mobilmercman

Thanks for the input.

I will ask the mechanic to check that first.

My bet is in the elbow, possibly right near the end.

When running, is any water coming out on the side that is overheating??????

If not, its blocked somewhere on that side.

Well the mechanic tried everything and they were never able to recreate the extreme overheat condition.

They were still seeing a 20-30 degree difference at the manifold, when measured with a laser temp gauge.

They ran it on muffs and for an extended period on the lake. WOT, stop-n-go, stop-n-heat soak.

They reversed the output from the thermostat housing and the temperature increase switched sides as well. They then ran a test using clear tubing and saw very few bubbles and the temp increase still followed the left side output at the T-stat.

Waterflow out of the thru-hull exhaust is equal on both sides.

They backflushed

They re-checked the impeller, t-stat housing, elbows, risers, gaskets.

Changed out the 160 degree t-stat for a 140 degree....that helped a little on both sides.

They even called Mercury Marine; who indicated that it was not uncommon for some motors to run up to 30 degrees hotter on one side or the other.

Also, the temp was returning to the normal range on both sides rapidly when returning to low speed and idle from WOT runs.

Thanks for the update, sounds like your boating again.

Yeah, but I hate that nervous, "Looking at the gauges all the time" feeling.

It's like when you think you heard your outdrive make "A Noise"!

Ran it myself this morning. Ran strong right up to the rev-limiter. No strange sounds or smells.

Air temp was 85 degrees.

Water temp was 85.

At idle in the slip it ran up to 170 degrees and was hotter on the left than the right.

At 3,000 RPM it comes up to 175 degrees on the gauge

At WOT 4,680 RPM for 15 minutes...it came up to 190 degrees on the gauge.

When I slowed back to 3,000 RPM it came back to 180 degrees immediately.

The left side is much hotter than the right side in all conditions.

I ran the RPM's up to 2,500 while out of gear; looked under the swimplatform and the water flow appeared equal from both exhausts.

I am considering adding an oil temp gauge as an added layer of protection. Where should the sender be placed? is it 1/8", 1/4" or 3/8"? I would have to replace the stock dash panel to add the gauge or I could just remove the non-functional depth gauge....never use it anyway; I just mind the markers & stay on the deep side.

I was looking at the gauges so much that everytime I looked up I had such bad persistence of vision that I could see 7 huge circles floating in the sky.

Decided to go ahead and add an oil temp gauge as a back-up

I don't like that the water temp gauge is at 185 @ WOT!

I need some reassurance that I am not boilin' oil