BLUEMOMENT

For a while I have thought that Seminole is a bit noisy when motoring .
One explanation by the local engineering guru was that the gearbox/shaft rigid coupling "is always going to make some noise".
Anyway I was feeling about and found the bottom bolt was loose. I got the offending bolt to the top to get spanners on it and it was no longer loose?
I turned the shaft until 2 bolts were E/W and tightened them up a couple of flats each. Then turned the shaft through 90 and did the same to the remaining bolts. It took a few repetitions until there was no slack in the bolts.
When tested against mooring warps in forward, the noise has stopped but the shaft doesn't look to be true, in fact there is visible movement, it doesn't look right to me.
When I got the panels off the far side of the engine I found that the port front mounting didn't have a bolt on it! I found it in the bilge and have replace it. Having 4 bolts on hasn't improved the wobble.
How easy is it to check/re-align the engine?
Internet searches give sketchy info but it seems that feeler gauges are used? I think I have some but all I have ever used them for is spark plugs.

I have asked a man to come but he said he would be a couple of hours @ 14:00 yesterday, I'm waiting.

After finding this on YBW:
http://www.ybw.com/forums/showthread.ph ... =alignment

And looking at this:
http://www.randdmarine.com/flexiblescinst.asp

It may be an R and D coupling, I even had a red(ish) bolt. It's on the gearbox side not the shaft side as the instructions say, will that make any difference?

I have had the feeler gauges out and got the following readings:
N 220 thou
E 160 thou
S 40 thou? Hard to see, did it by feel.
W 110 thou.
So it's miles out and not just up/down, it's gone sideways too.

The process is relatively simple but very repetitive. It is said that if you take less than 6 hours you haven't done it properly. It helps if you have another pair of hands to adjust the engine feet while you measure. (The red bolt is just to allow you to use fewer leaves of feeler gauge).

First make sure the engine mounts are intact and in reasonable condition (Yanmar recommend 5 year replacement IIRC but no-one ever does). Then it's just a matter of loosening the mounting bolts, levering, tightening until left/right is achieved, then up/down on the engine adjustments. Hours of fun so have a pee, make yourself comfortable before you begin and get your mind into zen-like calm.

I can vouch for all Marisca's advice but I can add that I have an old PBO article describing the technique in detail. I made up a spreadsheet to simplify the sums that can speed it up a bit - adjustments can be made using previous measurements to estimate the correction needed.
I could supply a scan of the article and a copy of the Excel if I can find them and you want them.

Derek

You need to get your head around the idea that you need to alter both back and front of the engine.

In your example, if you lift the front of the engine to make the N and S gaps the same, the engine flange will now be too low so now both back and front need to be lifted together.

Also you need to be able to hold the shaft so that it is in the middle of the stern tube.

Good luck and have patience.

Ash

cpedw wrote:I can vouch for all Marisca's advice but I can add that I have an old PBO article describing the technique in detail. I made up a spreadsheet to simplify the sums that can speed it up a bit - adjustments can be made using previous measurements to estimate the correction needed.
I could supply a scan of the article and a copy of the Excel if I can find them and you want them.

Derek

I found it tricky to measure the tiny gaps at NESW etc. so I nipped a 40 thou feeler at one bolt position and was able to measure the others and work out the differences. The hints about both tilting and or / lifting / lowering the whole engine are valid. If you alter the tilt you must level up or down or the line of the shaft will become off -centre. It's a pain, but just take your time thinking about which way the engine needs to move to get the centres at the right height and the faces parallel, and equal.

Graeme

lady_stormrider wrote:Is this going to solve the sudden engine noise change as we are motoring along at full throttle , doing 2,000 rpm at 5-ish knots? It might stop my heart lurches that happens.

By the way, thanks for all the advice boys.

The loose bolts might but you've still got a problem if you are only getting 2000 rpm and 5 knots at full throttle. If I remember correct was that was a 50hp engine? You should get up to hull speed easy and that should be about 7 knots. Is the prop and hull clean?

lady_stormrider wrote:Is this going to solve the sudden engine noise change as we are motoring along at full throttle , doing 2,000 rpm at 5-ish knots? It might stop my heart lurches that happens.

By the way, thanks for all the advice boys.

No, that's a different bag of scottish excrement.

aquaplane wrote:

lady_stormrider wrote:Is this going to solve the sudden engine noise change as we are motoring along at full throttle , doing 2,000 rpm at 5-ish knots? It might stop my heart lurches that happens.

By the way, thanks for all the advice boys.

No, that's a different bag of scottish excrement.

Oh - OK

It's due to be wet tomorrow so I may just have 6 or more hours to arse about fiddling.

I just want to go some where, anywhere.

Booby Trapper wrote:

lady_stormrider wrote:Is this going to solve the sudden engine noise change as we are motoring along at full throttle , doing 2,000 rpm at 5-ish knots? It might stop my heart lurches that happens.

By the way, thanks for all the advice boys.

The loose bolts might but you've still got a problem if you are only getting 2000 rpm and 5 knots at full throttle. If I remember correct was that was a 50hp engine? You should get up to hull speed easy and that should be about 7 knots. Is the prop and hull clean?

When the noise is cured and I have some confidence in the general set up I may look at winding out the throttle stop to see if we get more revs without black smoke, and see what speed we get. One step at a time.

.

If the shaft is aligned it will slide into the coupling with a slight clunk. If it is not aligned it will bounce off the side first, a double clunk.

The shaft can be centered in the stern tube by making a cone with a hole through it centrally the same diameter as the shaft then cutting the cone in half.

This may sound like bollox, but it works on a Vega.

marisca wrote:First make sure the engine mounts are intact and in reasonable condition.

Some thing I failed to mention. The mounts seem to have a pin through the rubber into holes both sides on the rigid bit bolted to the boat.

On 3 of the 4 mounts the pin is sort of central in the rigid bit bolted to the boat. The port front one, the one which was missing a nut, the pin is at the top of the limiting hole, this seems wrong. Putting the bolt back on hasn't improved alignment of the pin in the hole, or the differences in the feeler gauge readings at the coupling for that matter.

Should I be looking at the 5 yr old mounts before I do anything else?

Don't ever, not ever, have anything done by the cowboys at Sandpoint.
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