300CE-24 + 722.5 box

[ray_hennig]

Hello all.

Something for the brainy boys to ponder now that the evenings are drawing in.

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.

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

All the best to everyone.

RayH

 

[grober]

Looking at the specs of RENAULTMATIC D2 --- its made by ELF by the way,--- it seems very similar to Fuchs TITAN Dexron II and III autotransmission fluid spec in terms of viscosity/temperature gradients. However in the Renaultmatic D2 app notes it does warn " Do not use ELF RENAULTMATIC D2 in the automatic transmission or power assisted steering steering fitted to other makes of vehicle? " http://www.elfoil.com.au/admin/Products/ProdPDF/elf_Renaultmatic_D2.pdf

Selection of reverse in that box normally involves brake B3 and clutch K2 but since B3 is unique to reverse whereas K2 is used in 4th and 5th gear it points to B3 There are various working pressures in the system of which the so called Working pressure is the highest--co-incidentally its the pressure used by B3
I guess its possible the new fluid fails to reach operating pressure within a certain temperature range and thus fails to engage B3 ???

First thing is to change back to a fluid that has definite MB type approval such as Fuchs and see if the problem goes away.

 

[ray_hennig]

Thank you Graeme

.First thing is to change back to a fluid that has definite MB type approval such as Fuchs and see if the problem goes away.

Yes, this is what I'm thinking (or hoping) but for less scientific reasons than you - my thanks for that.

The Renault fluid went in early in 2008 and I'm dashed if I can recall whether I had the reverse problem before that. As you say, it makes sense to try 100% correct fluid and filter before assuming the worst.

Also, I can't help feeling that they might not have drained the torque converter - in a way I wish they hadn't! Although they did itemise 6.94 litres of fluid and that sounds about right for box and converter.

Oh well, we shall see.

Thanks again and bon courage.

RayH

 

[ray_hennig]

More developments ...

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 a teflon seal that can cause issues. Can anyone tell me more, please?

How easy is it to replace?

As already said, 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.

Is there any cause for cautious optimism or am I deluding myself?

Any further comments much appreciated.

My thanks in advance to all.

RayH

 

[jeremy 2516]

I used to have problems with second to third in my W124 320 that went away after we drained and flushed the tranny oil twice and renewed the filter twice . This ensures a nice clean inside to your 'box .