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Milemarker hydraulic pump

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I have had (for many years) a Milemarker H12 with the hydraulic pump that mounts on the 300Tdi aircon slot, as sold by the supplier who I think was called ?Alfred Murray Ltd back in the early 2000s. It's on its third vehicle (where it has been for 12 years) and has never missed a beat.

AM seems to have gone by the way over the years (the bookmark I have for 4x4winches.com has gone), as does Milemarker in the UK - I've seen First Four selling some spares for them I think, but not seen a winch for sale anywhere for a long time. Milemarker in the US still seems to exist, but I'm pretty sure the Land Rover fitting kit was something pulled together by the UK agent using some sort of power steering pump.

I have noticed that the winch doesn't seem to pull as much as it used to before the relief valve opens. Still a lot of power in low range but you can now stall it, which used to be impossible.

I have no idea where the valve is or how it operates - but I presume it's internal to the pump somewhere, rather than in the winch body. Does anybody know anything about these, to be able to to suggest what the issue might be and whether or not it's realistic to fix it? I don't even know what the make and model of the pump was at the time, or whether it (or spares) are still available.

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I'd start by checking the mechanicals of the winch - drum bearings , alignment of end castings and gear assy. then oil feed pipe to pump and whatever filter you have either in the return or suction line . If you have an OCV ~hydraulic lock ~ it may be that it needs adjustment or is failing .

The PRV is usually located in the spool valve block and often covered by a closed cap nut , under it will be a long "grub screw " and a lock nut , it should be around 170 - 180 bar to protect the motor .

hope that gives you some pointers

Steve b

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The pump supplied is a PAS pump off something or other I think, so probably internal relief? The Alfred Murray solenoids are a very compact solenoid block, I don't really think it is inside that but I'll have a look.

No OCV, cooler or anything like that - the AM kit was pretty basic to keep the cost reasonable, a small PAS reservoir supplies Dexron PAS fluid to the pump. through the valve block to return to the reservoir or divert to the pump when the in or out solenoids are triggered.

The thing doesn't sound any different to before, just seems to open earlier than I think it used to.

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Ah , yes , you are probably right about the prv location , maybe stick a washer under the relief spring to test ? or maybe run thicker hydraulic oil (SAE 46 )  to see if that makes a difference ?  A mate of mine runs 15/40 diesel engine oil in his U900 Unimog hydraulic tank . How often do you change the oil ?

Iirc the kits had ZF74 pumps ?  Does it run all the time or is there an EM clutch ?

Steve b

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4 hours ago, steve b said:

Ah , yes , you are probably right about the prv location , maybe stick a washer under the relief spring to test ? or maybe run thicker hydraulic oil (SAE 46 )  to see if that makes a difference ?  A mate of mine runs 15/40 diesel engine oil in his U900 Unimog hydraulic tank . How often do you change the oil ?

Iirc the kits had ZF74 pumps ?  Does it run all the time or is there an EM clutch ?

Steve b

Yeah, ZF74 rings a bell. It runs all the time, no clutch. Old photo of it in the vehicle before last when it was all shiny and new:

image.png.e1aeea1a42dbf47de2bf8af0d328e7b0.png

Fluid, er gulp about 2007 when it was fitted to the current vehicle? :unsure: still nice and clean and red in the tank, and doesn't get used that often so mostly it's just circulating through the pump.

 

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With the low total volume of fluid in the system I'd be changing it annually just for peace of mind , I reckon it will fix the difference in performance you have noticed

cheers

Steve b

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Give Peter Lamb (FirstFour) a call - he knows his winches..

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I contacted Peter a few weeks ago for parts as I'm rebuilding my Milemarker. This is what I got as reply:

Quote

The situation with Milemarker has changed a lot in the last 2 years or so. They no longer supply EU re-sellers directly, but use an agent. This made sourcing winches and parts very difficult. Eventually we took a decision to cease supplying hydraulic winches completely. We still have some parts in stock, but these are getting quite low now. The parts listed on the website should be what we actually have left in stock.

They also still have a hydraulic drive section, so definitely worth contacting. If you can identify the problem, any hydraulic specialist should be able to help you sort it.

Filip

PS: It's a real shame there's not much support anymore for Milemarker in Europe, real fine winches!

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Thanks, I will have a play but if it looks too difficult to get spares then I'll probably just get an electric winch instead.

I got the impression that neither the valve block nor the pump supplied by AML were Milemarker parts.

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How does water in oil affect the operation of PRVs? Given the small volume I'd be inclined to change it as if it's got water in either by leakage or condensation it'll affect it's operation.

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