Overheat at low speed

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Richard Cavanagh

Cadet
Joined
Apr 13, 2002
Messages
16
My 115 Johnson, new water pump, head gasket, etc., overheats at idle to about 2200 RPM. At WOT the engine runs like a charm and never overheats. Previous owner may have never/seldom flushed the engine after salt water use. I did sucessfully repair a crack in the water jacket, but now it is the other side that has heat problems. Any ideas?
 
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chumbucket

Petty Officer 1st Class
Joined
Oct 12, 2001
Messages
320
Re: Overheat at low speed

Did you check out by-pass valve for sticking?? Sometimes the rubber groment it fits in goes bad or maybe spring.
 
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Richard Cavanagh

Cadet
Joined
Apr 13, 2002
Messages
16
Re: Overheat at low speed

I haven't yet gone into the thermostat or bypass area yet. I can't seem to remove the lower cowel. No wrench combos will fit unless I raise the powerhead from the lower unit. If I pull the engine I can then remove the lower cowl and easily get at the thermostat block. I was simply hoping for the easy way out! Perhaps some extended highspeed running might help clean out clogged passages?
 
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DJ

Guest
Re: Overheat at low speed

Octo,<br /><br />I am assuming this engine is a Crossflow V-4. You can get the thermostat block out without removing the cowl.<br /><br />1. Remove all the bolts that that hold the cowl (lower pan) to the powerhead.<br /><br />2. Remove the exhaust tower upper cover (just below cowl).<br /><br />3. Remove the air intake silencer.<br /><br />With all of these bolts either out or loose, you can just get the thermostat block housing bolts out. You'll have told down on the lower pan (cowl) to accomlish this. It's tedious, but it CAN be done.<br /><br />I just did it on a 90.
 
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Richard Cavanagh

Cadet
Joined
Apr 13, 2002
Messages
16
Re: Overheat at low speed

Thanks. I'm going to try it. I may be able to save my most special curses for some other project! :)
 
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seahorse5

Rear Admiral
Joined
Jan 24, 2002
Messages
4,698
Re: Overheat at low speed

If you replace the thermostats, use the factory ones as they are stainless steel now. Make sure the white plastic pressure relief valves are "free" in the rubber grommets. Use a small file to file 2 small notches in the tapered sealing area. Position one down and one up. This will bleed off any airlocks and allow the housing to drain when the motor is shut off. The tiny bleed hole in the plastic valve housing plugs up very easily, then water stays in and corrodes the thermostats.
 
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