Audizine - An Automotive Enthusiast Community

Results 1 to 7 of 7

Thread: My S4 Rebuild

  1. #1
    Active Member One Ring
    Join Date
    Sep 16 2018
    AZ Member #
    426918
    Location
    Las Vegas, NV

    My S4 Rebuild

    Guest-only advertisement. Register or Log In now!
    Greetings everyone -

    I purchased my 2005 4.2 S4 back in June for $2300 with a blown clutch and a few other minor issues. Sorted those out and the car ran great! After a week or two of driving I noticed the oil was getting low. Ran through all the typical diagnostics and determined that the engine was experiencing oil loss through the guides / seals as well as possible issues with the piston rings. Ran compression test, leakdown, etc. to arrive at this conclusion. Only error codes I was receiving were for warm up catalyst which doesn't surprise me as the Pre-Cats were completely clogged up.

    I've decided to proceed with reconditioning of the bores with new rings via sunnen paste method, provided everything measures out. I've read all of the posts from Qdubz and Neilpaku which have been extremely helpful (Thank you!!!). While I'm in there I'll replace all the timing components. Mechanical Adjusters were a little worn but not terrible compared to others I've seen. The plastic spring seat had broken into several pieces on bank 2. I've got the engine torn down and will mic the bores and measure out the pistons before I proceed.

    Below are my initial findings...

    1. Heads:
    Burnt oil on the tops of the intake valve stems close to the guides. More so on the exhaust valves. Haven't disassembled the heads yet but I did rotate the exhaust cams and saw some considerable buildup on the stems and on tops of the valves. When I first changed the spark plugs one of the insulators was missing on Cylinder 1. Looks like it caused some minor damage to the top of the head. What do you guys think? Reuseable? I'm also guessing this contributed to the scoring in Cylinder 1.
    20181207_121123_resized.jpg
    See the damage in Cyl #1?
    20181207_121133_resized.jpg

    2. Bores
    Minor scratches in all bores with some fingernail catching scratches in 3-4 of them. ALL of them are glazed over.
    20181207_121245_resized.jpg
    Bores for Cylinders #1 and #2. These were the worst! the rest were minor. (See Attachment)



    3. Pistons / Rings
    Damage on the top of Piston #1 but the ring lands and sides of the dome visually appear fine. I'll mic em to be sure but I plan on reusing the piston. I was gonna clean up any sharp edges on the top. The ring grooves ALL have burnt oil and carbon build-up. Some of the relief holes on the oil rings were completely sealed up. This definitely couldn't have been helping things.
    Piston #1
    20181207_121157_resized.jpg
    20181206_211858_resized.jpg
    20181206_211911_resized.jpg
    20181207_120833_resized.jpg
    Notice the relief holes are completely choked with carbon
    20181207_120947_resized.jpg

    4. Rods - Visually the rods looked okay upon quick initial inspection. I was curious what you all thought about the small end wear at the bottom of the pin. Is this normal for an engine with 170K? Two rods that I've disassembled so far have identical wear in this location.
    20181207_121009_resized.jpg


    Oil Leaks pretty much everywhere with the exception of the timing covers and rear main seal. The oil seal to the back of the AC compressor was leaking which was a bit of surprise to me.

    With the amount of burnt oil I can see on the pistons and rings and the tight ring stack I'm hesitant to use dino oil for the break-in. I mean, didn't these cars come from the factory with Syn?

    I'll try to keep progress updated as we move along Still trying to figure out the best way to post pictures on here. Thoughts and feedback are appreciated!
    Attached Images

  2. #2
    Veteran Member Three Rings
    Join Date
    Aug 09 2012
    AZ Member #
    98417
    Location
    Bay Area

    Quote Originally Posted by 522sixth View Post
    Greetings everyone -

    I purchased my 2005 4.2 S4 back in June for $2300 with a blown clutch and a few other minor issues. Sorted those out and the car ran great! After a week or two of driving I noticed the oil was getting low. Ran through all the typical diagnostics and determined that the engine was experiencing oil loss through the guides / seals as well as possible issues with the piston rings. Ran compression test, leakdown, etc. to arrive at this conclusion. Only error codes I was receiving were for warm up catalyst which doesn't surprise me as the Pre-Cats were completely clogged up.

    I've decided to proceed with reconditioning of the bores with new rings via sunnen paste method, provided everything measures out. I've read all of the posts from Qdubz and Neilpaku which have been extremely helpful (Thank you!!!). While I'm in there I'll replace all the timing components. Mechanical Adjusters were a little worn but not terrible compared to others I've seen. The plastic spring seat had broken into several pieces on bank 2. I've got the engine torn down and will mic the bores and measure out the pistons before I proceed.

    Below are my initial findings...

    1. Heads:
    Burnt oil on the tops of the intake valve stems close to the guides. More so on the exhaust valves. Haven't disassembled the heads yet but I did rotate the exhaust cams and saw some considerable buildup on the stems and on tops of the valves. When I first changed the spark plugs one of the insulators was missing on Cylinder 1. Looks like it caused some minor damage to the top of the head. What do you guys think? Reuseable? I'm also guessing this contributed to the scoring in Cylinder 1.
    20181207_121123_resized.jpg
    See the damage in Cyl #1?
    20181207_121133_resized.jpg

    2. Bores
    Minor scratches in all bores with some fingernail catching scratches in 3-4 of them. ALL of them are glazed over.
    20181207_121245_resized.jpg
    Bores for Cylinders #1 and #2. These were the worst! the rest were minor. (See Attachment)



    3. Pistons / Rings
    Damage on the top of Piston #1 but the ring lands and sides of the dome visually appear fine. I'll mic em to be sure but I plan on reusing the piston. I was gonna clean up any sharp edges on the top. The ring grooves ALL have burnt oil and carbon build-up. Some of the relief holes on the oil rings were completely sealed up. This definitely couldn't have been helping things.
    Piston #1
    20181207_121157_resized.jpg
    20181206_211858_resized.jpg
    20181206_211911_resized.jpg
    20181207_120833_resized.jpg
    Notice the relief holes are completely choked with carbon
    20181207_120947_resized.jpg

    4. Rods - Visually the rods looked okay upon quick initial inspection. I was curious what you all thought about the small end wear at the bottom of the pin. Is this normal for an engine with 170K? Two rods that I've disassembled so far have identical wear in this location.
    20181207_121009_resized.jpg


    Oil Leaks pretty much everywhere with the exception of the timing covers and rear main seal. The oil seal to the back of the AC compressor was leaking which was a bit of surprise to me.

    With the amount of burnt oil I can see on the pistons and rings and the tight ring stack I'm hesitant to use dino oil for the break-in. I mean, didn't these cars come from the factory with Syn?

    I'll try to keep progress updated as we move along Still trying to figure out the best way to post pictures on here. Thoughts and feedback are appreciated!
    Sub'd. Glad to see your taking this task on. Wish you have the best of results at the end and welcome!

  3. #3
    Senior Member Four Rings VinnysS4's Avatar
    Join Date
    Nov 12 2015
    AZ Member #
    364349
    Location
    Oregon

    Couple things..
    Great buy! Stupid cheap, even with the issues at hand.
    First off, the "honing" DIY posted by q-dubz (Same thing Porsche guys have been doing for years) will do very very little for you. The felt honing pass is the final stage of the Alusil reconditioning process. What that step actually does is remove some of the aluminum from around the silicone particles in the bore. The bore diameter will not change doing this method because of the material hardness, thus any scratches or dings will still be there. The felt and paste used is softer than the silicone and harder than the aluminum. In a normal hone job, you are using a ball hone to put microscopic scratches on the cylinder walls for oil to ride in when the piston rings go by for lubrication. On the AluSil blocks you are pulling away some of the aluminum and exposing silicone and it's the microscopic holes from removing the aluminum, from around the silicone, where the oil rides in to lubricate the Rings. The Rings will ride on the silicone surface when you are done. This method is good to help refresh the motor, but won't do much at all for any cylinder scratching. For that you need to use honing stones designed specifically for Alusil blocks, THEN you do the felt lapping to finish it off. One of the unfortunate things with this process is the cost of the materials. Alusil honing Stones aren't exactly cheap and the hone they go in isn't exactly cheap either. You can make adapters for them to fit cheaper hones, it just takes some time and skill. I completed this job not that long ago and reached out to a bunch of different companies looking for parts and materials. Not many carry them.

    If you have a bunch of burnt oil on the valve stem near the guide, then you most likely need valve seals. By the looks of those valves and pistons, that engine consumed a nice amount of oil.

    Personally think the head and piston would clean up to reuse. The block depends on how many dings are in it. If it has any dings, it will consume oil past that spot. The block has some scratching so i would hone the cylinders and lap them to help oil consumption.

    All in all.. very nice snag. I'd love to find one for super cheap to rebuild like this. Keep us updated.
    Vinny

    Sent from my SM-N920V using Tapatalk
    1997 VW GTI VR6 (sold), 2003 Audi RS6 (sold), 2010 Audi A4 2.0T (RIP Totaled on 11/2/2015 ) 2005.5 Audi S4

    My build log
    http://www.audizine.com/forum/showth...-s-s4-timeline

    Texpoops "Correct, but a half inch difference isnít going to accelerate wear by much. Iím sure the front dips that much with a fatty in the front"

  4. #4
    Active Member One Ring
    Join Date
    Sep 16 2018
    AZ Member #
    426918
    Location
    Las Vegas, NV

    Thanks for the feedback Vinny. Much appreciated .

    At the rate of oil I was burning (150-200 miles a quart) I can't imagine things getting any worse. I'm currently weighing options on the best approach for this project. I reviewed the images that qdubz posted up on his block rebuild and they didn't look too dissimilar from mine. I mic'd Cylinder 1 / Piston 1 (worst) last night and all the measurements were in Spec (except for the scoring of course). Once I get the block cleaned up well I'll post some better pictures up of the bores. Hoping for some feedback on the condition of the bore scoring on this block vs. folks that have successfully completed this project.

    Were you able to use the OE rings for re-honing? Did you have it professionally done or DIY? There are some machine shops in my area that claim to offer Alusil Hone services so it might be worth looking into but depends on the expense. If I can just freshen up the block by lapping / new rings and get 1500 miles to a quart I'd be MORE than pleased . 1000% improvement, lol.

  5. #5
    Senior Member Four Rings VinnysS4's Avatar
    Join Date
    Nov 12 2015
    AZ Member #
    364349
    Location
    Oregon

    Quote Originally Posted by 522sixth View Post
    Thanks for the feedback Vinny. Much appreciated .

    At the rate of oil I was burning (150-200 miles a quart) I can't imagine things getting any worse. I'm currently weighing options on the best approach for this project. I reviewed the images that qdubz posted up on his block rebuild and they didn't look too dissimilar from mine. I mic'd Cylinder 1 / Piston 1 (worst) last night and all the measurements were in Spec (except for the scoring of course). Once I get the block cleaned up well I'll post some better pictures up of the bores. Hoping for some feedback on the condition of the bore scoring on this block vs. folks that have successfully completed this project.

    Were you able to use the OE rings for re-honing? Did you have it professionally done or DIY? There are some machine shops in my area that claim to offer Alusil Hone services so it might be worth looking into but depends on the expense. If I can just freshen up the block by lapping / new rings and get 1500 miles to a quart I'd be MORE than pleased . 1000% improvement, lol.
    Lol. Yeah can't get much worse than that. I bought new rings for the engine. Any time you use honing stones, you want to replace the rings.
    I did it myself. The thing you gotta remember is you are only honing just enough to freshen the bore up and rid it of scratches. Too much and you will mess with the piston ring gap.
    Oh and I've read that using synthetic oil on break in is a no no. Make sure to do a proper break in procedure. Lots of heavy acceleration/deceleration. No idling or steady cruising.

    New valve seals and pcv valve, and you should get more than 1500 per quart.
    Vinny

    Sent from my SM-N920V using Tapatalk
    1997 VW GTI VR6 (sold), 2003 Audi RS6 (sold), 2010 Audi A4 2.0T (RIP Totaled on 11/2/2015 ) 2005.5 Audi S4

    My build log
    http://www.audizine.com/forum/showth...-s-s4-timeline

    Texpoops "Correct, but a half inch difference isnít going to accelerate wear by much. Iím sure the front dips that much with a fatty in the front"

  6. #6
    Senior Member Three Rings mark_ma's Avatar
    Join Date
    Feb 25 2015
    AZ Member #
    317253
    Location
    Denver/Colorado

    My S4 Rebuild

    Itís crazy to see how these beauties have held their value so well compared to msrp back 10-14 years ago ;)


    Sent from the World Wide Web using Audizine
    Last edited by mark_ma; 12-09-2018 at 01:01 PM.
    Le build thread of mark_ma,
    500px ,Instagram , flickr_mark_ma
    4 wheels, 8 pistons, two mufflers , ultra light weight seat warmers, see through windows, carbon fiber turn signals, wireless key fob, photon reflecting side mirrors

  7. #7
    Active Member One Ring
    Join Date
    Sep 16 2018
    AZ Member #
    426918
    Location
    Las Vegas, NV

    Seeing how I couldn't afford one 10 years ago, I'll take it



Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


    © 2001-2018 Audizine, Audizine.com, and Driverzines.com
    Audizine is an independently owned and operated automotive enthusiast community and news website.
    Audi and the Audi logo(s) are copyright/trademark Audi AG. Audizine is not endorsed by or affiliated with Audi AG.