Suzuki DF6 -- Have I sheared the pin, or the stopper?

[Anonymous]

I have a Suzuki DF6 2005 model. I grounded the prop on some concrete this evening which resulted in me being able to get back to the yacht on around 30% power but any higher, led to high revs and slip.

I have removed the cotter pin from the prop nut -- which was fine. The engine is on the tender and it is very difficult for me to remove it at the anchorage as Mrs L does not have the strength to handle it from the tender.

I see from the user manual that there is a component called a "stopper". Is that effectively a shear-pin that I have probably sheared? If I can get a spare, should I be able to replace it easily by reaching over the stern of the tender, or should I get the engine on board?

If I cannot obtain a stopper locally, is there a work-around? We are at anchor and some 1nm from the harbour.

Is the slip deliberate and constant -- i.e. can I run the engine at low power indefinitely, or was I just lucky to be able to get back to the yacht? I don't really want to motor back in to the harbour in adverse conditions, to find that the drive fails entirely.

Many thanks

 

[VicS]

I would not attempt to replace the shear pin without getting engine at least into the dinghy.

Don't understand why a shear pin would be called a stopper though.

The symptoms you describe sound more like a "spun" hub. Does this prop have a rubber hub that is designed to slip when hitting an obstruction, There may be a pin driving the hub but not a shear pin,.

Generally a shear pin will drive if its intact or it wont if it has sheared A spun hub will behave as you describe. Drive at low speed but slip if you open up a bit.

If its spun hub it may well be a specialist job to repair the prop by fitting a new hub.

 

[Kylora]

I can't help, but others might make sense of this

Diagram1 and Diagram2

Item 24 in diagram1 is the 'stopper'.

Ash

 

[VicS]

Just a spacer or a thrust washer I reckon.

I think #22 will be the problem but I dont see how it is driven by the shaft. No pin shown and its not splined.

 

[Ariadne]

Do neither! Sling the prop, bight the bullet and buy a new one!

There is a rubber bush inside the prop (between the splined shaft and the blade casting) I suspect this has imploded and the prop is spinning around the rubber bush.

Symptons: runs ok at low rev's/tick-over but on applying any more rev's will run for a short time then the prop appears to cavitate and the engine over rev's; when you reduce power the prop works ok. This cannot be repaired and on two occasions has cost me new prop.

Suzuki DF6; who'd 'ave 'em??

 

[Cliveshep]

From the diagraghm it looks as though the prop is held at a point on the shaft by a packing washer, the"stopper" as you say, part 22 is the bushing inserted into the prop, one can only assume that as there are no splines shown on the propshaft for the bushing to grip the only way the prop can be fixed is via the threaded propellor nut which presumably has two flats on it to allow tightening up the prop bush against the stopper. In other words a friction hold. In that case, it is entirely possible that jamming the prop so that the shaft only turned might have worn away a little of the bush faces and that this problem might be solved by removing the split pin and merely re-tightening the propellor nut. That of course assumes that the bush has turned against the shaft rather than the prop but if the bush is rubber entirely then again re-tightening the propellor nut might compress it and still solve the problem. Weird system in any event.

 

[seabright]

At last, a topic arrives that I am a proper expert on.

We had this problem 3 times in the last 2 years with the DF6. It is the rubber bush inside the prop. We never hit anything but found that this happened just with heavy loading and usage (we spent a couple of year livaboard UK to NZ). No sensible way to mend it but I ended drilling through from outside though the pressed rubber bush into the central spine of the prop (not the shaft on the engine). I then tapped these holes as they went through the metal and screwed bolts through. Put prop beack on engine and we were in business again. This worked fine but you would, obviously, do alot of damage to the outboard if you hit anything again as the sacrificial weak link is no longer weak. We had to do this as we had already used our spare and we were in the middle of nowhere.

If there is any way you can buy a new prop then you'll just have to do it. Keep in mind that this seems a real weakness just in normal operation and take it easy if you are fullyloaded.

Sorry no good news.

 

[steve28]

I had the same thing many years ago, because of the price of the new prop i decided to try contact adhesive 3M)
The engine was still fine when it went to the dump last year.

 

[Cliveshep]

Seabright - well done, mystery explained then, leaving only the mystery of.......if the bush grips the prop, what keys/locates the bush to the shaft? Can you enlighten please as I'm curious, really curious.

Steve28 - that's a brilliant idea and I love collecting other peoples fixes that worked, one never knows when such info will be required. I'll remember that one as I'm always buggering about with old engines.

 

[Anonymous]

Thanks so much, folks. What a terrific place this is, so much knowledge and experience of really detailed things. Fortunately, I had a spare propeller; the original, as I have been using a fine pitch since we bought the engine, since we tend to run heavily-laden. Runs fine now. Interestingly(?) the old prop looks perfect. I am keeping it and will run some bolts through so that I have an emergency spare....I don't really want to keep this engine forever so don't want to buy another. I was able to change the prop without difficulty just reaching over the transom. No bits wanted to drop off (from the engine, I mean, some of mine threaten to drop off on a regular basis). I suppose that with a coarser prop we are in more danger of the same problem occurring though to be fair to Suzuki I am 99% certain that I hit the prop on some concrete leaving St Tropez old port last night. I just wish they'd use some kind of cheap easy to change shear-pin.

I might try the Evo Stik solution first.

 

[seabright]

Hi Cliveshep,

The prop shaft is splined. These engage with the splines on the central metal fitting of the prop. This fitting is held into the outer casting of the prop with a pressed rubber bushing and this is what fails. This is meant to happen if you hit something (called a slip prop I think) but also happens over time.

Found it difficult to fix simply as the pressed bushing does rely on friction with no key and once it goes very hard to fix back long term without slipping. I didn't have any luck with adhesives.

Hope this makes sense?