Yanmar Marine Seawater Pump Flow Loss
The YANMAR-SALTWATER-PUMP (Yanmar) diesel fault code means: Yanmar Marine Seawater Pump Flow Loss. This is a critical severity code.
Unverified. We could not confirm this code's definition against freely available manufacturer documentation, so treat the meaning, severity and fix guidance on this page as unconfirmed. Check it against the manufacturer's service information for your exact model and serial range before acting on it. This page is kept out of search engines for that reason, and we are working through this family manual by manual.
- Keep driving?
- No — stop driving
- DIY difficulty
- intermediate
- Estimated cost
- $40-$600
What Are the Symptoms of YANMAR-SALTWATER-PUMP?
- No water from exhaust elbow
- Overheat alarm pending
What Causes YANMAR-SALTWATER-PUMP? (Most Likely First)
- Failed impeller (annual service item) Very Likely
- Worn pump cover plate Likely
- Seized pump shaft Possible
Can I Still Drive with YANMAR-SALTWATER-PUMP?
No — stop driving. YANMAR-SALTWATER-PUMP is rated critical severity. Continuing to drive in this state risks further damage — get it looked at before your next trip.
Frequently Asked Questions
What is Yanmar code MARINE-SW-PUMP?
Yanmar MARINE-SW-PUMP: Yanmar Marine Seawater Pump Flow Loss. This code is reported on Yanmar equipment running the described engine family.
Can I keep working with Yanmar code MARINE-SW-PUMP?
Do not continue operating. Risk of engine damage or unsafe shutdown.
How much does Yanmar MARINE-SW-PUMP cost to fix?
Estimated repair cost: $40-$600. Off-road diesel shop labor runs $125-$175/hr in 2026. Dealer diagnostic software (Yanmar SmartAssist / YDT) is usually required.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose YANMAR-SALTWATER-PUMP?
Close seacock.
Remove pump cover, inspect impeller and cover plate.
Replace impeller and gasket; lubricate with glycerin only (petroleum attacks rubber).
Which Vehicles Commonly Get YANMAR-SALTWATER-PUMP?
- Hunter / Beneteau / Catalina sailboats with Yanmar 3JH / 4JH
- Trawlers and sport fishing boats with Yanmar 6LY / 6LF series
- Sailboat auxiliaries with Yanmar 2YM / 3YM / 3JH5 diesels
- Commercial fishing vessels with Yanmar 6LY3-UTP
- Yachts with Yanmar 6LY400 / 6LY440 / 8LV common-rail marine diesels
- Workboats with Yanmar 4LV / 4JH series marine propulsion
- Ski boats and express cruisers with Yanmar marine diesels
- Tenders and RIBs with Yanmar 3YM20 / 3YM30 sailboat aux
- Island-hopper ferries with Yanmar 6AYM / 6HYM commercial series
- Tug boats and small workboats with Yanmar 6HAL-HTP / 6HYM
Explore More
Was this helpful?
Send this to whoever is fixing the truck — your tech, or the person asking what the fault means.