Volvo Penta 2002 – Lack of Propulsion Problem

[Paul Kelly]

I have an 18hp Volvo Penta 2002 in a 5 ton Westerly Storm 33. I have two engine problems which may or may not be related.

1. Until recently I was getting a max of 2500rpm under load. I am sure I should be getting nearer 3000rpm. The prop is a 3 bladed folding Brunton. I know the engine is deliberately over-propped. A post by the previous owner on another site says he would expect 2750rpm at max throttle. The hull is comparatively clean. Why am I not getting 2750 – 3000rpm?

2. Last week coming back into Poole Harbour UK, the engine started up fine but on putting it into gear (ie pushing the morse lever forward) I was getting higher revs but had no forward propulsion at all and I had to be towed onto my mooring.

That aside the engine appears to run normally – it was initially revving up to 3500rpm when I encountered the problem. It has now settled back to 2500rpm max, but I have no propulsion. The shaft is turning as one would normally expect.

I have had a diver down today to look at the underside and:

a) The prop is there and there is nothing fouling it – apart from a small bit of weed.

b) It is unfolding and turning clockwise, but doesn’t seem to be turning anti-clockwise and I think these Volvos are designed to run anticlockwise.

c) The view from the surface suggested some reverse travel in gear, but there was no forward motion in gear.

I am not terribly mechanically minded, but this suggests to me some sort of gearbox problem.

Has anyone encountered anything similar on an engine of this size? Or can anyone with a better mechanical understanding than I suggest what the problem might be?

Many thanks for all contributions.

[DougR]

1. Your engine, the 2002, was rated for a maximum loaded RPM of 3200. If deliberately over propped, one might expect the RPM to be down two or three hundred, but to be down 700 RPM is way too much IMHO. This will cause premature wear, perhaps overheating, black smoke, etc.

2. This part of your post is confusing...you say the shaft is turning but there is no propulsion...then you say the shaft isn't turning...

The transmission that was fitted to the 2002 engine was the MS2, and it was designed to be able to use either a left hand or a right hand propeller. All you had to do was change the direction of shift cable movement to use an opposite rotation propeller.

It should be easy to isolate the problem to the propeller or the transmission...just watch for the shaft rotation. If the shaft turns but there is no propulsion, you have a propeller problem. If the shaft doesn't turn, the problem is with the transmission.

About the easiest check you can make is to be sure the shift cable is moving enough to actually turn the transmission shift lever the required amount. If the cable is loose in its mount bracket the cable might not be moving far enough to actually shift the transmission. You could disconnect the cable and move the transmission lever by hand to see if it shifts. You will feel a very definite " click" when the lever has moved the proper amount.

If you move the lever by hand, and the transmission still doesn't engage, it's probably time to get professional assistance. There could be a problem with the internal shift mechanism, or the shift cone could be polished and slipping, and that's something best left to an experienced mechanic.

Hope this helps you sort it out.

DougR

[Pete7]

Paul, Doug's post is spot on and I would have at a guess it's the gearbox or the shift cable that is the problem. Either way should be easy enough to fix once the problem is identified.

a new cable is a few quid once you know what length to buy.

Secondhand gearboxes are also readily available.

http://www.marineenterprisesltd.co.uk/

[Paul Kelly]

Thanks for both ereplies. Really helpful! And sorry for any confusion in point 2. What I saw on the boat was the shaft turning but no propulsion. According to the diver, the propellor is turning one way when in gear - in reverse - but not much if at all when in forward gear.

I am pretty sure the shaft is turning both ways. But I am going out to the boat again tomorrow to check everything. It struck me after posting that the problem could be the morse to gearbox connection. It may be revving fine but not properly in gear. So that's my next avenue to explore! As for the revs

As for the revs problem, I'll discuss that with an engineer. Dirty fuel has been suggested and also I want to get the compression checked.

If it turns out to be a gearbox problem or an expensive engine problem, I may re-engine her. I think the Storms are under-engined. 18hp isn't really enough for a 5 ton boat. But it'd be nice to be able to motor on and off my mooring first!

[Paul Kelly]

Propulsion problem now identified! A 6mm nut - or thereabouts - has worked loose and fallen off the control cable from the morse to the gearbox control causing the cable to become detached. So lots of revs but no drive! The smallest of things.... and I shall know where to look first next time.