Coolant leaks Yanmar H460

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   Really helpful contributor Keakaka recently advised that he had coolant loss on his H460
"We have one ongoing issue with the Yanmar 80 hp losing a small amount of coolant maybe 10mm over 5 hours running. The service agent says it is normal for these motors and the pressure test is okay. 
We have over 30 days and 1000Nm on it with no major issues." 

Is it normal? Have other owners also had the same experience?  Are the dealers saying the same thing?

Cheers
J

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460AUS Members Profile Send Private Message Find Members Posts Add to Buddy List Lieutenant Joined: 21 June 2024 Status: Offline Points: 46	Post Options Post Reply Quote 460AUS Report Post Thanks(0) Quote Reply Topic: Coolant leaks Yanmar H460 Posted: 31 March 2025 at 04:44
	Really helpful contributor Keakaka recently advised that he had coolant loss on his H460 "We have one ongoing issue with the Yanmar 80 hp losing a small amount of coolant maybe 10mm over 5 hours running. The service agent says it is normal for these motors and the pressure test is okay. We have over 30 days and 1000Nm on it with no major issues." Is it normal? Have other owners also had the same experience? Are the dealers saying the same thing? Cheers J

Typ2003 Members Profile Send Private Message Find Members Posts Add to Buddy List Sub Lieutenant Joined: 22 January 2025 Status: Offline Points: 12	Post Options Post Reply Quote Typ2003 Report Post Thanks(1) Quote Reply Posted: 31 March 2025 at 15:16
	Hello You must be worried a lot. There may be bubbles in the cooling line in the newly assembled engine. Check it continuously. Watch after sailing a few times. If it keeps decreasing, there's a problem. If there was no problem with the pressure test on the cooling line, the cooling water would not continue to decrease.

mr-ludi Members Profile Send Private Message Find Members Posts Add to Buddy List Captain Joined: 25 September 2022 Status: Offline Points: 152	Post Options Post Reply Quote mr-ludi Report Post Thanks(1) Quote Reply Posted: 31 March 2025 at 20:25
	I have about 50 hours on my 4JH80 and didn‘t notice any coolant loss.

Tranquillity Members Profile Send Private Message Find Members Posts Add to Buddy List Captain Joined: 01 December 2018 Location: Hamble, UK Status: Offline Points: 267	Post Options Post Reply Quote Tranquillity Report Post Thanks(1) Quote Reply Posted: 02 April 2025 at 21:29
	On our 418, sailed/motored from the factory to the UK without issue by then 90 hours on engine but the first time we took her out in a really big sea state motoring in waves the coolant had a serious drop which worried us as we had a 60 mile offshore passage the following day. The dealer reassured us this is normal on new engines and it was ! It has never been an issue since, 800 hour engine hours later all good and was put down to getting all the air out the system.

marsella Members Profile Send Private Message Find Members Posts Add to Buddy List Rear Admiral Joined: 21 June 2022 Location: Antigua Jolly H Status: Offline Points: 592	Post Options Post Reply Quote marsella Report Post Thanks(1) Quote Reply Posted: 02 April 2025 at 23:23
	I also had some coolant disappearing when i got my new 458 with 4JH57, probably during first 100 hours or so (had to add a liter of coolant) but after that the coolant level remains stable (300 hours now)

Darek Members Profile Send Private Message Find Members Posts Add to Buddy List Sub Lieutenant Joined: 16 January 2024 Location: Sweden Status: Offline Points: 18	Post Options Post Reply Quote Darek Report Post Thanks(0) Quote Reply Posted: 09 April 2025 at 20:39
	I experienced the same last season. It was the first season, I refilled in total 1 liter and bought already another 1 liter just in a case. I didn’t think it might be a problem. Thanks for bringing it up. I will observe it from now on more carefully. Every time I refilled a little I checked around the engine and couldn’t find any sign of leakage. But I agree it looks strange. 4JH57 is my engine.
	Darek "Summertime" Hanse 460 #92



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