Ageing Bmc Diesel (throttle Response)

[TeamElla]

BMC 1500 (and PRM100)

A couple of months ago, I had occasion to go from slow ahead to full astern whilst battling to hold the boat in position with a very strong following wind against the first 20 minutes of an outgoing tide at Reedham. At the time I was manoeuvring off Sanderson's yard to hold the right attitude in the water before moving in to lay alongside one of their boats for a pumpout. In the event we came in nice and gently but it highlighted a problem that I didn't know I had:-

I have never previously noticed a substantial delay before the revs pick up when quickly shifting astern and opening the throttle wide. It's not something that I would do normally, but I believe that I have done it before and not noticed a delay. It's nothing to do with the gearbox (which engages just fine), it's the slow pickup on engine speed, so my questions are:-

Is this just something to expect from a 45 year old engine, or could there be a connection with the fact that I had a new diesel injection pump fitted about a year ago?

Are there other timings that could be out of adjustment (bearing in mind that it appears to be just fine going ahead)?

Steve

 

[Cheesey69]

Hydraulic drive or gearbox?

[Cheesey69]

Ok, If the engine responds well in the ahead position then it can only be either the throttle set up in the stern position or the force of stopping your prop and the initial reluctance of water and force to change direction.

 

[BrundallNavy]

Are you sure that the gearbox fully engages. I had this problem with mine and it wasn’t going fully in causing a lag on response from the throttle. 

[Timbo]

Check for duvets!

[annv]

Hi Steve remove cover from lever check movement for loose locking nut then go to gear box and engine butterfly loose? if all looks well get a bar and prevent gear lever moving then work lever back and forth gently to check for  slack in cable if so replace cable, only check butterfly/or injector pump lever with fingers.John

[MauriceMynah]

Buy new boat.

[TeamElla]

Thanks for all the replies.

I haven't physically looked to see what's going on with linkages but I don't expect to find a problem.

The gearbox engages ok and I'm sure that the throttle linkage will be ok. The problem is the lag in engine response time to the control input. It does eventually respond (without any further change of control line input) but after an initial irritating lag.  I reckon that I will find that it's the same whether I'm going forward or astern, but like any other boat owner astern is my braking system. (Imagine your car brakes dithering about deciding to stop you) .