Re-ring Alusils?

[ironhorse]

Nobody has mentioned this ?

Is it a crack or a piece of debris?

If a crack, is it superficial?

[schpenxel]

Originally Posted by ironhorse

Nobody has mentioned this ?

Is it a crack or a piece of debris?

If a crack, is it superficial?

Yeah, I mentioned it in one of my earlier posts but didn't go into any detail. It was def. not superficial, as oh about 3 gallons of coolant came out of the oil pan when I went to drain the oil before pulling the engine, lol

I am using a different block for the rebuild though (the crack is the reason for the rebuild). Basically I was cleaning out the secondary air system ports on a BMW 2004 545i, and they are over-engineered such that the ports are right beside the exhaust valves and are bad about getting clogged up. I think I knocked some carbon loose and it got down into the cylinder or something, because when I started it after cleaning everything as best I could, my exhaust smelled sweet, then I noticed that the oil in the valve cover looked like a milkshake. Wasn't a good day.

The rest of the pistons had a TON of loose carbon on them when I got the heads off.. like I literally could have scooped it out with a spoon it was so much.

[schpenxel]

Here is a good shot of it. To BMW's credit, it had 207K miles on it on the original engine. The cylinders have next to zero wear at the top as well.. pretty impressive. Now if their seals just didn't suck they'd be in business

[schpenxel]

I figured with the amount of help this forum provided me, I should at least follow up with the outcome of my rebuild. This was on a 2004 545i with Hastings rings and original pistons. It is an N62B44 engine. I am the first person that I know of to do this process on a BMW engine--the only other person I know of that rebuilt their similar engine had a shop do the polishing process for them.

-------

Note: Throughout all of the initial driving, I did not baby it. I didn't redline it or anything, but I had quite a few runs up to 4-4.5K RPM's, then let it engine brake back down to 1500 or so (used manual mode on the transmission) like some break in procedures recommend. I don't know whether that helped or not, but I have certainly not taken it easy on it.

So, about 3 weeks ago I finally got the engine back in. After plugging in a few wires I apparently missed, it started right up.. and smoked like CRAZY and had some misfire codes. I thought for sure the rings weren't going to seat and I was going to be in trouble. I kept clearing the codes (on BMW's it will shut down a cylinder with a misfire code) and kept running it.. slowly but surely they all went away. At this point it was still smoking pretty bad, but ran decently so I decided to take it for a spin

I drove it.. first 5 miles or so, it was embarrassing to come to a stop it smoked so bad. 10-15 mile mark it was decent enough that I could drive it without a cloud of smoke behind me as long as the wind was blowing. Still a lot of smoke would catch up to me when I came to a stop.

By the 25-30 mile mark all smoking stopped, but I still had a little condensation/water smoke coming out it looked like. Since the car had been sitting in the weather for months, I hoped that water had just gotten into the exhaust system and needed to be burnt out (as opposed to a head gasket or something)

So, I kept driving it.. about the 50 mile mark all smoke, blue and white, went away completely. It now runs perfect and does not smoke a bit. Doesn't matter whether I'm flooring it or it sits idling for 30 minutes. No smoke at all and drives great. It has about 300 miles on it and I'm putting about 100 miles on it a day, so I should find out pretty quick if anything is going to break. I changed the oil twice already. The first change it was pretty dirty, to be expected I would say (no metal or anything like that). Second time it looked like normal barely used motor oil. i.e. not much different than the new oil that was replacing it. I am going to run this third batch of oil for at least 1000 miles before changing it, and have an oil analysis done on it then to see if there are any obvious issues

So, hopefully no one else has to go through this process like I did, but if you do, this process will indeed work on BMW's N62 (N62B44 in my case) engines. I will try to report back if anything negative happens in the near future.

[911 tweaks]

hi schpenxel... what did you wind up doing about the crack in your cylinder liner...?? maybe for peace of mind, do a compression test now and when u do oil changes to see if there are lurking issues about to be a big problem...thx for sharing...sounds like u may of made it all work...thx, bob

[schpenxel]

Originally Posted by 911 tweaks

hi schpenxel... what did you wind up doing about the crack in your cylinder liner...?? maybe for peace of mind, do a compression test now and when u do oil changes to see if there are lurking issues about to be a big problem...thx for sharing...sounds like u may of made it all work...thx, bob

Block was replaced with one out of a different car.. think I posted that a few pages back but I'm not sure.

The old cracked block may become a coffee table at some point

[DeutschMark]

Here is another angle to consider in re-ringing your Alusils, Quick Seat Piston Ring Assembly Lubricant. They claim an immediate ring seal to promote "proper" break in. I am in no way associated with Total Seal.

Quick Seat Piston Ring Assembly Lubricant, by Total Seal, 2 - Aircooled.Net VW PartsGrams

[Willem Fick]

What an awesome thread!

The only disappointment remains that you are limited in the availability of pistons either over-sized or specialized, which had me do a bit of research which I'd like to throw into the pool for consideration:

Electroplating of iron-cobalt alloy onto aluminum alloy parts

Method for direct plating of iron on aluminum

Willem

[bh912e]

If you have a good alusil block you do not have to re hone it or put scotch barite pads on where honing stones would be. Literally take dish washing soap and wash out the cylinders with a sponge and your done. You can use a scotch Bright pad with soap very lightly, it is important not to create new honing marks. You are only cleaning the cylinders! Buy the correct rings, gap them, install with some motor oil and your done. The beauty of alusil is that they use low tension rings which create less drag on the motor. Make sure you double and triple check ring gaps! If they are too tight you will score the cylinders!

[bh912e]

Almost forgot! Make sure your pistons still has the ferro coat on them! It tends to wear off with high mileage motors. The ferocoat is magnetic ! A small magnet should stick to the side of the piston!

[carl74344]

what are the right rings? my motor has 50k miles. can I just rering and go? thanks carl

[n00b0Rka]

First of all, I don't know whether I have the right to revive this epic thread or not.

I have to re-ring my BMW ALUSIL engine, and this thread has provided me some great info. After reading the whole thread, I'm curious whether you can replace the 60$ (and hard-to-source outside USA) Sunen AN-30 compund, which contains silicon, with something else? We've seen quartz based lapping compounds don't work very well, although the hardness is very similar, but maybe some silicon carbide would? Silicon carbide is significantly harder than silicon so I'm afraid it won't work too well either, and I was unable to find another silicon paste.

Is anyone out there who used something else for lapping? If my cylinders look nice, can I clean them only with Scotchbrite, as some people here suggested, and call it a day?

Thanks, nbK

[n00b0Rka]

I was hesitating if I should revive this epic thread a lot lately.
I need to re-ring (hopefully) my BMW N52 Alusil engine, and this forum, especially this thread has been extremely helpful for me to understand the theory of Alusil as well as the process itself in practice.

One question remained unclear, however: Did anyone manage to find a replacement for Sunnen AN-30 paste? Is there anyone out there who lapped the Alusil surface using a different compound? The originally recommended paste seems to be extremely hard to source outside the USA, and especially where I live.

I've red the entire thread, and seen some brief discussion going on around this.
@Rondinone even used Quartz based compound, which seemed like a good idea due to it's hardness being really close to those of silicon's. Sadly, miscroscopically, the results were not satisfying. Some suggested silicon carbide, and this would be the easiest to source (many valve lapping compounds contain it), but from my research, the original Sunnen paste uses Silicon, which is considerably softer than silicon carbide.

Maybe someone could share their thoughts or opinions on this subject?

nbK

[jjeffries]

More good stuff to read here:
Project 924 S engine replacement
Question: are your BMW rings actually in need of replacement? With my 180K mile 911SC engine, a local specialist honed then measured the cylinders, then measured the rings. They were fine. The reassembled engine (valve job, bearings, chains etc runs sweet and used minimal oil. I'm not saying that will be true for yours, but sharing my experience in case it's helpful.

[DannoXYZ]

Originally Posted by n00b0Rka

...I've read the entire thread, and seen some brief discussion going on around this.
@Rondinone even used Quartz based compound, which seemed like a good idea due to it's hardness being really close to those of silicon's. Sadly, miscroscopically, the results were not satisfying....

What was issue with quartz-based compound?
Did it remove aluminium from between silicon crystals? Too much or too little?
Did it damage silicon crystals?

If insufficient aluminium was removed, would extending lapping times help it perform like AN-30?

[mikedsilva]

I just read this entire thread.

I've come across my first Alusil cylinder 911 engine today..

At this point, cylinders appear to be in excellent condition. Pistons are also in quite good condition.

Was there a final consensus on using a grape hone? It was mentioned by Snowman several times.. (probably more) but he appears to be the only one that uses it.

My cylinders do not have any visible cross hatching and even the part at the bottom and top of cylinder also does not have any cross hatching. I'm tempted to just use scotchbrite and soapy water with strong detergent.

However, can I simply use the Goetze or Mahle rings as listed on this site? The description in the Goetze rings listing, says they are for use in both Mahle & KS pistons so does that mean they can be used in both Nikasil and Alusil cylinders?

Here is a pic of the pelican parts listing.. I don't understand the difference between the 2 Goetze listings.. same description, same thickness rings, but different part numbers?

[VFR750]

Tom Butler of Tom’s rennshop used to refinish the inside of alusil cylinders. Definitely don’t use a hone. Scotch brite and soapy water.

Alusil is the name for the casting process resulting in silicon carbide particulate in the aluminum substrate. (Matrix) You only want to lightly remove the aluminum and expose fresher SiC.

Rings? Well they say they work. I thought there were part number specific rings for Kobelschmidt cylinders.

How are the existing rings?

[mikedsilva]

Originally Posted by VFR750

Tom Butler of Tom’s rennshop used to refinish the inside of alusil cylinders. Definitely don’t use a hone. Scotch brite and soapy water.

Alusil is the name for the casting process resulting in silicon carbide particulate in the aluminum substrate. (Matrix) You only want to lightly remove the aluminum and expose fresher SiC.

Rings? Well they say they work. I thought there were part number specific rings for Kobelschmidt cylinders.

How are the existing rings?

Thanks for replying.
Yes, I have been advised by a couple of builders to try the scotchbrite and hot soapy water and to get them very very very clean.

Others have also mentioned the an-30 paste and felts on a spring loaded hone.

I think either of those 2 methods should be OK. What concerns me, is that the Goetze rings and Mahle rings on pelican site state they are for use in either Mahle or KS cylinders.. it doesn't say "Nikaskil and Alusil" cylinders. Also, the Porsche parts PET lists 930 103 967 00 as a genuine part number. And uses the name "Schmidt" as the reference. I believe these are ONLY available from porsche gen.. if they are still made.. I have sent the part number to my local porsche agent to see what he can find for me. If they are not available (or cost the world) then we have to decide if we take the gamble on the goetz rings. Incidentally, the stock rings that came out of the engine (150k miles and never rebuilt) have GOE written on them.

In terms of their condition, all intact, gaps are toward the large end of the tolerance. It seems wrong to put them back in as they are.

In addition to this, I called Pelican and they confirmed that the 2 listings for the Goetze rings for the same car with the same dimensions but different part numbers and prices, are exactly the same ring, but they are from 2 different suppliers.. just to make things interesting I guess!

[VFR750]

KS is Kobel-schmidt (Schmidt) and they are Alusil

I used scotchbrite pads, tie-wraped onto the stones of a spring loaded hone.

[jjeffries]

TomB did mine as described. 183K mile engine with excellent service history/oil changes, broken head-stud necessitated engine re-fresh. Saved me a ton of $$$ (by not having to go the replate route). Original rings measured (by Tom) OK, so re-used. 10K+ miles later all is still well. Alusil gets a bum rap, IMO. John