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Coolant leaks Yanmar H460

Printed From: myHanse.com
Category: Hints & Tips
Forum Name: 460
Forum Description: Model Hints, Tips and News
URL: https://www.myhanse.com/forum_posts.asp?TID=15041
Printed Date: 27 March 2026 at 03:51
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Topic: Coolant leaks Yanmar H460

Posted By: 460AUS
Subject: Coolant leaks Yanmar H460
Date 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

Replies:

Posted By: Typ2003
Date 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.

Posted By: mr-ludi
Date Posted: 31 March 2025 at 20:25

I have about 50 hours on my 4JH80 and didn‘t notice any coolant loss.

Posted By: Tranquillity
Date 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.

Posted By: marsella
Date 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)

Posted By: Darek
Date 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.

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Darek "Summertime" Hanse 460 #92