Cylinder liner replacement

[veloduke]

Has anyone here replaced the cylinder liner?
I read in manuals about how the liner (magically) drops out when the barrel is heated, but is that true?
Is a hefty press needed?

[Duccout]

Hi Max,

I've changed a few over the years. This is how I (an amateur) do it. I heat the barrel in the oven until spit sizzles on the fins, then, placing the barrel muff top down, on a Workmate, opened enough to allow the liner to fit through, I tap down on a piece of wood placed across the liner skirt with a mallet. When the liner is level with the muff, I switch to tapping it out with an aluminium bar. An old cushion must be placed under the Workmate to catch the liner.

I keep the new liner in the freezer and reheat the muff, then (this is the hard part) making sure that the liner is correctly positioned and lined up over the top of the muff, I place a block of wood over the top of the liner and tap it down into the muff.

This is probably all wrong, but it has worked for me over the years.

[ranton_rambler]

If you don’t fancy it yourself, I’m told that SEP at Kegworth are good, or you may find someone more local.
I used to work with Valtra tractor engines and their Chief Engineer told me that in the olden days they would change wet liners by taking the head and sump off and whack them out from underneath with a big hammer and a lump of timber.

[LaceyDucati]

Max

The liners do drop out quite easily in an oven as per the manual. Mind you you will smoke the kitchen, be warned!

They drop in much the same, easily, the only real issue is stopping the liner creeping out as it cools. This is the only time I ever use the press in the process, just to keep a light load on the top as it cools. If you don't you will find a few thou gap under the top flange. However I'm sure a bit of ingenuity could be used to hold it down, maybe a large stud/bolt and some spacers/plates and keep it under load during cooling. I always lap or machine the top face after installation to ensure a perfect flat seal.

There is a lot to liner replacement as often I find the muffs are distorted and need honing true and oversize liners. That said many don't consider this and get away with it.....

Regards Nigel

[Jordan]

I replaced a 350 liner once, in an oven, no press just gravity.
Warned about new liner creep-out, I placed a weight on it after dropping it in for cool-down.

As an aside, the old liner wasn't worn - it developed a crack starting at the corner of the square-edged slot for the conrod.
I filed the slot on the new one, so it was arch-shaped from one side to other.

[LaceyDucati]

Jordon

Yes the original slots with sharp corners are prone to propagating cracks. Like you i always leave a radius in the slot which solves the issue. Millling the slots with a small end mill is how I do it, but filing them and the other features in carefully is perfectly acceptable.

Regards Nigel

[blethermaskite]

just one other thing that I do.......... its well worth making up four 10mm diameter guide rods to slip down the cylinder bolt holes, this insures you get the bolt cut outs in the liner nicely lined up with the jacket, after I finally tap the liner down and get the "that's home ring" I put a 56lb weight on top of the liner to stop any contraction creep.
Cheers,
George