SKU: 11486502571

Thermostat 71°C (159.8°F) – Fits Yanmar Marine 2GM/3GM Series (Replaces 121750-49800)

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Description

Thermostat 71°C (159.8°F) – Fits Yanmar Marine 2GM/3GM Series (Replaces 121750-49800)Thermostat 71C (159. 8F) Fits Yanmar Marine 2GM 3GM Series (Replaces 121750 49800) This thermostat is designed for Yanmar's 2GM and 3GM series of small marine diesel engines, typically ranging from 830 HP. It ensures your engine maintains the correct operating temperature for optimal performance and efficiency. This part is a direct replacement for the following OEM and aftermarket part numbers: Yanmar 121750 49800, Worldthump 121750 49800, Sogoparts

Thermostat 71°C (159.8°F) – Fits Yanmar Marine 2GM/3GM Series (Replaces 121750-49800)

This thermostat is designed for Yanmar's 2GM and 3GM series of small marine diesel engines, typically ranging from 8–30 HP. It ensures your engine maintains the correct operating temperature for optimal performance and efficiency.

This part is a direct replacement for the following OEM and aftermarket part numbers: Yanmar 121750-49800, Worldthump 121750-49800, Sogoparts 121750-49800, and ZDCBMDB 121750-49800.

  • Rated Temperature: 71°C (159.8°F) opening temperature
  • Installation: Direct replacement with no modification required
  • Quality: OEM quality aftermarket part

Part Number Cross-Reference

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

Brand Part Number
Yanmar 121750-49800
Worldthump 121750-49800
Sogoparts 121750-49800
ZDCBMDB 121750-49800

Compatible Engine Models

Confirm your engine model/year in the table below.

Brand Model Rated HP Stroke OEM Part No.
Yanmar 2GM20F 20 4-Stroke 121750-49800
Yanmar 2GM20F-YEU 20 4-Stroke 121750-49800
Yanmar 2GMF 4-Stroke 121750-49800
Yanmar 3GM30F 30 4-Stroke 121750-49800
Yanmar 3GM30F-YEU 30 4-Stroke 121750-49800
Yanmar 3GMDF 4-Stroke 121750-49800
Yanmar 3GMF 4-Stroke 121750-49800
Yanmar 3HM35F 35 4-Stroke 121750-49800
Yanmar 3HMF 4-Stroke 121750-49800

Technical Specifications

Specification Value
Product Type Thermostat
Installation Direct replacement, no modification required
Rated Temperature 71°C (159.8°F)
Connection Direct fit to thermostat housing
Housing Material Metal
Dimensions Compact design for marine application
Operating Temperature 71°C (159.8°F) opening temperature
Other Technical Attributes OEM quality replacement part

Package Contents

1 x Thermostat (121750-49800)

Installation Guide

  1. Ensure the engine is completely cool before starting.
  2. Locate the thermostat housing on the engine block. It's usually where the main coolant hose connects.
  3. Place a drain pan underneath to catch any spilled coolant.
  4. Carefully remove the bolts securing the thermostat housing cover.
  5. Lift the cover and remove the old thermostat. Note its orientation.
  6. Clean the mating surfaces of the housing and cover, removing any old gasket material.
  7. Install the new thermostat in the same orientation as the old one.
  8. Place a new gasket (if required, sold separately) and reinstall the housing cover.
  9. Tighten the bolts to the manufacturer's specified torque. Do not overtighten.
  10. Refill the cooling system with the appropriate coolant.
  11. Start the engine and check for leaks around the housing as it comes up to temperature.

Troubleshooting & FAQ

How do I confirm this part fits my engine?
Cross-reference your engine's original thermostat part number with the numbers listed in the "Part Number Cross-Reference" table. Also, verify your engine model is included in the "Compatible Engine Models" list.

What are the signs of a bad thermostat?
Common symptoms include engine overheating, running too cold (not reaching operating temperature), erratic temperature gauge readings, and potential coolant leaks from the housing.

How often should I replace my marine engine's thermostat?
While there is no fixed interval, it is good practice to inspect it during regular cooling system service or replace it proactively every few years, especially if operating in saltwater.

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:
  1. 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
SKU: 11486502571

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4.5 ★★★★★
Based on 8 reviews
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Verified Purchase
Jeremy Elston
San Leandro, US
★★★★★ 4
Fun, enticing dog toy. As stated in description it won’t hold up for aggressive chewers
Color: Blue
Rating this based on description. My dog loved this toy. It was smaller than I had pictured in my head, but that was on me. I did read the description ahead of time, which clearly states this is not for aggressive chewers. My dog is trained not to rip toys apart so I wanted to give this a shot, but i guess just her jaw strength and teeth were too much. She carried it everywhere. I turned it on periodically. The movements are small, but enough for her to be captivated with the toy. It did mostly survive for about a day before I needed to take it away due to the Velcro opening. Once it started to pull apart she did chew a piece of the Velcro off. It might be helpful with a flap over design covering the Velcro. I have a singing Santa decoration like this where the Velcro is covered up and I have to pull it back a little to get to the Velcro opening. The gaps on the sides of the closure are a bit to large making it tempt my dog to pull and open it up. I wish there was a more durable option that could hold up to aggressive chewers, but this product was clear about that in the description. I think the opening to the batteries could use some improvement. Granted I do not have the perfect answer to fix this, but I am also not a toy designer.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 19, 2026
A
Verified Purchase
Amazon Customer
Natrona Heights, US
★★★★★ 5
My Dog Went Crazy Over This Electric Octopus Toy!
Color: Blue
I was worried sick my fur kid would be super bored home alone while I work, so when I stumbled on this electric octopus toy, I grabbed it right away—and it’s way better than I expected! Let’s start with the quality: the plush fabric feels soft and squishy but so sturdy. It’s not the cheap kind that sheds fur if you tug it, and the stitches are nice and neat. My dog loves chewing on toys, and he’s been playing with this for almost two weeks now—no pilling, no fraying. The durability’s seriously on point. Using it is totally hassle-free, too. It was already charged right out of the box—I just pressed the little button on the side, and it started moving. It has two modes: slow mode makes the octopus wiggle gently, like it’s crawling slowly. Fast mode? It wiggles and scurries around, and the speed’s perfect—my dog can keep up but still has to work a little. When he first saw it, he circled it three times, sniffed it, then backed up right away. He stared at it all cautious, even hid under the couch to spy on it for a bit. That little look was so funny and cute, I couldn’t stop laughing. Now they’re total best buds! Every morning, as soon as I turn the toy on, he runs over with his little bed in his mouth and plops down next to it, waiting for it to move. Sometimes the octopus crawls under the table, and he’ll paw at it for ages. If he can’t reach it, he’ll look up and bark at me like, “Hey, help me get it!” Watching him chase it around, jumping to pounce—his tail wags like a little flag the whole time. It makes the house feel so much livelier, and I don’t have to stress about him being lonely when he’s home alone anymore. Quick tips for all you fellow pet parents: First, the toy makes a tiny motor hum when it moves. It’s not loud, but if your dog’s super skittish or scared of small noises, give him a few days to get used to it. Second, always keep an eye on him while he plays. Mine tried to bite off one of the octopus’s tentacles once—I stopped him just in time. The toy has a motor inside, so you gotta make sure he doesn’t swallow any small parts. Oh, and the plush cover zips off! If it gets dirty, just throw it in warm water, wash it, and once it’s dry, it looks good as new. Super easy to clean. Overall, this electric octopus toy’s the best pet buy I’ve made lately. Great quality, no hassle to use, and it keeps my dog entertained for hours. Every time I see my fur kid’s happy little face while he plays, I think, “Man, this was totally worth the money.” Def recommend it to anyone who wants a fun little buddy for their dog!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on August 26, 2025
A
Verified Purchase
Amazon Customer
Fort Morgan, US
★★★★★ 5
Good quality and safe for my pet! Lots of fun to play with!
Color: Blue
Worth buying for your pet! My American Bulldog wouldn’t leave it alone !
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on June 11, 2026
K
Verified Purchase
Karyn Bennett
Waukegan, US
★★★★★ 4
Super fun but fabric not durable for rough play.
Color: Blue
My dog absolutely love this, but the octopus cloth fell apart within the first day. He doesn’t usually play rough with his toys, but he was able to shred this octopus fabric very easily. He was very passionate in his playfulness and he’s a big dog, but he was able to put massive holes in the fabric within the first hour of play. The Ball still works, however so hopefully we can find another toy to stick it in.
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Reviewed in the United States on May 8, 2026
B
Verified Purchase
Brady Perry
Charlottesville, US
★★★★★ 5
My dog's favorite toy to date
Color: Blue
Heavy duty material that my dog has not destroyed. The vibrating ball inside is made of hard plastic, so beware if your dog likes to shake their toys, it definitely hurts to get whacked by this. The velcro keeping the ball inside is also heavy duty and takes a lot of strength to open. All in all, its a great toy and one of my dog's favorites.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on June 10, 2026

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