Thermostat Kit – Fits Johnson/Evinrude V4 Crossflow 65-140 HP (Replaces 434841, 18-3673)

Vendor: JLM Marine
Availability: In Stock
Product Type: Thermostat
$31.49
$31.49
Subtotal: $31.49

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photo of jlm marine thermostat kit for johnson evinrude v4 crossflow outboard engines 65-80 jet 85-140 hp 18-3673 with two thermostats, springs, plastic connectors, rubber seals, metal rings, and two gaskets with multiple holes

Thermostat Kit – Fits Johnson/Evinrude V4 Crossflow 65-140 HP (Replaces 434841, 18-3673)

$31.49

Thermostat Kit – Fits Johnson/Evinrude V4 Crossflow 65-140 HP (Replaces 434841, 18-3673)

$31.49

Thermostat Kit – Fits Johnson/Evinrude V4 Crossflow 65-140 HP (Replaces 434841, 18-3673)

This thermostat kit is designed for Johnson/Evinrude 65-140 HP V4 Crossflow outboard engines, covering models from 1978 to 1995. It is a direct replacement for multiple OEM and aftermarket parts, ensuring a precise fit for a wide range of applications, including 80 HP Jet and various commercial models.

This kit provides a comprehensive solution for servicing dual thermostat systems, restoring proper engine operating temperature and performance. It is designed to replace Sierra 18-3673, GLM 13270, and a range of OMC part numbers including 434841 and 5005440.

  • Includes two 143°F (62°C) stainless steel thermostats for dual systems.
  • Engineered as a direct replacement for easy installation.
  • Complete kit with all necessary seals, springs, and poppet valves.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Brand Part Number
Sierra 18-3673
GLM 13270
OMC 434841
OMC 5005440
OMC 437414
OMC 393659
OMC 377148
OMC 377612
OMC 378065
OMC 321897
OMC 332369
OMC 318395
OMC 321692
OMC 317245

Compatible Engine Models

Confirm your engine model/year in the table below. For Johnson/Evinrude owners, here’s a guide to help you identify your engine’s serial/model: Johnson/Evinrude Serial Number Guide.

Brand Model Rated HP Stroke Years OEM Part No. Notes
Johnson/Evinrude V4 Crossflow 65 2-Stroke 434841 Not explicitly mentioned in all sources
Johnson/Evinrude V4 Crossflow 80 Jet 2-Stroke 1994-1995 434841
Johnson/Evinrude V4 Crossflow 85 2-Stroke 1978-1980, 1993-1995 434841
Johnson/Evinrude V4 Crossflow 88 2-Stroke 1987-1995 434841
Johnson/Evinrude V4 Crossflow 90 2-Stroke 1981-1995 434841 Includes 1994 Jet model
Johnson/Evinrude V4 Crossflow 100 2-Stroke 1979-1980, 1990-1995 434841 Includes Commercial 1984-1995
Johnson/Evinrude V4 Crossflow 110 2-Stroke 1985-1989 434841
Johnson/Evinrude V4 Crossflow 112 2-Stroke 1994-1995 434841
Johnson/Evinrude V4 Crossflow 115 2-Stroke 1977-1995 434841 Model 115790S only for 1977; All Crossflow models 1978-1995
Johnson/Evinrude V4 Crossflow 140 2-Stroke 1978-1985 434841

Technical Specifications

Specification Value
Product Type Marine Outboard Thermostat Kit
Installation Direct OEM replacement
Thermostat Temperature 143°F (62°C)
Engine Type V4 Crossflow
Housing Material Stainless Steel (thermostat)
Operating Temperature 143°F (62°C) opening temperature
Warranty 1 Year (YiheoZux brand)
Other Technical Attributes For dual thermostat system

Package Contents

  • 2 x Stainless thermostats (143°F)
  • 2 x Thermostat base seals
  • 2 x Poppet valves
  • 2 x Poppet seat seals
  • 2 x Poppet springs
  • 2 x Gaskets

Installation Guide

  1. Ensure the engine is off and cool. Disconnect the negative battery cable for safety.
  2. Locate the thermostat housings on the engine cylinder heads.
  3. Place a drain pan under the engine and carefully remove the housing covers and gaskets.
  4. Note the orientation of the old thermostats and poppet assemblies before removing them.
  5. Clean all mating surfaces of any old gasket material or corrosion.
  6. Install the new poppet valves, springs, and seals into the housings.
  7. Install the new thermostats, ensuring they are seated correctly, followed by the new gaskets.
  8. Securely fasten the housing covers.
  9. Reconnect the battery cable, start the engine, and check for any leaks around the housings.
  10. Monitor the engine temperature to ensure it operates within the normal range.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my V4 engine?

A: This kit is specifically for V4 Crossflow models. It will not fit 60° V6/V8 or Looper engines. Please check your engine model and year against the compatibility table. Cross-referencing your existing part number with the numbers provided (e.g., Sierra 18-3673, OMC 434841) is the most reliable method.

Q: Why does this kit include two of everything?

A: The Johnson/Evinrude V4 Crossflow engines covered by this kit use a dual thermostat system, with one thermostat assembly per cylinder bank. This kit includes all necessary components to service both sides.

Q: What are the common signs of a failing thermostat?

A: A thermostat stuck open will cause the engine to run too cool, leading to poor fuel efficiency and carbon buildup. A thermostat stuck closed will cause the engine to overheat, which can result in serious damage. An erratic temperature gauge is also a common indicator.

Q: OEM vs. Aftermarket?

A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?

A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?

A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

  • Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
  • This product is an aftermarket replacement part and is not an OEM component.
  • Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

  • Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
  • Fast Global Shipping: Free delivery worldwide in 5–15 days.
  • Direct from Manufacturer: Competitive pricing without compromising quality.

We can ship to virtually any address in the world with free shipping available for most regions.

For our typical US and Canadian customers , our shipping timeframes are as follows:

  • Amazon FBA: orders will be delivered within 1-5 business days after placing the order (during certain special periods such as major promotions, Christmas, etc., the delivery time of Amazon FBA may be affected).
  • US warehouse shipment: orders will be delivered within 5 days after placing the order.
  • China warehouse shipment: orders will be delivered about 12 days after placing the order.

When you place an order, we will estimate shipping and delivery dates for you based on the availability of your items and the shipping options you choose. Depending on the shipping provider you choose, shipping date estimates may appear on the shipping quotes page.

Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.

Founded in 2002, JLM Marine has established itself as a dedicated manufacturer of high-quality marine parts, based in China. Our commitment to excellence in manufacturing has earned us the trust of top marine brands globally.

As a direct supplier, we bypass intermediaries, which allows us to offer competitive prices without compromising on quality. This approach not only supports cost-efficiency but also ensures that our customers receive the best value directly from the source.

We are excited to expand our reach through retail channels, bringing our expertise and commitment to quality directly to boat owners and enthusiasts worldwide.

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