cooling system question sx250 (ox66)

[ttles714]

2001 SX250.... Can someone explain the cooling system water flow , The path through the engine ???? t-stats open ... T-stats closed ??? Water pickup in lover unit and using garden hose flush down fitting on port side of engine ?? thanks

[cpostis]

I just finished a tear down of my 2001 SX150TXRZ because of my first overheat problem. Although I religiously flushed the motor through the fresh water flush hose, I found my heads cooling passages blocked with deposits and many deposits within the block and exhaust guide (the component between the block and lower casing). I also noticed there are many orifices that appear to allow the heads and block to drain. The two passages on my motor within my exhaust guide were completely blocked, not allowing my block and heads to drain properly.

Here is a diagram I found that says it is of a Yamaha outboard. I don't know which model/year. Maybe Rodbolt or Boscoe can clarify for your SX250 and/or provide a better cooling passage diagram?

In my opinion the fresh water flush hose method is useless. The 1/4 " or less ID of the hose, and the even less ID of the inlet fitting on the exhaust guide can not have enough flow to flush sufficiently(I believe flow is more important than pressure to flush the cooling passages).

Since my teardown I now and always will flush my motor in a tank (See the attached link). This video of my flush method was taken just after my teardown with the motor running on 50:1 fuel/oil plus the oil injection hooked up (rich oil/fuel mix) thus the extra exhaust smoke. I allow enough time for the engine to warm and the t-stats open. I then let run at least 5 minutes longer.

Are you having problems with your motor and/or just want to know to prevent problems in the future? https://www.facebook.com/chuck.posti...4531213370606/

[ttles714]

overheat

I had an issue with the port engine, but I think i sucked up some weed. I pulled the stats, cleaned and re- installed ... pumped some vinegar thru the top of the cylinder head and thru the cowl flush port. Then flush with fresh water through both as mentioned .. Seems to be ok ??