19 June 2014

It all became clear in a flash…

Last week I explained how three things coincidently all failed during one drive: the alternator bolt, coolant line, and MAP reference hose. After extracting the broken bolt I was cleaning up the spilled coolant, idly wondering why it was oddly colored, almost like it had come from an old iron block engine – it was rusty colored, yet the Honda is an aluminum block. Separately, I also noticed a small dent in the engine cover, but discounted it as having happened the one time it nearly fell over. And finally, there was a heavy wire connecting the cylinder head to the chassis which was broken, but I figured maybe it got grabbed by the flailing water pump pulley a few months back and I just never noticed.

Back to the coolant residue… The odd colored residue was sort of oily which was strange, and seemed to be concentrated in the area of the broken coolant line, which is right next to, surprise, a failed Honda passenger-side engine mount – which is/was fluid-filled. The little bag/reservoir had torn open… and that’s when all the pieces of the puzzle started falling into place…

The mount wasn’t just torn, it was ripped in two, no longer connected to the engine in any way other than through gravity. The only thing left keeping the engine from going berserk was the driver-side mount and the rear mount (the front mount having been removed earlier). It meant that during acceleration, since the tires attempt to drive the car forward, the engine attempts to rotate the opposite direction, toward the rear of the car. Getting suspicious, I measured where the dent was on the engine cover, then measured where that point was on the engine itself, a stud on the valve cover, a good 2″ under the engine cover! The right side (crank pulley side) of the engine assembly had apparently lifted up and rotated toward the rear, and in a flash it became clear how everything unraveled: the engine mount broke first, allowing the engine to lift upward, leaving a dent in the engine cover. It pulled on the coolant line, ripping that open, in addition to breaking the wire to the cylinder head, and yanked the MAP reference line out of the throttle body. The only thing which appears to have happened independently was the alternator bolt breaking, which was entirely possible.

Just… wow. What’s surprising was that I didn’t notice when it happened; there was no tremendous bang, and there were no scratches on the chassis other than the dented cover. I’m sure the mount failure is due to the additional power of the turbocharger, and very likely also due to using used mounts of unknown integrity. However, having this happen was scary enough that I’m unwilling to risk it again, so urethane engine mounts have been ordered. While a lot of people don’t care for urethane mounts due to the increased vibration, they aren’t going to fail. As I typed this, I stopped and ordered the (optional) front mount for the security. This turbo engine, coupled with the sticky tires and great traction, is just too much of a risk to have the mounts let loose on me again…