Hello all.

Something for the brainy boys to ponder. The car is a 1991 300CE-24 Sportline with 722.5 auto box.

The car now has 360 K Kms. The gearbox has always worked but has had the odd 4/5th issue that now appears to be resolved, temporarily at least.

The filter and oil were changed 40 K Kms ago and I assume my local garagiste used a genuine MB filter. Oil used was Renaultmatic D2.

Since that, the only new issue has been that of an intermittent refusal to engage reverse. Symptoms as follows:

Car cold, reverse always fine. Engages in less than a second with a positive feel.

Car hot after, say, 30+ km run and reverse is, again, reliable. I have no worries when we're on a long journey.

Also, when working reverse is fine and strong. The box appears to exhibit no slipping of any sort. When it works, it works very well indeed.

However, after a shorter journey when I assume things are warm rather than hot, reverse MAY fail to engage. Some days all will be well but increasingly often it just sits there. There is a suggestion of a change in engine revs as it attempts to engage reverse but then nothing. The only answer then is to switch off and wait for a temperature change (I think). After that, if reverse engages, all is well until the next time.

My current plan is to do another oil/filter change, ensuring that the torque converter is drained too. I cannot be sure this happened last time.

To recap, once hot the box is performing really well, better than ever really. Quite rapid down-changes, strong engagement of all 5 gears, positive up-changes and a strong, positive reverse when it engages.

If anyone has any suggestions (aside from the high priced ones!), I should be most grateful.

All the best to everyone.

RayH

Reverse issues on that auto trans are always internal.

Most likely wear on the reverse clutches OR a weak teflon seal ring.

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Thanks for your comments.

Some of the hot/cold issues I described above have changed during a 400 KM trip today.

Cold this morning, no problem with reverse.

Drove 150 KM and stopped - no reverse.

Drove another 50 KM and stopped - no reverse.

Started up and drove 1 KM - reverse is back and performing like a good 'un.

Thereafter, including some scary moments in tight carparks and heavy traffic - no problems.

I have heard about this teflon seal. Can you tell me more, please?

How easy is it to replace?

My next plan is to change oil (torque converter and box) and filter, ensuring that a genuine MB filter is used. I cannot be certain that the torque converter was flushed last time or that a genuine MB filter was used. Last change was about 45 K KMS ago.

When the box was hot today, I checked the fluid level - slightly above the high mark. This on level ground with engine idling.

Another thing was that the fluid was a pale pink colour and it smelled fresh and fruity with no hint of unpleasant burning smells.

Any further comments much appreciated.

My thanks in advance to all.

RayH