Thermostat Cover Gasket – Fits Suzuki DT90-DT200, DF40-DF50 (Replaces 17685-87D10)

$2.39

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Product Details

This Thermostat Cover Gasket – Fits Suzuki DT90-DT200, DF40-DF50 (Replaces 17685-87D10) is designed for a precise fit on compatible Suzuki 2-Stroke Outboard DT models from 1986 and 4-Stroke Outboard DF models from 1999–2010.

It serves as a direct replacement for multiple part numbers, including Sierra 18-0797, Suzuki 17685-87D00/17685-87D10, and OMC 5031430.

Easy, direct replacement installation.
Designed to prevent coolant/oil leaks.
Withstands extreme temperatures and pressure.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Sierra	18-0797
Suzuki	17685-87D00
Suzuki	17685-87D10
OMC	5031430

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Suzuki models, this gasket fits a wide range of DT (2-Stroke) and DF (4-Stroke) outboards.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Suzuki	DT90	90	2-Stroke	Up to 2000	17685-87D10
Suzuki	DT100	100	2-Stroke	Up to 2000	17685-87D10
Suzuki	DT150	150	2-Stroke	1986–2003	17685-87D10	Includes DT150SS
Suzuki	DT175	175	2-Stroke	Up to 2003	17685-87D10
Suzuki	DT200	200	2-Stroke	1986–2003	17685-87D10
Suzuki	DT225	225	2-Stroke	Up to 2003	17685-87D10
Suzuki	DF40	40	4-Stroke	1999–2010	17685-87D10
Suzuki	DF50	50	4-Stroke	1999–2010	17685-87D10

Technical Specs

Product Type: Thermostat Cover Gasket
Installation: Easy, direct replacement
Dimensions: 12.0 x 9.0 x 1.0 in
Weight: 0.1 lbs (0.045 kg)
Warranty: 30 Day Return Policy (4Boats)
Other Technical Attributes: Designed to prevent coolant/oil leaks; withstands extreme temperatures and pressure.

What’s in the Box

1 x Thermostat Cover Gasket

Installation Notes

Disconnect the battery before starting work.
Allow the engine to cool completely and drain the engine coolant into a suitable container.
Locate the thermostat housing and remove the bolts securing the cover.
Carefully remove the old thermostat cover gasket, noting its orientation.
Thoroughly clean both the housing and cover surfaces, removing any old gasket material or sealant.
Position the new gasket correctly on the housing.
Reinstall the thermostat cover and tighten the bolts to the manufacturer's specified torque.
Refill the cooling system with the correct type and amount of coolant.
Reconnect the battery, start the engine, and carefully check for any leaks around the thermostat housing.

Troubleshooting & FAQ

How do I know if my thermostat gasket is failing?

Common signs of a failing thermostat gasket include visible coolant leaks or residue around the thermostat housing, engine overheating, or erratic temperature gauge readings. A thorough visual inspection is the first step in diagnosis.

Is this gasket reusable?

No, it is not recommended. Gaskets create a seal by compressing, and a used gasket will not provide a reliable seal if reinstalled. Always use a new gasket when servicing the thermostat or its housing.

What causes a thermostat gasket to fail?

Failure is typically caused by age, heat cycles, and exposure to coolant, which can make the material brittle and cracked. Improper installation or uneven torque on the housing bolts can also cause premature failure.

Can I use sealant with this gasket?

In most cases, this gasket is designed to be installed dry. Applying sealant can sometimes interfere with a proper seal. Always refer to your engine's service manual for specific recommendations.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost?

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns?

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

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