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Model: 2005 Volvo S40 2.4i / 5 speed automatic Mileage: 127k Miles / 3rd owner Transmission service history: not even changed ATF Other relevant services: replaced all engine/transmission mounts last month.

Hi,

I am experiencing an occasional issue when shift between R and D. Check engine light doesn't show any problem. The symptoms are:

  1. Delayed engagement for 1-3 sec, with slight engine rev up by ~100 rpm. Mostly when shifting to D.
  2. When engagement happens, it is abrupt and harsh with a bang under the engine bay, as if the vehicle is jolting.
  3. The problem only happened after driving for around thirty minutes. Cold start and shifting are smooth. However the problem persists after warm restart.

I asked a mechanic to check ATF, which is adequate and fresh, surprisingly. And I contacted a Volvo dealer, who says, over the phone, this is more likely a solenoid/valve body problem. He also suggest me keep driving until I need a rebuild.

Currently I am looking into the following solutions:

  1. Change/flush ATF
  2. Updare TCM
  3. Check/replace solenoid

Please provide your opinions about the root cause here, and how to fix it. I really appreciate the help!

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  • Welcome to Motor Vehicle Maintenance & Repair! If you are looking for us to tell you what to do, I think that is really up to you and your pocketbook. If you have a question about fixing the issues or if you are on the right track, you should change your question accordingly. Dec 21, 2017 at 3:13
  • As you say you changed the mounts - check that they are still tight and correctly located - that may be part or all of bang / jolt you mention.
    – Solar Mike
    Dec 21, 2017 at 8:15
  • After I changed the mounts, I do notice the vibration has been reduced from transmission to the cabin. However, what would cause the shift delay?
    – wenduowang
    Dec 21, 2017 at 23:43

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