Hi all,

This is in my 1980 240D. Over the past several months, I have noticed a growling at higher RPMs in 2nd and 3rd gear. The noise is not apparent at high RPMS in 1st or 4th.

I found a ripped reat axle boot, and had hoped that was the cause, but replacing the half shaft didn't quiet the noise (also had hoped new differential lube mioght help, but it didn't.

So next, I replaced the transmission oil. I had put Mobil 1 10W-30 in about 4 years ago. The Mobil 1 had a rusty color to it when I drained it. I replaced it with some dino 10W30.

Before pulling out the flamethrowers, I will mention that the original owner's manual specifies 20 weight oil in the gearbox in my model, so I followed MB guidelines (as best I could - 20 weight oil is not carried by anyone around my neighbourhood).

Now I am thinking about trying a heavier weight oil in hopes it will quiet things down. I line in a warm climate, so viscosity is less of a problem. Usually when I have read about people switching to Redline MT, they talk about quieting synchomesh during shifting. Not sure if that oil would also help quiet the tranny at other times?

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

It may help. Gear noise is usually symptomatic of a bearing(s) on its way out.

__________________
'83 300D, 126K miles.

do you "feel" anything when shifting or clutching? it sounds like input or output bearings to me... rust colored oil is not a good sign...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Mostly what I have read is these transmissions use ATF. when you drained the 10-30 4 yrs ago, what came out. If it had atf previously then maybe the new oil picked up some residual atf and colored it.

The noise sounds like maybe a bearing starting to go. there is a couple bearings behind the front cover, and looks like one on the Out Put Shaft and a couple more inside looking at the good old "Haynes manual" view of the innards.

When I was around 200K miles on my Datsun PU 5-spd, I developed a whine in the box coming back from Salt Lake City to Calif. Pulled the box and discovered one of the bearings behind the front cover was on it`s way out. this I guess let the Input Shaft drop enough to change the way the gears rode together. changed all the bearings and all has been good. now up to 473K miles.

Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

@vstech - Shifting is totally smooth. Better now than it was before I changed the oil 4 years ago. When in gear, there is a bit of a delay between or releasing or pressing the throttle and feeling the car respond. I have played with the throttle unter the hood and the engine seems to respond right away, so the hesitation is in the power trnasmission. My other 240D does this too, but much, much less severely. I recently replaced the clutch cylinders due to a weird depressurization problem. I did not see any obvious leak, but the rubber diaphragm had little dry-rot like cracks in it.

The depressurization would only happen after a few minutes of sustained high RPM driving. There was not brake fluid leaking out anywhere, so I suspect that at high RPM some of the brake fluid was moving through the diaphragm into the tranny. That might explain the off color of the oil?

@charmalu - I think it might have been ATF, but it has been so long now. Like I said, it could be some fluid from the clutch that colored the oil.

Is replacing the bearings DIY or a transmission shop job?
How can I tell if the bearings are shot?
Why would failing bearings only affect 2nd and 3rd gears?

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

There is no way Brake Fluid can get inside the Transmission.

Charlie

__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

a delay? that's gotta be a clutch problem. either the clutch disk has fluid on it, or the pressure plate is wonky...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

@ charmalu - Where would the fluid go if it leaked out of the diaphragm?
There was definately a leak in the clutch system, and the master was completely dry, as were all the lines and junctions. The only place I saw anything odd was the diaphragm on the slave cylinder. There was never any fluid or even wetness on the transmission housing, below the car, or on the slave itself.

Replacing the slave (and master) solved the problem. No more pressure or fluid loss.

@vstech. Why would the clutch affect throttle response while the car is in gear and moving?

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

If there is fluid on the clutch contact plates, they will slip a bit until they finally catch, and then you will get an effect much like sudden throttle response.

If the pressure plate is wonky, then it may hang or not fully apply force to the clutch contact plate upon release of the clutch pedal. This would be like driving with the clutch pedal depressed just a bit or "riding the clutch". The throttle response effect would occur when the pressure plate finally seats the contact plate.

__________________
2013 Volkswagen Jetta Hybrid SEL Premium (Sparky)
http://badges.fuelly.com/images/smallsig-us/193500.png

It's a car not a science experiment! Open the throttle!

Would this happen over and over again without reapplying the clutch? That is my situation.

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

Maybe not the transmission, but a leaky slave cylinder could bleed DOT 4 all over the chamber (bell housing) where the flywheel and clutch are located.

I suppose if the front seal of the transmission input shaft were really worn, and you were dumping buckets of DOT 4 into the Brake/Clutch Reservior (my '77 uses it for both Brake & Clutch), then, you might possibly have brake fluid in the transmission, but not before the clutch and is swimming in the stuff.

__________________
2013 Volkswagen Jetta Hybrid SEL Premium (Sparky)
http://badges.fuelly.com/images/smallsig-us/193500.png

It's a car not a science experiment! Open the throttle!

In the former case (fluid on clutch contact/friction plate) yes, untill you burn/wear off all of the fluid on the plate and flywheel. I'm not certain that you should experience this issue with every shift though.

In the latter case (wonky pressure plate) yes, and fixing the other issues (pressure loss & such) will not alleviate a wonky pressure plate.

I'm guessing that your pressure loss was a leaky slave cylinder and that the clutch may have had a good shower of DOT4 for a while. If this is the case, then it's just a matter of time before the problem goes away.

It sounds like your noisy 2nd and 3rd gear are probably the jack shaft bearings. I suspect that 1st and 4th are nice and quiet, right?

I had this issue and found a decent scrap yard replacement transmission and swapped them. I've been running synthetic gear oil in the 'new' tranny without any issues.

Either way, you will only know for sure about your clutch issues, if you drop the transmission for replacement. If you are going that far, you can replace mounts, flex disks and check your center shaft bearing.

__________________
2013 Volkswagen Jetta Hybrid SEL Premium (Sparky)
http://badges.fuelly.com/images/smallsig-us/193500.png

It's a car not a science experiment! Open the throttle!

1st and 4th are nice and quiet. So jack shaft bearings....that is the same as the drive shaft bearing ? Google didn't help.

Why does this only affect 2nd and 3rd?

RE: clutch - I suspect a wonky pressure plate as the hesitation problem remains a month after slave replacement. Not too keen on replacing it till it fails unless there is a reason otherwise.

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

It's the opposite, what I am talking about happens when I am NOT shifting. For example....I am in 4th on the Highway at 70 mph. I overtake a car in my lane (yes I can do it in my 240D ) and abruptly take my foot off the throttle. The car continues without changing speed for a split second, then lurches and slows. If the approaching car moves out of my way and I abruptly reapply throttle, the car waits a second at slower speed, then 'kicks' and accelerates. No clutch applied. I can avoid this by being less abrupt o nthe throttle.

That said, the slave was replaced a month ago, so I expect there is no more brake fluid on the flywheel.

But, the more pressing issue...

Jack shaft bearing....is that the same as the driveshaft bearing?

It is indeed nice and quiet in 1st and 4th. Why is this the outcome of a driveshaft bearing failure (instead of consistent noise across all gears)?

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

Hi!
The Mobil 1 10w30 is an engine oil, don't use it in the gearbox. The gearbox oil is hydraulic fluid (Mobil 1 Synthetic ATF).