Help with TT .46 fuel leak/bubbles

On 4/12/2004 12:23 PM Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

I wouldn't ignore it. Try find/fix it now - it is only going to get worse and possibly become not repairable.

I would try the following:

1. Try removing the inline fuel filter and bench run the engine. You might get lucky :)

1. If it still bubbles, pull the engine out of the plane (if you haven't already) and THOROUGHLY clean it. I mean use a toothbrush and/or a small stainless or brass brush along with some lacquer/paint thinner or carburetor cleaner. Do this outside and DO NOT SMOKE OR HAVE ANY OPEN FLAMES AROUND WHILE DOING IT. Wipe off any residue and let it dry. Then get a magnifying glass and start checking the general area at the MOST FORWARD AREA OF THE BUBBLES for cracks. Any suspected cracks check with the point of a #11 exacto blade or "T" pin. If/when you find a crack clean that area with some acetone to remove any oil/grease that may be in the crack and JB weld the area. The hardest part will be to get the area free of oil.

The "proper" way to repair the crack (to keep it from growing) is to find both ends of the crack and drill a small hole all the way through. Then make a "V" groove between the holes and clean the area. Then fill with JB Weld. The "proper" way will require disassembly of the engine. If you decide to go this route (instead of a surface patch), make sure you mark the piston/liner so you don't reassemble it backwards.

I doubt it is the rear seal. The bubbles are too forward of the backplate (the prop blast is going to push the bubbles back). You want to start at the most forward area the bubbles are showing. In the photo, it "APPEARS" that the bubbles are starting in the general area of the fuel filter or the rear bolt hole on the mounting lug/back part of the casting for the schnurle porting.

Hope this helps.

On 4/12/2004 1:52 PM Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

Yep - it might be cracked. I doubt it, but it is easy to rule out.

The backplate would be the first point of contact by the crank when it hits. If it went that far, it has likely damaged teh front bearing as well as that is what holds the crank in position. Remove the back plate and look for the impact point from the connecting rod or crank pin. If you don't see anything there, take the engine apart and have the crankcase checked with dye-penetrant NDI. A local machine shop should be able to do that quickly for you. You may also be able to get the stuff to do it at a good auto parts store.

Very plausible. The slipstream will blow the oil all over the place. One backplate bolt might have been slightly loose. It doesn't take much. Dr.1 Driver "There's a Hun in the sun!"