Cylinder liners frozen with liquid nitrogen before putting in 1

[dirk489]

Hi all,

I recently had an MGB block where one cyl. liner had to be replaced being scuffed.
The machine shop always will rehone the next cylinder as well as pressing in the liner will bring deformations in the cylinder next to it.
We discussed freezing the new liner in liquid nitrogen and preheating the block so it can be put in with minimal pressure,avoiding the next cyl. to be rehoned(this is a race engine,hence i do not like to rehone if not necessary)
The guy from the machine shop is hesitant because he is afraid that ice will form on the wall and that water will be brought in between the cyl. and the liner causing later problems.
What is Your feeling about it?
Thanks for listening!
Dirk/Antwerp

 

[IceStationZebra]

I don't have any specific experience with this, but I will say that normally when using liquid nitrogen you don't need to heat the other part unless is it a very tight interference fit.

ISZ

 

[MikeHalloran]

Using LN2 with or without heat does not change the stress situation between the liner and the block and the next liner, once thermal equilibrium has been restored. All it changes is the axial force required to push the liner into place, or out of place.

I think the machinist makes a valid point about the possibility of ice damage. I suppose you could rig up a zero-humidity workspace to mitigate that risk. Is it worth the effort?

Is the machinist willing to warranty work that he does, using unfamiliar techniques that you have requested?

Mike Halloran
Pembroke Pines, FL, USA

 

[pontiacjack]

I agree with Mike, that easing the sleeve installation has no bearing on the question of adjacent cylinder(s) needing to be made round.

 

[dirk489]

Thanks guys,seems like I will have to bend!
Dirk

 

[dicer]

Many different types of machine parts are frozen to accomplish a press fit. Water? there is no room for it, use a light oil before installing it. Do a search on cryo treatment. It may actually be benificial in more ways than one. If it was a press fit that is how I would do it. There are many engines that don't use a press fit for liners.

 

[Frederick]

Be careful how you freeze the liner. Dipping it in liquid nitrogen can cause surface cracks.

 

[patprimmer]

Typically, dry liners are a press fit, although not necessarily a shrink fit. This is necessary to ensure a good heat transfer between the liner and the metal it is pressed into.

Wet sleeves can be either. They can use press fit and sealant or slip fit and O rings to seal the water surrounding the sleeve from the crankcase and the engine oil.

Sometimes the interference is required to hold the sleeve in place, but mostly a step at the bottom and the cylinder head at the top hold them and the interference is simply for heat transfer or sealing of water.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[dirk489]

Thanks guys!
Meanwhile we went for a ,004" press fit.The reason for my asking is also that we noticed that when taking the engines apart, the sleeves usually sank down ,001", even with a ring at the bottom or with flange on top. The B-block already has a tendency to sink in between the cylinders, just a little. Net result is gasket problems with high compression engines under race conditions.
Dirk/Antwerp

 

[joedhall]

So put in a taller sleeve in deck the block.

 

[ToddG04]

I am currently in college, but before going back to college I worked in an automotive machine shop for a number of years. Whenever I installed a cast iron sleeve into a block I would get a box of dry ice and leave the sleeve in there for a couple hours. Then I could grab it with gloves and drop it right into the hole, no hammering needed. Then as it warmed up and expanded it would have the required press fit. I usually machined a .003"-.004" press fit with most cylinders. I never used liquid nitrogen and would be afraid to because I would fear that it would make it brittle, and like someone mentioned earlier, surface cracks. After the sleeve was in, I would resurface the deck of the block, and if it took too much off to get it flat, you can always run a thicker head gasket. You always have to check the cylinders next to the sleeve, and doing it this way I had minimal distortion of adjacent cylinders. May not be the answer you are looking for, but dry ice is an easy alternative.

 

[dirk489]

Thanks Todd for Your answer.We currently are waiting for the new liners to arrive. we will be using ,003"-,004" press fit.Your idea with the dry ice is appealing to me!
Dirk

 

[ToddG04]

No problem. You just have to make sure your sizes are correct otherwise it'll get stuck halfway down and you end up beating it in the rest of the way which defeats the purpose. I would leave a little step at the bottom to catch the sleeve as it went down. Then machine the top off, deck the block, bore/hone the cylinder and good as new.

 

[mfgenggear]

Dirk

I have the same experience as Todd, But I have also assembled many of gears by thermal, sub zero treatment in liquid nitrogen & never had issues. yes there will be ice build up, but if the mating part is thermally heated, it will dissipate any ice or water.
I have never observed or heard of problems.
It is easier to work with as Todd suggested.


Fredrick
Have you observed micro cracks by using liquid nitrogen, I know of heat treaters that have used it for years.


Mfgenggear