Mac5

High engine temperature

83 posts in this topic
3 hours ago, Woodski said:

@Mac5:  One area to check, the thermostat housing - the diverter mechanism that controls the flow to the exhaust manifolds, inside there is a rod / plastic ball / spring device that allows water to be diverted to the exhaust manifolds when the thermostat is closed.  In the above picture it is the two 5/8" hoses top front of the thermostat housing that lead back to the risers.  Typical failure mode is the springs fail thus not allowing the plastic balls to close and seal the diverter path.  By opening up the thermostat you created a lower restriction path which perhaps allowed enough water to flow to provide additional cooling.  Repair parts are available at SkiDim.com.  Note:  the circulation pump issues with the cracked impeller are normally associated with later model engines than your '94.

Here's an exploded view of the thermostat placement.

Thermostat placement design.pdf 

And a close up of the ball & springs.

 

 

 

Engine repairs 007.jpg

Edited by Michigan boarder

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16 hours ago, Mac5 said:

Here are some images of my spark plugs and the re-circ pump. 

IMG_0841-1.JPG

IMG_0827.JPG

While they may be just fine, the exterior of that plug looks awful.  I would definitely replace with new but wonder what the rest of the engine looks like...are you operating in or around salt water?!

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I see there's no "M" in front of the "R43.." meaning it's not a marine plug which is prob why they're rusty. Get the "M" replacements.

It's easy to mix up the hoses on the back of the raw water pump too. But I think that creates a full blown overheat.

Last year we found tiny pieces of impeller got past the transmission cooler screen and into the block passages on the 87 Nautique. We were wondering why it would get kinda hot sometimes but not others.

Have you checked the trans cooler screen?

Edited by JasonK
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2 hours ago, Woodski said:

@Mac5:  One area to check, the thermostat housing - the diverter mechanism that controls the flow to the exhaust manifolds, inside there is a rod / plastic ball / spring device that allows water to be diverted to the exhaust manifolds when the thermostat is closed.  In the above picture it is the two 5/8" hoses top front of the thermostat housing that lead back to the risers.  Typical failure mode is the springs fail thus not allowing the plastic balls to close and seal the diverter path.  By opening up the thermostat you created a lower restriction path which perhaps allowed enough water to flow to provide additional cooling.  Repair parts are available at SkiDim.com.  Note:  the circulation pump issues with the cracked impeller are normally associated with later model engines than your '94.

Woodski, attached are photos of the thermostat housing.  I don't see the rod/plastic ball/spring device at all??

Photo on 10-12-17 at 11.12 AM #2.jpg

Photo on 10-12-17 at 11.12 AM.jpg

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@Mac5:  MIA, looks like from the corrosion been that way for a while.  I suggest you restore to original configuration.  As noted, inlet side of trans cooler is a great debris trap, pull hose and feel inside for debris.

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38 minutes ago, Woodski said:

@Mac5:  MIA, looks like from the corrosion been that way for a while.  I suggest you restore to original configuration.  As noted, inlet side of trans cooler is a great debris trap, pull hose and feel inside for debris.

Just checked the trans cooler screen on both sides and it is completely clear and free of debris. Hoses are clear too. 

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Sounds (and looks) like a new thermostat housing might be advisable. If water is routing incorrectly, that could explain the symptoms.

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