P38 dse lost drive

Whilst towing trailer today, auto box has lost dive. If I put in low box it will try but at high revs. Oil level ok and was running ok as was just on motorway at 60mph with 2k revs, any ideas where to start looking would be appreciated, Thanks

Oil and filter change would be worth a shot.
Try setting off in 2 or 3. If that works OK, your sprag clutch has probably failed.
Does it drive OK in reverse?

Wazzajnr said:

Oil and filter change would be worth a shot.
Try setting off in 2 or 3. If that works OK, your sprag clutch has probably failed.
Does it drive OK in reverse?

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Thanks, No drive in 2nd or 3rd and just about moves in reverse, new oil and filter about 1k ago

@jamesmartin is very good with these boxes. He would know. Any noises?

Grrrrrr said:

@jamesmartin is very good with these boxes. He would know. Any noises?

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If you put into reverse and rev sometimes get a bang noise and some drive, also did it once in forward, cheers

Could be either the transfer box or the auto box as there is no drive at all, maybe the chain.

Would putting it into park only and trying to push it prove the transfer box's chain is or isn't broke?

You hear if the chain had broke

Mmm , oil pump failure.

Was running fine, just started pulling up hill, raised revs and lost drive, no noises will move slightly in low box on flat ground

Has it done a lot of towing, high miles?

Mark Piercy said:

Has it done a lot of towing, high miles?

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It's on 183000 mile, first time I've used it to pull trailer

Rock ape said:

It's on 183000 mile, first time I've used it to pull trailer

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Had it for year, been running great, new mot and just changed seals on injector pump, time for replacement box

A visit to ashcroft website!

I would check the gearbox oil ,if its got a dipstick its easy,if its not it needs to be running ,might have sprung a leak on a cooler pipe ,if its a petrol might be in the radiator and the gearbox might have water in it giving a false reading.And for the sprag clutch try first gear if it moves change up by hand .... small point if the pump has failed not sure if the oil will run out filler as its not getting pumped..and then theres the flexy plate ,another story... just noted diesel, petrol bit might help a petrol head ...

Rock ape said:

Had it for year, been running great, new mot and just changed seals on injector pump, time for replacement box

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If it's a diesel, fit a secondhand HP24 box, it's stronger than the HP22 fitted as standard and is pretty much a straight swap.

I found the clue in ,,changed pump seals ,,,got to be like Columbo sometimes.......

Sounds like forward drive clutch has failed. Usually caused by dirty fluid resulting in a sticky valve block. Or in extreme cases a failed oil pump.

The VC in the p 38 I believe is the same
As in the classic...
A few years ago this happened to me ..,
I turned out the be the spline gear that goes into the VC....
It will strip out over time as the VC fails...
When this happens you are not going to move....
You can pull the VC and this splined gear
Can be pulled out