MD7a gearbox heat

[davewillc]

Hi,

Could anyone tell me how hot an Md7a ms gearbox should run at?, I have just had the conical clutch linings replaced in my box and it is running pretty hot although it will run in forward, reverse and rest in neutral, I would like to get some idea before refitting the whole lot back in the boat.

Thanks in advance

Dave Connell

 

[penfold]

How hot is hot? A gearbox casing may get too hot to hold your hand on but be quite happy. I would not be concerned unless the oil temperature was rising over 70-80C, although I've not encountered a small engine gearbox get much over 50-60C unless there's summat wrong with it. Having written that I'm slightly concerned that it's getting hot when run on the bench; are you applying a running load of some kind or is it running unloaded?

 

[rosie]

I am more familiar with the MD7A/ saildrive but I think the MD7A / MS setup is meant to have a cooling seawater flow through the gearbox, which then goes to the seawater pump input. Perhaps you need this all connected & running to control the gearbox temp.

 

[VicS]

I am more familiar with the MD7A/ saildrive but I think the MD7A / MS setup is meant to have a cooling seawater flow through the gearbox, which then goes to the seawater pump input. Perhaps you need this all connected & running to control the gearbox temp.

The MS2 gearbox has water cooling.

I beleive the MSB fitted to the MD7A also has water cooling

 

[davewillc]

Thanks for the advice, I have connected water to the reduction box but the main gearbox is still hot, I was wondering if anyone knew how hot it can get before its a problem.

Thanks anyway

Kind regards

Dave Connell

 

[pampas]

My 7a runs cool, residual heat from the engine, cool but you can feel gentle warmth, Difficult to describe hope this helps, personally I would think that your plates are bedding in, never had the box to bits so I do not khow if there are shims fitted or not.

 

[davewillc]

Thanks,

I will have to dismantle the box again and check for wear.

 

[PhillM]

Mine ran cold enough to touch and only feel a small warmth. Cooler than a half hour old cup of tea. Luke warm.

Slightly strangely but warmer and faster in reverse than forward but I think a previous owner switched fwd for reverse so he could for a right handed prop. Cannot comment much more ad I've ripped it al out to replace with a new beta this winter.

Hope that helps.

 

[colvic987]

Mine runs cool it might warm up slightly once residual heat from engine has heated it up, but on a run cool to warm, but never hot, have you used the correct oil, same as engine, and fitted your raw water pipes correctly, inlet is on opposite side to the raw water pump, and outlet is on same side as raw water pipe, it should be fitted with a solid copper pipe from outlet to bottom of seawater pump.


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