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Author Topic:   Blocked cooling system on Johnson 15 hp

andygere posted 04-23-2003 12:55 AM ET (US)
I am troubleshooting the cooling system on a 1980 Johnson 15 hp outboard. The waterpump is new, installed correctly and pumping. I have removed the thermostat and housing, and I can get water to flow backwards from the tell-tale through the waterjacket and out the thermostat opening. What I can't do is get water or air to flow from the water tube through the head and out the thermostat opening. My assumption is that something went through the tube and is lodged in a cooling channel in powerhead. Any thoughts on how to unblock things without pulling the powerhead? Am I missing something? I have read and reread the OMC shop manual, and I'm running out of ideas. Any help will be appreciated.
Sal DiMercurio posted 04-23-2003 01:10 AM ET (US)
Ande, the water from the tell tail is coming directly from the water pump to the engine.
On omc engines, the water you see coming out of the tell tail is cold because it hasen't gone through the engine.
It's not flowing backwards, it's going into the engine, not out.
Sal
andygere posted 04-23-2003 01:26 AM ET (US)
I put a piece of tubing on the tell-tale outlet and used the garden hose to push water through the system. The pump and gearcase were off the motor at the time.
Clark Roberts posted 04-23-2003 08:14 AM ET (US)
Andy, there may be corrosion/restriction at water entry to power head. This opening is small and,if memory serves me correctly, a right angle bend! Pulling the power head is only way to clear the path.. been there, done that! Seem as though I drilled out larger openings... hummm could have been another engine make/model??? Happy Whalin',,, Clark ... SCN
andygere posted 04-23-2003 08:48 AM ET (US)
Clark,
This is what I feared, and from the shop drawings, it looks like it is a right angle bend at the bottom of the powerhead. Pulling the powerhead doesn't look all that tricky, how tough is it to get everything aligned and put back together? Any special tools required?
andygere posted 04-23-2003 01:48 PM ET (US)
One more question: After taking the powerhead off, what is the technique for unblocking thw cooling channel? Can some heavy weedeater line or downrigger cable be snaked through or can I use compressed air and blow it out? After thinking about this some more, I think the blockage might be caused by a broken off piece of the water tube grommet, which was badly mangled by the shop that originally did the waterpump job. The water flow problem didn't happen gradually as if by salt accumulation or corrosion. After not using the kicker for a month or so, I started it up and found no flow from the telltail.
Clark Roberts posted 04-23-2003 06:47 PM ET (US)
Andy, once power head is off you must remove all the corrosion mechanically (scrape, wirebrush and even drill out passages ..).. Clark
Steve Leone posted 04-23-2003 11:15 PM ET (US)
The water jackets in the head and side plate may also be clogged. My gut feeling is that the grommet at the powerhead is swollen and blocked. Salt build-up and damage will cause this. As for the tell-tale or pisser, if you put enough water through it it will go through the whole block and out the water pick-up and exhaust. I have dislodged many a plugged powerhead this way. Especially on 9.9 and 15hp O.M.C. applications. Steve
andygere posted 04-23-2003 11:38 PM ET (US)
Problem solved! Steve had the right call (as did Clark) but I got the pick-up tube grommet unclogged before I read his post. I figured it couldn't hurt to snake a wire shirt hanger up the pick-up tube and try to gently dislodge whatever was up there. Looking at the shop drawings, I was pretty sure the plug was right at the bottom of the powerhead and I was right. I dislodged a bit of splooge (technical term) and she flows like a beauty. I ran her with the thermostat out and uncovered for a few seconds just to be sure that she was pumping enough and she was. She is all back together now (with a new stat) and running like a champ. If my buddy at work doesn't buy her, she'll be on Marketplace later this week. Thanks for the great advice guys.

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Author	Topic: Blocked cooling system on Johnson 15 hp
andygere	posted 04-23-2003 12:55 AM ET (US) I am troubleshooting the cooling system on a 1980 Johnson 15 hp outboard. The waterpump is new, installed correctly and pumping. I have removed the thermostat and housing, and I can get water to flow backwards from the tell-tale through the waterjacket and out the thermostat opening. What I can't do is get water or air to flow from the water tube through the head and out the thermostat opening. My assumption is that something went through the tube and is lodged in a cooling channel in powerhead. Any thoughts on how to unblock things without pulling the powerhead? Am I missing something? I have read and reread the OMC shop manual, and I'm running out of ideas. Any help will be appreciated.
Sal DiMercurio	posted 04-23-2003 01:10 AM ET (US) Ande, the water from the tell tail is coming directly from the water pump to the engine. On omc engines, the water you see coming out of the tell tail is cold because it hasen't gone through the engine. It's not flowing backwards, it's going into the engine, not out. Sal
andygere	posted 04-23-2003 01:26 AM ET (US) I put a piece of tubing on the tell-tale outlet and used the garden hose to push water through the system. The pump and gearcase were off the motor at the time.
Clark Roberts	posted 04-23-2003 08:14 AM ET (US) Andy, there may be corrosion/restriction at water entry to power head. This opening is small and,if memory serves me correctly, a right angle bend! Pulling the power head is only way to clear the path.. been there, done that! Seem as though I drilled out larger openings... hummm could have been another engine make/model??? Happy Whalin',,, Clark ... SCN
andygere	posted 04-23-2003 08:48 AM ET (US) Clark, This is what I feared, and from the shop drawings, it looks like it is a right angle bend at the bottom of the powerhead. Pulling the powerhead doesn't look all that tricky, how tough is it to get everything aligned and put back together? Any special tools required?
andygere	posted 04-23-2003 01:48 PM ET (US) One more question: After taking the powerhead off, what is the technique for unblocking thw cooling channel? Can some heavy weedeater line or downrigger cable be snaked through or can I use compressed air and blow it out? After thinking about this some more, I think the blockage might be caused by a broken off piece of the water tube grommet, which was badly mangled by the shop that originally did the waterpump job. The water flow problem didn't happen gradually as if by salt accumulation or corrosion. After not using the kicker for a month or so, I started it up and found no flow from the telltail.
Clark Roberts	posted 04-23-2003 06:47 PM ET (US) Andy, once power head is off you must remove all the corrosion mechanically (scrape, wirebrush and even drill out passages ..).. Clark
Steve Leone	posted 04-23-2003 11:15 PM ET (US) The water jackets in the head and side plate may also be clogged. My gut feeling is that the grommet at the powerhead is swollen and blocked. Salt build-up and damage will cause this. As for the tell-tale or pisser, if you put enough water through it it will go through the whole block and out the water pick-up and exhaust. I have dislodged many a plugged powerhead this way. Especially on 9.9 and 15hp O.M.C. applications. Steve
andygere	posted 04-23-2003 11:38 PM ET (US) Problem solved! Steve had the right call (as did Clark) but I got the pick-up tube grommet unclogged before I read his post. I figured it couldn't hurt to snake a wire shirt hanger up the pick-up tube and try to gently dislodge whatever was up there. Looking at the shop drawings, I was pretty sure the plug was right at the bottom of the powerhead and I was right. I dislodged a bit of splooge (technical term) and she flows like a beauty. I ran her with the thermostat out and uncovered for a few seconds just to be sure that she was pumping enough and she was. She is all back together now (with a new stat) and running like a champ. If my buddy at work doesn't buy her, she'll be on Marketplace later this week. Thanks for the great advice guys.