How-TO: Hone Alusil Blocks

[q_dubz]

Believe it or not these engines can be saved!

If you experience excessive oil burning, alot of times it's caused by a bad pcv or bad valves seals, or even bad valve guides in conjunction. That is not ALWAYS the case however.

The Audi aluminum engines are made of an alloy known as AluSil. It contains 16~18% silicon. They aren't the only ones that use it either. BMW, Mercedes, and Porsche have used this alloy as well.

That silicon was added for cylinder longevity and resistance to normal wear and tapering. The cylinders are NOT resistant to carbon and contact with piston skirts. Another thing, silicon is highly abrasive and overtime will wear the piston rings down causing high oil consumption. Scoring can become an issue as well if it gets bad enough. We'll save that for another thread.

If your cylinders all measure out fine but you're burning oil, it might be time for fresh rings.

Tools Needed:

Standard 3-Arm Hone Available at many autoparts stores
Duct Tape
Hot Glue or Super Glue (gel kind)
Felt (try and find some that's 1/4" to 1/2" thick)
Sunnen AN-30 Silicon Paste
Lubricant (wd40, honing oil which is mineral oil, or ATF will suffice)
MANY RAGS
Acetone or some form of solvent for cleaning cylinders before and after
A plug or something to put down in the bottom of the cylinder to keep the paste from going on the crank
A paint brush
A drill (preferably one that is variable speed)

Setup Your Hone:


Apply the duct tape around the stones (so in case the felt rips off you dont rape your cylinders!)



If you have thin felt, fold it over so it's thicker and then superglue the felt to the SIDES of the stones.
Be sure to put some superglue between the layers of felt on the side for reinforcement.

DO NOT APPLY GLUE TO THE FRONT of the stones. This will cause a hard spot which means uneven honing (according to my brain lol)






Here's the before shots of each cylinder 1 thru 8 from top to bottom:
Yes there is some scoring at the top of each cylinder sadly. A couple cylinders have a score that runs a little longer. I can feel them with my finger nail. I am taking one for the team here as i dont have TIME to source another engine or get this one nikulsil plated. The story is this engine (i bought used) did NOT burn oil...we'll see about that










CLEAN THE CYLINDERS REALLY GOOD WITH SOLVENT.

Place plug at bottom of cylinder to protect crank and oil squirter.

Apply paste to all of the area the piston rings ride. You can see the change in cylinder appearance at the bottom in this photo.






Use WD40, Auto Trans Fluid, or honing oil and apply it to the felt on your hone. Then slather paste onto the felt directly.

Place the hole in the cylinder, at the top and turn your drill on to approx 200rpm and proceed up and down approx 60strokes/min ( ) That means every second you should be at the top of the cylinder again. DO THIS FOR ONE AND A HALF MINUTES TO TWO MINUTES. It's important to note this procedure is self-limiting so you can't really OVER do it, but in the interest of being consistent....

When i got to cylinder 5, i noticed the hone started to "chatter" or shudder a little. That means apply more oil to the felt pads.

I did have one felt pad start to come off so i stopped and redid the whole hone and finished the last 3 cylinders.

Here it is complete.











SHOUT OUT TO: NEILPAKU FOR SENDING ME SOME OF HIS LEFTOVER AN-30!!

[q_dubz]

IT IS IMPERATIVE THAT YOU CLEAN THE HELL OUTTA THE CYLINDERS WHEN COMPLETE!!

Don't want silicon powder floating around in bearings lol

[q_dubz]

Useful links:

https://www.goodson.com/technical_su...ding/AN-30.pdf

http://forums.pelicanparts.com/porsc...acement-2.html

[VinnysS4]

Nice job bud! i have a similar project underway. Lovin the results Q!

[Kambesama]

YES Thank you for this. Definitely going to be doing this when I get a second motor

[q_dubz]

Thanks for the support guys.


There's one additional/optional step.


That's the scotchbrite step (GREEN)

You put scotchbrite pads on the hone instead of felt and run them with oil for 30secs to a minute to break the glade. Then proceed with the AN30 paste with felt pads.


I've heard and read both sides of that as to whether or not it's necessary. I don't it hurts tho.

[badger.]

Awesome stuff! Great to have some photos of the process.

What did you use for the plug at the bottom of the cylinder?
Do you use the same size (as stock) piston rings when re-assembling?

[q_dubz]

Awesome stuff! Great to have some photos of the process.

What did you use for the plug at the bottom of the cylinder?
Do you use the same size (as stock) piston rings when re-assembling?

i pulled a top off a glass cleaning wipe bottle lol.


And yes you'd use a new set of OEM piston rings, check the gap with a feeler gauge, file if necessary.

Obviously my build is going a difference direction in regards to that lol ;-)

[Lucca M]

Awesome work! I might try that on my spare block

[neilpaku]

Great job Quintin! Another one saved from a premature demise. I like your approach of gluing the felt to the sides of the hone - definitely put that one in the DIY. I just stapled mine, which did hold but doesn't look as professional!. Looking at your scoring, (great photos by the way - I wish I had taken better pictures of mine) your gouges don't look as bad as mine were.
So folks, if you bores look like these, worse engines have been restored.
You're going to love that engine once it's back together. My wife's car is now getting close to 3000mi and I have not added any oil - it's about at maybe 3/8 of the stick, so I think it's going to make it to the 5000mi oil change.
(And thank you for the mention - you're most welcome particularly because you were willing to give the process a shot.)

[q_dubz]

Great job Quintin! Another one saved from a premature demise. I like your approach of gluing the felt to the sides of the hone - definitely put that one in the DIY. I just stapled mine, which did hold but doesn't look as professional!. Looking at your scoring, (great photos by the way - I wish I had taken better pictures of mine) your gouges don't look as bad as mine were.
So folks, if you bores look like these, worse engines have been restored.
You're going to love that engine once it's back together. My wife's car is now getting close to 3000mi and I have not added any oil - it's about at maybe 3/8 of the stick, so I think it's going to make it to the 5000mi oil change.
(And thank you for the mention - you're most welcome particularly because you were willing to give the process a shot.)

There you are!

Really your cylinders looked worse?? Well that's a relief. I prolly should have done the scrotch brite step buuuuuuut they do say the paste makes it's changes at the microscopic level so I didn't expect to SEE any drastic changes.

[emilio]

RING CAUCUS, FTW! cylinder scoring is a lie! piston rings are real! Santa Claus is fiction! the NSX isn't a supercar!

thanks for sharing this, folks need to know. the Porsche track guys have been honing and re-ringing blocks since at least the 80's, and those cars get far more harsh driving that most of ours do.

a re-ringing DIY would be rad, too, as that was once common knowledge for mechanics but is much rarer nowadays.

- emilio

[kevinye77137]

This is awesome! Definitely doing this when my engine Is out again

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[Quattrors4]

good job buddy!!

[2004B6S4]

Are these pictures really showing the scoring that people are so worried about? I want to say I've seen pictures of some deep gouges that were MUCH worse than this or neilpaku's, but I can't back that up cuz I don't remember where I saw those pictures...

[Quattrors4]

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this is an rs4 bns block that that my machine shop did, it went thru a 3 stages alusil honing process done with a torque plate,there where some light scratches and scuff marks,with this process it make the cylinders walls like new again!
thanks q-dubz for letting me post it on your thread

[neilpaku]

Are these pictures really showing the scoring that people are so worried about? I want to say I've seen pictures of some deep gouges that were MUCH worse than this or neilpaku's, but I can't back that up cuz I don't remember where I saw those pictures...

Yes that's a good point. I think when folks state that their blocks are scored, they need to qualify the scoring, because there's scored like mine and Quintin's, which are easily treatable, vs. someone that had a wrist pin let go and take a 5mm gouge out of the side, and every level of scoring in between. I think the concern is where someone (e.g. a shop) says "your bores are scored and the block is junk" and they don't say how scored it is. I would never let a shop tell me that without me eyeballing the evidence in person (not that I'd ever trust a shop to do a job like this...). The other concern is when folks that aren't familiar hear the line "scoring = junk" and possibly scrap blocks that just need a hone and re-ring.

[neilpaku]

There you are!

Really your cylinders looked worse?? Well that's a relief. I prolly should have done the scrotch brite step buuuuuuut they do say the paste makes it's changes at the microscopic level so I didn't expect to SEE any drastic changes.

Heh, I partly used the Scotchbrite to knock a few microns off the sharp edge of the gouges, because I still didn't want my brand new rings picking up on the vertical ridge. I did run a quick up/down/up/down in each bore to break the glaze with motor oil

[ven0m]

q_dubz, thanks for the write-up! This will be useful to many of us in the b7 V8 community!

[q_dubz]

q_dubz, thanks for the write-up! This will be useful to many of us in the b7 V8 community!

I hope so!

[REVOofRustler]

This is awesome! Thanks for taking the time to do this, man!

[q_dubz]

Bump for sticky

[emilio]

any udates? changes in consumption, tailpipe soot, mileage, general aura of good vibes, etc?

- emilio

[q_dubz]

Mine isn't running yet

[neilpaku]

Mine appears to be running as expected. No deterioration in oil consumption, no odd noises, starts and runs as expected, temps normal, fuel consumption not deteriorated, no smoke, clutch and transmission are good. Wife is not easy on it so it passes that test...

[Cygnets]

Thanks for this, I was reading up on the other thread posted about honing the block and was skeptical on doing it. With my motor almost ready to be pulled, I'll be sure to rip that sucker apart and check how bad my cylinder walls are (P.s. 1qt of oil every 300 miles, oh it was BAD).
Since I'm getting a donor motor with 50k miles on it, this motor I have now will be my test block and i'll see what I can do with it. Hoping for the best, maybe ill be able to salvage it.

Ill be sure to come back and update this with pictures of my walls, im sure everyone would be interested in them lol

[Terry.Reese]

Mine isn't running yet

He is still waiting for his flux capacitor to be able to convert the Dilitium crystals to engage warp speed.

[neilpaku]

Ill be sure to come back and update this with pictures of my walls, im sure everyone would be interested in them lol

If you can post some detailed closeup photos of your walls, that would help build a body of evidence regarding condition vs. salvageability. I'm annoyed I didn't get better photos of mine because the end result has been great. Unfortunately all I can say is that I had finger-nail catching vertical scratches on 3 cylinders and general scratching on all of them, plus a decent glaze. The worst scratch I had definitely did give me pause on whether the block was salvageable and I've built a few engines in my time (but not one of these alloy "non-rebuildable" blocks) so it was at least to me significant. However, there's not much more I could have asked for on the outcome - perhaps a little less oil consumption but improving from 1 qt. per tank of gas to 1 qt. per 2000mi. is a 10x improvement so that works for me. Plus the engine runs silky smooth now and with no extraneous noises. I've stopped really thinking too much about that engine now as it just delivers every day.

[q_dubz]

UPDATE:

The first 1k miles I burned about a half a quart.

The second 1k miles, I burned between 1/8-1/4

I have about 2600 miles on her now. Rings are def better seated as the miles went up.

Oil change intervals were at:
12mi
500mi
1500mi

[emilio]

nice results! i can't remember: did you also do the valve stem seals?

- emilio

[q_dubz]

nice results! i can't remember: did you also do the valve stem seals?

- emilio

I built a whole engine, upgraded valvetrain, forged rods and pistons. Etc...

[Terry.Reese]

What was the time frame it took you from start to finish to just hone them, not disassemble or reassemble.. looks freaking fantastic BTW

[MMMB00ST_A4]

What was the time frame it took you from start to finish to just hone them, not disassemble or reassemble.. looks freaking fantastic BTW

Honing realistically will take you about an hour if you pace yourself and don't take breaks. Factor for 1.5 hours if you want to provide overhead to account for torn felt, forgetting a step and having to go back on one cylinder,, etc.

[q_dubz]

2min per cylinder was what I did

[emilio]

do you know how bad the seals were beforehand? i still have the hunch that the oil consumption across BHFs is most commonly due to valve stem seals, then crankcase ventilation and piston ring wiping (not sure which is more common of those two).

if possible, i want to replace my stem seals before doing anything to the cylinders (currently consuming about 1qt/1000mi).

- emilio

[q_dubz]

I do not. I used different heads on this build but I do agree with your hunch.

[paul61]

Quattro,
Did you use a master cyl hone with the torque plate, or the de glazing tool shown here?

[q_dubz]

Quattro,
Did you use a master cyl hone with the torque plate, or the de glazing tool shown here?

He's not on this forum anymore. Ideally a torque plate is used but this deglaze/aluminum etching isn't really removing but a microscopic level of aluminum to expose silicon particles so you could do without. If you plan to actually use the stones and do the whole process, get a torque plate!

[paul61]

The question was re. the master cyl hone, which I believe he used?
You wouldn't need the torgue plate with the spring loaded de glazing tool, as it would follow the out of round bore.
Hate to see them called a "Hone", as they're not.
Thx tho

[Allroad2.7T]

Any update on how the engine is running? Curious to see how the oil consumption changes as you put more miles on it.


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