143°F Thermostat for Mercury Mariner 75–175 HP DFI Outboards – Replaces Mercury 833072002, 833072003, 833072004
143°F Thermostat for Mercury Mariner 75–175 HP DFI Outboards – Replaces Mercury 833072002, 833072003, 833072004 is backordered and will ship as soon as it is back in stock.
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143°F Thermostat for Mercury Mariner 75–175 HP DFI Outboards – Repl...
143°F Thermostat for Mercury Mariner 75–175 HP DFI Outboards – Replaces Mercury 833072002, 833072003, 833072004 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket 143°F (62°C) thermostat is designed for specified Mercury and Mariner DFI outboard applications from 75 to 175 HP. It is a single replacement thermostat for engines using the Mercury references listed below, including 1.5L three-cylinder DFI applications and 2.5L V-135, V-150, and V-175 DFI applications.
The thermostat begins opening at 143°F (62°C) to help regulate engine temperature within the cooling system. Verify the complete engine model and serial-number range before ordering; horsepower alone does not confirm fitment.
- Replacement type: Single aftermarket outboard thermostat
- Opening temperature: 143°F (62°C)
- Applicable brands: Mercury and Mariner
- Installation: Direct replacement when the listed model and serial conditions match
Part Number Matrix
These manufacturer and aftermarket references are provided for identification and cross-reference purposes. Confirm the reference against your engine parts diagram before installation.
| Brand | Part Number | Reference |
|---|---|---|
| Mercury Marine | 833072002 | Replacement reference for specified 1.5L DFI applications |
| Mercury Marine | 833072003 | Replacement reference for specified 2.5L DFI applications |
| Mercury Marine | 833072004 | Replacement reference for specified 1.5L DFI applications |
| Sierra | 18-3536 | 143°F thermostat reference for specified 2.5L DFI applications |
| Sierra | 18-3537 | 143°F thermostat reference for specified 1.5L DFI applications |
| OMC / Johnson-Evinrude | 5005440 | Separate cross-reference shown in catalog research; verify application independently |
| OMC / Johnson-Evinrude | 378065, 393659, 434841, 508626 | Separate cross-reference shown in catalog research; verify application independently |
Engine & Model Compatibility
The following applications are stated for the corresponding Mercury or Mariner thermostat references. Keep each engine family, displacement, horsepower, year, and serial-number condition together when checking fitment.
| Brand | Engine family | Rated HP | Displacement | Years | Serial range | Applicable reference |
|---|---|---|---|---|---|---|
| Mercury / Mariner | 75 DFI, 3-cylinder | 75 HP | 1.5L | 2006 and newer | OT980000 and up | 833072004 / Sierra 18-3537 |
| Mercury / Mariner | 90 DFI, 3-cylinder | 90 HP | 1.5L | 2004 and newer | OT801000 and up | 833072004 / Sierra 18-3537 |
| Mercury / Mariner | 115 DFI, 3-cylinder | 115 HP | 1.5L | 2004 and newer | OT801000 and up | 833072004 / Sierra 18-3537 |
| Mercury / Mariner | V-135 DFI | 135 HP | 2.5L | 1998 and newer | OG590000 and up | 833072003 / Sierra 18-3536 |
| Mercury / Mariner | V-150 DFI | 150 HP | 2.5L | 1998 and newer | OG590000 and up | 833072003 / Sierra 18-3536 |
| Mercury / Mariner | V-175 DFI | 175 HP | 2.5L | 2001 and newer | OT178500 and up | 833072003 / Sierra 18-3536 |
Important: The catalog data supports the applications above. Do not extend compatibility to other Mercury, Mariner, Johnson, or Evinrude models solely because they share a horsepower rating or a similar-looking thermostat.
Technical Specifications
- Product type
- Outboard engine thermostat
- Opening temperature
- 143°F (62°C)
- Application range
- Specified Mercury and Mariner 75–175 HP DFI outboards
- Engine applications
- 1.5L three-cylinder DFI and 2.5L V-135, V-150, and V-175 DFI applications listed above
- Installation
- Direct replacement for a matching application
- Product status
- Aftermarket replacement; not a Mercury Marine OEM component
What's in the Box
- 1 x 143°F (62°C) thermostat
This listing is for a single thermostat. Gaskets, seals, thermostat covers, and multi-thermostat kits are not included unless separately stated in the order details.
Installation Notes
- Confirm the engine model, displacement, horsepower, and complete serial-number range before beginning work.
- Switch off the engine, disconnect the battery where applicable, and allow the engine to cool completely.
- Locate the thermostat housing or cylinder-head thermostat location for your specific engine.
- Remove the housing or retaining hardware and note the original thermostat orientation.
- Clean the mating surfaces carefully and remove any damaged or contaminated sealing material.
- Install the replacement thermostat in the same orientation as the original part.
- Reuse or replace the required gasket or seal according to the engine service manual; no gasket or seal is included with this single thermostat listing.
- Reinstall the housing and tighten the fasteners to the manufacturer's specified torque.
- Run the engine using the appropriate water supply procedure for the outboard and check for leaks and normal temperature regulation.
Troubleshooting & FAQ
What temperature does this thermostat open at?
This thermostat is specified to begin opening at 143°F (62°C).
Which engines does this thermostat fit?
It is listed for specified Mercury and Mariner 75, 90, and 115 HP three-cylinder 1.5L DFI engines, plus V-135, V-150, and V-175 2.5L DFI engines. Year and serial-number conditions vary by engine family, so use the compatibility table rather than horsepower alone.
Are gaskets or seals included?
No. This product is a single thermostat. Required gaskets or seals must be reused only if serviceable or purchased separately according to the engine service manual.
Is this an OEM Mercury Marine thermostat?
No. This is an aftermarket replacement intended for the listed applications and reference numbers.
Can I use the thermostat on another engine with the same horsepower?
Not necessarily. Thermostat fitment depends on the engine family, displacement, model details, and serial-number range. Confirm all of those conditions before ordering.
What should I do if the replacement does not match my original part?
Do not force or modify the part. Compare the thermostat and housing arrangement with the original and verify the engine serial range. Contact support before installation if the application or physical fit is unclear.
Safety & Important Information
- Allow the engine to cool completely before servicing the cooling system.
- Follow the service manual for your exact engine when replacing the thermostat and sealing components.
- Verify the model, displacement, horsepower, year, and serial number before purchase.
- This is an aftermarket replacement and is not manufactured or endorsed by Mercury Marine, Mariner, Sierra, or OMC.
- Professional installation is recommended if you are not familiar with outboard cooling-system service.
About Sea Sierra
- Marine replacement parts — We provide aftermarket components for boat and outboard maintenance.
- Application-focused listings — Product information is organized around engine models, reference numbers, and fitment conditions.
- Support before installation — Contact our team if your engine details or replacement reference do not clearly match the information above.
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