Take a look at my holes eh?

[VR6OhMy]

So I bought this 2005 S4 knowing the timing chain guides had broken, but was hoping there wouldn't be any valve damage. Unfortunately all 8 center intake valves took a smack with the pistons. Here is a few shots of the cylinder heads and the cylinders.





The valves should be no big deal to swap out pending the seats are still in nice shape, but I am a little concerned about these cylinder walls. I've read that they have a special coating on them which is obvious now due to the lack of cross hatching, however it appears that this coating is starting to wear away in spots and I'd rather scrap this whole block then put it back in there if the missing coating means that I'd be on borrowed time with my compression. Anyone have any ideas on that?

[evildsmr]

Well IMHO of youre a good car tech/guru. I would buy new rings (if you're worried) and we do the cross hatch on the cylinder walls. Its so simple to redo the cross hatch but the rings are a different beats to tackle granted the spacing in between gaps and what not.

[jmcS4]

Well IMHO of youre a good car tech/guru. I would buy new rings (if you're worried) and we do the cross hatch on the cylinder walls. Its so simple to redo the cross hatch but the rings are a different beats to tackle granted the spacing in between gaps and what not.

i thought we couldn't restore the cylinder walls???

[seishuku]

You can, it's just a slightly different process with Alu-Si vs traditional iron.

[2004B6S4]

You can, it's just a slightly different process with Alu-Si vs traditional iron.

more info?

I've always read that it was impossible, and that a block with scored cylinders is trash. I always imagined the scoring would look different than what the OP's pictures show, I'm not sure if his would be considered scored or what. But either way, if it's possible to restore a v8 s4 cylinder block then please elaborate

[seishuku]

Its not a honing process like iron cylinders, you actually etch away the aluminum, leaving microscopic silicon crystals exposed.
Those crystals are what the rings ride on, and technically should last nearly forever (rings wear out before the cylinder).

The silicon content also makes boring a bit harder as well, you have to use diamond tooling.

[SprintBlueWorld]

I found this article with regard to honing Alusil bores. It doesn't sound impossible. However, it does sound extremely technical, with very small tolerances. The article was written in May of 2008 and mentions that OEM variation in the chemical composition of the Alusil alloy prevents a standardized cookie cutter honing process. Sound like something JHM may be tackling?

http://www.sunnen.com/NewsDetails.aspx?NewsID=11

[BCsniper]

I remember this topic several years ago....weren't there only like 1 or 2 shops in the US that have the tools and proper stones to refurb the AluSil cylinders. It was determined that you could fix them but pretty much every shop you talk to about it is going to turn you away


This was all a long time before JHM started their built motors...now you can just get huge sleeves for your motor instead and no longer have to worry about scored cylinders

[Guitarmageddon]

Not even worth the gamble. I'd scrap it or if you have 10 g's send it to JHM to build it. I hope they fine tune their production process to chop a few grand of the end cost of their motors. That would make keeping this car for 10 years much more appealing. Otherwise, you're just on the slippery slope of oil consumption and more wall scoring.

[VR6OhMy]

So is the general consensus is that the block is toast? The spots are very small as seen in the pictures so I was hoping it wouldn't be a huge ordeal. I definitely don't have money for a JHM motor and I'd be very concerned about buying used as it very well may be in the same condition as mine.

Ughhhh WTF did I get myself into?

[Slow4]

So is the general consensus is that the block is toast? The spots are very small as seen in the pictures so I was hoping it wouldn't be a huge ordeal. I definitely don't have money for a JHM motor and I'd be very concerned about buying used as it very well may be in the same condition as mine.

Ughhhh WTF did I get myself into?

Your engine is NOT toast!

You can buy the OEM valves (brandywine went this route) or buy the JHM HD valves with Titanium retainers for about 1K plus whatever it costs for a machine shop to rebuild the heads. (Or buy the complete set of heads from JHM for 3500):

Prior to your engine skipping timing and the intake valves kissing the cylinder heads, did you do a leak-down or compression test to gauge the health of your cylinders? If yes, what did they read? Your bottom half might be salvageable and you'll just end up with mild oil consumption due to scoring.

Seek professional advice though, as the cylinder you posted has that rough patch that seems suspect otherwise clean out the debris and roll on.

TL-DR:

The top end is rebuildable and bottom is salvageable depending on the health of those cylinders. GL.

EDiT:

My #6



#1 - #4


Pass. Cylinder Head - Exhaust valves at rear were the ones that got kissed

[VR6OhMy]

Thanks for the picture sir! My cylinders definitely look better than your #6. There aren't any scoring lines that are running vertical and otherwise they look perfect, just a couple of faint spots like the one pictured that looked off to me.

The shit in the cylinders and everything else will be immaculate before reinstalling, this picture was taken less than 5 minutes after removing the head. I wanted to make sure it wasn't toast before spending time on any cleaning if the walls were considered damaged.

As for the condition prior to, I honestly have no idea as I bought the car knowing it had bad timing chains. So obviously I won't be able to tell what the compression is until I spend more money to put it back together and run a test.

[Slow4]

No prob man, some of us have been through this before and understand the frustration. My #6 is considered "moderate" scoring, can you imagine what severe scoring would look like?!

I would check the health of your cylinders before deciding on what to do with your heads. How you would go about testing the cylinders beyond my scope of "expertise" as your intake valves took a severe beating; contact JHM and ask for one of their tech guys, they should be able to help...best personal advice I can give you.

GL with your journey

[VR6OhMy]

Did you end up putting yours back together as is or did you replace the entire engine?

[Slow4]

Did you end up putting yours back together as is or did you replace the entire engine?

Rebuilt the top end (heads); sent JHM my old one and they sent me a set of rebuilt heads. This all happened while my Avant was under for timing guide/tensioner/adjuster replacement amongst other things. I intend on getting myself a rebuilt bottom half from JHM in the distant future, once they figure out a better way to streamline the program but no intentions of going FI.

I have a progress thread titled "Hello" somewhere within the last two pages; chronicles my fun with this platform

[Dirtracer603]

Man, those cylinders don't look bad at all. The dull spots aren't even an issue as there is no gouging. I wouldn't do anything to the cylinders/bottom end, fix the head and rock and roll. Just keep your oil changed and let the engine fully warm up before putting a load on it. It's my belief that the cylinder scoring on these cars is from failure to let the car warm up completely before putting a load on the motor, this causes 'cold seizure' and is even more suseptable in our cars because of the tight cold piston/cylinder clearances due to the Alusil design of the engine. Too much of a load when cold heats the piston, expanding it before the block can heat up (and expand) and there becomes zero piston/cylinder clearance. The resulting lack of clearance causes friction between the cylinder and piston and ultimately displaces the fragile cylinder wall (scoring).