SailNet Community banner
  • SailNet is a forum community dedicated to Sailing enthusiasts. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more!

1999 Yamaha 9.9 hp outboard. Cooling water issue.

13K views 4 replies 4 participants last post by  AdrenalineJunkie 
#1 ·
Well its May 2016 and I broke out my sailboat for the season. It has a Yamaha 9.9 outboard. I'm not sure exactly of the model year but between 1997-1999. As I do with with my boats every year i check the engine after winter storage. This year i have no cooling water coming out of the pee hole. I checked for clog in the exiting tubing and found it clear. I hauled the boat off to the marina for repair. After getting home I did some research and discovered there is a thermostat. Now I wonder if i prematurely took the boat to the marina without doing my diligent troubleshooting. Did I do the right thing going to the marina or can it be something as simple as a thermostat? Would this be something the marina would check or will they just jump in and remove the lower unit?
Thanks,
Chuck
chdawebb2003@gmail.com
 
#2 ·
Your water indicator stream is merely a small hose with a plastic nozzle that bleeds some water from the water jacket to indicate that the cooling system has water under pressure from the water pump. 99% of the time no water from the "pee" hole is only caused by debris blocking the nozzle. Straighten out a paper clip and stick it into the nozzle hole while the engine is running and the blockage will be squirted out. You may need to do this two or three times to completely clear the hose. This motor's cooling system in your case is unaffected by any blockage in the nozzle. If you have any reason to worry that your motor is really overheating then you will need to take off the motor cover and either feel the top of the block (and don't get your fingers caught in the timing belt) or confirm the block temperature with an infra red digital thermometer.
 
#3 ·
I had the exit tubing cleared and the exit port. No debris found obstructing. If there is a clog it's internal where i can't get at it. I wish i had used compressed air with back pressure prior to taking it to the marina. Guess it's too late now. Thanks though.
 
#5 ·
I think "99% of the time it is a blockage" is a bit of an exaggeration. The best way to unclog the telltale is to get a piece of 150 to 300# monofilament which is stiff enough to unblock the hose but not stiff enough to damage anything. The telltale should ALWAYS be producing a stream, regardless of the thermostat, otherwise you would not know if your impeller is pumping water.

Watch a video on how to take off your lower unit and change the impeller. It is a $20 part and should be changed every year or two. That's a new one in the package and the old one on the drive shaft with no blades in the pictures. When they fail, your engine will overheat before you realize it and be ruined.

These photos are from a Yamaha 9.9 4 stroke I recently acquired. The owner had taken it to a dealer because it wouldn't start and got a $600 repair bill. It started twice OK, then the next time it started it wouldn't "pee." The (Yamaha certified) mechanic that charged $95 per hour didn't advise the owner that this particular version has an autochoke and didn't like to start cold, apparently didn't clean the carburetor very well because it started better after I recleaned it, didn't notice it was missing the anode, didn't grease the prop or recommend changing the gear oil and impeller. When I took off the lower unit, there were bits of impeller in the water intake outlet, the impeller blades were completely gone, one of the bolts holding on the cover for the impeller was completely seized and had to be removed with a torch etc etc etc.

Maintaining a small outboard is not rocket science. DO NOT delegate this critical maintenance to an expensive mechanic!
 

Attachments

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top