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De-scaling OX66 200

Old 04-28-2020, 02:04 PM
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The water jackets in the block are surprisingly clean. Had to go get “cleaning vinegar” as apparently the distilled doesn’t have enough acid. Still a slow process and I’m considering bead blasting everything.


Old 04-28-2020, 02:13 PM
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Originally Posted by noelm View Post
Poppet won't cause high speed over heat, but, you have done the right thing, dig out all the crap you can from in the block as well, that looks pretty serious to me, I think your model allows access through the exhaust cover as well?
Actually it will. Poppet ( or bypass valve) opens under increased pressure from water pump at higher RPM to bypass the thermostats and flow additional water since thermostats, even when fully open, do not flow enough enough water at high speed. The reason his thermostats look new is because someone changed those already trying to cure the problem. OP also has the old style poppet valve that was very susceptible to sticking shut with less corrosion than that.
Old 04-28-2020, 04:13 PM
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Originally Posted by ddogopti View Post
Actually it will. Poppet ( or bypass valve) opens under increased pressure from water pump at higher RPM to bypass the thermostats and flow additional water since thermostats, even when fully open, do not flow enough enough water at high speed. The reason his thermostats look new is because someone changed those already trying to cure the problem. OP also has the old style poppet valve that was very susceptible to sticking shut with less corrosion than that.
yeah, theres a new style poppet valve. I was having the same issue, new thermostats, new poppet, new impeller, thermoswitches and temp checked good...heads were caked. tried every possible combo of pumping descaler etc and it wasnt enough. I was really close to pulling the heads but tried running the motor in a tub (trash can) until warm, and a few times with vinegar mixture. Shit kept coming out, then i just continued flushing with water in the tub after every trip. Now its so good i just flush with the flush port and occasionally flush in the tub. Havent had an overheat in a year.
Old 04-28-2020, 05:17 PM
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Originally Posted by madmanmarz View Post
yeah, theres a new style poppet valve. I was having the same issue, new thermostats, new poppet, new impeller, thermoswitches and temp checked good...heads were caked. tried every possible combo of pumping descaler etc and it wasnt enough. I was really close to pulling the heads but tried running the motor in a tub (trash can) until warm, and a few times with vinegar mixture. Shit kept coming out, then i just continued flushing with water in the tub after every trip. Now its so good i just flush with the flush port and occasionally flush in the tub. Havent had an overheat in a year.
Moving forward this is what I'll do. At least now I know the state of the cooling system and really for a few hours work and $300 it's well worth it for peace of mind. I'm assuming the new poppet is designed to just rest against the rubber grommet instead of going through it?
Old 04-29-2020, 10:27 AM
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Originally Posted by Lifeislarge View Post
Moving forward this is what I'll do. At least now I know the state of the cooling system and really for a few hours work and $300 it's well worth it for peace of mind. I'm assuming the new poppet is designed to just rest against the rubber grommet instead of going through it?
Yes. New one will be smooth dome shape on one side and have the spring keeper on the other side. When I first had this issue years ago, It was a Saturday and I ground off the part that extended through the rubber grommet. It only takes a little corrosion of the aluminum to swell the rubber grommet enough to grab hold of the old style poppet and keep it from opening.

Your block passages look remarkably good. I would not sand blast anything. Manually clean carefully and leave behind as much of the original green finish inside the castings as you can. Removing the heads like you did and cleaning those will prevent hot spots.
Old 04-29-2020, 11:05 AM
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Port side is clean without sand blasting. Water pump is done and it too looked great but who knows... Let the starboard side soak for 24 hours and hopefully get it all back together tomorrow.








Old 04-29-2020, 11:33 AM
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Originally Posted by Lifeislarge View Post
Moving forward this is what I'll do. At least now I know the state of the cooling system and really for a few hours work and $300 it's well worth it for peace of mind. I'm assuming the new poppet is designed to just rest against the rubber grommet instead of going through it?
Yeah the tub flush is way way better, and way way quieter, just be sure to have a hose pumping in fresh water if you're running it for a while as the water can get too hot and melt seals.

Amazing work cleaning up the heads!
Old 04-29-2020, 11:33 AM
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What a difference.
Old 04-29-2020, 11:59 AM
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Some people need anti-corrosion, parts/bolts look horrible.
Old 04-29-2020, 02:20 PM
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Sorry if I missed it, how many hours on the motor?
Old 04-29-2020, 02:21 PM
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Originally Posted by dseg42 View Post
Some people need anti-corrosion, parts/bolts look horrible.
I don't understand. It's a 2001 OX66 that's been in salt water it's whole life. It's actually pretty damn clean for what it is.
Old 04-29-2020, 02:30 PM
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Replace the head and block anodes while you have things disassembled. I replaced mine this past weekend.
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Old 04-30-2020, 10:56 AM
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And I'm done. Got it all back together this morning and ran it on muffs for 15 minutes with a good solid pee stream and no alarm. Guess I'll find out for sure if it's good next time I'm out on the water.

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