"Outboard Motor Maintenance Tip" | Stuck Thermostat

Sometimes we encounter our outboards not running properly. I was the prime example. I went to test the oil level in my Yamaha Outboard and saw the oil was milkshake color. This is an indication of water entering the oil pan area. I first of all made sure the not use the motor (water and oil mixed is a bad recipe for use in your motor. Long term it can overheat and seize up). Thankfully for some good friends who have encountered a similar experience with their own boats they suggested looking at the thermostat to the motor. I found my motor to have a seized thermostat and is most likely the culprit. Take a look at this video as this may be helpful for you down the road if these symptoms show.

[@truvintage5800]

All these people saying bad thermostat can't cause water (condensation) to build and get past the rings into the oil haven't done their homework. Good video and a simple starting point especially if the thermostat is bad.

[@HolyMolyOutdoors]

Thanks for watching, appreciate your support

[@geffthebricky]

Thanks for the info, just ordered a thermostat and fingers crossed.

[@brentsandy95]

I'm getting one tomorrow thanks 4 the advice got same issue cheers

[@HolyMolyOutdoors]

Thanks for watching and the support!

[@bankerlies6121]

If you are running your exhaust on a 2 cycle in a barrel,that will put oil in water

[@rakituma]

Your motor initially overheated, likely due to a cooling problem such as restricted water passages, bad impeller or running without water. This caused the thermostat to pop. The oil in water may be related to the overheating but could indicate a faulty head gasket. A new thermostat is unlikely to solve the bigger problem.

[@rakituma]

Above should read water-in-oil

[@BrockOBauma]

You should have mentioned how this causes milky oil. It's because the engine doesn't reach operating temp and the condensation in the crankcase doesn't evaporate.

[@hijinX13aa]

Water in oil Is totally unrelated to the water in cooling system. Yep the thermostat is trash, but you still have not resolved the water intrusion into crankcase.

[@sebastiangreenwood3019]

over along period of time for one the moisture in the oil from normal combustion will condensate and you will get water in your oil

[@hijinX13aa]

@@sebastiangreenwood3019 the moisture that condensates in four stroke crankcases will evaporate if the motor reaches operating temperature for any length of time

[@marccormier2310]

@@hijinX13aa not if the thermostat is stuck open engine will run cold happened to me while troubleshooting my outboard with garden hose at home that water was super cold (and temp outside was 5c) had barely any heat on cylinder head near plugs

[@hijinX13aa]

@@marccormier2310 yea, I was thinking in normal course of operation the condensate is usually evaporated but I see your situation happening too. I’ve run many hundred hours on Yamaha four strokes and yet to have a thermostat stick opened or closed. I usually replace them when replacing the anodes.

[@terryknutson3202]

Hello. Can you tell me where thermostat is on 1970 Chrysler??????????????? Thanks

[@marccormier2310]

i have a yammy kicker 8 hp four stroke after testing found mine was stuck open also and my oil was also milky :( yes i do run in salt water.

[@franklinantoniorodriguezpi8186]

Cual es la temperatura normal en un Yamaha 15 enduro

[@pitsmcgoo]

Thermostat stuck om my pinto years ago got water in my tail lights.

[@marccormier2310]

lol

[@keytrash]

I HAD THIS SAME ISSUE. MY LOCAL MECH TOLD ME I HAD A BAD BLOCK, LETTING WATER INTO THE OILPAN. TOLD ME THE MOTOR WAS SCRAP. IT WAS THE THERMOSTAT.

[@daleneudorf9447]

Good video- I had this happen on a 6cyl inboard with a stuck thermostat. Basically created condensation in the crankcase. Looking at buying a little 5 hp honda with the same issue and hoping its a thermostat as well.

[@marccormier2310]

agree same happened to me a few weeks ago ,thermostat stuck open cold water and weather equals condensation

[@marccormier2310]

bullcrap they want to make money off of you unfortunately, had my local boat shop here told me my yammies 8 hp had a bad foot jumping out of gear on reverse come to find with lots of head scratching the pin in the clutch dog was broken and not doing its intended job!!! been 12 years never had any more issues

[@ronaldrichards9683]

Your thermostat shouldn't have anything to do with water getting in your oil ? 🤔

[@truvintage5800]

it's called condensation

[@DavidRodriguez-gi2ir]

Bad head gasket water in the oil

[@stonedjedi87012]

A stuck Thermostat won’t turn your oil into a milk shake. Most likely that’s due to a blown head gasket or a cracked head and the smallest crack even the ones you can’t see will do that let water into your oil. The thermostat is to control the engine water temperature hotter the water the more the thermostat opens best way to see if you have a cooling problem is to check the telltale if it’s warm it’s working if it’s cold thermostat is gone replace asap