Throttel cable...I think

[Carmel2]

Hi,

We have a Volvo MD2040D, On the last few outings, running 1500 to 1800rpm, the revs suddenly drop by about 100 rpm. When I put the revs back on it´s ok for the rest of the journey, even on a long run; last one 70nm. Do I have a cable problem that could get drastically worse if nothing is done?

 

[Carmel2]

If I need to tighten up what I have since learnt to be the clamp bolts, which ones are they from this diagram??

http://www.marinepartseurope.com/en/volvo-penta-explodedview-7740690-27-9348.aspx

 

[Salty John]

I don't think they're shown. In my experience the cable tension device of choice is simply a cable clamp around the cable and tensioned to increase friction and stop creeping. Teleflex tried to make it a bit more sophisticated with a Teleflex cable brake, but it's basically the same thing - just a collar you tighten around the cable.

There is probably some sophisticated electronic device used to achieve this cable tensioning on modern engines, it's a few years since I tinkered with diesels on boats.

 

[chrishelen]

This used to happen to my boat.. as I pulled away from the quayside the revs would drop from 1500 to around 1200. It would be fine all day running after I reset the throttle.
I think it was an omen because the cable parted at the Morse control not long after. A pretty simple job to replace once I took half the wheelhouse apart to get at it.

I think 6.7.8 are the clamp bits.

 

[Carmel2]

Another opinion has said it's more likely to be at the handle end, which is a right bugger of a job to take it apart, and somewhere in there is a grub screw you can tighten maybe not even a half a turn.

Anyone done this, or have an opinion as to whether this is right?

 

[Salty John]

Yes, some throttle controls have friction adjustment screws in them - have a look at a Teleflex/ Morse catalogue. However, many simple sailboat engine controls have no friction screw, so you can make your own with a cable clamp or you can buy a Teleflex cable brake which is a ridiculously expensive cable clamp.

 

[onesea]

Having no rev counter I do not know the rev's but my Morse cable slips back to 4 knots when I am motoring. I looked into a solution but it cost money, I found a simple solution when I want to motor 5-6 knots I put the main sheet coiled on the handle. When you need to slow down you can just knock the rope off and you know your doing 4 knots, basic but it works .