Issues? Removing Alusil Pistons From Cylinders?
 

I am thinking of reusing my Alusil P and C's.

I have searched and not found much. I just cant see how it would make any difference to remove and inspect them while keeping the parts matched.

Or am I missing something?

Thanks!

James

So..... what exactly is your question?

Are you wanting to know if you should remove the pistons to inspect them?
No one can answer that if we don't know WHY you think you need to inspect them. You should be able to just look at the top of the pistons and see what you need to know.

Unless you have a compression leak or something, then perhaps something happened to the rings.

Motor was in storage. Leak down tests from an engine in storage are in my opinion not the best.

Wayne's book said to put them on a shelf and leave them in the cylinders. It said to reuse them if the motor in low mileage.

Is there an issue with removing them from the cylinders? Does it affect the ring seating? Engine is apart, I want to inspect/measure them.

For what I understood, Wayne suggest to leave the piston inside the cylinder to make sur you don't break rings... as you can't buy them anymore...

I agree with deftom that the Wayne rebuild book recommendation is based on breaking old rings when you reinstall the pistons in the cylinders. However, rings get gooped up with oil coking over time and it's a wise idea to clean the ring area and free up the ring movement. Sometimes it's hard to do that with the rings on the piston. But you can soak them in solvent for a long time to clean the coked oil. Berryman chem dip is a pretty good solvent. So if you remove old rings from the piston, there's even greater likelihood of breaking one. Plus the alusil cylinders use chrome plated rings which are apparently more brittle.

But the recommendation for leaving the pistons in the cylinders also has a major downside. If you have a broken ring(s), not because you physically broke them with your handling of them but because breakage occurred during engine operation, how are you going to discover this if you leave the pistons in the cylinders?

An equally important consideration here is new vs. old rings. The alusil cylinders are said to be highly sensitive to re-ringing. Meaning, if you use new rings (which ARE available- part number 930-103-986-01) then you're at risk of having them not seat with the cylinder walls and you'll have a lot of oil consumption. You need to hone the cylinders to allow the new rings to properly seat.

This thread went the whole 9 yards talking about re-ringing alusils. http://forums.pelicanparts.com/911-engine-rebuilding-forum/137346-re-ring-alusils.html


Not to mention, if you leave them in the cylinders, how are you going to measure the cylinders for wear, taper or out-of-round?

Thanks for the replies.

Perhaps I will remove them from the cylinders and not remove the rings. I can at least measure them.

Be very carreful when you remove them... very easy to break them at this stage!

good luck

I would remove them, clean and inspect the pistons and rings. Keep all the parts in the same position when you reinstall them. Measure the ring land clearance and the ring end gaps. You will probably find they are still well within the wear limits. I wouldn’t re-ring them. In the past I’ve found that new rings measure worse than the old ones. (This has been true of many parts).

-Andy

Thanks everyone.

I would not have thought there was a risk of breaking the rings with just removing the pistons?

Eagledriver, I think I read a thread where you used stock SC cams with alusils in your race motor. I "think" you had interesting numbers in term of performance. However, I do not know any more details about your motor.

Good luck with the Alusil cylinders . I have always found them to be out of round .

IMAO. I think you could get accurate measurements without removing the pistons.

IF they are in spec AND you weren't smoking or using oil, I would leave the pistons IN.

My thinking is that your rings have mated with the cylinders. New rings will tend to rotate in the cylinders. After a number of years/miles that would tend to stop and the rings will settle into a certain position. Let's say you pull the pistons out. Let's say when you re-assemble with the old rings and they are not in the same orientation. Will they return to their original position or will they re-break-in or will it be a mess?

There is a special method of honing these. If you choose to re-ring, you may want to investigate that option.

I will measure. Eventually I want the 9.5 CP pistons.

Thanks for all the replies.

Why don't buy a set of CP pistons and rings you want, send those and the cylinders off to be bored and Nikasil'ed at either EBS or Millenium and they will come back with perfect roundness and clearance and forget the worries of Alusil?

This is probably the cheapest way to restore your P&C's to like new anyway.

It would be ideal, and it would be $2000. Too much for now.

If you break one, I have good used spares I keep, just in case.
Bruce

Myth...........something else.
 

James,

Listen to people with a lot of experience like Andy. I had removed and installed pistons with rings from Alusil cylinders many times over and have not broken one so far. The engine tear down classes that were attended by 39 participants did the removal and installation of the six (6) cylinders. And this process was repeated four (4) times. Unless you do not know how to remove and install these pistons with rings using the appropriate tool/s then you could break or damage them.

How come these people that have not done it before were able to remove and install them back? Simply because they were using and following a proven method.

Tony

I like the sound of what you are saying, the cylinders are covered in grease. It is hard to clean the cylinders after the heads have been removed. Not that that is terribly relevant however perhaps cleaning the ring lands is.

Can I put the cylinders in a parts cleaning tank?

I am now removing the pistons and cleaning the.

They look in excellent condition. While removing one stubborn ring clip, I made a VERY tiny mark on the skirt of a piston. I can barely feel it with my finger, however I do feel it. What can I do to make it smooth?

I really appreciate any advice.

Thanks
James

I wouldn't worry about the scratch/mark. It shouldn't be in contact against anything, as your pistons rings are the only thing that will be closest to the cylinder wall.

Good to hear. Thanks!