[xgeetx]

How much cheaper could a transmission that is incredibly robust cost? My brother picked up 2 for 200$ from Dons sportcars. You should check them out. They will have everything you need. 

Wait a minute is your car clean? Its junk Sell it for cheap.

328's are the best. 

 

 

Is that a salvage yard? Was it a used transmission then?

[Rowleym]

How much cheaper could a transmission that is incredibly robust cost? My brother picked up 2 for 200$ from Dons sportcars. You should check them out. They will have everything you need. 

Wait a minute is your car clean? Its junk Sell it for cheap.

328's are the best. 

 

 

Is that a salvage yard? Was it a used transmission then?

Used with 100k on them. Yea it's a salvage parts place. Can't really go in the yard unless you know what's up.

Nothing wrong with used items like zf trans.

[xgeetx]

I will definitely look into them. How would I isolate the transmission as the true issue? Pop in with a stethoscope (or are those things a joke ?). I'm also willing to just take it to a mechanic for inspection, but I always like to do the work myself.

[patsbimmer1]

I LOVE my stethoscope!  When I was in a shop that thing was magic!  I got teased ever time I pulled it out but it worked and that shut everyone up lol.  

[xgeetx]

I LOVE my stethoscope!  When I was in a shop that thing was magic!  I got teased ever time I pulled it out but it worked and that shut everyone up lol.  

 

Think it'd help in this case? Do I buy one of the mechanic ones for like $15 then point it against transmission while someone is pushing gas pedal?

 

Is it safe to run back wheels in 1st/2nd while it's up on jack stands?

[patsbimmer1]

It's perfectly fine to jack it up and run it.  Just take every safety step you can to make sure it won't come down.  I usually put all four wheels in the air on jack stands because I am a bit paranoid but it is alright to put 2 jack stands in the back and chock the front wheels.  I usually put the stands under the LCA's in back.

 

The $15 stethoscope works just fine for this job and you just move it around on the case until you think you have pinpointed your noise.  I always listened without it first then with and compared noises.  You may not need anyone pushing the pedal unless it is at a certain rpm/mph.  Once you put it in gear the wheels will spin.

[xgeetx]

It's perfectly fine to jack it up and run it.  Just take every safety step you can to make sure it won't come down.  I usually put all four wheels in the air on jack stands because I am a bit paranoid but it is alright to put 2 jack stands in the back and chock the front wheels.  I usually put the stands under the LCA's in back.

 

The $15 stethoscope works just fine for this job and you just move it around on the case until you think you have pinpointed your noise.  I always listened without it first then with and compared noises.  You may not need anyone pushing the pedal unless it is at a certain rpm/mph.  Once you put it in gear the wheels will spin.

 

You don't need to apply gas in 1st to stop it from dying? I guess that makes sense since it has no car to push... never thought of that.

 

I only have 2 jack stands... would it be it worth it to grab 2 more for this, you think? For some reason I picture 4 stands as less safe than 2 Do I chock both sides of the front wheels to be safest? Never had to jack up the rear, and when doing the front I always had E-brake and in gear so chocking the back I never second guessed.

 

Is there a reason you use the control arms instead of the sides under the jack points?

[patsbimmer1]

I like have all 4 wheels off the ground anytime I work on the car for clearance and safety.  With all 4 off the ground I can give the car a SOLID hip check and it won't move.  If you are only going to lift the back I would put a chock front and back of at least one wheel.  That's how I have done it and I have never had an issue.

[xgeetx]

Hmmm well I like safety. We're working on my GF's exhaust soon, and we could barely get under with only the back or the front popped up. I think $26 for more stands would be well worth it. Good tips, thank you.

[jc43089]

I would recommend a pair of 6 ton stands, the footprint is much larger and more stable then the smaller 3 ton stands, I have 2x 6 ton stands and use 2x 3 ton stands so it is more stable when yanking on wrenches etc underneath.  They can be gotten at for not much more cost and saving a few bucks won't matter much if a car falls on you.

[xgeetx]

Can i have 6 ton stands on one side and 3 ton stands on the other, or would the height not match up?

[jc43089]

Use them in pairs on an end of the car, ie 6ton in back and 3 ton in front.  My 6 ton are about the same height at the shortest setting as the 3 ton on their longest height, so I usually have the 6 ton at the lowest or one notch up and the 3 ton extended most of the way.