2008 9.9 4 Stroke Nissan--Thermostat

[unlivks]

Hi,

Can anyone tell me if the thermostat fails , (1) a cause for no water showing in the pee hole, and/or (2) can cause engine overheating? Can the thermostat be intermittently faulty?

My engine is running fine now but coming off my last saltwater trip, I noticed that when flushing the engine, there was no water coming out of the pee hole and the engine got real hot to the touch after about 1-2 mins idling. I flush the engine after each trip as soon as I get home and never had this problem before. I pulled off the pee hose and it was clear as well as the small plastic nipple. Found that only hot air puffs were coming out of the engine metal nipple. Was ready to take it to my dealer the next day and tried to start it one more time with the flushing ear muffs--powerful water stream thru the pee hole at start idle speed!! My eye was trained on the outlet from the instant the engine started and the water stream was instant, clear with no debris ejected. Hope this rambling lets you know why I am asking the questions.
Thanks, Don

 

[pvanv]

Re: 2008 9.9 4 Stroke Nissan--Thermostat

The thermostat will not affect the pee tube. Apparently you weren't pumping before. BTW, the thermostats usually fail open, resulting in prolonged warm-up.

 

[unlivks]

Re: 2008 9.9 4 Stroke Nissan--Thermostat

Thanks for the reply. I think you mean the pump was not "pumping" water, but I know it was pumping warm/hot air. If the thermostat did fail closed, I guess you are saying that this would not affect the pea tube stream nor would it cause overheating. Any clarification?
Thanks, Don

 

[pvanv]

Re: 2008 9.9 4 Stroke Nissan--Thermostat

Don,

The water pump pressurizes the incoming water gallery in the base of the motor. That's where the pee tube connects, so it indicates a pressurized system (only). From the base, the water enters the cooling jacket of the motor. After circulating through the motor, the water is discharged into the exhaust stream, finally exiting, with the exhaust, in the hub of the prop.

If your pump is not delivering water, the exhaust will back up into the cooling system, exiting through the pee tube. That's your warm air stream at the pee tube.

So... the pee tube should flow water whenever the motor is running, regardless of the thermostat being open or closed.

A thermostat could fail shut, though that's not the norm. A stat could also be clogged with salt. But if the pump is working, you would still have water pressure, and if the pee tube is not clogged, it should flow, even if the stat were jammed shut, and the motor were running hot.

Since you had no water at the pee tube, but rather exhaust, that's proof that the pump was not delivering water to the base of the engine. And then the motor is guaranteed to overheat, of course.

If you are having intermittent pump delivery, check the water pump. You may well find a vane has broken off of the impeller. That chunk of rubber could jam in the water system, blocking water flow to the motor. If the rubber chunk is loose if the system, it could cause an intermittent blockage of water from the pump to the motor. I have seen this problem a year after someone changed the impeller. They missed the broken off piece, which stayed floating around in the system, even though the new impeller was pumping fine.

Regardless, no water, but rather air (exhaust) coming from the pee tube means that no water is going to the base of the motor.