Cooling system flush on Merc 9.9 4 strooke

[Kisinana]

I want to flush the salts from my cooling system and I think I probably need to replace my pump as I have replaced the impellor every year in the past 3 years and they do not seem worn. What do you use to remove salts from the system?
When I first clean the cooling system and replace the impellor it runs fine for the first couple of hours and then it slowly peeters away. I thought maybe there was something in the cooling system but I have backflushed with the leg off and and blown air through quite easily. If anyone has any suggestions they would be much appreciated.

 

[scott craven]

Try flushing with "Salt- away"in a barrel.
i've heard good things about the product.

 

[high tide]

Some thing a lot of home mechanics over look is also the thermostats ........ think about changing them out too, and Flush every time after salt use if you can, if using a garden hose be sure it CANNOT kink !
Where the water come out of the spitter some times also gets a build up of hardened salt, use a tooth pick or a wire if it appears to spit rather then flow, you might be surprised what comes out in your hand.
HT

 

[Kisinana]

Okay so here is a breakdown of the block. The 2 small parts numbered 24 go into the side of the block and connect to the pisser line 48. If I open these connection I can not get any flow back into them but I can get flow through pipes 44 and 49 which goes to the thermostat and down the leg to the pump. Question is should I be able have air flow back through these 2 ports (24) as well if they are for cooling? And if I should have flow through them, how do I clear them?

http://www.crowleymarine.com/mercury-outboard/parts/815_110.cfm

 

[Hookin'up]

will they flow in any direction? can you blow through them? they appear to be just a union, but could be a check valve as well (only allowing flow in 1 direction),
you may not have any movement through them untill the t-stat opens if this is the case then if you pull the t-stat you should have flow in all directions

 

[Kisinana]

will they flow in any direction? can you blow through them? they appear to be just a union, but could be a check valve as well (only allowing flow in 1 direction),
you may not have any movement through them untill the t-stat opens if this is the case then if you pull the t-stat you should have flow in all directions

Thermostat and housing are presently off. I think one way valves would be more hassle than not, but something does seem to affect reverse flow. I am not sure where opposite side of housing from these junctions would be.

 

[Hookin'up]

you should be able to blow through them at will then do you have them off the block and they are still pluged?
they appear to screw right into the coolant chambers for the head which feeds threw the block, if you have the thermostat out you should be able to freely blow thru it unless one of the galleries is corroded up and plugged, have you tried a little compressed air to clear it out?
my merc 9.9 had a week telltale and I ended up replacing the complete water pump as the housing seemed warped a bit, now it has a strong telltale

 

[trophywife]

Some thing a lot of home mechanics over look is also the thermostats ........ think about changing them out too, and Flush every time after salt use if you can, if using a garden hose be sure it CANNOT kink !
Where the water come out of the spitter some times also gets a build up of hardened salt, use a tooth pick or a wire if it appears to spit rather then flow, you might be surprised what comes out in your hand.

HT

kind of like kidneys and kidney stones,, OUCH

 

[salmonkiller01]

Something to look at is where your impeller sits is a ss base plate if it is grooved you lose pressure and the new impeller will quickly lose its seal, i find that buying the complete impeller kit vs just the impeller lasts longer and is about 20 bucks more. Just a thought.

 

[Kisinana]

Still not able to deduce where the small connections go on the inside of the block. Has anyone ever had there engine apart and seen the 2 chambers they mount into the side of? Are they exhaust or for cooling?

 

[Fisher Down]

I looked at the crowleymarine link, didn't notice any year, but it looks like my early 90's Yami hi-thrust. I had the identical issue a few years back and tried Salt-a-Way without any success. I spoke with a very helpful Yami mechanic who took the time to show me exactly what needed to to be done on a motor he already had torn down in his shop (he explained that this vintage of Merc's/Yami's were manufactured with this passage machined too small which caused the blockage with salt). First, pull the cover (part 35), then pull the head (part 21). On the leading edge of the head, you'll see the 'looping passage', which in my case, was 99% blocked with hardened salt crystals (so hard, I had to drill out the passages, slowing increasing the drill bit up to ~3/16"ø). Once the passages were drilled ~1" deep (you can feel the difference between salt and aluminum), take a stiff piece of wire to scoop out the rest of the salt between the drill holes. A couple of new gaskets and hi-temp silicone, and you're done. I'm no mechanic, but this really was simple (I don't even change my own oil in the truck; it's only my Yami's that get my personal attention).

Good luck with the simple teardown,
F D

 

[Kisinana]

So I took FD's advice and tore down the block. It was plugged solid with salt etc. Unfortunately it has a crack in the water jacket that runs along the exhaust vent. I discovered they no longer make the replacement for this unit as it was a yami and they had an inherrant problem with the cooling channels in the head. Just a heads up for anyone who has a 95-97 9.9 Merc or Yami 4 stroke, make sure you flush it really good to clear any build up or it may fail the same way.
Trying to find a new head but the price is higher than the engine is worth. I may have to look at finding a new kicker.
I thought giving it a flush each time I went home was suffice but because of the size of the holes they plugged up anyways.