hi everyone

Ive got a brand new norvel .061(not rc) big mig. The engine is running very well. However i got a problem with the muffler. This muffler is in two piece and there is only a wire holding it on its place. After i ran the engine a couple of times the two pieces of the muffler started spliting in to two. It just gets saperated when the engine is running. When i try to put it back together i need to apply some force and it looks like it is tight.

Does anyone have the same problem. Or any suggestions??

Yup -- little bit of a problem here. There are a few things you can do. If your engine is a new model, there will be a tab on the crankcase on the front and back immediately below the fins on the cylinder. Make sure the retainer spring sits in the groove formed by this tab and the lower fin. The tab keeps the spring from working downward and allowing the muffler to tilt. Also make sure the spring clips have not spread apart -- when attached, the spring should squeeze the endcap and muffler body together.

You must make sure the muffler is correctly seated on the exhaust port of the crankcase -- if tilted up or down or shifted forward or rearward, it has a tendency to move around. Over time, unless correctly seated, the port on the crankcase and the opening into the muffler will begin to round -- this allows the muffler to move even more and you may see dark oil on the crankcase below the crankcase port. This is due to leakage and vibration wear at the exhaust port/muffler opening.

With your spring lying flat on the table, make sure the sides that clip over the muffler are either parallel or slightly bent inward. If spread outward, they will have a tendency to pull the muffler apart. Sometimes, in reattaching the muffler, we inadvertently spread them apart. See image.

You can safety wire it by wrapping light wire around it between the muffler and cylinder to hold the spring together -- to keep it from spreading when the muffler endcap tries to work out.

Once the endcap starts to work loose, it just seems to get worse over time -- I've had them come completely out in flight, but have not lost one yet. The final solution is more permanent. I usually decide about what angle I want the exhaust pipe, clean the cap and body very well with acetone, rough the surfaces lightly with sandpaper and JB Weld it together. Aside from redirecting the exhaust, there is no reason to need to rotate the exhaust pipe or open the muffler.

the "other" andrew

If you don't get that muffler fixed then send me your address and I will send you one of the old style that is one piece. I have several of them that I don't need as I used to modify AME .049 for CL Combat and then sent the engines without the muffler.

Thanks andrew. When i checked the spring i found out that it wasnt sitting where it was suposed to sit. Now i ran the engine and its not coming out anymore.

thanks again