Misaligned engine

[Gareth E]

My engine is ever so slightly misaligned to the propshaft. I know this because I recently removed the 'pusher' part of the gland assembly to measure for new packing. When I tried to push it back in it wasn't perfectly aligned, I had to use a screwdriver to lever it into the housing.

 

I can see from where the pusher meets the housing that the engine is aligned perfectly in the vertical plane. The misalignment is in the sideways plane.

 

My engine sits on bearers that are, I think, fairly standard: bolts underneath, then the engine, then bolts on top, allowing you to adjust the height of each corner. This is no help because it's already aligned in this way.

 

I removed the engine last year for a rebuild then recommissioned it myself. I gave no thought to alignment, just had the engine fork lifted onto the bearers and tightened the bolts.

 

There doesn't seem to be any provision within the bearer system to make sideways adjustments.

 

I was wondering, might it be worth loosening the engine bolts then tapping one side of the engine block with a mallet, in the hope that the small tolerance between the engine bolts and the holes in the engine block into which they locate, aided by the 'spring' of the propshaft might move it that fraction that I need?

 

Otherwise, how might I go about this task?

 

Many thanks.

[Eeyore]

Most mounts (with two holes for mounting to the bearer) have one one plain and one slotted hole. With any luck the slotted holes will all be at the same end. Slacken the nuts slightly and gentley knock the slotted end in the direction required. You will only get a small amount of ( available) movement, but it sounds as though thats all you require.

But maybe you’re talking about a “vintage” engine bolted down to timber bearers?

Edited June 4, 2018 by Eeyore

[Tony Brooks]

I can't picture what you mean by the holes in the engine block. I suspect you mean the holes in the engine feet that the mount studs go through.

 

If so then yes, loosen the to nuts on the stud  and try sliding the engine through any clearance between the stud and hole. However I doubt a mallet would shift it. I would disconnect the coupling and the try to lever the engine sideways. If there is no clearence I think you may have to lift the engien and file the holes in the feet.

 

try Eeyore's solution first.

[ditchcrawler]

I would suggest you aim for something better than being able to slide the packer in.

[Bee]

If the feet just bolt on to the block then remove the thing and stick it in a vice to file it, one at a time, much easier. I expect the rear feet will be part of the engine backplate though so you will maybe need an electric drill and raspy thing to do the job. Being the worrying kind I would check the whole thing, up, down, angular, parallel alignment as well but that's just me.

[Machpoint005]

9 minutes ago, Bee said:

Being the worrying kind I would check the whole thing, up, down, angular, parallel alignment as well but that's just me.

No, that's just good engineering practice.

[ditchcrawler]

The couplings can be spot on both height and vertical so the packer will slide in but it could be out angular with the engine pointing to one side or up or down.

[Gareth E]

I removed the engine nuts this morning. Unfortunately the bolts are a pretty tight fit to the holes in the engine feet so no adjustment is possible this way.

 

It seems I'm now faced with removing the engine, elongating the holes in the engine feet, then re installing. The nightmares of removing it last time, and re installing it, are still fresh in my mind, as are the series of water leaks I needed to solve over the following month.  

 

I'm wondering what damage continuing with this slight misalignment might do in the short, medium and long term? I'm not a prolific cruiser, maybe average 100 miles a year, or so.  

[Tony Brooks]

It will wear the bearing and gland until the shaft can line itself up. By then there is a fair chance you will have produced a mincer for the gland packing.

[nb Innisfree]

27 minutes ago, Gareth E said:

I removed the engine nuts this morning. Unfortunately the bolts are a pretty tight fit to the holes in the engine feet so no adjustment is possible this way.

 

It seems I'm now faced with removing the engine, elongating the holes in the engine feet, then re installing. The nightmares of removing it last time, and re installing it, are still fresh in my mind, as are the series of water leaks I needed to solve over the following month.  

 

I'm wondering what damage continuing with this slight misalignment might do in the short, medium and long term? I'm not a prolific cruiser, maybe average 100 miles a year, or so.  

You could investigate fitting a Aquadrive or Python drive, it might be the lesser of two tasks, it would eliminate any uneven wear and as a bonus significantly reduce vibration.

[Gareth E]

I'm starting to think on the basis that this misalignment may well have been in place since I've owned the boat, nearly 5 years now. I'm thinking this because I haven't adjusted the mountings at all, the engine was removed by fork lift then plonked back in the same spot. As there's no adjustment side to side, tight holes in the engine's feet, I'm struggling to think how this might have caused a misalignment.

 

I've now re packed the gland but before this it leaked very badly. 2 hours cruising would see more than drips, a steady stream coming in. I've dealt with this for 2 years by pumping large amounts of grease in then cruising a couple of hours then repeating. No adjustment was possible on the stern gland nuts, they were tightened as much as possible.

 

A couple of things I've noticed: First, when I removed the drive plate, when removing the engine, it was difficult to push the propshaft clear. I put this down to some wear on the propshaft maybe caused by packing but I didn't investigate further. Is this normal? 20 year boat I should add.

 

Also when I tightened 3 of the nuts that secure the engine they tightened down nicely. When I tightened the fourth the bolt that goes through the engine feet began to spin before the nut was fully tightened. I solved this by putting a spanner on the top of the bolts, where it's squared off, then tightened down. Is this normal or does it maybe point towards a problem with that particular mounting?

[Boat&Bikes]

1 minute ago, nb Innisfree said:

You could investigate fitting a Aquadrive or Python drive, it might be the lesser of two tasks, it would eliminate any uneven wear and as a bonus significantly reduce vibration.

I was thinking this as well. Or might it be possible to remove all the nuts holding down the engine, then tip the engine so that the rear feet lift off the bolts. Maybe then you could elongate the rear feet holes to allow sideways adjustment.

[Tony Brooks]

45 minutes ago, Gareth E said:

I removed the engine nuts this morning. Unfortunately the bolts are a pretty tight fit to the holes in the engine feet so no adjustment is possible this way.

 

It seems I'm now faced with removing the engine, elongating the holes in the engine feet, then re installing. The nightmares of removing it last time, and re installing it, are still fresh in my mind, as are the series of water leaks I needed to solve over the following month.  

 

I'm wondering what damage continuing with this slight misalignment might do in the short, medium and long term? I'm not a prolific cruiser, maybe average 100 miles a year, or so.  

Have you investigated what Eeyore said about possibly having slots in the actual engine mount. Where it bolts to the metal engine bed?

[reg]

1 hour ago, nb Innisfree said:

You could investigate fitting a Aquadrive or Python drive, it might be the lesser of two tasks, it would eliminate any uneven wear and as a bonus significantly reduce vibration.

If its only a small misalignment then a Centaflex might be easier and cheaper to fit. I believe they allow for a small amount of misalignment. 

Edited June 6, 2018 by reg

[Tony Brooks]

Apart fro their version of the Aquadrive I doubt it. Most allow about 2 degrees of angular misalignment but fer single element couplings allow for radial. There may be one other Centaflex that does so before you buy make sure you check the specification in writing, not verbally from the vendor.

[reg]

24 minutes ago, Tony Brooks said:

Apart fro their version of the Aquadrive I doubt it. Most allow about 2 degrees of angular misalignment but fer single element couplings allow for radial. There may be one other Centaflex that does so before you buy make sure you check the specification in writing, not verbally from the vendor.

This from their blurb

"CENTAFLEX-A is one of the most versatile flexible couplings available and is installed in countless applications in many different industries. Not only does it overcome four-way misalignment, it is available in a wide range of model types and SAE sizes, and copes with a wide range of nominal torques. "

How much misalignment it allows I don't know, would require studying the appropriate Pdf. Which might be worth doing if OP has any interest in going down this route. Cost wise seems to be around £380 + any associated costs. 

 

 

Glad I looked into it though because I wasn't previously aware of the Centaflex-AR replacement coupling which is certainly of interest to me. 

 

Edited June 6, 2018 by reg

[Eeyore]

2 hours ago, Gareth E said:

 

 

A couple of things I've noticed: First, when I removed the drive plate, when removing the engine, it was difficult to push the propshaft clear. I put this down to some wear on the propshaft maybe caused by packing but I didn't investigate further. Is this normal? 20 year boat I should add.

 

 

Yes, but most of the wear will be from the gland being too tight. A mooring post at the local boatyard is made from a worn shaft, it has an "hourglass" shape and is worn from 1.5" down to about 0.75"; and was fun to remove from the boat.

[Tony Brooks]

1 hour ago, reg said:

This from their blurb

"CENTAFLEX-A is one of the most versatile flexible couplings available and is installed in countless applications in many different industries. Not only does it overcome four-way misalignment, it is available in a wide range of model types and SAE sizes, and copes with a wide range of nominal torques. "

How much misalignment it allows I don't know, would require studying the appropriate Pdf. Which might be worth doing if OP has any interest in going down this route. Cost wise seems to be around £380 + any associated costs. 

 

 

Glad I looked into it though because I wasn't previously aware of the Centaflex-AR replacement coupling which is certainly of interest to me. 

 

I have ahd a quick google for a Centaflex AGM (not AR) and find its a twin element coupling just like an Aquadrive and just like the Aquadrive its longer than the typical Centaflex couplings s may no fit the OPs boat. I did not waste too much data trying to find the specifications for all the couplings it as I said the single element ones I looked at all seemed to only give angular displacement, not radial. A photo of an A series also shows it to be a two element coupling and longer than most

 

Centaflex make a range of couplings and drive plates so it may not be very helpful to the OP assert that a "Centaflex" coupling will accept radial misalignment, some will, most won't. A model must be given.

 

Edited to add that the A series did not seem to have a thrust bearing so in most cases the coupling will have to transmit positive and negative axial loads and the engine mounts will still be stressed by prop thrust. I think that if one can be fitted and Aquadrive or Pythondrive would be the way to go.

Edited June 6, 2018 by Tony Brooks

[Bee]

Aquadrive / Python is a very good coupling but its expensive, takes up at least 12" (?) and will need a mounting plate welded in the hull or on the bearers. Just leaving it be is not really the way forward. Centaflex etc are also quite dear and really you need to have a plummer block on the shaft just in front of the gland or the big heavy Centaflex might just choose to follow the same path that your shaft does now - I don't know but it might. Have you got mains electric? If you have then I would just enlarge the holes on the engine feet and fiddle with the alignment until all the bits of shaft go back together in a nice relaxed way and treat yourself to a beer. It'll cost nothing and with luck only take a day.

[Gareth E]

Right I'll have a go at the engine bearers tomorrow, see if I can get some adjustment there. Some of them are a pig to get to, just adds to the challenge I guess!

 

There's only about 5 inches of propshaft, plus the couplers, before the gearbox plate. This seems to rule out fitting an aquadrive or similar, from what I've read on here.

 

Looking at my set up (I know little of these things): There's a plate at the gearbox and a clamp type round thing on the prop shaft. Between these there's a plastic or similar thing. It's beige in colour, looks a bit like bakelite. Looking around on various sites it looks very much like what's described as a 'flexible coupler'. If this is flexible, is there still the need for 100% alignment or does this coupler allow you to get away with a bit of misalignment?  

[J R ALSOP]

I think you are referring to a R&D isolating coupling, which a really for isolating stray current. Having said that there is a few" thou' of tolerance in it.

[Tony Brooks]

Yes, I think that describes an R&D so called flexible coupling. In my view close to a bad mis-description. (see above).  Almost any other type of flexible coupling would provide better vibration isolation and allow more angular misalignment but would do nothing for you radial misalignment.

 

You still need as close to perfect angular alignment to minimise vibrations although a little angular misalignment might be accommodated. Radial misalignment such as you have needs to be as close to perfect as you can get it.

[nb Innisfree]

Python recommend a small radial offset, that is both shafts need to be parallel, this ensures lubricant reaches all bits of the cv joints.I assume Aquadrive is similar. 

 

Maybe the engine/gearbox could be slid further forward to make room?