Thread: Certainly not what I expected.

Tweet

Today I dropped the pan and pulled number 7 piston out..........more confused than before.............everything looks normal. No holes, no broken piston lands, no cracked rings, etc........looks just like a piston should except the top is very carboned up from my overly rich condition.

The rings look good and have nice tension to them. I removed the two top rings and checked the end gap by putting them down in the hole, it was right at 20 thousandths, well within specs. So I started looking at the combustion chamber and valves in that cylinder. I removed both the exhaust and intake valves and they are definitely carboned up, but I don't know if that would be enough to drop the compression to zero. It might make it low, but to lose all the compression seems a stretch.

I cleaned up the heads of both valves on the wire wheel and then used a rotary wheel to clean up the chamber and valve seats, and reinstalled those 2 valves. The only thing I see left to do is put new rings on that piston and button it back up with new gaskets. For sure I have to cure my too high fuel pressure and am ordering a pressure regulator this week.

To get the engine decarbonized once I have the fuel pressure in line, I am going to run a heavy dose of a product we sell at work. It is made by Yamaha Marine for their 4 stroke engines and is called "Ring Free." As the name implies it is designed to remove carbon and glazing from cylinder walls. Our techs swear by it and run a shock treatment dose on engines we are having trouble with sometimes. Even the Honda and Suzuki reps say "I'm not supposed to say this, but put some Ring Free in our motors that are gummed up too." It is that good of a product.

Finally, one indicator that this thing is just dumping gas down the cylinders is the condition of the oil pan when I pulled it. The entire bottom was sludge, and I use Rotella T oil and change it often. I have got to get that fuel pressure problem under control. Here are some pictures of what I found today.

Anyone have any suggestions of a better way to decarbonize the entire engine?

Don