SKU: 49012935796

129940-42310E V Belt for Yanmar 4JH3-HTZA 4JH3-HTZ1 4JH3-HTZAY 4JH3-HT 3JH3 4JH3-HTZY1 3JH3Z1 3JH30A 3JH3Z 4JH3-DT 4JHYE 4JH3 4JH3-DTZA 4JH3-T 4JH3-T1 4JH3-TZA 4JH3-DTZ 4JH3-DTZAY 3JH25A 4JH3-TZAY 3JH3Z2 4JH3ZA | JLM Marine

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Description

129940-42310E V Belt for Yanmar 4JH3-HTZA 4JH3-HTZ1 4JH3-HTZAY 4JH3-HT 3JH3 4JH3-HTZY1 3JH3Z1 3JH30A 3JH3Z 4JH3-DT 4JHYE 4JH3 4JH3-DTZA 4JH3-T 4JH3-T1 4JH3-TZA 4JH3-DTZ 4JH3-DTZAY 3JH25A 4JH3-TZAY 3JH3Z2 4JH3ZA | JLM MarineV Belt for Yanmar 4JH3 HTZA 4JH3 HTZ1 4JH3 HTZAY 4JH3 HT 3JH3 4JH3 HTZY1 3JH3Z1 3JH30A 3JH3Z 4JH3 DT 4JHYE 4JH3 4JH3 DTZA 4JH3 T 4JH3 T1 4JH3 TZA 4JH3 DTZ 4JH3 DTZAY 3JH25A 4JH3 TZAY 3JH3Z2 4JH3ZA This V Belt is engineered for reliable performance in Yanmar 4JH3, 3JH3, and 3JH25A series marine inboard engines. Designed to meet the demanding conditions of marine applications, this belt ensures smooth power transmission and long lasting durability for

V Belt for Yanmar 4JH3-HTZA 4JH3-HTZ1 4JH3-HTZAY 4JH3-HT 3JH3 4JH3-HTZY1 3JH3Z1 3JH30A 3JH3Z 4JH3-DT 4JHYE 4JH3 4JH3-DTZA 4JH3-T 4JH3-T1 4JH3-TZA 4JH3-DTZ 4JH3-DTZAY 3JH25A 4JH3-TZAY 3JH3Z2 4JH3ZA

This V Belt is engineered for reliable performance in Yanmar 4JH3, 3JH3, and 3JH25A series marine inboard engines. Designed to meet the demanding conditions of marine applications, this belt ensures smooth power transmission and long-lasting durability for your engine's auxiliary systems.

This aftermarket replacement directly substitutes Yanmar OEM part numbers 129940-42310E and 25152-004400, providing a cost-effective solution without compromising on quality or fit.

  • Precision-engineered for exact OEM fitment on Yanmar marine engines
  • Durable construction designed to withstand marine environment conditions
  • Simple installation process with standard belt replacement procedures

Part Number Cross-Reference

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

Brand Part Number
Yanmar 129940-42310E
Yanmar 25152-004400

Compatible Engine Models

Confirm your engine model/year in the table below.

Brand Model
Yanmar 4JH3-HTZA
Yanmar 4JH3-HTZ1
Yanmar 4JH3-HTZAY
Yanmar 4JH3-HT
Yanmar 3JH3
Yanmar 4JH3-HTZY1
Yanmar 3JH3Z1
Yanmar 3JH30A
Yanmar 3JH3Z
Yanmar 4JH3-DT
Yanmar 4JHYE
Yanmar 4JH3
Yanmar 4JH3-DTZA
Yanmar 4JH3-T
Yanmar 4JH3-T1
Yanmar 4JH3-TZA
Yanmar 4JH3-DTZ
Yanmar 4JH3-DTZAY
Yanmar 3JH25A
Yanmar 4JH3-TZAY
Yanmar 3JH3Z2
Yanmar 4JH3ZA

Package Contents

Your package includes the following components:

  • 1 × V Belt

Installation Guide

  1. Ensure the engine is completely shut down and cooled before beginning any work. Disconnect the battery to prevent accidental starting.
  2. Locate the V belt on your Yanmar engine, typically running between the crankshaft pulley and alternator or other auxiliary components. Take note of the belt routing path.
  3. Release tension on the belt by loosening the adjustment bolt on the alternator or tensioner pulley. Move the component toward the engine to create slack.
  4. Remove the old V belt from all pulleys, inspecting the pulleys for wear, damage, or debris. Clean pulley grooves if necessary.
  5. Route the new V belt around all pulleys following the exact path of the original belt. Ensure the belt is properly seated in all pulley grooves.
  6. Adjust the tensioner or alternator position to apply proper tension to the belt. The belt should deflect approximately 10-15mm (⅜"-⅝") when pressed midway between pulleys.
  7. Tighten all adjustment bolts securely once proper tension is achieved. Double-check that the belt is centered on all pulleys.
  8. Reconnect the battery and start the engine. Listen for any unusual noises and observe the belt operation for proper tracking.
  9. After the first few hours of operation, re-check belt tension and adjust if necessary as new belts may seat and stretch slightly.

Troubleshooting & FAQ

Q: How do I confirm this V belt fits my Yanmar engine?
A: Cross-reference your engine model number with our compatibility table above. Additionally, verify that your original belt matches OEM part numbers 129940-42310E or 25152-004400. If your model is listed but you notice any discrepancies in belt dimensions, contact us before purchasing.

Q: How often should I replace the V belt on my Yanmar engine?
A: V belts should be inspected every 100 operating hours and typically replaced every 500-1000 hours or annually, whichever comes first. Replace immediately if you notice cracking, glazing, fraying, or excessive wear. Regular inspection prevents unexpected failures.

Q: What are the signs that my V belt needs replacement?
A: Common warning signs include squealing noises (especially during startup or acceleration), visible cracks or fraying on the belt surface, glazing or shiny appearance, alternator/charging issues, or belt slippage. If you notice any of these symptoms, inspect and replace the belt promptly.

Q: What's the difference between this aftermarket belt and the original Yanmar OEM belt?
A: This aftermarket V belt is manufactured to OEM specifications using comparable-grade materials in an ISO9002-certified facility. It provides the same fit, function, and durability as the OEM part at a more competitive price point, making it an excellent value for routine maintenance.

Q: Is this an OEM part or an aftermarket replacement?
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.
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: 49012935796

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A
Arty
Natrona Heights, US
★★★★★ 4
Boys vest
Color: Black, Size: 8
The vest looks nice. It seems well made and looks high quality. The fabric is nice. The buttons seem very sturdy. The vest is lightweight and shouldn’t be too sweaty. It’s a nice versatile piece. Can be dressed up or down. The fit is a smidge awkward on my boys, but they still like it.
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Reviewed in the United States on April 19, 2026
Q
QueenofAwkward
Port Orchard, US
★★★★★ 5
Looks very nice and sizing is right
Color: Navy Blue, Size: 14, Color: Navy Blue, Size: 14
I ordered this for my 13-year-old who currently wears a size 12-14. He's closer to the 12, but has enough clothes in that size, so I ordered the 14 in navy blue. He chose the color, although it took him a while to decide. My kids so far have preferred not to go to school dances or dressier school functions, but I try to keep an outfit on hand in case they need it, and he does have to dress up a little for school band performances. He doesn't really have any kind of clothing preferences (yet), and is just as likely to look dressed up as he is to wear something completely wrinkled (but clean). This vest fits as expected. It is a bit large on him to the same degree that the other size 14 clothes he has are. He is pretty skinny, so while I think it would fit someone who is more average sized, I'm not sure how well it will do on huskier sizes. It has a nice buckle on the back as most men's vests like these have, so it can be adjusted in that sense. The navy color is a bit of a brighter shade than your average navy, but not outside of the normal range for navy. I like it. It’s hard to get the exact color in pictures. The fabric and construction both seem to be good quality. The fabric feels average compared to my husband's dress vests, better than the lower quality/cheaper ones and not quite as nice as the ones he spent more on. This boy's dress vest is currently being sold for approximately $20, which I think is great for a nice dress vest like this.
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Reviewed in the United States on February 27, 2026
C
C. Snyder
Omaha, US
★★★★★ 5
"Navy Vest & Pocket Square Charm; Formal Polish for Perfect Pairing
Color: Navy Blue, Size: 8, Color: Navy Blue, Size: 8
This very charming boys navy blue vest pairs perfectly with the accompanied pocket square, adding formal charm to dockers or navy khakis. My boys look dapper in matching sets. A timeless style that elevates any outfit. Made with quality fabric that appears to resist wrinkles, with the pocket square folding neatly for that polished touch. Comfortable and event ready.
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Reviewed in the United States on April 14, 2026
S
sunflower
Dallas, US
★★★★★ 5
Adorable boys vest! Dress up or down!
Color: Light Gray, Size: 5, Color: Light Gray, Size: 5
Super cute vest! Made of quality materials. The buttons on the front all work very well. My four year old can easily button and unbutton them himself. All 3 pockets in the front are functional cute little pockets. There are vertical line stitchings making this vest look just like dad's. The back is easily adjustable. I will stay I was nervous it was going to be too big for my almost 4 year old - I ordered the smallest size available, size 5 and it actually fits him perfectly. In fact, I could even have gotten him the size 6 and it would have fit so I recommend to size up. It's a breathable vest. The gray color goes with lots of other colors. It's an adorable vest. You can dress it up with a nice suit or dress down. It's adorable with a t shirt and jeans. The inside back is a nice silky material. This vest is very well made - its thick but breathable and a great value for the dollar. I highly recommend.
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Reviewed in the United States on March 6, 2026
S
Sweet_Gato
Boise, US
★★★★★ 5
Perfect Fit and Amazing Quality – Highly Recommend!
Color: Black, Size: 12, Color: Black, Size: 12
I am absolutely thrilled with this boys’ formal vest! The size was spot on—it fit perfectly without being too tight or too loose, which can be hard to find for kids’ dress clothes. The material feels premium, soft yet structured, and it looks much more expensive than it actually is. I ordered it for a wedding where my son was the ring bearer, and it photographed beautifully. It gave him such a classy, well-dressed look while still allowing him to move comfortably through the day. The stitching and finish are top-notch, and the color stayed vibrant even after washing. It paired perfectly with a white shirt and dress pants we already had. I also appreciate how versatile it is—it’ll be great for Easter, family photos, or any other special occasion. Overall, I’m extremely happy with the quality, fit, and style of this vest. Definitely a 5-star purchase that I would buy again without hesitation!
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Reviewed in the United States on March 6, 2026

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