Outdrive Power Trim

[SeaAce]

My BMW B190 outdrive leg is dropping very slowly (from full tilt to lower position in a couple of days). There are no oil leaks so am I right in assuming that it is due to a valve in the pump? If so, is it easily serviceable and where would I be likely to obtain a schematic diagram of the pump.
TIA

John

 

[Col]

It could just as likely be the piston seal on the ram. you need to check if its the pump or the ram before you start tearing things apart.

 

[jfm]

Col may be right, but.....
The rams are push pull AFAIK so even though the closed loop is not losing oil it could be a seal. Thing is though, it would take a seal leak in BOTH sides to cause your symptoms. If just one side leaked the other side ram would do all the work. A duff seal both sides is unlikely unless you have had barnacles or whatever, so could be pump valves like you say.

Sorry, this is raising more questions than giving answers. But if you have the gaskets the pumps are easy to dismantle, they're just simple gear pumps

 

[SeaAce]

Thanks for the feedback - I didn't mention the fact that I have had the system drained for the last five months when I removed the leg to overhaul various parts of the unit. I think I'll obtain the gaskets and strip the pump first, as it could probably do with a clean out - when the weather gets a little better!

John

 

[Col]

If system drained, could possibly be aerated fluid in rams causing probs, all air has to be expelled.Operate rams fully up + down several times, leave a day or two, check fluid level in resovoir, repeat untill all air removed ( fluid looses frothy consistancy) try this before more drastic measures.
ps: most of the rams I have seen are linked, so a leaky piston seal on one ram could still cause your rams to sink ( I know volvos are like it, I had one do this, I guess your Bee Emm is similar )

 

[SeaAce]

Thanks Col - I'll try what you suggest first! My rams have two separate pipes feeding them from the pump, I looks as though the only place they are linked is in the pump.

John