# Cyl. liner fit



## Putt-Rite (Jul 18, 2013)

Why do cylinder liners have to be pressed in so tight? The head fits tight on the cylinder, which sits tight on the deck, shouldn't that hold it? Why are commercially made engines' cylinder liners always pressed in so tightly?


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## stevehuckss396 (Jul 18, 2013)

If the block has water jackets in it the liner needs to be tight to seal the water jacket. Other than that I would think that a slip fit would be ok as long as the head traps the liner.


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## johnny1320 (Jul 18, 2013)

The Detroit 2 stroke 6-71 have slip fit sleeves, and it is water cooled, but my air cooled Kawasaki has press in sleeves, it my help with heat transfer having pressed in sleeves.


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## John Rus (Jul 19, 2013)

6-71, my Dad had 8V-92. That thing could really scream! Reliable as heck too.

John.


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## Mechanicboy (Jul 19, 2013)

In air cooled engine the cyliner liner has light press fit due heat expansion. If the measure was same both in the cylinder liner and cylinder jacket, it will be play between and will make poor cooling when the engine is in working temperature. As you can see the cylinder liner is not dropping into the cylinder jacket (crankcase) by own weight. 

As i will do it with the engine as here:

Air cooled engine: Cylinder liner in cylinder jacket = light press fit.

Water cooled engine: cylinder liner contact with water = no press fit, seal only, cylinder liner in cylinder jacket with watercooling = light press fit.


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## Jasonb (Jul 19, 2013)

Also depends on the engine design, not all liners have a lip at the top. This is the liner for my current 1/3rd scale Galloway, three different diameters all press fits and all just a few thou different to seal the top & bottom of the water spave and fit the block.


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## doortoh (Jul 19, 2013)

Not all sleeves are a tight fit..some perkins diesels have loose fitting liners to allow these agricultural diesels to be repaired in the tractor..they have a small top flange and are press fit by hand...on other engines the fit is usually is about .001" per 1" of dia of liner in a cast iron block..there are exceptions on some large diesel blocks..wet sleeves are usually sealed by o'rings or gaskets..and are seldom very tight....in fact some are rather loose....alloy blocks are a different story and the liners are best fitted by warming the cyl. or block and chilling the liner so they drop in..fit is tighter than iron blocks..it is hard to say what fit is required..water cooled is different to air cooled and wall thickness has to be taken into account...not all liners are flanged...many production iron blocks have liners held by interference only...alloy blocks are usually flanged..alloy blocks {buick/rover etc} have a step at the bottom and this stops liner movement and use a plain liner...most liners are cast iron...some are steel..notably side valve fords from  war time production era...some chrome plated liners exist for long wear.......


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## stevehuckss396 (Jul 19, 2013)

johnny1320 said:


> The Detroit 2 stroke 6-71 have slip fit sleeves, and it is water cooled, but my air cooled Kawasaki has press in sleeves, it my help with heat transfer having pressed in sleeves.



Thats true. The sleeves are sealed with rubber o-rings.


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## lohring (Jul 19, 2013)

In small two stroke engines the main issue is keeping the cylinder round. The uneven heating due to the hot exhaust and cool transfer ports make this a problem.  Even a very slight out of round condition will cause failure in a high output engine. See below.  If the sleeve is thick it can be a slip fit.  That's the case with most commercial model engines.  If the sleeve is thin as in the Quickdraw, the sleeve should be pressed in.

Lohring Miller


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## johnny1320 (Jul 19, 2013)

stevehuckss396 said:


> Thats true. The sleeves are sealed with rubber o-rings.


 
Hi Steve, the 6-71 liners had no sealing "o" rings on the liners, the blocks contain the coolant and the liners fit in the bore of the block (dry liner), I do believe the 92 series does have "O" rings as well as the 53 series. Cat has non press fit with "O" rings as does 60 series Detroit and Cummins have "O" rings with press fit at the top of the liner only, which makes it a pain for doing line protrusion.


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## Mechanicboy (Jul 19, 2013)

lohring said:


> In small two stroke engines the main issue is keeping the cylinder round. The uneven heating due to the hot exhaust and cool transfer ports make this a problem.  Even a very slight out of round condition will cause failure in a high output engine. See below.  If the sleeve is thick it can be a slip fit.  That's the case with most commercial model engines.  If the sleeve is thin as in the Quickdraw, the sleeve should be pressed in.
> 
> Lohring Miller




The photo showing is a ABC/ABL cylinder or AAC cylinder (difficult to see color of material in the photo)

The cylinder who is made of brass or aluminium do not need press fit in the cylinder jacket.


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## Putt-Rite (Jul 19, 2013)

The reason I ask is I have this cyl. from a lawn mower I think. I wanted to get the liner out for melting the Al down. I may have to work around it tho. :fan:

I thought it interesting that the liner is milled with splines like that. Must be for heat transfer. I don't think I'll go to that trouble when building an engine.


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## stevehuckss396 (Jul 19, 2013)

johnny1320 said:


> Hi Steve, the 6-71 liners had no sealing "o" rings on the liners, the blocks contain the coolant and the liners fit in the bore of the block (dry liner), I do believe the 92 series does have "O" rings as well as the 53 series. Cat has non press fit with "O" rings as does 60 series Detroit and Cummins have "O" rings with press fit at the top of the liner only, which makes it a pain for doing line protrusion.





That makes sense. When I was working at the plant in detroit they were building the series 60 and I thought the liners had orings.


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## Lakc (Jul 19, 2013)

Putt-Rite said:


> I thought it interesting that the liner is milled with splines like that. Must be for heat transfer. I don't think I'll go to that trouble when building an engine.


That is probably an indication the liner was cast in place. 
Sometimes its needed for all the previous reasons given, but one reason I think was passed over was for protection from fretting. A liner trapped between the head and block wont move in that (Z) axis, however, depending on the mass, stress, and frequencies of stress, a cylinder can begin to ring like a bell in the x-y axis. If that happens the parts rubbing against each other becomes a bad thing.


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## johnny1320 (Jul 19, 2013)

stevehuckss396 said:


> That makes sense. When I was working at the plant in detroit they were building the series 60 and I thought the liners had orings.


 
series 60 do have "O" rings


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## kf2qd (Jul 19, 2013)

Putt-Rite said:


> The reason I ask is I have this cyl. from a lawn mower I think. I wanted to get the liner out for melting the Al down. I may have to work around it tho. :fan:
> 
> I thought it interesting that the liner is milled with splines like that. Must be for heat transfer. I don't think I'll go to that trouble when building an engine.



Just cut the block in pieces and melt the aluminum off the cast iron. Aluminum melts at a lower temperature so it should cause no problem.


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