PRM 160 PROBLEM

[LOZANDEBS]

Hello there

I'm hoping someone can give me some idea of what is causing this problem.... I have a PRM gearbox now if I cruise for a short time ie half an hour I don't have a problem but if I cruise for an hour when I turn round and select reverse ect its fine after this my box sticks in forward drive and I cant select neutral at all and if I go into reverse it stalls the engine. Its been doing this for a few weeks now and iv checked the oil changed the oil as well but still got the problem on longer cruising. After I moor up and leave it for a about half hour start her up and it frees itself and works fine again until I do a longer cruise. There is no nasty noises when its working only when its stuck until its frees itself again could I have a overheating issue ? Any help would be appreciated. Thanks in advance.

Loz

[Tony Brooks]

First step on hydraulic gearboxes - is the oil level correct and is it the correct oil (engine oil not ATF).

Edited July 17, 2018 by Tony Brooks

[Boater Sam]

I think you have a wear problem in the valve assembly on the top of the box where the lever goes in. Unusual but possible. 

It sounds like it is leaking pressure into the forward and reverse clutches at the same time when the oil is hot and thin. Is the oil 15/40 engine oil or thicker? Is there a heat exchanger oil cooler on the gearbox pipework?

Check that the cable is operating the lever correctly, in fact if you can, try taking the cable off when the box is warm and stuck and see if operating the lever manually solves the problem.

Ensure that the centre detent on the lever is holding the box in neutral without the cable pulling or pushing the lever.

 

If the valve assembly is badly worn it may be expensive unless you can find an old box for spares. The valve block just bolts on with a gasket, easy to change.

If the box is old and generally well worn consider fitting a new 280 PRM for around £1400, its a straight swap, and sell yours for spares to someone.

The 160 used paper clutch linings, any water in the oil wrecks them, the later 260 and current 280 use sintered bronze.

[RLWP]

It could be worn splines in the forward clutch, especially in an old gearbox. Do the basics (oil level/type/control cable) first

 

Richard

[Chris G]

We had a problem with a PRM150 (a hydraulic box). The forward clutch pack seized partially so that in neutral the prop still turned. Not enough to move the boat much. Solution was a replacement clutch pack.

[Tony Brooks]

13 minutes ago, Chris G said:

We had a problem with a PRM150 (a hydraulic box). The forward clutch pack seized partially so that in neutral the prop still turned. Not enough to move the boat much. Solution was a replacement clutch pack.

I think that is far from uncommon on any gearbox with multi-plate clutches and it is usually oil drag, not a partially seized clutch.

 

If you can stop the shaft by putting your boot on it I would say just ignore it.