ZF 5HP24 Gearbox Oil Drain and Findings....is it Good News or Bad??

Saint.V8 said:

How much fluid was changed? All or Partial?

If it was all, it may be an idea to drain the fluid again, and see if the metallic sheen is still there....if it is it could be a sign soemthing is wearing out...

If only a partial refill was done, if you drain the fluid you *may* still get a sheen of metal in it as it has mixed with old oil which was carrying it...

With the GM box, oil changes will only delay the inevitable...it won't prevent it!

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Just a suggestion, but was ther anything already on the container that you drained the oil into that might have sat on top of it to give a shine??

It was a complete drain and refill. Will try another one. Excuse the ignorance but is the 'preventative solution' a TC replacement or TC and ?


@ Deasy the sheen was on sump pan once oil emptied from it.

gold rover said:

It was a complete drain and refill. Will try another one. Excuse the ignorance but is the 'preventative solution' a TC replacement or TC and ?

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AFAIK it is a TC and a Valve Block from Sonnax (Or Solex or Sonnex or how ever it is splet!!)

The problem is the original valve block was made from soft aluminium and the valve bores wear...particularly the one that controls the TC Lock Up Clutch....

The wear causes a reduction in hydraulic pressure that controls the LUC, and the clamping force is reduced causing slippage in the TC...the system tries to compensate by modulating the LUC valve more but this continuous pulsing of the LUC Modulationg vavle wears the valve bore more, this causes the LUC to wear...dumping more stuff into the oil, which has a 'Cutting Paste' effect and wears the components in the box more....until the LUCfriction material wears out to metal and you atart getting metal fragments in the box and it basically eats itself....

A new valve block from the company begining with S does a valve block made from better quality Aluminium to prevent this wear, and a remanufactured TC from some one like JPAT or Mackies (I think they do the GM TC - I know they are a ZF stockist) will be the best preventative medicine....but at a cost £££

Thanks Saint. I will quietly start looking into the parts. If she hears me talking about it, she's likely to throw a fault in a strop. Although to be fair she hasn't been as stroppy as some of the others on here. A fuel pump and a brake pipe seems small change in comparison to some