Removing/refitting a cylinder block

[James W]

Hi guys,

As part of the ongoing engine rebuild i've got to clean out the cooling channels in my cylinder block. It's going to be a right pain to do it in situ on the boat, so I want to take it off and bring it back home.

Getting it off won't be a problem but when it comes to re-fitting it, is it possible to just to compress the piston rings and then drop the block back over the piston? Obviously the piston will need to be supported in some way but would it be as simple as that?

Any help would be much appreciated.

Thanks!

 

[VicS]

Hi guys,

As part of the ongoing engine rebuild i've got to clean out the cooling channels in my cylinder block. It's going to be a right pain to do it in situ on the boat, so I want to take it off and bring it back home.

Getting it off won't be a problem but when it comes to re-fitting it, is it possible to just to compress the piston rings and then drop the block back over the piston? Obviously the piston will need to be supported in some way but would it be as simple as that?

Any help would be much appreciated.

Thanks!

You dont say what engine (MD1B ???) but I am sure we have done it with an MD11C.

Needs a "special" type of piston ring clamp. That can be clamped around the pistons below the block and then removed once the rings are in the bore.
Like the ones used for 2T motorcycle engines where the cylinder and head are all one piece

 

[James W]

You dont say what engine (MD1B ???) but I am sure we have done it with an MD11C.

Thanks Vic, that's given me some hope.

Yes, it's that blessed MD1B. If you've managed it with an MD11C, it should be similar. Not straightforward i'm sure, but at least it can be done.

 

[30boat]

You can compress the rings with the tips of your fingers but there a good chance of breaking a ring.There's a way of doing it that works well even in three cylinder engines (My old Triumph trident) which is:Get hold of some 1mm sheet mild steel strip wide enough to span the rings and a bit and shape it over the piston.Make it longer than the primeter of the piston.Drill two 5mm holes at each end and then bend the ends at 90º.Make it so that there is a gap when you place it over the piston rings.Now pass a machine srew (slotted head) through the holes and you have a piston ring compressor.Sand or file the edges smooth so you don't scratch the piston.Oil it, tighten the compressor making sure the ring gaps are not in the same line and offer the cylinder block.Tap it gently over the piston and as soon as the rings are in ,undo the screw and remove the compressor.Stuff a rag into the cranckase so that nothing falls in.It takes me less than 20mns to make one of these clamps.

 

[James W]

Thanks for all your help, much appreciated......now on with the job!

 

[30boat]

You can compress the rings with the tips of your fingers but there a good chance of breaking a ring.There's a way of doing it that works well even in three cylinder engines (My old Triumph trident) which is:Get hold of some 1mm sheet mild steel strip wide enough to span the rings and a bit and shape it over the piston.Make it longer than the primeter of the piston.Drill two 5mm holes at each end and then bend the ends at 90º.Make it so that there is a gap when you place it over the piston rings.Now pass a machine srew (slotted head) through the holes and you have a piston ring compressor.Sand or file the edges smooth so you don't scratch the piston.Oil it, tighten the compressor making sure the ring gaps are not in the same line and offer the cylinder block.Tap it gently over the piston and as soon as the rings are in ,undo the screw and remove the compressor.Stuff a rag into the cranckase so that nothing falls in.It takes me less than 20mns to make one of these clamps.

Forgot to say you need a nut for the screw.