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Mercury Mariner 6-200hp Thermostat - 120 Degrees Fahrenheit (OST145)

Genuine Part # : 14586, 18-3549

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  • 1 YEAR


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Thermostat opens at 120 degrees fahrenheit.

This part replaces part #: 14586, 18-3549.

This part suits the following engines: Mercury Mariner 6-9.9hp 1986-2003 serial # A197112 & up, USA & Belgium models, Mercury Mariner 15hp 1988-2016 serial # OB292414 & up, USA & Belgium models, Mercury Mariner 18hp 1982-1986 serial # 6443973 to OB238463 XD models, Mercury Mariner 20hp 1988-2006 serial # OB238464 & up models, Mercury Mariner 25hp 1984-2006 serial # 5705532 & up USA & Belgium models, Mercury Mariner 40hp 4 Stroke 2003-2016 serial # OT178500 & OT598999 models, Mercury Mariner 40hp EFI 4 Stroke 2003-2016 serial # OT409000 to current models, Mercury Mariner 50hp 3 Cylinder 1990-2015 serial # OD000750 & OG589999 models, Mercury Mariner 50hp 4 Stroke 2003-2016 serial # OT178500 to current models, Mercury Mariner 60hp 3 Cylinder 1990-2015 serial # OD000750 to current models, Mercury Mariner 60hp 4 Stroke 2003-2016 serial # OT178500 to current models, Mercury Mariner 75hp 3 Cylinder 1988-2015 serial # OC222000 to current models, Mercury Mariner 90hp 3 Cylinder 1989-2015 serial # OG760300 to current models, Mercury Mariner 100hp 4 Cylinder 1988-2002 serial # OB209468 to current models, Mercury Mariner 115hp 4 Cylinder 1988-2005 serial # OC100000 to current models, Mercury Mariner 125hp 4 Cylinder 1988-2005 serial # OD283222 to current models.  

Note:  Can also be used as replacement for 143 degree thermostat in V6 Mercury/Mariner 2 stroke Outboards


About The Brand

Outboard Spares brand of parts are tested in Australia's harsh marine environment with a focus on quality and durability. Outboard Spares parts are used by professional fishermen who depend on their parts to stay on the water and in business. So next time you service your engine choose what the professionals use, choose Outboard Spares.

Standard Shipping is FREE on all orders or Express Shipping is $10 flat rate.

Oils & Lubricants can only be sent via Standard Shipping.

Pick up is available from our warehouse at 1/84 Brunel Road, Seaford VIC 3198 between the hours of 8:30am to 3:30pm weekdays. You will be notified by email when your order is ready for pick up.

Delivery Time

Orders are dispatched same business day if ordered before 3:00pm AEDT. All orders are dispatched from Melbourne, Victoria and are sent via Australia Post.

For delivery time estimates with Australia Post please use their delivery calculator here:

If you have any questions relating to shipping, please contact us by emailing

Review Mercury Mariner 6-200hp Thermostat - 120 De

By: on 2 February 2022
Thanks for service and parts old Mariner hasn’t run so good.

Gasket and Thermostat

By: on 26 March 2021
Received my spares in excellent delivery time and condition now fitted and working many thanks to the team for there help in ordering and supply.

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