JCB 3CX moves loses drive

[Timmusdavies]

Hi, I have a JCB 3CX 1986, and when it drives, it very quickly loses momentum and drives really slow. It seems fine when I’m driving into earth pile, it’s just when I start travelling any distance It starts losing drive power. The engine doesn’t slow down though. Anyone have any ideas what this could be?

[essexpete]

If you have checked the fluid level and the filter has been changed there is not much you can do without a proper pressure diagnostic test.

[orange maxus]

Have you tried driving it with the hydraulic filler cap loose, it's meant to breathe through there and they can block.