Quote:
Originally posted by Mike Diaz
Here's my theory that I discussed with a long time Acura tech. There's a few reasons why the Legend engine blows head gaskets.
Theory #1. The Vibration effect - once you remove the heads, you'll notice that the cyilnder walls sit out in the open by themselves with the coolant jacket surrounding it. No structural support at the top of the cylinder walls. What we discussed was the fact that engines vibrate, and the vibration eventually eats away at the gasket allowing coolant to flow into the cylinder. Typically it does this more at the rear of the engine (#3 and #6 cylinders). Next time you're in your car, rev it up to about 1500-2000 RPM's and feel the vibration that I'm talking about. Think about that vibration happening for 100k-150k miles and how that affects this area of the engine.
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So, the cylinders are free to move at the top of the block (Deck). These are steel barrels, cast into the aluminum block I assume. Perhaps the Honda engineers figured that the heads would "grip" the tops of the cylinders (sort of an interference fit when the heads were torqued).
Interesting. Now what I'm curious about is whether other manufacturers use similar designs, and if so, whether they have problems with head sealing at the cylinders. Any more info on this?