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-   -   Re-ring Alusils? (http://forums.pelicanparts.com/911-engine-rebuilding-forum/137346-re-ring-alusils.html)

Nathan M 11-26-2003 01:32 PM

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

Doug E 11-26-2003 04:26 PM

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.

Bobboloo 11-27-2003 01:03 AM

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.

Nathan M 11-27-2003 03:10 AM

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?

Porsche_monkey 11-27-2003 05:12 AM

My vote: Do what Wayne says.

Doug Zielke 11-27-2003 06:32 AM

Quote:

Originally posted by Nathan M
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.

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

Bobboloo 11-27-2003 05:07 PM

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.

Nathan M 11-28-2003 04:29 AM

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.

Superman 11-28-2003 03:15 PM

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.

Doug E 11-28-2003 05:41 PM

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.

snowman 11-28-2003 08:28 PM

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.

Nathan M 11-30-2003 12:33 AM

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

Doug Zielke 11-30-2003 07:34 AM

Quote:

Originally posted by Doug E
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.
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!

niner11 11-30-2003 04:09 PM

bump

Alan Cottrill 11-30-2003 06:08 PM

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.

snowman 11-30-2003 07:02 PM

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

Alan Cottrill 11-30-2003 07:50 PM

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

snowman 11-30-2003 08:36 PM

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.

Wayne 962 11-30-2003 08:41 PM

Quote:

Originally posted by PBH
My vote: Do what Wayne says.
Walt at Competition Engineering also recommends this...

-Wayne

Doug E 12-01-2003 06:30 PM

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 ?????


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