I bought a BCMA SPE 40about 8 months ago. I have had a constant problem with the muffler bolts loosening up. I tried blue and red locktite. I called Adam and he suggested drilling holes in the bolts and using a wire, they still loosen up. Adam said he maybe the hub is out of balance and he would send me another one...never arrived. I called him back a couple months later and he said maybe i have a vibration problem and he would send me a special vibration reducing mount....never arrived. I thought it was a good engine, now i'm not so sure. I know if i keep tightening the bolts that eventually (soon) they will strip out of the head. Then what?? Has anyone else had this problem?? This engine has only been run about a dozen times.

Single cylinder gassers are a little prone to vibration issues, which is one of the reason so many go to such great lengths in prop balancing. I'm sure that you already balance the blades of a prop but do you also balance the hub? That's often a source of troubling vibration. If not, there's a pretty good video on prop balancing located at down on the deck. As for experience with your type of engine, no I do not have any.

I am relatively new to gassers but i did have a MUCH more experienced club member balance my prop. This guy owns a few 30%+ planes one of which was a 36% (i think) Katana that was wrecked last year due to unknown reasons. He is the best in our club. I'm sure that prop balance is not the problem. Its not the spinner either because i dont have one on this plane ( its a GBY with just a nut).

If the muffler has a gasket, leave it out...Check to see that the cylinder surface and the muffler surface are both flat..Get some Permatex Ultra Copper silicone sealer from an auto supply...Clean the threads on the bolts and in the cylinder...Put a thin layer of the Ultra Copper on the muffler and some Green Loctite 609 or 680 on the threads..Tighten securely...
The Loctite takes 400 degrees F to loosen, if your cylinder is getting hotter than that something else is wrong....The Ultra Copper is good to more than than 400, so it won't leak...
The muffler on a G38 is thin steel and is in two parts...Ultra Copper on the joint has not melted out or leaked yet...Same for the joint at the cylinder and muffler....No gasket...

Thank you for your response Ralph. I'm not too familiar with small gas engines, but i have been an auto mechanic for 24 years. I think that although head temp should not get that hot, exhaust gets alot hotter. Anyway the biggest part of my complaint is that BCMA has not followed through. I own alot of other engines that the muffler bolts dont loosen up in 5 minutes of running. Most never loosen up. I am worried that if i keep "trying this and trying that" when the bolts finally strip out I will have a useless motor (I can put thread inserts in but where does the warranty end?)

P.S. Is your wife on the phone?? I have been trying to call you for about 2 hours!!

Naw, Ralph's prolly into one of those 3.99/minute phone conversations...[sm=omg_smile.gif]

Check your PM, this computer is on the shop line...
AT&T, $20 is all it can cost, 24/7
I checked a few engines the other day, right at the exhaust port on the cylinder, none was over 400...

One of the problems with aluminum is that it expands far more than steel when heated. This commonly causes "loose bolts" and "loose muffler" problems with small engines.

The trick is to (re) tighten the bolts while the engine is still hot. This takes up the slack caused by the aluminum's expansion and stops them from coming loose next time the engine is hot.

Hey Pat, how do YOU know about those $3.99 phone numbers ?

No, he's on the internet and he's too cheap to pay for a DSL or cable line so his modem ties up his phone line while he's here on RCU harrassing everyone.

He's real good at harrassing the moderators. But he seams to concentrate on one guy in particular.

Anything other than this 26.4 dial up would be great. Only option is DirecWay, I AM too cheap for that.....I CAN talk and harass at the same time, there are two phone lines...
And be nice or your engine will be delayed even longer, it's almost finished...[>:]

drbenz

My G38 does the same thing. Because of the rear mounted B&B muffler, it's not easy to retighten the bolts on the plane while the engine is still hot. I have wired the bolts, and it seems to work (took me a couple of attempts to get it right). I don't think it is so much a vibration problem as a metalurgical one (aluminum vs steel expansion). To be sure, vibration is there. Even with the wires,and the bolts fully tightened down, after running, I can detect a very small amount of movement on the muffler. However, it doesn't get any worse with additional running. Next time, I will try some green locktite and see how that works.

Hey drbenz,

I own one of Adam's BCMA SPE 40's as well, and follow the BCMAEngines thread here on RCU fairly closely. First of all, let me tell you that in my experience (with a great many more than a dozen or so flights) my engine's muffler bolts have never loosened....nor is it a problem I've seen reported before. So, I'd certainly be inclined to suggest that you look for the problem, not just try to resolve the symptom.

Next...and of, in my opinion, more importance, regarding your experiences with Adam. That report surprises me a whole lot more than loose muffler bolts do, to be honest. I've never had anything less than exceptional service from Adam, and that is the reputation he maintains with ANYONE else I've ever spoken to who's done business with him.

I'm certainly not trying to suggest that you're misrepresenting the issue...I would, however, suggest that you have almost certainly been the victim of some unfortuneate situations and, honestly, coincidences. I certainly can't know what might have led to the current condition, but I can say with near certainty that Adam simply doesn't realize how things have combined to give you this experience...if he did, I'm as certain as I can be that A) He wouldn't have let these things happen and B) he would have gone out of his way to resolve the issue.

I'm going to ask this not because I owe Adam anything...nor do I work for BCMA in any way...but simply because I believe it's an outstanding company that offers a good product at a good price, and the hobby needs more of those. I'd ask that you e-mail Adam, and explain (as calmly and politely as you've done here) that you are, to this point, dissatisfied with the service you've received, and the reasons why...and then give him a fair and appropriate standard by which you feel he can resolve the isue and restore your faith in his service.

I'd lay pretty good odds he'll take care of you.

I will add: make sure the threads and bolt holes are clean in the 1st place and follow Ralphs advice, never had one come loose other than one I inherited where the owner had put the silicone on the threads as well!