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Need help to trouble shoot over temp alarm on starboard head, 1989 Johnson 110

leaky

Regular Contributor
Hi,

After completely going through this engine, bored/rebuilt, pretty much everything got cleaned, new gaskets, thermostats, anything one might reasonably replace I did - seemed to be tip top and I got it mounted on the boat.

Today, with all the gauges/controls hooked up I started it on the flush. After 5 minutes or so I could see the starboard (higher) head was running a little warmer (have a temp gauge in each head), very shortly after I got an overheat alarm :(.. Disconnecting the sensor on that side showed it was the starboard sensor.

The water pressure was about 8 PSI on the flush in the 1000 RPM range. It was pumping water - from day 1 I never felt this thing has a really strong stream but pumps steady.

During the overheat I could put my hand on the head for a couple seconds - not stupid hot or obviously overheating but from the temp gauges (which are dummy gauges) I could see that head was indeed like 3/16 inch hotter on the scale. So I can't really say for sure it was overheating but I know from the gauges it was running hotter.

Sensors I would normally just swap but I'm worried the water jacket bolt that holds the retainer is going to snap..

Anyone have a trouble-shooting strategy for this?

Was thinking #1 check the water pump since this engine now has about 1.5 hours of running on the flush, potentially at some point a flush wasn't seated well and I managed to burn up the pump; #2 try to swap the sensors, maybe just cut the retainer to avoid breaking bolts; #3 maybe this engine is one that just doesn't like to run on the flush - this is the first time I ran it for long with the cover on, try it actually on the water? #4 pull heads and/or t-stats and start hunting?

My book (seloc) provides no clue what to do with this sort of thing.

Thanks in advance.

Jon
 
Thanks anyway - I *might* be all set.

I swapped out the water pump (which was really new, ie 1.5 hours on it or something) and started the engine in a barrel this time, with my temp gun handy. #1 thing the pressure went up a couple pounds, also #2 I witnessed water exiting the exhaust relief holes, which really wasn't happening before.

The temp gun revealed the starboard head going up to 170 degrees then dropping to 135 and staying around there. The port head actually seemed to hover around 150 now (other head running hotter).. Tried it a bunch and can't make it do anything bad.

Also, strangely - before changing the water pump I was noticing a very prominent squeak out of the water pump when cranking, and to me that binding seemed to be even bogging the starter down to some extent. Upon changing the water pump the engine cranks faster, even after I ran it and blasted any grease out. I didn't notice anything different about the pumps but maybe there was something funny with the impeller.

So I put the boat in the water and now I have a fun new problem. Will re-post on that.

Jon
 
You can't reveal the "fun new problem" yet? Why the big secret?

Is it only me or do more and more posts sound like 'Mad Libs'. Member those?

I just don't know anymore ...

No offense!
 
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