Re-ring Alusils? - I HAVE!!
 

Just pulled my first cylinder out (not completely) to discover KS marks (Alusil) on the bottom. This is something I'd not actually considered (for some reason thought all late models were Nikasil).
I've already got new Goetze rings but now ot sure whether to fit them. My motor's covered approx. 80k miles. Should I re-ring or leave the existing pistons/rings in place as per Waynes book? I've heard of successful re-ringing for Alusil but on higher mileage motors. Mine had great performance & good compression across all cylinders before strip down (due to valve guide wear).

thanks

Nathan

Sounds like we might be in the same boat. I'm pulling my cylinders on Saturday and fully expect to find they are Alusils.

Given that you had good compression I'd probably be temepted to leave them alone but then again I haven't decided yet if I'm going to roll the dice and re-ring mine or not.

I know a few members on the board have done this successfully even though Wayne's book recommends against it but it will be interesting to hear what the others think as well.

If the specs are good on the pistons and you had good compression then I would stay with the current rings.

From what I understand, with Alusil, the cylinder walls break in to the rings as opposed to the ring breaking in to the cylinder like on Nikasils and most other P+C's. I would think putting in new rings would just add unneccesary wear on the Alusil cylinders.

Besides, I don't think you can use the rings you have. Alusil rings are different than other rings. I believe they are a harder material than Nikasil rings.

I dont think the ring material is an issue. Goetze make rings for Porsche OE and their catalogue doesn't differentiate between Nikasil & Alusil ie 1 ringset fits all.
Wayne even goes so far as to say don't remove pistons from cyls. Are you going to pull yours out Doug to check specs, and re-install if OK?

My vote: Do what Wayne says.

Not true.

For '80-'83 3.0 motors (for example):
#930 198 986 00 (Mahle/Nikasil)
#930 198 985 00 (Kolbenschmidt/Alusil)

Ref.: Porsche Parts & Technical Reference Catalog

Per the factory manual...

Installation Instructions For "LS" Cylinders and Pistons.

"The Alusil cylinder (eutectic aluminum- silicon alloy) and the Ferrocoat piston combination is known as "LS" cylinders and Pistons.
In this system the surface coating is applied to the piston."

"The assembly of the cylinder and piston must be made with particular care to avoid breaking the piston rings; the rings are chrome plated and are thus harder and more brittle."



As stated above. The rings and the piston are the "hard items" in a LS set and the cylinder is the "soft" item so when break in occurs the cylinder is the item that gives. If you are "refreshing" the motor then the item to "refresh" would be the cylinder not the piston and rings. Not that anyone would do that because you'd probably just replace the whole set.

Further investigation has shown the Goetze interchange actually reflects both 930 198 985 00 & 986. The rings are phosphated to improve seating, and as such are catalogued for all 3.2 variants, irrespective of cylinder type.The Goetze ring sells in excess of 5000 per year (in European Aftermarket) with no warranty issues, ever. On this basis I guess I'm going to re-ring my existing p&c's.

I re-ringed my Alusils with good results. I'd suggest you clean them REAL GOOD. Mine went through a big parts washer and it changed their appearance. I used the tiniest little bit of engine oil to lube the cylinder walls prior to assembly. Nearly none, but a little bit. Then when you start it up, drive the pi$$ out of it. Accelerate, decelerate. Flog it good.

Nathan - at this point I'm thinking of just leaving the P's inside the C's like Wayne suggests as I wasn't intending to do any kind of spec check. My real objective is to replace the lower head studs since 3 of them are broken right now.

If you do choose to re ring, first hone the cylinders with the Grape style hone. The hone has little balls on the ends of wires that look like grapes on a vine. The silicone balls will put a suitable finish on ANY type of cylinder. That is they will not take off any real metal, but put a fresh cross hatch pattern on the cylinders that will almost instantly seat a new set of rings. This type of hone will also remove any extranious metal left by the previous rings or typical stone hone. Talk to the mfg if you have any doubts. They work well.

Superman, how many miles have you done since you re-ringed? Have you have a compression/leakdown test since?

Not a good idea......

Before I took my motor down for head stud repair, it ran very well; didn't smoke; lots of power; no leaks, etc. It was such a sweet-running motor, I was pissed at having to open it *just* for a broken head stud.

For a time, I considered the "method" of removing the cylinder and pistons as a unit, so as not to disturb them. But luckily, I talked this over with some pro-wrenches. They said NO! The only proper way is to remove the P&C's and measure with accurate tools (or have them measured by your machinist).

I'm glad I took their advice, as I had 2 pistons with *broken oil rings*!! How would I have known this otherwise? Especially when the motor had good compression numbers and didn't use a lot of oil.
I was told by one expert mechanic, that the broken oil rings were not uncommon.

So, do the right thing....pull the cylinders, measure, and re & re as required. You'll be glad you did!

bump

snowman,

please believe me when I say to you that I do not mean any harm with these questions.

have you personally taken a flex hone to an alusil cylinder?

if so...

was it your own car or some one elses?

how many have you done?

how many miles have the engines you've done this to logged since you did this?

have you checked compression/leakdown after break in on these motors? what were the results?

do you work for motor meister? (ok... that was meant in jest)

the reason i ask these questions it that, once again you have given advice that flys in the face of convention. every authority including the manufacturer says not to re-use alusil cylinders let alone take a hone to them. so I just want to know your experience with the process you suggest. I would certainly hope you wouldn't give unconventional advice unless you had good results in practice of the advice you give.

Well don't take my word for it by any means. Go to the mfg of these type of hones and tell them exactly what you have in terms of a cylinder and ask them what they recommend.

These type of flex hones just put scratches in the surface and do not remove metal (except for the scratches themselves). They also remove unwanted stuff left by conventional honing and stuff left by old rings. In other words they "freshen" the surface, even hardned surfaces so that new rings can seat and there will be enough groves left to hold some oil for lubrication. At least thats my understanding of it. It has ALLWAYS worked well for me

ok...I hate to cross examine but... is that a "yes, I've honed alusil cylinders and it always worked well for me"

YES

The process only involves 7 or 8 strokes of the hone, 15 seconds or less. Dosen't sound like much, and it isn't, except for the new surface created.

For more info see a process called plateau honing. Its just a small step, but so very important in terms of performance.

Rehoning a used set of cylinders is very similar to plauteau honing. In this case it removes junk left behind by the old rings, and leaves a new surface for the new rings to adjust to.

Please NOTE!!! This does NOT mean rehoning with stones!!!, just grape style hones.

Walt at Competition Engineering also recommends this...

-Wayne

Doug - like many things in life the best laid plans go to waste ... when I got to the point of trying to pull the P's & C's together we couldn't get the wrist pin out simply by pulling on it. After a meeting of the minds (ie., 3 Pelicanheads/NoVa members who were in the garage with me) we decided to roll the dice and separate them. Worst case scenario I figured was that everything was OK and I could simply slide the P's back in using a ring compressor since with my Alusils I didn't want to install brand new rings.

In hindsight this made removing the wrist pins much easier b/c we used a 12 mm 1/4" deep socket on an extension and drove them out ... I don't see how anyone simply pulls those suckers out with how tight mine were in there.

After separation we closely inspected the rings and didn't find any damage. As of right now I'm going to clean the P's and then re-install them (same direction they were removed) using the same rings.

Thoughts / comments ?????

Ok...
If you ever find a tight wrist pin, heat the piston crown with a heat gun, or propane torch. The piston will expand enough to allow the pin to side out with only finger pressure.

I'm not sure if re-using the same rings is a good idea. If you want to do this, I'd make sure the end gap is within spec. The usual way to check this, is by placing a ring in the cylinder, pushing it down square to the bore about an inch, then measure the gap with feeler guages. The gap spec is listed in the shop manuals.

The other critical point if you wish to re-use the pistons (and rings), is the condition of the ring lands (grooves). The must not have more width than spec, or the rings may rock in the groove, and eventually break.
The side clearance spec is also in the Porsche spec book and Bentley.

Finally, Jim 'Superman' Christensen has posted how John Walker treated his Alusils for a re-ring. Find those posts, and consider how a pro did it. Jim's car runs like a scalded cat!

The method that snowman speaks of sounds familiar (same thing i'm having done). Except the shop told me that it technically wasn't honing, since it doesn't widen the bore at all, just reintroduces the cross scratches that force break-in during initial run. They called it laping, and they said that reringing is gamble since your not guarenteed that it'll properly break-in. They said in some cases reringing alone will cause the motor to take like 10k miles just to break in, while this process will force the rings to break-in to the cylinders within the normal break-in period. And of course his real recommendation was to replace them with a new set of Nikasil's, but sometimes financial status forces you to take what's behind door #2.

Doug, while you have them out, you might as well measure the P&C's, ring groves etc. I have the tools you can barrow. I did mine and found them to be w/in the wear limits. I re-ringed them. I cleaned the cylinder walls with scotch brite pads sandwitched between the cylinder wall and a off the shelf 3 arm stone hone connected to my cordless drill. About 25-30 seconds each 10-15 strokes up and down and there was a very minor cros hatched pattern on the walls. This worked well for me I've got about 2,000 miles since the rebuild and they sealed just fine.

If you want PM me on the NO Va site and you can barrow all the tools.
The tools take a little getting used to but it's a good piece of mind knowing what you have in your engine. I've spent some money on the tools so I wish they would get used more than once. Charlie used them
ask him about it.

William - thanks for the offer and maybe one day I'll take you up on it.

I spoke to Walt (at CE) today and he was of the opinion that at only 97k miles my engine was just about getting broken in :) He said to visually check for any broken rings but other then that he didn't see a problem with just compressing the rings and sliding them back in. Right now my intent is to do just that but if I were to come across a set of cheap Nikasil's that idea just might change :)

Walt is da man! So do what he suggests.
I got a lot of good info from him, JW, and my local pro.
My motor is flawless, thanks to their generous advice.

Although I could have re-used my P & C's (they were well within spec at 80k), I got a good deal on a new Mahle (Nikasil) set. Glad I went with it, as the motor runs stronger than ever.

The issue of re-ringing Alusils comes up periodically. My distillation of the "facts" leads me to conclude:

1) Nikasils - re-ringing and honing are ok.

2) Alusils - re-ringing is ok, honing is not.

I've done (2) and the engine has been just fine.

Yes, but your only one dude. That is what bothers me about people posting here sometimes. They put up "hey, this worked for me fine..." and then everyone assumes that it will work in all cases.

If you put a single bullet in a gun, spin the barrell, and then pull the trigger, and it doesn't fire, then can you assume that you're safe 100% of the time - NO. You can say that you 'dodged a bullet.'

This is why I repeatedly echo comments made by people who have done these things thousands of times, like Walt Watson of Competition Engineering. In writing the book, I took his knowledge (along with many, many other people's knowledge), and filtered out fact from fiction.

The bottomline? Re-ringing Alusil is a crapshoot - it may or may not work. Walt's suggestion is what he has learned from past experience...

-Wayne

Wayne,

You're right. A statistic of one, or two, isn't much to go on, (although it is a lot better than a statistic of zero, which is the basis for the majority of advice proferred on this and other boards).

and then everyone assumes that it will work in all cases

They shouldn't. It's only one point on the curve. However, one of the beauties of a board like this is that it can collect a lot of information from a wide variety of sources, and often it's enough to comprise a meaningful statistic. If fifty guys pop up and say, "Hey, it worked for me." that would be useful to know, I think.


I take your point, though, which is a good one. Don't offer advice or experience unless you've had a professional's equivalent of experience, or unless you are quoting one, or unless you quantify your experience level, which you will note I was careful to do.

Bob

I beleive this is what we refer to as anectdotal evidence. Provided it is offered as 'it worked for me' as opposed to 'this will always work' it is useful information.

And that "anectdotal evidence" is what makes this board tick.

It worked for me!

I tried it knowing the risks and accepting them. This is on my car and I am the only one to blame if I have to pull it apart again at some point.
I chose to invest the 2K+ money in other parts of my car. I also like most people on this board have a limited budget for my toy and I want to get the most bang for my buck. I don't count my time because working on my car is a hobby, not a business. It's something I love to do. If my risk went south I would say goodie, I can tear it apart again and rat's because now I have to spend the money on the P&C's.

If it was my business and my reputation there is only one way to do it. Do it right the first time or it will come back to haunt you and cost you later. The pro's on this board are speaking from this point of view and they are correct in their recomendations. If you want to do it right the first time, do everything you can to eliminate the risk. Any pro that doesn't do it this way is an idiot (There is a certain rebuilder that consistantly get's bashed on this board because of this.)
That's why it costs so much to get a porsche engine rebuilt by a respectable pro or to buy all the parts and machining to do it yourself.

Everyone has to make their own choices and again I chose to take the risk. Why? My car now has 255,000 miles on it. My plan is to drive it daily as I have for the 2 years I have owned it. (Except the few months while I was rebuilding the engine.) I do my own work because I have seen what wrenches can do to screw up a car. I rebuilt the engine because it had a broken ring and I wanted to extend it's life. I followed Waynes book pretty much to the letter except this one issue. For me it was worth taking the risk. I'll let you know in a few years or sooner if it fails.
My car will never be worth much because of the miles. It has great value for me because I drive it daily and relative to anything new it's pretty cheap transportation.

I bet many people who frequent this board are in simular situations and would take simular risks knowing the consequences. I don't think the board is intended for pro's but for enthusiasts. These are people willing to take some risks. There is a right way for pro's to do things and for those that are racing and others that want perfection. What's right for one guy may not be right for another. I know what's right for me and that might not be right for others. So again:

It worked for me! (Maybe I should qulify that) It worked for me so far!

Well stated William, especially d-i-y vs professional choices.

In answer to someone's question, yes, I did a compression check. Again, the engine did no smoking and still does no smoking. The rings seem to have seated just fine. I don't have the compression test results here in front of me, but there were no particularly weak cylinders.

Doug is right on the money, as usual. Ring lands, and cylinders must be in spec. Mine were, but I would not try this without measuring first.

I'd agree this is probably a crap shoot. It worked for me. I certainly needed no honing tool to clean up the cylinder walls, since my cylinders made a trip through John's BFPW (large parts washer) and were clean as a whistle. As I've posted previously, I think this was key. The washer changed the color and appearance of the cylinder walls. Those cylinders were measured (rebuild was at 183K miles) and the most wear we found on any cylinder was .0015". One and a half thousanths. In other words, those cylinders were about as straight and parallel as could be. If they were tapered, this probably would not have worked.

And finally, Doug is also correct about wrist pin removal techniques. Don't pound on them! Heat the piston, and the wrist pin will nearly fall out.

FWIW, I did not replace my wrist pin bushings, and if I were in there again, I'd do that. Mine was one of those Neanderthal/Kamikaze rebuilds. Hey, it's a motor, okay.....?

"Life not worth living without taking some risks."
Besides, worst thing that happens is that it doesn't work and the rings don't seat properly. Now your out of a few gaskets and an oil change, and back to square one with needing new P&C's.

During my rebuild I sent my pistons and cylinders to EBS. Told them 'do what you think is best'. They measured everything and used new rings, properly gapped, and send it all back to me. The motor has performed flawlessly.
Good luck,

Does anyone have a "this DIDN'T work for me" story in relation to re-ringing their Alusils?

Can those of you who have re-rung alusils comment on the type of rings used? Im going to be rolling the dice as Im in the process of re-assembling a motor with alusils. I purchased a set of GOETZE rings (930.103.963.00) from our host for the job and have been hesitant since I have found a previous posts that is saying there is another specific factory part ID for alusil rings (930.198.967.00).

Here is a link its the last post in the thread.
http://forums.pelicanparts.com/porsche-911-technical-forum/87658-what-price-my-3-0-p-cs.html

Could these be the same rings with different part#'s? Should I be concerned or run with the set I have?

Simon, call the guys at EBS (http://www.ebsracing.com) and ask them. They are extremely helpful and I am sure they would tell you what they use. As I said, in my case I would have bought new P&C's if they had said the word, but their assurance was that the new rings would work - and they have.
Good luck,

Mine were the Goetze rings. Don't know/have the part number with me.

William - after looking at the documentation, mine were Goetze as well.