Seized Up Motor (30HP)

[bryson99]

So my brother gave me his fishing boat over Thanksgiving weekend. It was prodominantly used in Illinois and was all freshwater fished. He bought it relatively new (early 2000's) and only used it for a few years. As soon as he bought this motor, he had the heads planed for extra horsepower. I drove the boat from Illinois to Florida and it is now in my possession.

We took it out a few times with no issues. Then we took it out again when the motor seized up after shutting off a few times. When we got the boat back to my house, we pulled the plugs and WD-40'd the motor. After a day or so, the motor unfroze by hand turning the pull start.

We took the boat out again the next weekend and it started up fine. After 5 hours of being on the water (mostly slow/trolling at the beginning and running 2/3-full throttle the last 2 hours) the motor seized up again.

We got it back home and pulled the plugs again and did the same thing. This time it is partially unseized. You can pull the motor and about 1/4 turn it will be free and then become harder/seized, then you can pull another 1/4 and it will do the same thing. It isnt fully seized, but becomes difficult to pull after each 1/4 turn.

No overheating happened (or atleast the alarm), it was pissing water fine and no smoke other than the normal grey smoke. It literally just shut off

In between the first and second seize, we originally thought it wasnt receiving oil from teh injector so we removed the oil injecion reserve and started mixing the oil and gas.


Any thoughts?

[keakar]

pull the heads and replace them with regular heads and examine the cylinders condition and see if its rusty or scored up, if it looks good just replace the heads with "normal" heads and you should be ok. check for salvage yard set of heads if new isnt in your budget.

you didnt say if it was 2 stroke or 4 stroke but if 2 stroke then run double the normal oil mix untill you run 3 or 4 tanks thru it, if its a 4 stroke then change oil and filter and check for any metal in the oil, if all looks ok then just run the normal 2 stroke mix of oil to help lube it up for the same 3 or 4 tanks of gas run thru it then go straight gas after that.

these engines arent designed to be "hopped" up and shaving the heads to increase horsepower so all that does is make them overheat and it does more damage then ANY possible increase in power you will get. the increased compression is likely overheating the engine causing the seizures and one time it will throw a rod thru the block on you.