Engineering opinion please

All the ideas and feedback are very much appreciated thank you, I think that when I go back down next month I'll be armed with quantity of 'C' washers and half nuts to cover all the above ideas !
As an aside, the rubber shaft seal appears to be very stiff, such that there's hardly any movement in any direction
 
Hi, as said check shaft alingement and work back from there, had to put my Nanni back in last year so have recently done a similar job, but after reading boat building books etc the shaft alignment is the all important thing, if your studs are welded to the mount then as suggested U cut shims would be the way to go, just take your time and adjust little by little and think about what affects your adjustments will have on the opposite side/ end of your engine, I thought I had it sussed only to find an adjustment on an opposite mount made all the difference.
Hope that helps...
 
Lightwave395 said:
All the ideas and feedback are very much appreciated thank you, I think that when I go back down next month I'll be armed with quantity of 'C' washers and half nuts to cover all the above ideas !
As an aside, the rubber shaft seal appears to be very stiff, such that there's hardly any movement in any direction
Click to expand...

Just because the shaft seal hose is stiff, I don't think that assures the shaft is actually exactly on the line that it should be.
If you were to take the hose off and centre the prop shaft in the hole, you might get a different answer?
I assume the boat is ashore?

The shaft seal needs to move around with the engine, given the engine is on flexible mounts.
 
lw395 said:
Just because the shaft seal hose is stiff, I don't think that assures the shaft is actually exactly on the line that it should be.
If you were to take the hose off and centre the prop shaft in the hole, you might get a different answer?
I assume the boat is ashore?

The shaft seal needs to move around with the engine, given the engine is on flexible mounts.
Click to expand...

The boat has an Orbitrade seal, rather like the Volvo shaft seal. These are very stiff rubber and won't move around much at all.
 
pvb said:
The boat has an Orbitrade seal, rather like the Volvo shaft seal. These are very stiff rubber and won't move around much at all.
Click to expand...

I'm not familiar with that model.
Worth checking it's not sagged under the weight of the propshaft while the motor's been out?
Is it something that can be turned up the other way?
 
So I have just read your post and make my response without reading any of the responses already received. Here is what I would do.

BTW the photo looks like you have an angular mis alignment as well as an axial one, so mounts front and rear will likely need adjustment.

Remove the spring washer beneath the bolt lock nut - this provides 2-3 mm downward movement.

Slim the locknut on a lathe to ~ 2/3 thickness to provide the rest of the adjustment space needed.

If necessary take a light skim on the support nut beneath the engine foot, to a minimum of 3/4 original thickness, although better to remove any washer above this nut as it is supporting the weight of the engine all the time.

Use Loctite grade 242 or 243 in place of the lower spring washer.
 
pvb said:
The boat has an Orbitrade seal, rather like the Volvo shaft seal. These are very stiff rubber and won't move around much at all.
Click to expand...

They are stiff, but not so stiff that they will not distort under the weight of the shaft. As your boat is in the water you cannot just take it off to check, instead you need to lift the shaft and see how far up it will go. First press it down to establish whether it is in fact, as I suspect, touching the bottom of the tube. Then lift it and measure how far up it can go before touching the top of the tube. You need some packing under it so that you can measure accurately, then you need to put more packing under it to hold it central. Check sideways as well as vertically. There is no point trying to align the engine until you are certain that the shaft is correctly centred in the stern tube. My shaft has about 4.5mm to 5mm clearance all round in the tube. I have had both Volvo and Eliche Radice seals, the Orbitrade is similar, and with the flanges disconnected I could move the shaft to touch top, bottom or sides of the tube; it just needed a bit of force to do so, particularly lifting it to the top.

I am serious about sideways alignment. I had to shift my engine mounts about 3mm sideways to get the shaft central. It had been installed with new engine mounts and aligned OK vertically but not done properly laterally.
 
I would remove the height adjustment nut and use washers as shims. I would want full washes as well so no chance of them coming out. You will most likely be able to unbolt the engine part of the mount (do one at the time) to fit the washers while supporting the engine/gearbox with wedges on the bearers. Its most important that the faces of the coupling are perfectly parallel to each other before bolting up (after you have aligned the shaft.) From the pic. it looks miles out.
 
Cant add much to what has already been said apart from : It might help to measure the height of the old mounts that you took off which will tell you pretty much where the new ones should be. It may well be that the shaft has dropped but comparison should tell you....
 
How is the bracket fixed to the engine block, can you not remove that and modify it? be much easier than messing around with the bed or mounting.

But are you sure the mounts are correct see https://www.parts4engines.com/yanmar-3ym30-parts/ they are recommending different mounts front and rear with the front being stiffer than the rears, That might allow it to align.
 
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Dont forget ... unless you have fitted a centering collar, the propshaft will be resting on the bottom of the stern tube. You need to pack it up and center it in the stern tube, or make a centering collar for it. You may well find it aligns correctly with the gearbox when raised up to it's correct height.
 
Hi
Likely been suggested by now, I haven’t read all posts...but start with making sure your cutless bearing has the shaft running true and central through it. If that’s good, get a dti gauge (dial test indicator) and attach the magnet base to a fixed point near the shaft flange. Rotate the shaft and look for excessive movement on the gauge...or if it’s that bad, you’ll see it by eye.
if that’s good and within tolerance, it’s the engine mounts that need adjusted. As someone said earlier, it looks to be miss aligned on 2 axis (if your shaft side is known to be good).
that being the case, a good old leverage device like a crow bar or similar is usually handy to jack or lever the engine to a suitable alignment. you and a willing volunteer with spanner’s at the ready for locking off makes it easier.
 
davidwf said:
How is the bracket fixed to the engine block, can you not remove that and modify it? be much easier than messing around with the bed or mounting.

But are you sure the mounts are correct see https://www.parts4engines.com/yanmar-3ym30-parts/ they are recommending different mounts front and rear with the front being stiffer than the rears, That might allow it to align.
Click to expand...

Yes, those are the mounts I have, two stiffer ones at the front, less than half the price of Yanmar and appear identical
 
rszemeti said:
Dont forget ... unless you have fitted a centering collar, the propshaft will be resting on the bottom of the stern tube. You need to pack it up and center it in the stern tube, or make a centering collar for it. You may well find it aligns correctly with the gearbox when raised up to it's correct height.
Click to expand...

Noted thanks, but the Orbitrade shaft seal is so stiff there's hardly any movement with the shaft disconnected. The picture posted was taken with the shaft pulled up as far as it can be
 
QBhoy said:
Hi
Likely been suggested by now, I haven’t read all posts...but start with making sure your cutless bearing has the shaft running true and central through it. If that’s good, get a dti gauge (dial test indicator) and attach the magnet base to a fixed point near the shaft flange. Rotate the shaft and look for excessive movement on the gauge...or if it’s that bad, you’ll see it by eye.
if that’s good and within tolerance, it’s the engine mounts that need adjusted. As someone said earlier, it looks to be miss aligned on 2 axis (if your shaft side is known to be good).
that being the case, a good old leverage device like a crow bar or similar is usually handy to jack or lever the engine to a suitable alignment. you and a willing volunteer with spanner’s at the ready for locking off makes it easier.
Click to expand...

Unfortunately I can only estimate how central the shaft as the boat is in the water but as mentioned previously the shaft seal is very stiff and doesn't move much
 
The pictures there show the front mount and the (displaced) linkage and from the look of the link I’d say that the rear is high and need lowering by several mm and the front is even higher. To my mind this means removing at least one nut from front and rear and then taking up the ‘slack’ with shims.
 
Lightwave395 said:
..................the shaft seal is very stiff and doesn't move much
Click to expand...
However stiff it is, it is still made of rubber and you should be able to lift the shaft enough to make the shaft contact the top of the tube, and push it down to contact the bottom, though I think it is actually sitting on the bottom of the shaft tube.. Use however much force it needs to do this, and get help if you need it. If you don't establish a true centre position you are wasting your time doing anything else. Once you have established the vertical centre , check it side to side and fix it centrally with packing.

If you really find the rubber seal too stiff, try this. First get a shaft anode and fit it just in front of the rubber seal. this is to prevent the seal being pulled off the tube. Then slacken the clamp holding the seal. It does not matter if a little water leaks in but slackening the seal clamp will allow you to lift the shaft more easily because the seal will move a little. Re-tighten the seal once the shaft is centred and packed at the correct height and wedged against sideways movement.

Whatever you do I would slacken then re-tighten the seal with everything centred and the boat in the water as this will let the seal adopt a position where it is not distorted. When these rubber seals are fitted with the boat on land they are centred correctly but a boat is often slightly distorted when supported by a cradle and only adopts its true shape when evenly supported by water. This can lead to shaft misalignment and IMHO final adjustment should be done afloat.
 
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