About 200 hrs on new engine and rubber mounts. (PA18/O-320)
upper mounts look fine, lowers have taken a weird set and are misaligned, both sides (photo). Dont recall it being an issue when i mounted the engine.
What gives? need for concern?
200 hrs. is pretty early for them to look like that. Some sagging of the lowers is normal but the way those forward lower bushings are off-center with the bolt, they look like they are being degraded by oil. The uppers don't sag because they don't carry any vertical load. They just keep the engine from tipping forward off the firewall.
newer conical rubber some times softer material causing the problem you are having some worse to the point the motor mount makes contact with the engine!!
Thanks for reply,
they were tightened to spec (1.84) during assembly, also appeared to be properly aligned. I'm prepared to replace them.
whate a reliable source for quality rubber mounts?
Are you using Lycoming conical, or the experimental cheaper conicals from ACSpruce?
i used the experimental ones and suspect them as not great. I have nearly the same issue at 500 hrs and I think they aren't dampening vibration well anymore either.
I've ordered a new set of lycomings to give them a try. Will have them on in the next week or so.
there aren't a lot of conicals available like there are for dynafocal. Also, beware there are older, shorter alternate part number conicals for 0-290 and smaller Lyc's..
My engine was removed yesterday after about a 13 month install. I used Superior bushings from AERO tightened to 1.84" on install and found all nuts pretty loose yesterday. I think the bushings compressed a bit in service but will have a better idea when I get new ones to compare. I think they should be checked after a few months in service. Have not decided on using Superior again or Lyc's. Not very happy with Lyc right now as I have been neutered by SB 632. Lyc piston pin bushings coming out and Superior going in whether they pass Lyc's foolish test or not, Jim