Posted by paulinkansas on May 15, 2012 at 08:54:54 from (108.220.171.60):
This is an Onan NHC 23 horse, 2 cylinder engine. A while back I posted my problem with the loss of power on here. One symptom was that blue flames come out from one of the mufflers.
I removed the exhaust valve from that problem cylinder, and the valve seat fell out. There was a gap about the size of a toothpick between the outside of the valve seat and the hole where it"s supposed to sit.
Before taking the engine apart, I ordered a new seat, valve, springs, and head gasket. The new seat is smaller in diameter than the old seat that was in the engine.
I"ve found an aftermarket supplier of valve seats. You can choose the seat you need by o.d. i.d. height and seat angle.
For simplicity sake, let"s say the diameter of the hole in the block where the seat goes in is 2.000" The supplier I found doesn"t have 2.000" seats, but they have 1.996" and 2.004".
Which one should I buy? They are only 6 bucks each, but they have a minimum purchase amount of $25. I haven"t taken the other cylinder head off, but I"ll do that next and see what the other exhaust valve seat is like.
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Today's Featured Article - Tuning-Up Your Tractor: Plugs & Compression Testing - by Curtis Von Fange. The engine seems to run rough. In the exhaust you can hear an occasion 'poofing' sound like somethings not firing on all cylinders. Under loaded conditions the tractor seems to lack power and it belches black smoke out of the exhaust. For some reason it just doesn't want to start up without cranking and cranking the starter. All these conditions can be signals that your unit is in need of a tune up. Ok, so what is involved in a tune up? You say, swap plugs and file the points....now tha
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