swaping pistons and block/

[harry.s.truman]

I keep hearing that the block came with 3 different bore diameters from factory, they then matched the pistons to each cylinder ...


Make long story short, i got stuck with a problem car, the previous owner cracked a rod a some point, paid a shop to change everything on the car (complete chain guides , clutch , mounts, etc..)


BUT, they decided to gamble with a gauge on the lower part of the cylinder, which ultimate means the rebuild failed and they dumped the car, this happened a couple of times till it ended up in my hands wholesale (im in the business)....


Im now looking at the most ridicules build i have ever seen, there is silicone everywhere, compression was fine when i pulled it, but something was def wrong, burning major oil, power was off...


They ended up sticking a ford auto light in the problem cylinder and pushing it away...


I have a large shop with skilled guys, but this might be the breaking point car... ha


I am going to recondition the alyusil block, and re ring... The Porsche guys do this frequently but i don't see much of it in these forums...


im now faced with the problem of rods and piston.... i wanted to go with scat rods, but it looks like they will not fit on the stock pistons...


Do i really feel like dumping 4k into rods and custom pistons on a problem platform... I keep Reading that the piston expansion is the major issue causing this scoring..... which makes me reluctant to throw more money into having something flawed in the end... if the stock pistons and rods go, then so be it... am i wrong?


Will the salvageable pistons from og block fit into the new/er block.... or is there size discrepancy from factory...


Yes that was long..

[JS4Avant]

Howzit going man, crazy dilemma you got there. I'm stuck with a problem car as well. Piston scoring seams to be the culprit on mine. Were you thinking of sleeving up the block? I'm still figuring out what to do with mine. Problem with me I don't think there's anyone where I live big island Hawaii) to do the special work to fix this. Probably end up buying a engine. Would love to hear/ see your process If you do rebuild. I know, this is my second 4.2 S4. I just really like'em! Good luck, aloha!


Sent from my iPhone using Tapatalk

[4point2]

wow seems like the "quality" work from others is just landing you in a real pickle.

Most folks on here are owners rather than in the industry, some are both. I (and others I'm sure) would be very interested in your process too for the alusil recondition as most of the folks on here have the fear of scored cylinders tugging away in the backs of their heads, let alone the timing chain guide issue.

If you're doing this potential refurb to own a solid car then it might very well be worth it, especially in avant (wagon) form; there is very little else out there that even comes close in terms of comparables.

If this is a business move to then sell the car and cover your overheads / turn profit I fear you might be into a tough deal.

sadly depending on your situation it might be best to thing with your head (not your heart - if that's a factor) and walk away and write it off as a lesson and possibly against business earnings.

Good luck, keep us updated if you can

[rgtorque]

i am also in the car biz and was blessed by having an a dirt cheap s4 nagaro 6spd avant bless my lot... with a bad motor. it came in running and driving , but low compression on several cylinders. i did some back and forth and found out it have scored cylinder walls. i looked at rebuilding and the cost and lack of definitive answers on the rebuilds longevity steered me to purchase another motor, with lower miles and warranty.

[badger.]

I have nothing technical to add, but there was a lot of interest/discussion/arguing in the thread I linked below about the potential to sleeve the block and other ways to salvage a motor with cylinder scoring. If there is a way to recondition the alusil and save the block I think a lot of people here would be eternally grateful. You mentioned "I am going to recondition the alyusil block, and re ring... The Porsche guys do this frequently but i don't see much of it in these forums... " Can you share a link to those discussions or suggest a shop?

http://www.audizine.com/forum/showth...eving-a-S4-4-2

[Nollywood]

Solve the S4 V8's issues once and for all.

077-series V8 block it.

[harry.s.truman]

the days of this car being a flip are long gone... this is a personal car or a paper weight at this point..



I read the sleeve thread... not a lot of optimism...



The new block is not that bad... but i have to recondition it based on the fact the rings will not seat properly if i do not re expose the silicon...


whether the reconditioning covers up any small scratches or scoring, i cant tell you yet...


If this work or fails i can also not tell you yet but i will gather more info and post some results....

[emilio]

i read up on Alusil cylinder restoration a while back, and it doesn't sound like too crazy: it's more or less a typical cylinder wall honing. what's different is the specific materials and tools that are used, which are definitely rare in the US and would likely only be at a shop that does work on 70's Porsches and Mercedes-Benzes.

Alusil works by creating a mix of aluminum metal and silicon crystals, then just the aluminum is polished away from the cylinder walls to leave a microscopic layer of silicon crystals poking out. these crystals are jagged and the piston ring would break them or get damaged, so the next step polishes down the silicon crystals themselves so they become more like smooth nodules that the rings can ride on.

the Alusil reconditioning process basically repeats this: grind away the bad layer of silicon nodules, then start all over with revealing the silicon. i think the amount of material removed is so minute (i'd guess <.002") that you can use the stock piston rings without getting oversized ones. i'd still replace all the rings, though, even tho they're like $100 a cylinder!

at some point we're going to run out of good engines to swap in, and this process may be the only one left to keep a 4.2 running.

- emilio

[4point2]

interesting emilio, thanks for sharing that

[harry.s.truman]

People have recommended these guys to me as far as recondition the blocks...



I have not used them to say if the product is good or bad, but i did talk to Cisco there, they have done many alusil blocks...


http://motorworkssd.com/home/2599005

[harry.s.truman]

Dangerous place to be

[VinnysS4]

NICE!

[emilio]

Dangerous place to be

sweet! what's your plan?

- emilio

[harry.s.truman]

im going to felt/paste hone it, new rod/crank bearings and seals...

rebuild the heads...



still haven't decides on the pistons and rods... do i put money into custom setup, then i can hone the cylinder down 100% get rid of the scuffs on the walls with a finishing hone before i felt hone it...



or do i just felt and re ring the pistons....



These rods and pistons go... these are facts..... BUT we still have no idea what causes the scoring.... there's scoring all the way to the top of the walls where the skirts cant reach.... might be carbon related...

Do i just re ring and hope the rods don't go, or do i get custom rods and piston and hope the walls hold up....

[QIKRNU]

Typically the scoring is caused by hooning the motor before the oil is up to temperature. I have to see 170 F oil before I'll go over 3000 rpm's. My car burns maybe one half quart in 7500 miles.

[Brandywine050]

Stuck rings caused by excessive carbon build up from blow by can be attributed to cylinder scoring. if the rings fail to rotate in the cylinder, if your in cylinder temp becomes too hot due to blow by gases reducing oil film on the cylinder wall, or if you have a fuel dilution issue washing out the cylinders, all of which has an affect on these engines. but most commonly for these engines I've seem pretty well carbon coked PCV diaphragms/valves which inhibit the ability to prevent high crank cases pressures and oil consumption, correlating to carboned up crowns of the pistons down to the ring lands.

[emilio]

im going to felt/paste hone it, new rod/crank bearings and seals...

did you find an Alusil-specific process to use? i would be super cautious on how to hone an unlined block. but if it works... i'd probably do it some day!

- emilio

[harry.s.truman]

did you find an Alusil-specific process to use? i would be super cautious on how to hone an unlined block. but if it works... i'd probably do it some day!

- emilio

Yes, i already had the sunnen hone... just got the correct paste...

[harry.s.truman]

Things keep getting stranger....


I looked at the codes on the original engine and its for a Allroad... BAS code....



Did these guys fuck this engine up twice? maybe it was losing oil so they did a swap with an allroad short block.... it was built incorrectly, threw a rod... brought it back to the same place, they put a new piston in with a gouged cylinder and try to patch it up,,, but it failed...


This car keeps surprising me.... I bet the guy that owned it posts somewhere on here, if he does... your an asshole, well your mechanic is an asshole....

[4point2]

I bet the guy that owned it posts somewhere on here, if he does... your an asshole, well your mechanic is an asshole....

I know that feeling well, I've often wondered if the PO of mine is on here, cos he did a number on hiding the oil consumption / leaks, guess that's a lesson learned for both of us

[harry.s.truman]

2 medium scores did not lap out...

[emilio]

weird, is that an angled gouge in the last image?

pretty sweet to see, though, thanks for sharing! do you have new rings to put on there? i imagine stock rings have enough play to open into the very minor amount of honing you're doing.

is it a single-stage process, or are there separate cutting and silicon-polishing stages? how did you find the right paste to use?

- emilio

[draggingto]

This is very cool to see. I will be following this for sure. First time I have seen someone attempting to repair scoring in these motors.

[BCsniper]

2 medium scores did not lap out...

I can't hardly even see them in the pictures. There are several folks here with some pretty decent scoring and still only use a quart or two between oil changes (5k miles) I would say if you are anywhere in that realm after the rebuild I would be happy. Hopefully you've fixed the majority of the damage at this point

[pwest15]

OP, very nice work. Curious, do you have any "before" pictures of the cylinder walls?

Sent from my potato

[Lucca M]

Great thread. Waiting for results!