ST G90 went down hard.
04-25-2002, 06:33 PM
#1
Senior Member
Thread Starter
Join Date: Mar 2002
Location: New Mexico
Posts: 139
Likes: 0
Received 0 Likes
on
0 Posts
ST G90 went down hard.
*Here is a story for the "Sole US Distributor." This is/was my WM P-51. Nice plane with retracts and a G90 up front. I have had some problems with the engine which I usually attribute to the carb.
*I had enough of it and ordered a Perry replacement.
I took it up for another spin. Went a few laps an it quit again.
I took the engine apart to clean it up and found something interesting. The "head has four holes for the mounting screws to go through and thread into the cylinder wall.
*I turned the head over to clean it. This angle has me looking at the bottom of the glow plug to give you an idea here. I am wiping away and there it was, 3 of the holes were perfect and round and drilled right through the metal. the fourth hole was drilled to close to the inside and was exposed on the side, thus providing a nice airleak with a lack of compression followed by overheating.
To all of those who made this crash moment possible, we appreciate it!
*I had enough of it and ordered a Perry replacement.
I took it up for another spin. Went a few laps an it quit again.
I took the engine apart to clean it up and found something interesting. The "head has four holes for the mounting screws to go through and thread into the cylinder wall.
*I turned the head over to clean it. This angle has me looking at the bottom of the glow plug to give you an idea here. I am wiping away and there it was, 3 of the holes were perfect and round and drilled right through the metal. the fourth hole was drilled to close to the inside and was exposed on the side, thus providing a nice airleak with a lack of compression followed by overheating.
To all of those who made this crash moment possible, we appreciate it!
04-25-2002, 10:01 PM
#2
Senior Member
My Feedback: (40)
Join Date: Dec 2001
Location: Merrimack,
NH
Posts: 1,597
Likes: 0
Received 0 Likes
on
0 Posts
ST G90 went down hard.
Tailbacker, your story is worthy of everyone's sympathy. The moral is, do not trust any engine manufacturer to be perfect. Disassemble your new engine before you ever mount it, clean out the stray chips, check for burred machine cuts, finger the bearings, give it a thorough look-over, refresh the oil. It's amazing what the curious and critical eye will find. Think of it as a pre-flight physical.
04-30-2002, 05:55 PM
#3
Senior Member
My Feedback: (2)
Join Date: Jan 2002
Location: Tuscola,
IL
Posts: 2,636
Likes: 0
Received 0 Likes
on
0 Posts
ST G90 went down hard.
Tailbacker, Sorry to hear of your problems with your ST90. We will be happy, as always, to stand behind our products and service your engine for you.
Please visit http://www.hobbyservices.com/ for a service worksheet and information to ease the process of sending your items for service.
Please visit http://www.hobbyservices.com/ for a service worksheet and information to ease the process of sending your items for service.
04-30-2002, 06:04 PM
#4
Senior Member
My Feedback: (2)
Join Date: Jan 2002
Location: Tuscola,
IL
Posts: 2,636
Likes: 0
Received 0 Likes
on
0 Posts
ST G90 went down hard.
The four screw holes in the cylinder head do cut through adjacent to the cylinder head gasket, but they do not cause air leaks. If the holes actually penetrated into the cylinder, you'd have a problem, but they don't. If you look closely, you'll see that the cylinder head gasket is intact, along with the rim on the top of the cyliner liner. That's where the seal is made. We've never seen problems because the head screw holes sometimes cut into the channel in the cyliner head where the top of the liner rides.
If the cylinder head gasket had a leak, it would not be leaking air in, but combustion products out, and you'd see a burn mark on the gasket where the gases are leaking.
Usually, if an engine will run for a while in the air and then quits, it's usually going lean somehow. Air leaks, fuel foaming, and so on. The engine quits because it's overheating.
Other things to check are engine cooling airflow and the fuel. Many models may not allow proper cooling of the engine. The cowl may have large intakes and exhaust areas, but if the air doesn't actually flow through the cylinder fins, you get no cooling.
Water-contaminated fuel will cause the engine to overheat, which produces symptoms similar to going lean.
Sincerely,
Mrs. AnnMarie Cross
Senior Manager, Proprietary Services and Support
Great Planes Model Distributors
[email protected]
www.greatplanes.com
www.bestrc.com
NO AUTORESPONDER
If the cylinder head gasket had a leak, it would not be leaking air in, but combustion products out, and you'd see a burn mark on the gasket where the gases are leaking.
Usually, if an engine will run for a while in the air and then quits, it's usually going lean somehow. Air leaks, fuel foaming, and so on. The engine quits because it's overheating.
Other things to check are engine cooling airflow and the fuel. Many models may not allow proper cooling of the engine. The cowl may have large intakes and exhaust areas, but if the air doesn't actually flow through the cylinder fins, you get no cooling.
Water-contaminated fuel will cause the engine to overheat, which produces symptoms similar to going lean.
Sincerely,
Mrs. AnnMarie Cross
Senior Manager, Proprietary Services and Support
Great Planes Model Distributors
[email protected]
www.greatplanes.com
www.bestrc.com
NO AUTORESPONDER
