Beta 75......

[stagedamager]

Morning all,

On Oak we have a Beta 75 with PRM260 D2 gearbox. When I go into gear there is a massive clunk, with noticeable movement of the engine on its flexible mounts. The fluid levels are fine, in reverse it is still there but not as severe. My gut feeling is that the 260 is slightly too small for the engine but does anyone have an idea as to what could be causing it??

Regards

Dan

[Tony Brooks]

Loose or broken mounts/feet. Drive plate starting to fail, too high tickover, maladjusted control revving engine before gear is selected?

[Bee]

According to Calcutt boats the 260 is ok for up to 100 hp. If I am right there is a kit for a soft shift for your box, They do go in with a big clunk as they accelerate the shaft and prop from 0 rpm to tickover - say 700 rpm instantly, if you have a long, heavy shaft and a big prop that is a hell of a lot of inertia. It can't be good for keyways and everything else. I think asap supplies do a kit and probably others as well.

[magnetman]

I fitted a Beta 90 in my barge in 2012 (non commercial) with a prm 260 box. It's rated up to 100hp as mentioned, for non commercial use. I get a little bit of a clunk when going into gear but at one time it was particularly loud and this was due to a loose engine mount - the part bolted to the engine feet not the part bolted to engine beds. Forward engine mount on port side iirc

I have also experienced a clunk when initially fitting and testing the engine when a coupling bolt came loose.

 

Nothing in the prop is there?

[stagedamager]

Thanks all. The prop is clear, I thought the tick over sounded a bit high so I may adjust. The control doesn't appear to rev before gear is engaged and hopefully not a drive plate. Something is not right with the install as looking at the book, in 10 years she had a new set of mounts, new gearbox and new stern gear. ...Most bizarre.

Dan

[alan_fincher]

Thanks all. The prop is clear, I thought the tick over sounded a bit high so I may adjust. The control doesn't appear to rev before gear is engaged and hopefully not a drive plate. Something is not right with the install as looking at the book, in 10 years she had a new set of mounts, new gearbox and new stern gear. ...Most bizarre.

Dan

 

This isn't entirely a tongue in cheek remark, Dan.

 

Surely the way this engine was treated by its former owner could be a large amount of any problem you now have.

 

When I observed him, he seemed to think it only had two speeds - stop, or flat out, (in one direction or the other).

[stagedamager]

It's a very valid point Alan.

As a single motor, I find tick over is a good cruising speed.

Anything else is just a bit OTT.

I think it's a classic example of getting the maximum horsepower for the money without really looking at the job in hand.

Give me an AS2 or AS3 Any day, even with the noise!

[GUMPY]

If tickover is normal cruising speed then you could well be very overpropped.this could give the effect yoi describe.

Does it reach the same top revs both on and out of gear.

I run a beta 50 in a nb and have no problems at all

[stagedamager]

When we bought her back we discussed her being overpropped, however we haven't had her out the water yet to check the size.

[GUMPY]

Easy way to check run the engine up to temp. Find some straight deep water run engine flat out both in and out of gear and as you are on a river up and downstream. Revs should be near enough the same. If its less tham 2k im gear then you are seriously overpropped. Mine pulls 2800 out of gear and 2400 in gear and is overpropped but not by enough to make me change. 2400 is 7mph

Edited July 6, 2015 by Loddon

[magnetman]

Is Oak a narrow boat? A beta 75 in a narrow boat sounds a bit extreme. My beta 90 is in a 58x12ft modern English barge and is easily enough power. I put it in to replace a nackered Perkins M90 as it was a close power/torque match but a 75 would have done the job easily I'm sure. It does seem a very large unit for a narrow boat.

 

If it has been hammered by a previous user maybe it's the drive plate as suggested.