Yanmar Cooler Gasket 129693-44420 — 4JH Series Marine Diesel Engine
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Yanmar Cooler Gasket 129693-44420
This genuine Yanmar OEM cooler gasket seals the heat exchanger or oil cooler assembly on 4JH series marine diesel engines. The cooler circuit operates under sustained heat and pressure cycling — conditions that quickly expose any compromise in gasket integrity. Using the correct OEM gasket ensures the right material composition, thickness, and cut profile to maintain a leak-free seal at the cooler mating surfaces.
This gasket is a standard replacement item during heat exchanger cleaning, raw water circuit service, or any time the cooler assembly is opened. Never reuse a previously compressed gasket — it will not re-seal reliably.
Part Details
- Part Number: 129693-44420
- Brand: Yanmar
- Type: Cooler / Heat Exchanger Gasket
- System: Cooling System — Heat Exchanger / Oil Cooler
- OEM / Aftermarket: Genuine OEM
- Engine Family: Yanmar 4JH Series Marine Diesel
Compatible Applications
- Yanmar 4JH series marine diesel engines
- Verify fitment using your engine model and serial number against the Yanmar parts diagram for your specific 4JH variant (4JH2, 4JH3, 4JH4, 4JHE, 4JH-TE, 4JH-HTE, 4JH-DTE)
- Consult your Yanmar service manual to confirm cooler position and gasket part number before ordering
Service Interval
- Replace any time the heat exchanger or cooler is disassembled — never reuse a previously installed gasket
- Inspect for coolant or oil seepage at every scheduled service (250 hours or annually)
- Replace immediately if weeping or staining is observed at the cooler joint
- Recommended replacement during annual winterization or spring commissioning if the cooler has been opened
Related Parts
- Yanmar Water Pump Gasket 129486-42050 — OEM cooling system seal for 4JH series
- Yanmar Thermostat Gasket 129150-49811 — thermostat gasket for 4JH series engines
- Yanmar OEM Coolant Filler Cap — 4JH Series 129673-44131 — cooling system service item
- Yanmar Genuine Coolant YG30R — OEM antifreeze/coolant for Yanmar marine diesels
- Yanmar Cooler Gasket 127881-18180 — cooler gasket for other Yanmar engine families
Technical FAQ
Q: Can I reuse this gasket if the cooler was only briefly opened?
A: No. Cooler gaskets compress and conform on first installation. Even brief disassembly breaks the seal. Always fit a new gasket on reassembly.
Q: Should I use sealant with this gasket?
A: Yanmar OEM gaskets are generally installed dry. Do not add RTV or thread sealant unless your Yanmar service manual specifically calls for it at this joint.
Q: What causes cooler gaskets to fail prematurely?
A: The most common causes are improper torque sequence, reuse of old gaskets, contaminated or corroded mating surfaces, and coolant system overpressure from a failing pressure cap.
Q: How do I confirm this is the correct gasket for my engine?
A: Cross-reference your engine model and serial number with the Yanmar parts diagram for your specific 4JH variant. Serial number determines which sub-variant and parts revision applies.
Parts Desk Insights
This gasket is most commonly needed during heat exchanger cleaning — a service that should happen every 1–2 years on a saltwater-cooled engine to clear scale and debris from the raw water side. When you pull the heat exchanger end caps or disassemble the cooler stack, this gasket needs to come out with it. The most common mistake is trying to reuse the old gasket or skipping the gasket entirely and using RTV — neither holds up under the pressure and temperature cycling of a marine diesel cooling circuit. If you're doing a full cooling system service, order the thermostat gasket and water pump gasket at the same time so you're not making a second trip for parts mid-job.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
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