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Noise under acceleration

Posted By: inquirer

Noise under acceleration - 05/27/18 03:48 PM

Car is a Mitsubishi Lancer 1.5L.
Engine: 4A91
Transaxle: F5MGA (Getrag 452)

The incident has happened twice. With the car moving forward a noise that I would compare with the sound of reverse gear (but more abnormal) could be heard. First time loud enough, while in 1st gear, till I came to a stop. Second time it started like during the first time, but it lasted for a whole day. It could be heard with 2nd and 3rd gears engaged too, but again disappeared. (I rolled down the window and paid more attention this time.) It happens only while pressing the throttle and with the throttle depressed stopped immediately.

Any ideas?
Posted By: WyrTwister

Re: Noise under acceleration - 05/27/18 03:54 PM

Is that an automatic or manual . Either way , check fluids .

Just a shot inn the dark .
Posted By: inquirer

Re: Noise under acceleration - 05/27/18 04:02 PM

Originally Posted By: WyrTwister
Is that an automatic or manual . Either way , check fluids .

Just a shot inn the dark .


Manual. The noise was quite loud, so something is going on. But on the other hand it disappeared without intervention.
Posted By: mx5miata

Re: Noise under acceleration - 05/27/18 04:25 PM

do you physically feel a mechanical problem with the transmission?

I had a 91 Acura Integra 5spd it made a reverse whining sound under acceleration but it was just a bad ground in the electrical system.
Posted By: inquirer

Re: Noise under acceleration - 05/27/18 04:34 PM

Originally Posted By: mx5miata
do you physically feel a mechanical problem with the transmission?

I had a 91 Acura Integra 5spd it made a reverse whining sound under acceleration but it was just a bad ground in the electrical system.


Twice 1st gear was stuck, while the car was not moving, and I was not able to disengage it. I'm not sure how I did it. Maybe I rolled the car? I really can't remember. But that was also coincidental.

Furthermore, sometimes I can't engage reverse. I have to depress the clutch pedal and press it again, but as far as I know this is common.
Posted By: mx5miata

Re: Noise under acceleration - 05/27/18 04:40 PM

its common to reverse and still be slightly rolling when first gear is selected and taking off could just be wear and tear on the gearbox and synchros.
Posted By: inquirer

Re: Noise under acceleration - 05/27/18 04:50 PM

Originally Posted By: mx5miata
its common to reverse and still be slightly rolling when first gear is selected and taking off could just be wear and tear on the gearbox and synchros.


Yes, that's what I'm wondering. Does the sound come from worn out transaxle parts?
Posted By: mx5miata

Re: Noise under acceleration - 05/27/18 04:57 PM

worn axles make a clunking/rattling sound when taking off
Posted By: inquirer

Re: Noise under acceleration - 05/27/18 06:10 PM

Another thing I would like to mention, although it may be normal.
When in 5th, the shift stick moves while pressing - depressing the throttle. It does not jump out of gear, but the shift stick visibly moves.
That's something that is happening for a long time, if not since i bought the car.
Posted By: WyrTwister

Re: Noise under acceleration - 05/27/18 06:11 PM

Check fluids . Drain and refill if needed . Look for metal , shiny particles in old fluid .
Posted By: inquirer

Re: Noise under acceleration - 05/27/18 06:21 PM

Originally Posted By: WyrTwister
Check fluids . Drain and refill if needed . Look for metal , shiny particles in old fluid .


Had changed it 2 years ago. I had Motul Motylgear 75W-80 (GL4/GL5, but it said it was OK for yellow metals) for a few years and then I changed to Red Line MTL 75W80 GL4. I have the MTL for 2 years now.

The car requires 1.9L. I used 2 bottles of MTL which is 1 quart each, so actually 1.89L both, but I don't think that makes any actual difference.
The mechanic expected for the oil to reach the filling hole, but it didn't, so he used an allen key to check the level of the oil and he said it was OK.

The problem appeared recently. The 1st time it happened was 1 or 2 months ago. No metal particles visible, as far as I can tell, the 2 times the oil was drained.
Posted By: Kira

Re: Noise under acceleration - 05/27/18 06:30 PM

What is the year and mileage of this vehicle?

I'm guessing a worn bearing within the gearbox. Does your long axle have a "mid bearing"?

Any sheet metal touching a moving part would sound like a scraping, not a "reverse gear" noise.
Posted By: inquirer

Re: Noise under acceleration - 05/27/18 06:42 PM

Originally Posted By: Kira
What is the year and mileage of this vehicle?

I'm guessing a worn bearing within the gearbox. Does your long axle have a "mid bearing"?

Any sheet metal touching a moving part would sound like a scraping, not a "reverse gear" noise.


Around 70k miles.
I have no idea what bearings the gearbox has.
The noise resembles reverse gear, but there is some rattling. It happens only when the throttle is pressed and stops immediately when I take my foot off. The higher the revs, the higher the pitch of the sound. And as I said it disappears without intervention.
Posted By: Trav

Re: Noise under acceleration - 05/27/18 07:10 PM

Does this go away as soon as the clutch is depressed? The Getrag 452 is well know for gear rattle, sounding like a box of marbles go dumped in it, all sorts of noise as they age but none are life shortening.
Check the inner CV joint and for loose heat shields and belly pans and check the engine mounts.

Pentosin MTF 2 works better than every other fluid I have tried in Getrag and ZF boxes (that require a GL-4), it is a GL-4 fluid.
This fluid is the answer to cold weather shifting issues found with some units like VW but is able to handle high summer temps with no problem.
Posted By: JC1

Re: Noise under acceleration - 05/27/18 07:15 PM

Originally Posted By: inquirer
Originally Posted By: WyrTwister
Is that an automatic or manual . Either way , check fluids .

Just a shot inn the dark .


Manual. The noise was quite loud, so something is going on. But on the other hand it disappeared without intervention.


Is the noise loud on a cold start and then goes away once the motor warms up?
Posted By: inquirer

Re: Noise under acceleration - 05/27/18 07:40 PM

Originally Posted By: Trav
Does this go away as soon as the clutch is depressed? The Getrag 452 is well know for gear rattle, sounding like a box of marbles go dumped in it, all sorts of noise as they age but none are life shortening.
Check the inner CV joint and for loose heat shields and belly pans and check the engine mounts.

Pentosin MTF 2 works better than every other fluid I have tried in Getrag and ZF boxes (that require a GL-4), it is a GL-4 fluid.
This fluid is the answer to cold weather shifting issues found with some units like VW but is able to handle high summer temps with no problem.



Well, it happens when the throttle is depressed. When I take my foot off the throttle it goes away immediately. But it happens randomly. It has happened twice as far as I can remember. It is relatively loud, making you thing that something is going bad, but then it goes away.

I had used Motul Motylgear 75W-80 in the past which is a GL4/GL5 and it actually made gear changes easier and softer. Then I switched to Red Line MTL which has the same performance with the Motul one, but it is a GL4 oil.

Probably, I have to check if something is loose too as you said.

Also the clutch release bearing is making a whistling noise. It goes away as soon as I touch the clutch pedal, even with the slightest touch. It isn't very loud, but it is noticeable when the car is not moving.
Posted By: Trav

Re: Noise under acceleration - 05/27/18 09:04 PM

You may just have a throwout bearing going bad.
Posted By: inquirer

Re: Noise under acceleration - 05/27/18 10:21 PM

Originally Posted By: Trav
You may just have a throwout bearing going bad.


I hope it is something as simple as that. As I said when the car is not moving a whistling sound can be heard from the release bearing. That's something that is going on for years. I'm not sure though it is the source of the sound I describe in this thread.
Posted By: inquirer

Re: Noise under acceleration - 05/29/18 03:27 PM

A few points related to the transmission issues:

  • The gear stick moves when in 5th. It goes back when I lift my foot from the throttle and moves forward when I depress the throttle. This behavior is going on for years now. I'm not sure if it used to do it since I have bought the car.
  • 1st gear got stuck once again today. I turned off the engine and with the clutch depressed I easily put the car in neutral. With the engine on though it was difficult, if not impossible, to disengage the 1st gear.

Any thoughts about these 2 issues?

Posted By: WyrTwister

Re: Noise under acceleration - 05/29/18 04:07 PM

Sad to say , but it sounds like you might consider pricing a tranny rebuild or a salvage yart tranny . Or start pricing replacing the car .
Posted By: mightymousetech

Re: Noise under acceleration - 05/29/18 04:35 PM

Originally Posted By: inquirer
A few points related to the transmission issues:

  • The gear stick moves when in 5th. It goes back when I lift my foot from the throttle and moves forward when I depress the throttle. This behavior is going on for years now. I'm not sure if it used to do it since I have bought the car.
  • 1st gear got stuck once again today. I turned off the engine and with the clutch depressed I easily put the car in neutral. With the engine on though it was difficult, if not impossible, to disengage the 1st gear.

Any thoughts about these 2 issues?



For #1. Sounds like it is a shift rod type of shift lever. There will be two actual rods, one at the bottom of the shift lever that does the actual shifting, and a second rod attached to the transmission that goes to the pivot point of the shifter. You have worn bushings on the pivot point rod.

#2 is just a worn clutch not able to fully disengage.
Posted By: inquirer

Re: Noise under acceleration - 05/29/18 04:48 PM

Originally Posted By: mightymousetech
Originally Posted By: inquirer
A few points related to the transmission issues:

  • The gear stick moves when in 5th. It goes back when I lift my foot from the throttle and moves forward when I depress the throttle. This behavior is going on for years now. I'm not sure if it used to do it since I have bought the car.
  • 1st gear got stuck once again today. I turned off the engine and with the clutch depressed I easily put the car in neutral. With the engine on though it was difficult, if not impossible, to disengage the 1st gear.

Any thoughts about these 2 issues?



For #1. Sounds like it is a shift rod type of shift lever. There will be two actual rods, one at the bottom of the shift lever that does the actual shifting, and a second rod attached to the transmission that goes to the pivot point of the shifter. You have worn bushings on the pivot point rod.

#2 is just a worn clutch not able to fully disengage.


1. Are you sure? I read elsewhere that the movement is caused by problems inside the gearbox. If it was cause by the bushings wouldn't all gears jump around? For example:
http://www.vauxhallownersnetwork.co.uk/index.php?threads/gearstick-movement.439118/
or
http://www.rav4world.com/forums/99-4-3-m...tle-pushed.html

2. Worn clutch? You mean either release bearing or pressure plate?
Posted By: inquirer

Re: Noise under acceleration - 05/30/18 07:47 AM

Originally Posted By: WyrTwister
Sad to say , but it sounds like you might consider pricing a tranny rebuild or a salvage yart tranny . Or start pricing replacing the car .


I guess I have to wait and see. The noise goes away without intervention. So I'm not really sure what the right diagnosis is.
Posted By: Trav

Re: Noise under acceleration - 05/30/18 10:53 AM

The stick moving in 5th gear is normal for some manual transmissions. You may have bent pressure plate fingers where some of the fingers so the clutch do not totally disengage.
You need to take it apart, all this guessing isn't helping much as it has to come out anyway. I would do it sooner than later, if there is nothing wrong inside the transmission now there could be in short order running it like this.
Posted By: inquirer

Re: Noise under acceleration - 05/30/18 12:21 PM

Originally Posted By: Trav
The stick moving in 5th gear is normal for some manual transmissions. You may have bent pressure plate fingers where some of the fingers so the clutch do not totally disengage.
You need to take it apart, all this guessing isn't helping much as it has to come out anyway. I would do it sooner than later, if there is nothing wrong inside the transmission now there could be in short order running it like this.


I'm not sure if there really is a problem with it.

If the clutch had issues wouldn't they be permanent? The 1st gear has stuck only 3 - 4 times within a period of lets say the same number of months.
The 5th gear has this behavior for a couple of years, if not since I bought the car. I need to investigate if other cars have the same behavior, if it is normal for some models.
The noise happened only twice and disappeared. It was relatively loud, but again a damaged gear would be permanently noisy.

Taking apart the transaxle would require a few hundred of Euros I guess, so I need to be sure that taking it apart will have results.
Posted By: WyrTwister

Re: Noise under acceleration - 05/30/18 01:02 PM

If you can DIY it , may not be too bad .

I have gotten too old , fat and stiff to tackle a tranny .

Best of luck . :-)
Posted By: inquirer

Re: Noise under acceleration - 05/30/18 02:10 PM

Originally Posted By: WyrTwister
If you can DIY it , may not be too bad .

I have gotten too old , fat and stiff to tackle a tranny .

Best of luck . :-)


I can't do it myself. I don't have the tools, I don't have adequate space, I don't have the experience.
Personally, I don't think that it is something urgent and I can adopt a wait and see approach. I hope I'm not wrong.
Posted By: inquirer

Re: Noise under acceleration - 06/12/18 04:14 PM

I found out what the problem was. I got the car to a garage and they opened the transaxle.

It was a spacer that had started to wear out (both sides) and the input axle was able to move. That's what caused the gearstick jump back and forth while in 5th and that's what caused the noise to come and go. Thankfully no other parts had visible damage!

Just a few points - questions:
  1. I got machined a new spacer at a machine shop. According to the guy the original spacer hadn't gone through a quenching process, but he quenched the one he machined. Probably the new spacer will be stronger, but I hope that does not mean that it will make other parts to wear out.
  2. The guys in the garage used a small amount of grease in order to keep the magnet sticked in place inside the transaxle, while closing the case. Would a few grams of grease alter the properties of the gear oil?
  3. I also got the clutch set changed, because the disc was almost worn out. The clutch makes a clicking noise only when the engine is turned on, that can be heard while releasing the clutch pedal with the car in neutral. The quicker the pedal gets released, the louder the sound. This noise can be heard at the same point where the car starts to roll when in gear. Maybe it also happens when changing gears while driving, but it's not audible in that case. Is that normal or not?


Thanks!
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