In our machining of all German engines, the 3.0 version of EA839 is different from all others iron coated or OE cast-in sleeved block such as EA855, S55/B48/B58/S58, N54/N55, M156/M177. The 3.0 version of EA839 is pretty much the only modern German turbo boosted engine with "straight flangeless iron sleeves" that sit at the bottom ledge. In EA839, the bottom ledge is at about deck surface minus 130-ish mm deep. The 6 flangeless sleeves are interference fit into the block with no anaerobic adhesive. You can smell and feel the oil residue between the aluminum parent bore and the OD of the flangeless sleeves after you chisel out the OE sleeves (once you machine them thin enough for chisel). This is never a good sign. Whether oil migrated up during service or VW/Audi applied oil to facilitate sleeve installation, we don't know. In the official Audi document, they use a term "Thermally joined cylinder liner".
As you are probably aware of, cast iron sleeves and cast aluminum block material do NOT have the same thermal expansion rate (11 for iron and 19 for high silicone aluminum in relative terms), so flangeless sleeves that sit at deck minus 130-ish mm ledge go through heat cycles of growth and shrinkage on deck surface. (That is why performance shop always install "flanged type" sleeves)
What we see here in our shops is high horsepower EA839s, especially those with stock internals yet larger turbos with aggressive tunings (knocking / overheating / piston crack/melt / ruined bearings/bore scoring/melt plugs... ) Whenever they have bottom end problems that require taking apart, 7/10 have OE sleeves sinking by at least 0.1~ 0.2mm ( very obvious by finger nails ). Do they cause head gasket sealing issues if ignored? We think maybe ok maybe not thanks to the generous 93mm bore spacing of EA839. We suspect head gasket sealing rings over the 87.5mm diameter that sit on aluminum still provide sealing, especially if you do a simple surface regrind/fly cutting. But many local race teams/owners, seeing the issue of flangeless sleeves sinking, do not want to take any risks. When they decide to go to forged internals, they also want the OE flangeless sleeves removed. So far the feasible solutions are flanged sleeves or wet sleeve conversions.
I have also seen other local shops put in larger OD flangeless sleeves at 2~2.25mm wall thickness have worsened head gasket blowing issue. In these cases, sleeve sinking happen again yet less aluminum parent material is available for sealing.
In future videos, we will post how we sleeve EA855, EA837, B48, B58, S58, S55, S63, M113K, M156, M157, M177, 3UR, 1GR and many other blocks.
15 сен 2024
