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Old 08 September 2011, 06:48   #11
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Interesting observation 9D. Is it possible that when they were removed something else was adjusted at the same time? On a cold start initially the engine (and water) will be cold anyhow. The engine wouldn't start to warm through for a minute or so in that case. The fact that there is an effect on a warm start implies some other change to me.
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Old 08 September 2011, 07:08   #12
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You can tell when the thermostat is open or not on my Mariner 15 2-stroke as it changes the way the telltale flows. At idle and with very gentle trolling it does shut the stat on and off a fair bit but once on the plane it's open all the while so I'm guessing leaving it out with perhaps a mild restrictor fitted will not effect any outboard used under load.

Having said that I replace the stat in every used outboard I buy... just in case.
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Old 08 September 2011, 11:37   #13
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Quote:
Originally Posted by Courageous View Post
Interesting observation 9D. Is it possible that when they were removed something else was adjusted at the same time?
The poppet valve weas also deleted. I got fed up puddling & threw it at a repair shop for final tuning, but I would guess it's running slightly richer / with microscopically more throttle opening at idle than it used to.

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Originally Posted by Courageous View Post
On a cold start initially the engine (and water) will be cold anyhow. The engine wouldn't start to warm through for a minute or so in that case. The fact that there is an effect on a warm start implies some other change to me.
Yeah - nothing to sieze closed! In all seriousness, the poppet valve is also removed by the change, and it usually only opens when the engine hits (I think) 1500ish RPM. The hole left by lack of it makes a huge increase in area at idle water flow. The other interesting (but not surprising) thing is that the telltale flow isn't quite as strong at idle - probably because it is tapped from the "always open" passage, but of course now at idle there is a far higher proportion of the water going straight to the block cavities. It still clears the toob by 3' when running!

As for longevity effects, I'll post back in 10 years!


Note for any clamshell owners planning on following suit - there is a vent hole in the cover behind the poppet diapragm that will need plugged! (it's the one that leaks if your diagpragm has burst)
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