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No cooling water at telltale and running hot.

Posted: Sat May 13, 2017 8:21 am
by danhaun
Hi all,

Suddenly no water at telltale and head is very hot to touch compared to working engine. Hose and telltale port are clear. I feel exhaust puffs from telltale port but not a drop. Water pump is intact but I put in a new kit anyway (it was 3 years old). Still no joy.

I am off the dock and don't have compressed air etc.

I thought blown head gasket, etc. but engine starts and idles normally and oil is not milky and at the correct level.

Any thoughts are appreciated.

Dan Haun
TomKat

Re: No cooling water at telltale and running hot.

Posted: Sat May 13, 2017 5:39 pm
by amytom
Maybe clogged cooling lines or failed thermostat. Either way open up the thermostat housing and look at it. How often do you rinse the engine?

Re: No cooling water at telltale and running hot.

Posted: Sun May 14, 2017 4:59 pm
by danhaun
Hi,

I rarely get to flush and I am the second owner so I don't know the history. I pulled the thermostat and it looks normal to me. I did find a yamaha shop on the harbor who will assess tomorrow. Most troubling to me is the exhaust pulse via the telltale and the sudden nature of onset (working one day and not the next). ... seems more acute than chronic.

Thanks for the reply.

Dan

Re: No cooling water at telltale and running hot.

Posted: Sun May 14, 2017 5:17 pm
by duetto
this may or may not apply here.

it's been a while since i looked at a yamaha water pump so i'm not sure this applies. when you checked the water pump did you check to see if the impeller hub had spun free of the rubber vanes?

another longshot. a friend has a mercury which just stopped pumping water and overheated. we assumed the impeller and dropped the unit but the impeller was intact. checked everything and couldn't find the problem. local dealer pulled the head and found an o-ring which slides onto water pickup tube had slid up the tube and collapsed blocking the water passage.

Re: No cooling water at telltale and running hot.

Posted: Sun May 14, 2017 6:42 pm
by Marc Gershel
Forgive me if this sounds demeaning, but did you try running the engine without the thermostat? I've missed that in the past and it cost me a lot of lost time.
Marc

Re: No cooling water at telltale and running hot.

Posted: Sun May 14, 2017 9:30 pm
by danhaun
Hi all,

Thanks for the good suggestions.

Regarding the spinning hub: This is such a good suggestion but yes, I checked the impeller for hub spinning as that happened to me in past (like in 1975 on an Evinrude). Yesterday, I put a new water pump kit in anyway since the old one was three years in service. I don't think the seal on on pickup the is the problem because the issue started before I pulled down the lower unit.

As to running without the thermostat, I believe that the thermostat would be downstream from my problem. From what I read, the telltale should show water even when the thermostat is defective. So the motor should pee in either condition -- thermostat open or thermostat closed. I think this is how it works because when cold, the motor will pee and when warm, it still pees. Please someone correct me if I am wrong about this.

BTW, I don't find any suggestion demeaning it really helps to have the brains working together to reach a better understanding of a problem. I really do appreciate your help.

Thanks,

Dan

Re: No cooling water at telltale and running hot.

Posted: Mon May 15, 2017 4:02 pm
by danhaun
Fixed.

Water pump housing was worn allowing SS insert to rotate out of position and leaking from drive shaft exit.

Replaced housing and all is good now.

Thanks to all the commenters.

Dan