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tortuga guy

Engine mounts

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Hello all you wonderful people, i have a question , when changing engine mounts, does the engine need to be lifted out or can they be changed one at the time without it being lifted , please excuse my ignorance  any reply will be greatly appreciated, thank you all for your time.

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19 minutes ago, tortuga guy said:

Hello all you wonderful people, i have a question , when changing engine mounts, does the engine need to be lifted out or can they be changed one at the time without it being lifted , please excuse my ignorance  any reply will be greatly appreciated, thank you all for your time.

I've not done this, but it should not need a lift out. The critical bit however is the alignment of the engine/gearbox to the propeller shaft afterwards by adjusting the level of each mount. If this is out it is not good news. If the current mounts need replacing, then it is likely that the alignment is not brilliant anyway. Sure someone will be along shortly to explain how to line everything up.

Jen

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The engine can be lifted enough by using a bar over the back end and chain ratchet, doesn't need more than an inch or 2 normally. 

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22 minutes ago, tortuga guy said:

Hello all you wonderful people, i have a question , when changing engine mounts, does the engine need to be lifted out or can they be changed one at the time without it being lifted , please excuse my ignorance  any reply will be greatly appreciated, thank you all for your time.

One at a time is possibly the best way.

Assuming that the engine alignment is correct before you start, undo the nut on top of the first engine bracket and count the number of turns you undo it, this is important. Then undo the bolts holding the mount to the bearer. Then carefully jack up the engine no more than you need to slip out the old mount and place in the new one, having  set the lower nut on the new mount at the same height as on the old. Repeat for all 4 mounts, paying attention to the heights of the old nuts and setting the new mounts nuts at those heights. When tightening up the two nuts on the studs, hold a spanner on the lower nut and gently tighten down the top nut.

Does that make sense?

  • Greenie 1

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I was told on my last engine check that one of them was running out of thread and so to replace all four 

1 minute ago, tortuga guy said:

I was told on my last engine check that one of them was running out of thread and so to replace all four 

Still earning , yes that does make much sense , thank you very much.

23 minutes ago, Stilllearning said:

One at a time is possibly the best way.

Assuming that the engine alignment is correct before you start, undo the nut on top of the first engine bracket and count the number of turns you undo it, this is important. Then undo the bolts holding the mount to the bearer. Then carefully jack up the engine no more than you need to slip out the old mount and place in the new one, having  set the lower nut on the new mount at the same height as on the old. Repeat for all 4 mounts, paying attention to the heights of the old nuts and setting the new mounts nuts at those heights. When tightening up the two nuts on the studs, hold a spanner on the lower nut and gently tighten down the top nut.

Does that make sense?

Yes it makes a lot  of sense , thank you 

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Once you you have done the swap as above, check the alignment is right.   Slack off the top nut on the mounts.  Bring the propshaft coupling up to the gearbox and check that it will mate easily with its other half on the box.  Move the engine bodily up or down as needed by adjusting all the lower nuts the same amount.  Then mate the couplings without bolts and check the two halves are parallel top to bottom using feelers between the two halves of the coupling to measure.  Get the gap thessme by adjusting the lower nuts on the front mounts.  Then repeat side to side, adjusting by moving the engine laterally at the front.  

Once you are happy check all the measurements again and tighten the top nuts the way stillearning says.  Depending on how your engine is installed there may be a widget ( eg a pythondrive) which will allow some misalignment to be acceptable.  If this is the case get the errors as good as you can and within the limits for your widget.

Take your time and make small adjustments.

N

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32 minutes ago, Jen-in-Wellies said:

I've not done this, but it should not need a lift out. The critical bit however is the alignment of the engine/gearbox to the propeller shaft afterwards by adjusting the level of each mount. If this is out it is not good news. If the current mounts need replacing, then it is likely that the alignment is not brilliant anyway. Sure someone will be along shortly to explain how to line everything up.

Jen

The present enlignement is fine but I think that when first fitted the threads and nuts were not entirely at the same height and so after years of tightening when needed one has run out of thread , it is the reason I'm having to change them as on my last engine check the engineer realised that one of them could not be tightened any further . Thank you for you input .

7 minutes ago, BEngo said:

Once you you have done the swap as above, check the alignment is right.   Slack off the top nut on the mounts.  Bring the propshaft coupling up to the gearbox and check that it will mate easily with its other half on the box.  Move the engine bodily up or down as needed by adjusting all the lower nuts the same amount.  Then mate the couplings without bolts and check the two halves are parallel top to bottom using feelers between the two halves of the coupling to measure.  Get the gap thessme by adjusting the lower nuts on the front mounts.  Then repeat side to side, adjusting by moving the engine laterally at the front.  

Once you are happy check all the measurements again and tighten the top nuts the way stillearning says.  Depending on how your engine is installed there may be a widget ( eg a pythondrive) which will allow some misalignment to be acceptable.  If this is the case get the errors as good as you can and within the limits for your widget.

Take your time and make small adjustments.

N

Thanks , that's great advice .

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You ,may well have to undo the shaft coupling (if not already said) yo allow the back of the engine to lift enough if the mounts have long studs on them. That is unless the studs can be unscrewed.

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1 hour ago, Tony Brooks said:

You ,may well have to undo the shaft coupling (if not already said) yo allow the back of the engine to lift enough if the mounts have long studs on them. That is unless the studs can be unscrewed.

Thank you for that extra bit of info , you're all wonderful , happy new year !.

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Fit an Aquadrive or Python Drive and forget about alignment problems.

 

Can't understand that you are running out of thread 'cos of retightening mountings, if that is do the mounts must have collapsed so the alignment must be out.

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I would agree with Boater Sam. If the mounts have '"run out of thread" then something has failed. It might be that a loose spindle nut has allowed engine movement which in turn damaged the thread. Whatever the reason the mounts will have to be changed and to do this the engine has to be lifted slightly.

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If the engine has needed regular tightening of the mounts, it almost certainly has either some misalignment or imbalance between mountings.

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23 minutes ago, Slim said:

I would agree with Boater Sam. If the mounts have '"run out of thread" then something has failed. It might be that a loose spindle nut has allowed engine movement which in turn damaged the thread. Whatever the reason the mounts will have to be changed and to do this the engine has to be lifted slightly.

Assuming the mounts are conventional a decent 24mm ring combination and a 24mm deep socket are invaluable. Where are you moored? Are you going to tackle the job yourself and if so when? It's possible I have some gear that may help. If you respond to this by 2pm today it might speed things up. Also what type of stern is your boat?

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59 minutes ago, BWM said:

If the engine has needed regular tightening of the mounts, it almost certainly has either some misalignment or imbalance between mountings.

Only one of them has run out of thread, its what I learned from my last RCR inspection, he said it may need to be done at some point, the boat runs fine with minimal vibration, I think he means that if it ever needs tightening it will need changing and as I gather when one needs changing the lot are changed. 

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Lets have photos of the offending mount and some others.

 

The only "running out of thread" I can imaging on the common type of mounts is of the rubber has collapsed to such and extent the bottom of the stud is sitting on the bed (which woudl prevent the stud getting any shorter) or id the shaft had dropped so far the nuts on the mount were tight against the actual base of the mount but then it woudl be two mounts not one plus the gland would be pouring water in.

 

Something seems not right to me.  Also lets have a photo of the shaft and gland.

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26 minutes ago, Boater Sam said:

Ah, its an RCR inspection then. Must be perfectly OK.

 

 

I don't think!

I too would be dubious about anything an RCR inspection said. The guys who did my last one nearly got RCR banned from my mooring site entirely and made a mess of the whole thing. I'd get it looked at by a real engineer first, but if it's running fine, why risk changing anything? 

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1 hour ago, Boater Sam said:

Ah, its an RCR inspection then. Must be perfectly OK.

 

 

I don't think!

Well it never has needed to be adjusted, he stated that the day it does that particular one won't be able to be tightened, so I thought I'd get them changed anyway for peace of mind, though saying that I've not noticed any difference in the 3 years I've had the boat, so it's become a job to do in not too long future I suppose. Thanks 

 

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19 minutes ago, tortuga guy said:

Well it never has needed to be adjusted, he stated that the day it does that particular one won't be able to be tightened, so I thought I'd get them changed anyway for peace of mind, though saying that I've not noticed any difference in the 3 years I've had the boat, so it's become a job to do in not too long future I suppose. Thanks 

 

We can't give any informed opinion unless you we can see exactly what you are talking about, hence the request for photos. I think it is fair to say at present most of us have doubts about what may be wrong.

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18 hours ago, matty40s said:

The engine can be lifted enough by using a bar over the back end and chain ratchet, doesn't need more than an inch or 2 normally. 

 

I've never done it myself but wouldn't a car jack used to support the engine do the job? If all 4 mounts needed changing then doing each mount in turn and moving the jack to an appropriate position for each one? They'd still need setting for correct alignment of course.

 

Just thought that a car jack is a more ubiquitous bit of equipment than a chain ratchet.

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8 minutes ago, blackrose said:

 

I've never done it myself but wouldn't a car jack used to support the engine do the job? If all 4 mounts needed changing then doing each mount in turn and moving the jack to an appropriate position for each one? They'd still need setting for correct alignment of course.

 

Just thought that a car jack is a more ubiquitous bit of equipment than a chain ratchet.

Yes, an old scissors jack, like I used to have in my Morris Traveller was perfect, those jacks wind down very low, and fit under most engines.

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9 minutes ago, blackrose said:

 

I've never done it myself but wouldn't a car jack used to support the engine do the job? If all 4 mounts needed changing then doing each mount in turn and moving the jack to an appropriate position for each one? They'd still need setting for correct alignment of course.

 

Just thought that a car jack is a more ubiquitous bit of equipment than a chain ratchet.

Yes, as long as you can get the jack between the base plate and engine/gearbox. If I were going to do that sort of job I would be placing the cross bar between a brick etc. and the jack     then strap the engine /gearbox to the bar. That way stuff the a boater will probably have access to can be used without the possibility the jack will prove to be too tall.

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7 minutes ago, Stilllearning said:

Yes, an old scissors jack, like I used to have in my Morris Traveller was perfect, those jacks wind down very low, and fit under most engines.

 

I have one in my engine room that slides under the engine. I can't even remember where it came from? I think I scrapped a car about 15 years ago and kept it. I keep all sorts of junk. Bound to come in useful one day! 

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43 minutes ago, blackrose said:

 

I've never done it myself but wouldn't a car jack used to support the engine do the job? If all 4 mounts needed changing then doing each mount in turn and moving the jack to an appropriate position for each one? They'd still need setting for correct alignment of course.

 

Just thought that a car jack is a more ubiquitous bit of equipment than a chain ratchet.

Tis fine in an engine bay with as much room as you have, but a narrowboat may well have very restricted access, for the jack or space to use the handle, or no access at all.

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Aaargh! Engine mounts and alignment! Changing the mounts is not rocket science, just a matter of undoing various nuts and things, a few blocks of wood and wedges and some sort of jack. Running out of thread....? Dunno. What you are trying to achieve is the engine sitting level side to side, not tilted and the gearbox drive flange nicely mating with the flange on the propeller shaft. This is done by raising and lowering the engine on the big threaded bolt thingys that stick out of the top of rhe mounts. This can be fiendishly difficult sometimes. Lift the front and the back drops, lift the back and its perfect at the top of the flange but now its wrong at the bottom, get it right and the blasted thing is on the tilt, finally get it right and the exhaust will not connect up.  I exaggerate a bit but it can take a long time sometimes. Also, don't have the engine poised on tiptoe right at the top of the threaded thingy, if that happens then pack under the mounts with wood to raise them. Even if you have an Aqua / Python drive you can't just bung the thing in. Good luck, it is not hugely difficult but it can be awkward, and don't forget the various fuel pipes. water and exhaust that may (or not) have to be disconnected.

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