I have cracks too.
I wrote Vans and included large pictures of the cracks so they could see them, instead of just talking about them. Their response was that they were not going to fall off, but they should be fixed. Several comments like rough landing strips or lots of grass strips may have caused them, etc. But they weren't sure. Also, it seems to be mainly on the bigger engine planes as well.
They do sell Gussets that make the -6 mount more like the -7 mount. The gussets mount on the bottom of the engine mount under the gear socket horizontally, it is about 3 to 3.5 inches IIRC and close up the triangle formed by the existing engine mount members. Since these cracks are on the top side and not the bottom, you might think the mount is plenty strong with positive G's and landing, but maybe less than strong enough on negitive G's. The gusset appears to reinforce that situation.
Note:.....these cracks are TINY....hair line fractures!!! very very small. easily missed on inspection. Especially since the area they are in gets a little dirty being the bottom corner of the cowling.
I found mine because my mount is a white color from 1995 and it had some brown looking goo coming from the crack that appeared to be rust and oil or something like that. That caught my attention and made me look closer.
My hangar mate had to pull his engine for OH and we looked close at his mount too and since his was painted metal flake red, it was harder to inspect, but we found tiny fractures in the same place as mine. since we had the engine off, we removed the mount and stripped the paint off and when the paint was off, the cracks were gone too.....that is correct, the crack was only in the paint on his mount. We went ahead and welded the gusset on anyway and repainted the mount back white like it should be in my opinion.
The welder made a brass dowel the same size as the gear leg itself to absorb the heat and not deform the socket, which seemed like a great idea to me. He is a senior welder with tons of experience and I was thankful of that for sure.
This gusset can not be welded on while the engine mount is in place.
well.......at least a proper job could not be accomplished anyway.
You might get by with re-welding the tiny crack on top, but I'm pretty sure it isn't or wasn't the weld's fault for the crack as this location must be an odd place for -G's..... It didn't seem right to re-weld on the mount at the socket area with the gear leg in place for fear of it attaching to the steel gear or deforming the socket without the brass heat sink in place. Mainly, I think it will re-crack without the gusset in place.
Or maybe not! There are 2 other lower time -6's with 0-360's on my field and they don't have cracks or any sign of cracks. Mine and my hangar mates were both 600 hour plus airframes with 0-360's too.
The solution is, if you actually have cracks, is to pull the engine mount, strip the paint or powder coating, either just in the local area or the entire thing.
Then have the gusset welded in place and repaint or powder coated.
I know it is seems like a big job and it is, but since we didn't build our planes, it was a good time to update the firewall things like the gascolator, firewall penetrations and swap to SS heat boxes and change the lower cowl hinges that were broken to screws and nut plates, etc.
Someone asked for pictures, but the cracks are so tiny it is hard to see with the naked eye, we actually had to use extra light and a magnifying glass to see them, so a picture would be hard to show them. That is why I printed pictures out 8x10 with pointers at the cracks and sent them to Vans with a letter, so even if they couldn't see the cracks, they would know where they were.
Good Luck.
