1996 MERCEDES BENZ E320 VACUUM VERSUS TRANSMISSION

  • Tiny
  • Mike Petrik
  • 1996 Mercedes Benz E320

Transmission problem
1996 Mercedes Benz E320 6 cyl Two Wheel Drive Automatic 135000 miles

Help! My MB 1996 E320 is acting funny. When traveling at Interstate speeds the RPMs are sometimes at 4000+ when they normally hover around 3000, and altered performance is noticable. You can certainly hear the engine working harder than normal. I emphasize sometimes. I can go a week or more without an incident. It is episodic. I took the car to a highly regarded neighborhood AAMCO (owner been in business for decades and reputedly very knowledgable), and he told me transmission was OK, but car was experiencing vacuum issues (whatever those are), and recommended I take to the dealer where I normally have the car serviced. Dealer then told me I need a new transmission. Who should I believe? The AAMCO would rebuild or replace the tranny more cheaply, but it would be odd to return to request a new transmission after they already told me it was working fine. If vacuum repair/replacement is fairly inexpensive should I do that first and see what happens? If so, do I return the car to my normal dealer/technician and insist on that repair first even though they have told me the transmission is kaput? I'm at a loss as to next steps. Many thanks for your kind assistance.

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Tuesday, December 8th, 2009 AT 1:52 PM

4 Replies

  • Tiny
  • mhpautos
  • Expert
  • 30,587 posts

Hi there,

Thank you for the donation,

I would ask the dealer why they recommend the transmission work, they should be able to give you a written report on there findings, and not just say "do this"if they do, give this information to the Trans specialist for his consideration, if the dealer insist on the transmission work, I would look for a second opinion on the engine tune issues around the vacuum leaks, this can affect transmission operations to some degree, as the trans received power and load input information from the ECU, Having the engine Vacuum system check and getting any repairs done will be far cheaper than the trans, an in any case if there is a vacuum issue this will have to be addressed regardless, best to get this confirmed of discounted first, so I would look for a workshop with Benz experience for a second opinion first.

Mark (mhpautos)

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Wednesday, December 9th, 2009 AT 5:47 PM
  • Tiny
  • Mike Petrik
  • Member

Many thanks. I will find a good Benz specialist and have the vacuum system thoroughly tested and fixed if necessary. I will then proceed with transmission fix only if the problem persists. Appreciate the advice very much.
One last question: should a good independent Benz repair outfit be able to test and repair vacuum system?

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Wednesday, December 9th, 2009 AT 6:12 PM
  • Tiny
  • mhpautos
  • Expert
  • 30,587 posts

Hi there,
Yes this should not be a problem for a Benz workshop, and in any case the basic vacuum system is something that most mechanics should be able to sort out, but just to make sure I would prefer to see you take this to a Benz shop just in case there is something particular to Benz that may need attention.

Thank you for using 2carpros,

Your feedback is always welcome.

Mark (mhpautos)

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Wednesday, December 9th, 2009 AT 6:25 PM
  • Tiny
  • Mike Petrik
  • Member

Perfect, Mark, thank you.

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Wednesday, December 9th, 2009 AT 6:28 PM

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