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Description
Thermostat (60°C/140°F) – Fits Mercury/Mariner 75-225 HP Outboard Engines (Replaces 8M0175321, 855676004, 8M6010296)Thermostat (60C 140F) Fits Mercury Mariner 75 225 HP Outboard Engines This thermostat is designed for a direct fit on Mercury and Mariner outboard engines, including 75 HP, 80 HP, 90 HP, 100 HP, and 225 HP 4 stroke models. It is compatible with specific models based on the serial number ranges provided in the compatibility table. This component directly replaces Mercury part numbers 855676004, 8M0175321, 8M6010296, 8556761, and Sierra 18 3632.
Thermostat (60°C/140°F) – Fits Mercury/Mariner 75-225 HP Outboard Engines
This thermostat is designed for a direct fit on Mercury and Mariner outboard engines, including 75 HP, 80 HP, 90 HP, 100 HP, and 225 HP 4-stroke models. It is compatible with specific models based on the serial number ranges provided in the compatibility table.
This component directly replaces Mercury part numbers 855676004, 8M0175321, 8M6010296, 8556761, and Sierra 18-3632.
- Engineered for direct OEM replacement to ensure proper fit and function.
- Maintains optimal engine temperature with a specified 60°C (140°F) opening temperature.
- Constructed with a durable brass and stainless steel housing for corrosion resistance in marine environments.
Part Number Cross-Reference
Use this table to confirm equivalent part numbers across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Mercury | 855676004 |
| Mercury | 8M0175321 |
| Mercury | 8M6010296 |
| Mercury | 8556761 |
| Sierra | 18-3632 |
Compatible Engine Models
Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.
| Brand | Model | Rated HP | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Mercury | Outboard | 75 | 4-Stroke | 855676004/8M0175321/8M6010296 | CARB models (Serial 0G960500 through 1B226999) |
| Mercury | Outboard | 75 | 4-Stroke | 855676004/8M0175321/8M6010296 | EFI models (Serial 0G1B172291 through 1B366822) |
| Mercury | Outboard | 80 | 4-Stroke | 855676004/8M0175321/8M6010296 | EFI models (Serial 1B227000 through 1B366822) |
| Mercury | Outboard | 90 | 4-Stroke | 855676004/8M0175321/8M6010296 | CARB models (Serial 0G960500 & Up) |
| Mercury | Outboard | 90 | 4-Stroke | 855676004/8M0175321/8M6010296 | EFI models (Serial 1B172291 through 1B366822) |
| Mercury | Outboard | 100 | 4-Stroke | 855676004/8M0175321/8M6010296 | EFI models (Serial 1B227000 through 1B366822) |
| Mercury | Outboard | 225 | 4-Stroke | 855676004/8M0175321/8M6010296 | EFI models (Serial 0T653945 & Up) |
Technical Specifications
| Specification | Value |
|---|---|
| Product Type | Marine Engine Thermostat |
| Installation | Direct OEM replacement |
| Temperature Rating | 60°C (140°F) |
| Housing Material | Brass/Stainless Steel |
| Operating Temperature | 60°C (140°F) opening temperature |
| Other Technical Attributes | Designed for closed cooling systems in outboard marine engines |
Package Contents
- 1 x 60°C (140°F) Thermostat (Replaces 855676004/8M0175321/8M6010296)
Installation Guide
- Disconnect Power: Ensure the engine is off and cool, then disconnect the battery terminals to prevent accidental starts.
- Drain Coolant: Place a container under the engine and carefully drain the coolant from the system.
- Locate Housing: Identify the thermostat housing on the engine block. It is typically a metal cover with a coolant hose attached.
- Remove Housing: Loosen and remove the bolts securing the thermostat housing. Gently tap the housing if it's stuck, but avoid prying.
- Remove Old Thermostat: Lift out the old thermostat and its gasket or seal. Note its orientation.
- Clean Surfaces: Thoroughly clean the mounting surfaces of the housing and engine block, removing all old gasket material and corrosion.
- Install New Thermostat: Place the new thermostat into the engine block in the correct orientation. Install the new gasket or seal.
- Reassemble: Re-attach the housing and tighten the bolts to the manufacturer's recommended torque specifications.
- Refill Coolant: Reconnect all hoses and refill the cooling system with the appropriate type and amount of coolant.
- Check for Leaks: Reconnect the battery, start the engine, and let it warm up. Carefully check for any coolant leaks around the housing.
Troubleshooting & FAQ
How do I confirm this fits my engine?
The best way to confirm fitment is by matching your engine's serial number to the ranges listed in the "Compatible Engine Models" table. Also, compare your original part to our product images and the listed OEM replacement numbers (855676004, 8M0175321, 8M6010296) to ensure a match.
What are the symptoms of a failing thermostat?
Common signs include the engine overheating or, conversely, not reaching its proper operating temperature. You may also notice fluctuating temperature gauge readings or poor engine performance.
Why is the 60°C/140°F temperature rating important?
This specific temperature rating ensures your engine warms up quickly and maintains the optimal temperature for efficient combustion, performance, and longevity, as designed by the manufacturer.
OEM vs. Aftermarket?
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.
How fast do you ship and how much does it cost?
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.
What is your warranty and return policy?
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.
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.8 ★★★★★
Based on 2339 reviews
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Product Reviews
★★★★★ 5
Great mouse
Number of Items: 1
Definitely reduces fatigue. Easy to use. Great response with less space needed for mouse movement. Stays charged for months you actually forget to charge it, ask me how I know :). I play video games with it and never have any issues with the movement and response time of mouse. And since my car wreck where I broke my thumb this is the only mouse that gave me the same as before the wreck abilities to move and operate the mouse. Highly recommend. One very broken thumbs up :)
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Reviewed in the United States on May 31, 2026
★★★★★ 4
Experience after one year of usage
Number of Items: 1
I had mainly used a MX Master 2S before this and because of my heavy usage I did start to feel uncomfortable after a few hours of use every day and that's when I decided to purchase MX Vertical. Now after almost 9 months of usage this has become the mouse I use on a daily basis, completely replacing MX Master 2S.
Comfort: It took me about a day or two to really get used to using it because of the positioning and ever since then my wrist has never felt any discomfort, literally. I don't have a mouse pad but because of the angle that my wrist is contact with the desk when I use it, this has never been a problem. What I also love about the ergonomic design is that my hand can actually just rest on it when not doing specific tasks, and it just fits my palm perfectly.
Functionality: I don't use it for gaming so I can't comment on that. However, comparing it with my Master 2S, there are some very obvious disadvantages. If you use Excel sheets a lot, or anything that requires horizontal viewing, the scrolling option is terrible. You can set up the function key on Logi Options+ and I use the side buttons for scroll right+left mainly because how easy it was to use with the Master 2S's side scrolling buttons. It is not comparable at all. With Master 2s, horizontal scrolling is smooth and precise. With this, it's basically useless. There are sites that just aren't responsive to the side buttons and when they do, you can never get to the precise point you want. Huge disappointment with that because I don't really use the side buttons for anything else. There is also no scrolling control with the middle button unlike the Master 2S, so you can't really scroll vertically as fast as you can when using Master 2S either. However I do use the middle button sometimes to just do the job for me so I'm ok with its basic functionality.
The top button is mainly used as a look-up button for me, so far its working pretty well and honestly it probably makes not much difference if they just completely take this button out for me. Maybe some people can find use in it as a switch for scrolling or mouse speed, or something else. Overall, the customizability of these buttons is very good, and depending on personal use, I can see it being very useful.
Battery life: Battery life is fantastic, never had any problem with it yet. I haven't really kept track but with my heavy daily usage (probably 10+ hours with no intense gaming), it can usually go for more than a month. You can also use it while it's being charged.
Durability: I have unfortunately knocked it over the desk a couple times on hard vinyl floor and there seems to be no problem with it at all. Before purchasing this I saw some comments about how it stopped functioning after being dropped to the floor and I was really worried about it. However that is not my case at all. It is very durable in my opinion and does its job perfectly even after dropping it a few times.
Overall, extremely comfortable to use. It helped with my wrist pain tremendously and now I use it for hours without feeling any discomfort. The functionality is severely disadvantageous compared to Master 2s and 3s, and possibly other gaming mouses as well, but if you are here because of wrist pain, this is the right product.
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Reviewed in the United States on May 24, 2024
★★★★★ 5
Finally, a comfortable vertical mouse for guys with large hands!
Number of Items: 1
I've been using the Logitech MX Vertical Wireless Mouse for about 8 years now, and I love it. Any time I have to use a traditional mouse it's an uncomfortable disappointment.
If you haven't used a vertical mouse yet, there are a couple things you need to know.
First - this is just a normal mouse, but it's turned about 60-degrees to the right. This let's your hand rest on the mouse in the natural position your arm wants it to be in without any effort to rotate.
Second - you will knock it over, repeatedly, for a few weeks. Because you're used to a mouse that's a just an inch and a half or so tall, your natural movement from keyboard to mouse is going to be interrupted by the height of the MX Vertical. In time, you will get used to this, but for a week or two, you will knock it over when moving to the mouse, and when moving back to the keyboard. Don't worry, your muscle memory will change and this will stop.
Third - once you get used to using the MX Vertical, you won't want to use any other mouse. It's a dramatic change in ergonomics, and you will feel the strain your wrist and forearm are under any time you have to use a traditional mouse.
There are other verticals that are also great, but as a guy with large hands, this is the best I've found. I have 4 of these now - one at my office, one at my dining room table, one at my desk, and one that travels in my backpack. I don't need all of these, but its handy having them where I need them. Another reason for this is the mouse can pair with 3 devices. I have different devices in each of these locations, so it's handy not having to re-pair when I move between locations.
The MX Vertical fits my hand perfect, and all buttons are where my fingers and thumb are naturally positioned. I've dropped them, knocked them down, bumped and tossed them and they keep on working properly, so from a durability standpoint, this will last. It's easy to pair with a push of a button - working with my Windows computers, MacBook, android phone and iPad. This thing just works great!
The only downside I'd mention is the coating. After a couple of years, the coating tends to migrate where you apply pressure. This is most apparent where the thumb and pinky finger rest. This doesn't cause any functional issues, and is entirely cosmetic, but just be aware that after a couple years it won't look pristine.
All-in-all, this is the vertical mouse to buy if you're a guy with larger hands. Get one, get used to it, and you won't regret it.
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Reviewed in the United States on February 6, 2026
★★★★★ 5
Highly recommend! Best in the market bar none
Number of Items: 1
I would like to say this is the perfect mouse and probably the best mouse you could buy on the market and it doesn't even come close. You can modify the mouse however you like with a click on the app. It's truly been a life changing experience with this mouse. With that being said, the perfect mouse does have a few flaws but nothing that would make me not recommend it to anyone only just be aware of these things. 1. It's a vertical mouse, sometimes it gets in the way and your wrist will knock it over, it will happen I promise you. 2. Logitech has a Flow feature meaning you can connect the mouse to three different computers at once if need be, qyeah I'll say it again, three computers connection! Wow! Well I only use it for two computers, the Flow works flawlessly but my gripe is how it sometimes doesn't sync with my Logitech keyboard Ergo K860, unfortunately, the keyboard doesn't come with the same Flow feature meaning I have to depend on the mouse to do it and it doesn't work sometimes and I have to switch between the mouse transition button to the key board transition button which makes for a long headache sometimes. 3. Believe it or not connection is sometimes an issue, it losses Bluetooth connection often and it doesn't matter which computer I use I have the same issues at work and home so I use the dongle for straight connection. Oh wait there are issues with the dongle connection too? Say it ain't so? It is! The issue comes when you have two dongles like me, the keyboard and the mouse, and try to connect both, like I said I have two computers and Logitech will not allow for their ”universal dongle” to connect to two different computers at the same time terrible design flaw. 4. Again, this mouse is incredible but it can sometimes be a little too much incredible, I know, I know but hear me out. The mouse is flawless fast, one quick wrist jerk and that mouse pointer on the screen is jumping all over the place, it's been hard to find a happy medium with the pointer, it's either you adjust to slow it down, making it too slow, or adjust to make it fast, which is too fast, again no happy medium even though there are plenty of settings to toggle with. I believe most vertical mouse tend to be that way anyway only with this mouse you can really tell the difference and that could be a good thing or bad thing depending on your perspective, it's sometimes a bad thing for me on Excel sheets. So the final verdict is this is still the best mouse out there and worth every penny and I would still give this 10 stars if possible, it's been a wonderful experience with this mouse. Again, the negatives are not bad or to make someone not buy it and considering the other features this mouse can do I recommend anyone who works all day on a computer to buy this product I highly recommend it.
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Reviewed in the United States on July 28, 2021
★★★★★ 5
Excellent Ergonomic Mouse for Long Workdays
Number of Items: 1
If you spend many hours at a computer and are looking for a comfortable, high-quality mouse, I highly recommend the Logitech MX Vertical. It has made a noticeable difference in my daily comfort and productivity.
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Reviewed in the United States on June 5, 2026