Update :
Broke both thermo bolts heads when trying to remove thermo housing, were extremely salted and stuck, didn’t want to cede a bit after a long W-40 soak application. Heating both bolts with a propane torch did the trick, Internal thermo housing was found a mess, rusted, crusted, was polished to perfection with a Dremel Drill, small wire brushes and holy patience.
Prior installing new thermo and gasket, all water passages were conveniently high water flushed with a Karcher washing machine set at min pressure. Now OB pees as a teenager than before. This is no indication that heavy salt layers already built inside powerhead will have been removed to perfection, for this task will need to tear head, side lids apart to have all water paths crusts mechanically removed.
Installed a new thermo and gasket. Installed muffs while OB sat on a stand, opened the water faucet, throttled the OB till reached its proper operating temp. While thermo opened and closed properly could feel the water temp difference on hand palm at rear middle leg.
OB tended to die at idle speed, so idle screw was adjusted a bit CW to increase rpm for OB not to die.when geared forward. Throttled to 2-2.5 K constant revs while squirting small doses of CRC EngineTune Up for 15 minutes. OB needs to be geared forward to have a load. Just be aware that prop is spinning high and will chop anything standing next to it.
As the product was removing carbon build ups on piston rings while being burned on combustion chambers, OB started to smooth out. Squirted a final overdose till OB died, let it soak for one hour, started OB and let product clear itself till min smoke was visible exiting through prop.
Mounted OB on a boat and with 2 up went for a 10 mile wot run as if stealing the combo. Now OB remains ON at idle, purrs as a kitten and revs very fast throughout the whole throttle range than before. Can't precise how much compression the OB has gained as didn't have my compression tester handy to check that out again. Saint CRC Engine Tune Up has done a superb long decarbonize job. LOL!!
This product is highly recommended, just don’t expect to remove severe carbon build ups with few product squirts, need at least to squirt 1/4 to 1/3 can contents through the carb. If applied as previously described will clean much better, deeper and faster.
Happy Boating