Search found 1 match
- Sun Dec 16, 2007 12:35 pm
- Forum: Outboard Engines
- Topic: water circulation 9.9 block
- Replies: 15
- Views: 22718
I also had blocked cooling passages through the head on my 1998 Yamaha 9.9's. To remove the blockage, I removed the valve cover, and drilled out the cooling passage plugs (in my case they were both tightly seated), using first a small drillbit directly in the center of the plug, and then a 1/4 in. b...