Engine Replacement Project

[Jokani]

Gemini a 1976 Westerly Centaur has the original MD2B engine that has become hard to start from cold and smokey at higher revs, it's time for a new engine.

To try and keep the costs down and reuse as much of the existing sterngear as possible I have purchased a Volvo MD2020B with approx 1500 hours on the clock, it is complete with MS2B gearbox, mounts, control panel and wiring loom.

I have little mechanical experience, none prior to purchasing Gemini eighteen months ago. I have fitted a cutlass bearing, rope cutter, PSS seal, flexible coupling, plus more experience than I would have liked with water pumps and impellers. Despite the limited skillset, I am going to try an fit the new engine myself, as much as for the knowledge and experience as the money saved. Bits that I am unsure of I'm hoping to ask for advice in this thread.

Rather than lots of individual threads I'll try and document the whole engine replacement process in this just this one, in the hope that it will become a resource for others in the future.

Photos of the existing engine installation:

The plan so far is:

Disconnect:

1. Wiring
2. Diesel delivery and overflow pipes
3. Water input pipe
4. Gear cable
5. Throttle cable
6. Cold start cable
7. Stop cable
8. Exhaust pipe

Remove existing engine using a 2 ton block hoist and the boom. Boom supported by mainsheet halyard above lifting point, and topping lift as backup..

Hoist in new engine, trial fit on existing engine bearers. I am hoping that the new engine will align with the shaft without additional work, if it doesn't I'll plan from there.

Problem No1

I need to move the engine towards the stern by approx 16" so that the engine lifting eye is clear of the cockpit access. But removing the shaft coupling, shaft and PSS seal would create only 12 inches of space in to which the engine can slide. So the engine may need to be tilted to get the gearbox clear over the stern tube.

The top of the lifting eye will be only just clear the top of the cockpit access.

The centres of the engine mounts are 17" apart, so if the engine were to slide forward by 16", the front mounts would still be on the engine bearers, therefore I only need to support the rear until I can attach to the lifting eye.

What would be the best way to move the engine to the rear so that I can access the lifting eye and start the hoisting process?

 

[aluijten]

Why don't you separate the gearbox from the engine first? That saves some weight from lifting and makes the clearance problem smaller.

 

[nickd]

Take the gearbox of in situ to reduce length
Take the flywheel off in situ to reduce weight
It will probably be quite manageable then

 

[Jokani]

Looking at the workshop manual it looks like it only requires four bolts to be removed to get the gearbox off.

Nothing in the workshop manual at all on removing the flywheel. Looking at the photo it looks like it may be just be some bolts in the center?

 

[Tranona]

If you can get direct access overhead through the companionway, then take it out forward. It is obviously lighter if you remove the gearbox and flywheel, but the latter can be a challenge to remove. Would not think trying to get it out of the cockpit hatch is viable.

A 2 Ton hoist is more than man enough to lift the engine. You may need to build some sort of temporary support for the front of the engine to pull it forward far enough to get a straight lift.

 

[ghostlymoron]

If its like my MD1, the gearbox has about 6 bolts holding it on plus two 'easing screws' which push it off the splines.
The flywheel is more tricky and you need a VP special tool to pull it off the tapered and keyed shaft. I'm going to make a puller which will be a chunk of steel plate about 70mm square with 4 holes 60mm apart to attach with bolts to the tapped holes in the flywheel (which appear to be m9 thread), and a tapped central hole for a 10mm bolt to push off, bearing on the central shaft. If anyone's got the VP special tool, I'd very much like to borrow it.

Looking at the workshop manual it looks like it only requires four bolts to be removed to get the gearbox off.

Nothing in the workshop manual at all on removing the flywheel. Looking at the photo it looks like it may be just be some bolts in the center?

 

[chrishelen]

Interesting thread. I replaced a perfectly good petter for a volvo 2001 on my old Eventide, what I didn't know was that the ms2b gearbox was the down angle type!!! So..... much chopping and changing of engine beds to suit.

 

[Jokani]

The flywheel is more tricky and you need a VP special tool to pull it off the tapered and keyed shaft.

So long at the flywheel will fit through the hatch, I think that means means, for me at least, it will be staying on!

 

[Jokani]

So..... much chopping and changing of engine beds to suit.

For me, I think that both the new and old gear boxes are either the same of very similar, part of the reason I decided to replace a Volvo with a Volvo.

Hopefully I will be lucky, we will see!

 

[chrishelen]

Good luck.

 

[ianat182]

Have you checked the rotation of the new gearbox to suit the existing prop.It maybe a lefthand turning shaft or vice versa.

ianat182

 

[Tam Lin]

My old engine came out through the companionway hatch in one piece. We made a template of the new engine's feet out of scrap pieces of steel so that we could see where they would go before lowering the new engine in. A lot simpler than discovering that it won't fit the beds when it is in there!

 

[jerrytug]

Very interesting I have an MD3B which is ok at the moment. What will you be doing with the old Volvo?

 

[Jokani]

Very interesting I have an MD3B which is ok at the moment. What will you be doing with the old Volvo?

It depends, the Yard Manager has an MD7, but would like some more HP. If I get in to trouble with the installation of the new engine, then I may trade the MD2B for help/advice.

 

[VicS]

So long at the flywheel will fit through the hatch, I think that means means, for me at least, it will be staying on!

The four bolts you referred to earlier just hold the drive belt pulley to the flywheeel.

The flywheel itself is keyed onto a taper and secured with a single large nut on the end of the shaft. It is very tight (500lb.ft!) Id think getting the flywheel off could be more of a challenge than getting the whole engine out of the boat.

 

[garvellachs]

The four bolts you referred to earlier just hold the drive belt pulley to the flywheeel.

The flywheel itself is keyed onto a taper and secured with a single large nut on the end of the shaft. It is very tight (500lb.ft!) Id think getting the flywheel off could be more of a challenge than getting the whole engine out of the boat.

Gearbox comes off easily.

The flywheel nut can be undone with a chisel (or drift) and a big hammer. To loosen the flywheel off its taper try bolting on one of those pullers that has a plate with slots in it and a big central bolt that screws into the central shaft of the flywheel. A gear puller maybe? Wind it up as tight as you dare then hit the central bolt hard with a big hammer (if I remember rightly). If you are bold enough, the flywheel will come off the taper explosively with a bang - beware of it falling because it's very heavy, so rig up something to contain it. I've done it twice on different engines.

 

[JumbleDuck]

The flywheel nut can be undone with a chisel (or drift) and a big hammer. To loosen the flywheel off its taper try bolting on one of those pullers that has a plate with slots in it and a big central bolt that screws into the central shaft of the flywheel. A gear puller maybe? Wind it up as tight as you dare then hit the central bolt hard with a big hammer (if I remember rightly). If you are bold enough, the flywheel will come off the taper explosively with a bang - beware of it falling because it's very heavy, so rig up something to contain it. I've done it twice on different engines.

I've had consistent success using air-driven impact wrenches to remove crankshaft nuts on cars.

 

[Len Ingalls]

Cut a length of 2x4 lumber to span across the top of the drip box that surrounds engine.
Place a stout rope or chain around the gearbox tail & use the hoist to pull eng. back & up over the shaft & coupling,until you get the lifting ring out into cockpit.
Place 2x4 under eng. & lower eng. to sit on it.
Relocate hoist to lifting ring & remove eng.

It may be handy to have some extra lumber scraps on hand for prying,blocking,etc.
It would be very handy to have another stout lad to give you a hand.

You will likely find the new eng. will install nose down first also.

Make some overall height from mounts to top of eng measurements as well as mount to bed comparison measurements before you put new eng. in the hole.

Cheers & good luck / Len

 

[reeac]

Cut a length of 2x4 lumber to span across the top of the drip box that surrounds engine.
Place a stout rope or chain around the gearbox tail & use the hoist to pull eng. back & up over the shaft & coupling,until you get the lifting ring out into cockpit.
Place 2x4 under eng. & lower eng. to sit on it.
Relocate hoist to lifting ring & remove eng.

It may be handy to have some extra lumber scraps on hand for prying,blocking,etc.
It would be very handy to have another stout lad to give you a hand.

You will likely find the new eng. will install nose down first also.

Make some overall height from mounts to top of eng measurements as well as mount to bed comparison measurements before you put new eng. in the hole.

Cheers & good luck / Len

I had a Centaur reengined some years ago. The very experienced engineer who did it lifted the engine a few inches using a chain hoist and a timber across the top of the companion way. He then swung it for'ard into the cabin so that it was directly below the open companion way roof. The lift was then done by hired JCB which transferred the engine (MD11C) to a trolley that I'd made so that it could be moved about. The JCB then lifted in the replacement engine which was initially placed in the cabin whilst I did a big cleanup and painting job on the engine compartment before using the chain hoist to swing it into final position. The engineer used a timber mock up to modify the engine mounts to suit the new engine. Be warned ...in our case it turned out that the propshaft was off the centre line between the engine bearers by at least an inch.

 

[ghostlymoron]

To remove the large nut I borrowed a large socket (about 56mm as I recall) and smote the bar through it with a sledge hammer. I checked the four bolt holes with a tap and they seem to be between m8 and m10. As there doesn't seem to be an m9 size, does anyone know what size they are?

The four bolts you referred to earlier just hold the drive belt pulley to the flywheeel.

The flywheel itself is keyed onto a taper and secured with a single large nut on the end of the shaft. It is very tight (500lb.ft!) Id think getting the flywheel off could be more of a challenge than getting the whole engine out of the boat.