Vintage Tractor Engineer has a customer with a hydraulic fault on his FE35 golden grey.  The tractor will lift light implements such as a ridger or spring tine and will lift heavy implements when cold, but when the hydraulics get warm it takes high engine revs to lift the heavier implements such as a rotavator.  The customer suspects the filter on the hydraulic pump. 

fe35-lasso

So here is what Ian has to say :-

If the tractor is lifting OK when it is cold, but not when it is warm then I do not think it will be the filter.  It is when the oil is cold that a clogged filter is most likely to cause problems, and as the oil warms up the oil would pass more easily through a clogged filter (so the opposite symptoms to your tractor).

If the hydraulics are performing OK when cold, but not lifting very well when the oil warms up, then this suggests a leak somewhere in the system (which becomes more apparent as the oil becomes less viscous).  So it is a case of finding out where the leak is occuring.  As shown in the troubleshooting section of the Hydraulics DVD, there are several components which could be the cause.  The easiest (and cheapest) place to start is with the o’rings on the stand pipe, which can be accessed by removing the oil transfer cap under the right hand side of the seat.  Remove the pipe, check the o’rings (replace if necessary) and then refit the stand pipe – see if that solves the problem.
Also consider removing the right hand side plate from the transmission housing and looking through whilst the tractor is running (don’t put your hands inside whilst doing this).  You may see an obvious leak somewhere, although this is unlikely given the symptoms you have described (i.e. the hydraulics will lift with high revs even when warm).

So that leaves either the pump (including control valve and relief valve) or the lift cylinder.  Most likely is the pump.  If you follow the rebuild of the pump as in the Hydraulics DVD, then this is most likely to solve the problem.

I would always use a genuine control valve and relief valve on the pump, as the non-genuine brands do not seem to be made with sufficient precision.

Ian VTE

Hello Steve and Ian,
Thank you for you’r prompt reply, it does help, I’ll try the (o) rings and with the help of the DVD and the bracket shown on it which my son is at present making for me it should be a “doddle” to fix,

Thanks once again,Richard.