Recently installed a new water pump kit on my 2000 C70hp Yamaha. Put a new one on every couple of years. This go 'round, I take it out for a quick trip up the Wando, and while idling the overheat buzzer goes off. I give it a bit of throttle (what little I can while the computer is retarding rpms) to increase the water pressure and sure enough the buzzer stops. As long as I am not at idle all is good. Next I replace the thermostat, thinking possibly it was stuck. Nope, same problem. Removed the t-stat and ran it, still overheating. I think it is in fact overheating since the head is fairly hot to the touch. I can’t hold my hand on it longer than about 3 seconds. Pee stream is the same as it’s always been since the motor was new.
Is it possible this blasted water pump kit was defective (impeller mainly)? I dropped the lower unit again this morning, disassembled and reinstalled the pump, checked the gaskets and plate to be sure everything was correct. What gives?? If it’s not the pump, I can only assume that I’ll need to pull the head and clean the water passages, in case they are clogged. I just find it an odd coincidence that the overheating happened immediately after I put in the new water pump.
Any advice is welcome! Thanks.
P.S. I’ve heard stories about a bad Poppet Valve, but I don’t think the 70 hp has one.
I had a 70 Johnson and put the impeller on wrong,TWICE.
Stonoman
Stonoman-
Thanks for the reply. I took a hard look at the impeller when I pulled the pump apart. It will only slide on the Woodruff Key one way, but I’m wondering about the “vane” orientation inside the metal cup? Shouldn’t the vanes automatically position properly when power is applied?
I was told to grab the drive shaft and turn clockwise while pushing down on the impeller cup. Also that if you don’t start with them the right way they can shear off.
2000 SeaPro 180CC w/ Yammy 115 2 stroke
1966 13’ Boston Whaler w/ Merc 25 4 stroke “Flatty”
Thanks Optiker. I heard that also and did turn the shaft clockwise. What I might do, short of checking the thermoswitch, is just buy an actual Yamaha Water Pump kit and try it. The one I installed was special order (Sierra) from West Marine. Never had a problem with those in the past, though. I figure if it doesn’t solve the problem then at least I have another water pump kit for 2013!
Hope I don’t have to pull the head to clean the water jackets. Not major hours on this motor, and I always flush it, but guess it could still be clogged up.
i was leaking after installing water pump (not the entire kit). Then i went and bout brand new Yamaha OEM complete water pump kit and no problems since a month or two ago. prob put at least 30-60 hours on since.
Always get OEM Yamaha stuff if you can. It does make a difference according to my sources.
make sure you are greasing stuff properly too.
ft worry.
Thanks Cordray. That’s the kind of stuff I want to hear. Totally agree on OEM with alot of items. I might spring for a new pump housing too. If that doesn’t fix it then I’ll diagnose the temp sensor (not really feeling like that is it) and then to the water jackets.
Thank you to all who have responded.
I’ll update my results in case anyone else ever runs into this.
Picked up a Yamaha OEM water pump kit and also bought a pump housing from Seel’s here in MtP. I compared the parts during disassembly/assembly, and other than the gasket material being slightly different, that was about it. Put the Yammy goods on, cranked it up and noticed the pee stream was slightly stronger, AND, most importantly, the overheat alarm never came on. Maybe it was the housing, maybe the gaskets sealed better, I don’t know? Cordray, you get the consulting fee for pushing me over to buying an OEM kit.
P.S. Wish Seel’s didn’t charge extra on top of the retail price for this stuff, but guess that’s what you have to pay for convenience and stuff that works.
glad to help. i used to pay to have work done. until this motor, so i bought the shop manual and am acquiring tools as i need. I do have a new respect for marine mechanics and what they do. there are so many “tricks of the trade” . . .
ft worry.
Thanks for the update. Glad you got it going. I’ve always used the OEM so haven’t run in to a problem
2000 SeaPro 180CC w/ Yammy 115 2 stroke
1966 13’ Boston Whaler w/ Merc 25 4 stroke “Flatty”
I’m use to doing fairly heavy mechanical work on all my old greasy Jeeps, so I’m not too afraid to jump in…but I do know my limits and will probably have to visit this Chris V guy at some point. He sure doles out some good free advice!
and we dont charge more than yamaha retail pricing for our parts
www.teamcharlestonmarine.com
www.joinrfa.org
Nice to know, Chris! I’m in and out of the airport up that way every week, so I’ll just time the “Yamaha parts hoarding” at your shop to coincide with my flights.