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Mercedes-Benz 300-Class, Engine, Fuel System, Diesel, Coupe, Sedan
#677 of 2328 Problems with The Reverse Position of the Transmission
Aug 14, 2005 (1:33 pm)
Hi, I am new at this forum. maybe some of you can give me some help.
I have a 1992 Mercedes 300D Turbo Diesel which recently started with problems on the transmission. It works fine on D position, but on Reverse it takes about 4 or 5 seconds or even more to start moving, and then the reverse shift enters very smothlly and slowlly. When the car starts moving on rear direction, it makes a strange noise like vibration or jerking, till it finally stops the noise and starts working fine. Other thing is that if I press the acelerator down to increase speed before the reverse shift is completely engaged, the car jumps a little before it starts runing right.
I remember I had some problems before with the transmission of the same car and the problem was a vaccum valve that was in stock, do any of you have had a problem like the one I have? Remember that my problem is only in Reverse position of the shift.
Thanks for your help.
#678 of 2328 caliper overheating and "performance"
Aug 15, 2005 (8:13 am)
Greetings, I'm new:
Car is an '82 300 TurboD, converted to run on used veg oil (dual tank, in line heater). No previous eccentric behavior in brakes. Sat. I drove 35 mi. About midway, after accelerating from a stop I noticed a strange vibration that made the rear view mirror vibrate noticeably at 60 MPH. I assumed the worst (car about to fly apart) and was about to pull off when it diminished then went away. Upon arrival I did a walk around and found the driver rear wheel and rotor badly overheated, i.e., spit test produced sizzles.
Next morning's return trip was uneventful, with no excessive heat on that wheel, though I drove slow and tried not to brake much. Short trip to work today normal.
So, I'm trying to figure what, if anything, to fix before embarking on exploratory surgury. I had a similar problem once on another car that was a swollen flex brake line preventing fluid return. Also, and this is a long shot, I drove through some road oil/fresh tar last week, and it ocurred that some might have dripped onto the pads and caused the transient sticking before getting cooked off. Other ideas?
And this followup to a recent post; I bought one of those "performance intake" packages sold on E-bay that was mentioned recently, and can point out some problems. The "K&N style" air filter is a cheap knockoff that doesn't perform well. I was notified of this by a disgruntled user and can confirm, after checking, that the filter lets fine grit into the intake, a VERY undesireable feature. Fortunately, I didn't have it installed too long. I trashed it and bought a legitimate K&N after spending quite a bit of time researching size requirements and getting one that fit the intake pipe. Also, the breather hose to the oil scavenger and intake was too small on the original and that also required a lot of retrofitting. I understand he has this fixed, but I think he is still selling the substandard filters. As for performance, seems about the same, but it does make the engine look good. and things on that side are easier to get to.
Hints about the brake malady are appreciated.
#679 of 2328 Re: caliper overheating and "performance" [pselaphid]
by Mr_Shiftright HOST
Aug 15, 2005 (8:23 am)
Your post isn't clear. You got the vibration while accelerating, or while braking at 60 mph or ????
Spit test doesn't mean anything. Brake rotors get VERY hot in normal operation anyway. Best test is with a pyrometer, then you have a number relative to other rotors.
Anyway, vibration while braking means a warped rotor, and it's not going to un-warp, so if that's what happened, that's one problem you have. What CAUSED the warpage is another issue.
If you got a vibration while ACC-elerating, that's probably a wheel balance or bent wheel or driveshaft issue, but again, those things don't just go away.
#680 of 2328 Re: caliper overheating and "performance" [pselaphid]
Aug 15, 2005 (8:25 am)
I need to add another detail regarding the previous description. After the vibration phenomenon, I noticed that the brake pedal was spongy and non-responsive unless pumped, a sign of brake fluid vapor lock. Brake fluid level normal.
OK, that's it.
#681 of 2328 Re: caliper overheating and "performance" [pselaphid]
by Mr_Shiftright HOST
Aug 15, 2005 (8:27 am)
When's the last time you flushed out the brake fluid?
#682 of 2328 Re: caliper overheating and "performance" [Mr_Shiftright]
Aug 15, 2005 (8:31 am)
Thanks for the quick response. Vibration noticed after reaching highway speed, gradually worsened, then went away, but DID NOT return, either during completion of that trip or return trip, at speeds up to 60. That wheel and brake rotor were the ONLY one of four that was frying pan hot, others could be touched. Car has demonstrated no rotor vibration warpage even during stop and go city driving, when usually it is obvious.
#683 of 2328 Re: caliper overheating and "performance" [pselaphid]
Aug 15, 2005 (8:44 am)
It'll have nice fresh brake fluid by next week!
#684 of 2328 Re: caliper overheating and "performance" [pselaphid]
Aug 15, 2005 (9:14 am)
If your vibration is while braking, check your brake pads- how old are they? They could have debonded from the steel backing plate, or they could be all worn out so that there is metal to metal contact between pad/ rotor.
And get good pads like Mintex or Pagid. I can tell you the friction material makes a hell of a lot of big difference.
I had same problem, and my front pads were debonded.
Tip: If you change pads, put new rotors also- they are cheap now that Chinese stuff is coming in. The aftermarket rotors have more thickness variation than OE (about 20 microns), but still ok, unless you are braking from a very high speed- then could feel some judder; but normal driving ok.
#685 of 2328 Re: caliper overheating and "performance" [brakeengr]
by Mr_Shiftright HOST
Aug 15, 2005 (9:23 am)
Pagid is good, worked fine on my 300D.
You STILL haven't told us if this vibration occurs while you are braking or while you are accelerating.
#686 of 2328 Re: caliper overheating and "performance" [brakeengr]
Aug 15, 2005 (9:29 am)
Vibration, and presumably overheating occurred at full speed, NOT while braking, though I had braked to a stop previously. This was followed, after some miles and disappearance of vibration, by spongy brakes. This is what made the episode so worrisome.