Posts: 352
Joined: 6/7/2004 From: KATY,
TX, USA Status: offline
I know seizures and melted pistons happen in gas engines of cars and motorcycles when they overheat bad enough. I know the amount of heat is different between a big internal combustion engine and these small glow engines.
So, for my learning experience, what is the kind of permanent damage that we can expect in these little engines?
Posts: 13468
Joined: 3/20/2002 From: San Bernardino County,
CA, USA Status: offline
....how about fried to a crisp....K&B .61
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An engineer says.... "That won''t work". A mechanic says..."Oh yeah, watch this". "Old Age, and Treachery will overcome youth and skill". Revver Bro #4.
Glow fuel engine temps are cooler than gasoline, so I don't think you could ever get one to the point where something melts or burns as a result of detonation, the only exception might be a competition type engine. I think the easiest way to burn up a typical glow engine is to run a brand new ring lean and cause it to seize. This may not even happen with a OS engine as they are designed to break in very quickly. A STigre would surely seize from abuse.
Posts: 3471
Joined: 3/31/2003 From: Tokoroa, NEW ZEALAND Status: online
If you get lubrication film failure then you'll get piston-scuffing and if it just runs *very* hot there's a chance you'll get detonation, with resulting damage to the piston-crown and head (due to erosion of the metal).
Posts: 1171
Joined: 5/10/2007 From: coralville,
IA, USA Status: offline
Dave Dave Dave. How could you do such a thing to a beautiful Baffle ported engine? I had a little trouble with a K&B .28 reccently that could not easily be explained. Maybe metal shavings in the crankcase? Brand new in the box.
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Castor, its like Vitamin C for glow engines. I am not Dom from Airwolf but I do resemble him.......Unfortunately
Posts: 465
Joined: 9/24/2004 From: Annapolis,
MD, USA Status: offline
I had a Magnum Pro .45 that I ummm, ran a bit lean and it seized in flight, bent the rod and banged up the liner so bad it wouldn't come out of the case... Of course that was almost 20 years ago before I leaned how to properly tune a glow engine. No pictures though...
How about it, any more "when bad things happen to good engines" pictures?
Posts: 5198
Joined: 7/21/2005 From: Greensboro,
NC, USA Status: offline
I bought a used Webra Silverline .40 that had been run lean too many times. The piston, wrist pin and top of the rod were jet black with carbon. The damage was in the form of egged bushings in both the piston and the rod. I started a thread on this a while back and the consensus was that, 1) it was run lean and overheated, 2) revved too high and, 3) run without enough lubrication. Detonation might also have played a part.
Posts: 1171
Joined: 5/10/2007 From: coralville,
IA, USA Status: offline
The junk on the bore is pitting. Apparently it is a common problem with K&B Sportsters, the new replacement cylinder was the same way. Porus castings, maybe it saves weight?
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Castor, its like Vitamin C for glow engines. I am not Dom from Airwolf but I do resemble him.......Unfortunately
Posts: 6220
Joined: 12/8/2002 From: Valdese,
NC, USA Status: online
Just guessing here but I bet there is some sand/harder debris caught in those voids that are causing your problems. Can you tell if there is any material folded over those spots? If so that would also be a source of material apperaring inside when they come loose. You might consider chasing the bore with a dingleberry hone and do it with alternating directions. VERRRRy lightly though so you don't loosen the bore size though. Otherwise you could use a scribe to poke around in them to loosen any junk.
Here is a novel idea...drop a few extra bucks and buy a better engine to start with. LOL
Posts: 7736
Joined: 1/21/2002 From: Acworth,
GA, USA Status: offline
quote:
The junk on the bore is pitting. Apparently it is a common problem with K&B Sportsters, the new replacement cylinder was the same way. Porus castings, maybe it saves weight?
Probably for oil retention? The bore is the aluminum surface and the piston is the chrome surface, the oposite of most engines.
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Permanent damage in overheated engines - 
RE: Permanent damage in overheated engines - 
RE: Permanent damage in overheated engines - 
Piston and liner look good.
