Gearbox worries me

[Tony Brooks]

29 minutes ago, Sid Charles said:

Turning the prop shaft by hand is the same in both directions and there is no play in any direction, I think it will be OK, it's probably me being aver cautious 

 

If you are not used to them, mechanical boxes do tend to go into gear with a bit of a bang. As to investigate further involves stripping the box I think suck it and see is probably the pragmatic way forward. If ahead is slipping slightly, giving a softer engagement, you will soon find out, then the box will have to be stripped for overhaul or replaced.

[Sid Charles]

On 23/02/2026 at 08:12, Tony Brooks said:

Another point you may not be aware of. When an engine runs, there is no scientific law that says the engine will stay still and the crank will revolve, it is only the engine mounts and any tie bar that force the block to stay more or less still and the crank to turn. In you have soft mounts, broken mounts, loose mounts, or mount rubbers that have softened then the engine will try to tip to one side each time you alter the load on it. This is called torque reaction. However, unless there is a mount fault, I think this should be similar for ahead and astern.

Tony: Today I had a closer inspection of the engine mounts and when you really test them using a crowbar they are shot, I can't run the engine at the moment due to the expansion tank being off, but 2 of the mounts at the front are definitely done for, I took a picture to Midland Chandlers in Willington I also took the measurements, they showed me all they had, and I decided on 2 which I think are 150lb strength? is that how they are measured? next question do you think I will be able to sneak them in without lifting the engine? I can see a few hours of fun and games looming.

[Tony Brooks]

Just now, Sid Charles said:

Tony: Today I had a closer inspection of the engine mounts and when you really test them using a crowbar they are shot, I can't run the engine at the moment due to the expansion tank being off, but 2 of the mounts at the front are definitely done for, I took a picture to Midland Chandlers in Willington I also took the measurements, they showed me all they had, and I decided on 2 which I think are 150lb strength? is that how they are measured? next question do you think I will be able to sneak them in without lifting the engine? I can see a few hours of fun and games looming.

 

It depends upon the type, if they use a dolt to secure them to the engine foot then yes, as long as you can jack the engine up a little. If they are secured with a stud sticking out the top, then, yes if you can unscrew the stud, otherwise it will probably have to be a more major engine lift to clear the stud. 

 

Remember that you will need to check and probably realign the engine to the shaft.

 

I can't comment on the "strength" because I don't know what the manufacturer/mariniser specified.

 

If both the front mounts are bad, then it should affect both ahead and astern as far as torque reaction is concerned. If it was a mount fault, I would have expected it to be on one side, even just one mount.

 

 

[Sid Charles]

All the dimensions are the same, so I think these will be OK

[Tony Brooks]

If the stud unscrews, which it looks as if it may, by the hexagon on it.  However, it looks as if it may screw into that thick plate seated in rubber ends. If that can move about it may make screwing the stud back in more difficult.

[Peugeot 106]

Can I suggest “Air Wedges” may be your friend for engine lifting and help with alignment. Or a Spanish windlass. Search for them on the forum and all will be explained

Also R&D may be able to assist confirming the mount sizing though last time I used them they were a bit terse

[Sid Charles]

Due to being an Engineer who installs machines, I have various hydraulic jacks that will do the job nicely, I'll just suck it and see on the weight thing, I think the ones I have are beefy enough. Oh and I said 150LB they are actually 410LB load bearing, so plenty I would say

Edited February 25 by Sid Charles

[Sid Charles]

The job went quite well I  split the drive coupling and after taking the bolts out that go through the mounts and thick lumps of wood and the main nylock which passes through the engine plates, I eased the engine up slowly until I could sneak the old mount out, then the new one in after taking careful measurements of where the lower nut should be set however, I think it may have been a waste of time because to my disbelief before I began the work I was leaning on the engine mount near the exhaust (I must have walked on this a hundred times) and I noticed a clunk and the engine jumped to the side, there was a big gap under the plate to the lower nut, so looking at it all from a totally different perspective, it is no wonder there was a clunk when I engaged the reverse gear, the bloody lot was loose, amazing that I had never noticed this, I have cleaned, painted and re wired stuff and never noticed just how bad these engine mounts were. I have halted the work to purchase all new bolts, nuts and washers, might as well whilst it's apart, it will be Friday now before I finish the work.

[Peugeot 106]

1 hour ago, Sid Charles said:

amazing that I had never noticed

Not really amazing. I get blind to all sorts of other jobs that need doing when I have decided the one I’m on will put everything right. It’s called selective sight. The to do list never gets shorter

 

i couldn't justify expensive hydraulic lifting gear though I did lust a bit over the low profile rams.The air wedges are my  poor man’s version!
 

Anyway I bet you’re pleased with yourself. Make sure you align it properly. Another job that definitely kept me amused. Make sure you get the weight on all 4 mounts (not just 3). Probably teaching Granny to suck eggs

 

We may have trod a similar path. I renovated mine over a couple of years but was lucky to have access to a barn. 

 

 

 

[Eeyore]

A common method of installation is to minimise the gap below the lower nut by adjusting the thickness of the packer between the engine beds and the mounts.

Its a bit unusual to see what appears to be wood used as packers, but nothing wrong with it.

Instal and set up as is, then measure the gap between the lower nut and the shield on the top of the mount. Add additional packing of this thickness below the mount (or just made new packers to suit).

You'll probably need a minor adjustment after a few hundred hours, but the gap below the lower nut will still be minimal.

Of course some will instal shims on top the mount and just tighten down from above.

Hey presto - granny taught to suck eggs 😎😇

 

Edited February 26 by Eeyore

[Sid Charles]

Well I wouldn't like to do that job again in a hurry, I'm a bit too old and overweight to fit into places where I normally would, blimey my legs will be hurting for days, however, I got all the engine mounts fitted, getting a spanner to hold the bolt from below the engine bed was the worst part, and the nyloc nuts had to go about 25mm down the thread, I tried all types of tricks but nothing was successful, so it was just grin and bear the pain. Strangely enough the bit I was dreading, the lining up of the drive was dead easy, I measured from the base of the old mounts to the top of the bottom nut, it was 81mm, I put all 4 mounts in and tightened to 2 bolts which on this boat pass through lumps of hardwood, and without tightening the large nut on the top of the engine frame, I tried the coupling, up/down seemed spot on, but side to side was about 1mm out, I used a big lump of wood the gently squeeze the engine over and it was in line however, when I took the pressure of the lump of wood it sprung back, it was only about 1mm and the rubber mounts would take that, but I was being a bit finnicky, so I went to the trouble of slackening the 4 bolts holding the mounts (there is a little bit of space) I did the trick with my lump of wood, this time the 4 coupling bolts didn't spring sideways and I re-connected it all up loosely, then carefully tightened the 4 bolts on the mounts, keeping on checking the prop shaft was turning freely, when everything was as tight as hell the prop shaft turned more freely than it ever as, so I'm proper chuffed despite needing pain killers. I think it all needs a good clean now and maybe a touch of paint.

Edited February 27 by Sid Charles

[Alan de Enfield]

 

Doesn't it feel great when you successfully achieve something (which you were not looking forward to) ?

 

Well done.

[Jen-in-Wellies]

2 hours ago, Sid Charles said:

Well I wouldn't like to do that job again in a hurry, I'm a bit too old and overweight to fit into places where I normally would, blimey my legs will be hurting for days, however, I got all the engine mounts fitted, getting a spanner to hold the bolt from below the engine bed was the worst part, and the nyloc nuts had to go about 25mm down the thread, I tried all types of tricks but nothing was successful, so it was just grin and bear the pain. Strangely enough the bit I was dreading, the lining up of the drive was dead easy, I measured from the base of the old mounts to the top of the bottom nut, it was 81mm, I put all 4 mounts in and tightened to 2 bolts which on this boat pass through lumps of hardwood, and without tightening the large nut on the top of the engine frame, I tried the coupling, up/down seemed spot on, but side to side was about 1mm out, I used a big lump of wood the gently squeeze the engine over and it was in line however, when I took the pressure of the lump of wood it sprung back, it was only about 1mm and the rubber mounts would take that, but I was being a bit finnicky, so I went to the trouble of slackening the 4 bolts holding the mounts (there is a little bit of space) I did the trick with my lump of wood, this time the 4 coupling bolts didn't spring sideways and I re-connected it all up loosely, then carefully tightened the 4 bolts on the mounts, keeping on checking the prop shaft was turning freely, when everything was as tight as hell the prop shaft turned more freely than it ever as, so I'm proper chuffed despite needing pain killers. I think it all needs a good clean now and maybe a touch of paint.

Excellent result. Have you tested if the gearbox still clunks? 

[Sid Charles]

Jen

I'm dying to but I have the water expansion tank off, it's split and can't find another, so I am going to attempt to glass fibre it in the morning when my legs are working.

[Jen-in-Wellies]

13 minutes ago, Sid Charles said:

Jen

I'm dying to but I have the water expansion tank off, it's split and can't find another, so I am going to attempt to glass fibre it in the morning when my legs are working.

One from a car scrap yard may well do the job. 

Know what you mean about the legs. I am reasonably small and go caving for fun. I still find contorting myself in to engine holes and spannering stuff gives me aching muscles. 

[Tony Brooks]

9 minutes ago, Sid Charles said:

Jen

I'm dying to but I have the water expansion tank off, it's split and can't find another, so I am going to attempt to glass fibre it in the morning when my legs are working.

 

Well done.

 

Got a photo of the tank because if it is a remote one, a different, but replacement should not be too difficult to source. Or tell us the connections it has on it and where they go to. Some re-piping may be required, but as it is a heat exchange system (I think) the volume of the tank will be far less critical than on a tank or keel cooled boat.

[ditchcrawler]

Others are available https://www.ebay.co.uk/itm/187641529263?  

 

Edited February 27 by ditchcrawler

[Peugeot 106]

Barrus Shire do quite a nice rectangular expansion tank as I think used on hire boats. ( mounted above deck) 

 

tolerance axial and radial on single R&D coupling is 0.25mm. Not sure about your two coupling arrangement though

 

 

when I work on the engine I am always surprised how much it hurts when I crack my head on steel

[Ex Brummie]

Not wishing to be a prophet of doom, but apart from checking the alignment, did yo measure the distance between the drive couplin, did you also check that the distance apart was equidistant all round?

[Sid Charles]

11 hours ago, ditchcrawler said:

Others are available https://www.ebay.co.uk/itm/187641529263?  

 

Yes I already purchased a similar tank, but it just will not fit in the area of the old tank (I'll post pics of old one) it was a ford car one from 1970's and obsolete now, the one I purchased is a bit like the one you have shown, but the outlet is not in the right place and too small in diameter for my water pipe 

This is my original

[Tony Brooks]

All I can see is the small air vent hose that attaches high up on the engine or heat exchanger/manifold to help vent air when filling and a blanked off main connector stub. There should be another hose attached that goes into the engine low down. Possibly T'd into the engine water pump inlet hose.

 

Both hoses can be extended, so the header tank can go anywhere as long as the hoses run slightly uphill to the tank and do not bow up or down to avoid air locks. I can't be 100% sure about this because we don't know about where the connections run to and the fact it is not a common marinisation.

 

There seems possibilities here https://www.spareshut.com/collections/coolant-expansion-tanks  Amazon list a lot as well, and there is always vehicle breakers who, if you take yours to them, may well find you a close match.

 

 

Personally I doubt glassing the cracks will provide a long term solution, not much seems to stick to HDPE. 

 

If only the top is cracked then I will stick my neck out and say that for CANAL use there is no need for pressurisation of the cooling system, so as long as you leave the pressure cap off the engine is runnable. The pressurisation is only used to prevent localised boiling inside the head when running under high load and speed. 

[Sid Charles]

Sorry there is a bottom outlet i didn't get on my shot, I am trying the glass fibre then take it from there

[Tony Brooks]

16 minutes ago, Sid Charles said:

Sorry there is a bottom outlet i didn't get on my shot, I am trying the glass fibre then take it from there

 

That is what I would expect so any header tank of any shape that you can mount somewhere will do the job as long as it has one large at the bottom and one small at the to pipe stubs to suit the size of hose needed, any extra stubs can be blanked off.

[Jen-in-Wellies]

There are people who will make you a custom aluminium, or stainless header tank with the size and take off stubs you specify for that engine hole bling. For a price. The Gucci solution. 

[Tony Brooks]

1 hour ago, Jen-in-Wellies said:

There are people who will make you a custom aluminium, or stainless header tank with the size and take off stubs you specify for that engine hole bling. For a price. The Gucci solution. 

 

Or, as the OP says he is an engineer maybe fabricate his own from scrap copper sheet and solder. I very much doubt it needs a pressurised system.

Just had a thought, I think an old stainless steel saucepan and a few tank fittings and hose tails would do the job.