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Old 07-15-2013, 11:56 PM
GlynnC GlynnC is offline
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Shindaiwa T282 with Low Compression & Heavy Carbon in Exhaust Port

Have a Shindaiwa 282 with low compression--70 lbs. Spark plug shows signs of running lean. The exhaust port was almost plugged with carbon. The guy runs Shindaiwa oil and 87 octane with 10% ethanol. Is it possible the plugged exhaust port caused excess heating to cause the low compression? I have not removed cylinder and piston, but see no cylinder or ring scoring thru exhaust port.

I've cleaned many exhaust ports with no long term effect on engine. I'm puzzeled why this engine went down. This guys runs a lot of older Shindaiwas, and this is the first engine, (one of his newest, but out of warranty), he's lost due to low compression.
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Old 07-16-2013, 10:52 AM
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BigFish BigFish is offline
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The rings are prolly stuck = low compression. You should be able to push in on 'em with a small screwdriver,etc. and feel a bit of "spring" or give. ( thru the exh. port)
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Old 07-16-2013, 03:09 PM
GlynnC GlynnC is offline
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Originally Posted by BigFish View Post
The rings are prolly stuck = low compression. You should be able to push in on 'em with a small screwdriver,etc. and feel a bit of "spring" or give. ( thru the exh. port)
Should have included this info--was told by the owner that the guy running the trimmer said it was running fine, started vibrating real bad (see below), started losing power, died, then would not restart. Would rings stick while the engine is running? Also has a strange sound --like maybe something is loose inside. Remember the sparkplug showed that it had been running lean--probably building heat--would this cause the rings to stick while it is running?

Bad vibration was almost guaranteed to be the fact that only one line was sticking out the string head--didn't trouble shoot this since the engine wouldn't run.
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Old 07-16-2013, 05:13 PM
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BigFish BigFish is offline
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Here's a thought...........
Tear the dang thing apart and fix it !
That's what the guy's payin' ya for, right?
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Old 07-16-2013, 10:46 PM
GlynnC GlynnC is offline
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Originally Posted by BigFish View Post
Here's a thought...........
Tear the dang thing apart and fix it !
That's what the guy's payin' ya for, right?
He's also paying me to be smart about what I fix for him. As I said, he runs older Shindaiwas, for the most part, if his trimmers have major problems, they become parts suppliers. Yes, I could fix it--if the cylinder and piston are gone, it could cost him the better part of $250 to repair it, and if it's running lean that caused the problem in the 1st place, it could either happen again, or I could put on a new carb--another $50 or $60. Is older trimmer worth that much repair--no. My question was not how to repair the immediate problem, it was "could the almost plugged exhaust port cause an engine overheating problem?" Only if someone has experienced this problem before, can they really provide the answer!!!!!!!!!!
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Old 07-16-2013, 11:13 PM
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dutch1 dutch1 is online now
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As Fish has indicated, you can't tell a whole heck of a lot just looking at externals and peeking through the exhaust port. I have seen numerous occasions that things looked decent through the exhaust port only to find piston/jug scoring in the vicinity of the exhaust port which can't be seen without disassembly. For what it's worth, my opinion is that if the unit can't be repaired for less than 40% of new, it is not a cost effective effort.
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Old 07-16-2013, 11:25 PM
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Breezmister Breezmister is offline
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Quote:
Originally Posted by GlynnC View Post
"could the almost plugged exhaust port cause an engine overheating problem?" Only if someone has experienced this problem before, can they really provide the answer!!!!!!!!!!
In my experience, no. It would cause back pressure that would cause the unit to bog down at full speed.

A guess on my part with out seeing the unit, would be that your lean fuel problem is from a greater the 50 to 1 mix.

That alone would cause excessive wear on the piston, rings and cylinder, without seizing it up.

I think you have a parts machine there...........
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Old 07-16-2013, 11:52 PM
GlynnC GlynnC is offline
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[QUOTE=Breezmister;4817602]In my experience, no. It would cause back pressure that would cause the unit to bog down at full speed.

This has also been my experience of all the carbon build up--clear the port and it runs great.


A guess on my part with out seeing the unit, would be that your lean fuel problem is from a greater the 50 to 1 mix.

Always a possibility--none of the other equipment seemed to have a problem with that batch of mix. He does run at 50:1 with Shindaiwa oil (at least that's norm for him).

That alone would cause excessive wear on the piston, rings and cylinder, without seizing it up.

I think you have a parts machine there...........[/QUOTE]

My thoughts--especially with the unusual sound--it's not just worn rings, will probably tear it down for learning purposes--but not to repair!

Thanks for your input.
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Old 07-17-2013, 02:37 PM
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BigFish BigFish is offline
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Quote:
Originally Posted by dutch1 View Post
As Fish has indicated, you can't tell a whole heck of a lot just looking at externals and peeking through the exhaust port.
Actually Dutch, that's not what I indicated at all!
The very first thing I do when working on a hand held is to pull the muffler and plug and inspect the condition of the piston/rings and cylinder.

If this guys Shindaiwa was truly running lean, then the piston could have a caved in or cracked dome, which would be visible thru the exh. port or plug hole.
Generally speaking, Shindaiwa's are usually worth fixin'.


But to be on the safe side, we should ask lawnBOY Dan. I hear he's a Shindaiwa expert!!
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Old 07-17-2013, 04:46 PM
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dutch1 dutch1 is online now
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Fish, a valid comment of the piston dome but I've only seen a cracked/caved piston dome on one Shindiawa in the last 20 years. I was basically referring to the carbon blocked exhaust port. A high percentage of time that I've encountered a blocked port and lack of compression it has been scoring on the piston and jug above and below the port or carbon locked rings.

I would agree with you that Shindiawa's for the most part are worth repairing.
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