Merc 9.9 cooling woes

[briguy1960]

Recently acquired merc 9.9 two stroke sn# OG288440 Which I believe makes it a 1995 or so.

When given to me i was told it does not cool. I dropped the lower unit and looked at the impeller--it looks fine ie no missing blades but maybe a bit worn? I was quoted 114 dollars which seem like a lot. Also I can't help but notice that the interconnect between the impeller discharge seems kind of under engineered. ie it just butts up to the rubber thingy at the bottom of the pickup tube---seems a bit goofy to me. The motor has a thermostat which seem fine although I also tried running the motor with the thermostat removed. Very little water comes out of the telltale and the water that does come out seems very hot. When I tried it withe the the thermo in it came out too hot to stick my hand under and at idle the telltale all but disappears.

I removed the telltale from its exit out the engine and tried blowing compressed air through it and only a few bubbles came out of the barrel immersed leg. It really seem like either the impeller is not pumping much or a lot of the water it pumps out it leaking out where the the pickup tube joins the impeller (alot of water seems to be coming out about halfway up the leg) or the cooling passages are plugged up.

Any troubleshooting advice would be appreciated

Brian

 

[Indian Ground]

Re: Merc 9.9 cooling woes

$114 dolars for what? If you have the lower unit off already just put a new impeller in, maybe even a new impeller housing. It should not be too much at all. It seems under engineered because it's an overly simple system (but also very important). Sounds like the impeller just needs replaced.

 

[briguy1960]

Re: Merc 9.9 cooling woes

$114 dolars for what? If you have the lower unit off already just put a new impeller in, maybe even a new impeller housing. It should not be too much at all. It seems under engineered because it's an overly simple system (but also very important). Sounds like the impeller just needs replaced.

$114 is what they quoted me for an impeller. Maybe its a kit with the housing---I don't know. Maybe it even comes with a new pickup tube reciever(aka) the thingy at the end of the pickup tube. Again that method of joining the pickup tube with the impeller output seem very mickey mouse to me, there is not even a tab to align the two components--maybe my engine is missing a piece?

TIA

Brian

 

[bgbass.1]

Re: Merc 9.9 cooling woes

114.00 are they out of there minds i wish i could get that much i would do them all day long for that price and not need to do anything else. the water oulet tube just hangs there replace the hole unit. make sure when you slide water tube in you dont push o ring down. also blow air or water up tube to make sure its not pluged

 

[briguy1960]

Re: Merc 9.9 cooling woes

114.00 are they out of there minds

the water oulet tube just hangs there replace the hole unit. make sure when you slide water tube in you dont push o ring down. also blow air or water up tube to make sure its not pluged

Well I found another shop that had the impeller for 28 dollars. Much more reasonable!

I'm not quite sure I get what you mean about not pushing the O ring down.

I do think that something may be partially plugged. Even with the new impeller there is not a good healthy stream at low idle. I tried it without the thermostat and it is not really any better. I seem like the pump is pushing lots of water I even have water coming out at mid leg where the shift rod exits the lower leg.

I'm pretty sure I got the rubber thing at the bottom of the pickup tube aligned properly. If the water passages are restricted is there some chemical I can use to clean out the passage ways. I'm pretty sure there are no foreign bodies in there as the screen was in place and the impeller had no missing bits.

It it normal for the discharge water to be about 100 degrees F?

Thanks for all the help

B

 

[bgbass.1]

Re: Merc 9.9 cooling woes

take a air hose and push a little air down tell tale hose it may work if not take apart and go from bottom up

 

[bgbass.1]

Re: Merc 9.9 cooling woes

where the pickup tube goes into pump there is a o ring it should be flush on top if it gets pushed down it will restrict water flow