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Post by mesteve on Aug 26, 2021 13:00:49 GMT
We have a slow coolant leak that I witnessed dripping midway back on the port side of the engine. I understand this is where the raw water pump is, but there shouldn’t be coolant through that...
I admittedly have not had a chance to get a closer look with a bright light through the correct access hole, but wanted to ask to see if I’m missing something larger.
cheers
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Post by bereboot on Aug 26, 2021 17:19:43 GMT
We also had a coolant leak. After much searching it was the coolant filler cap which was not completely closing.
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Post by sleighride on Aug 26, 2021 18:56:36 GMT
I replaced all coolant hoses over a year ago and discovered a slow leak that was difficult to locate. I then tightened all hose fittings on the engine(same as yours) and no more leaks!😊 Easiest repair I ever had to make.
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Post by NZL50505 on Aug 26, 2021 20:55:01 GMT
I replaced all coolant hoses over a year ago and discovered a slow leak that was difficult to locate. I then tightened all hose fittings on the engine(same as yours) and no more leaks!😊 Easiest repair I ever had to make. +1
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Post by Mistroma on Aug 26, 2021 22:15:20 GMT
Our 4JH4AE has a leak from the alternator mounting bracket. I removed the bolt years ago and discovered coolant coming out. It seems that Yanmar decided to pass the bolt holding the alternator adjustment arm through a water gallery.
Perhaps you have a different but equally silly design fault. I made up a grommet to insert in the hole and it is mostly squeezed into the hole. Hermetite or sealant solves the leak until the end of the season and it returns when I remove the fan belt. I completely remove the adjusting bolt on the alternator and never touch the bolt on the inner end. No leak is visible but it has always returned by the time I'm ready to launch. It isn't a big leak but is annoying.
I always lift the cap on the expansion tank and leave the dip-leg clear of the coolant after lifting out. I've found that this prevents most of the leakage around the bolt during winter.
The leak is so slow that the source isn't obvious and it tends to appear in a depression on port side above the starter motor. I found it by wedging or taping pieces of kitchen roll to the engine and following the soggy ones.
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Post by Tom on Aug 27, 2021 1:47:36 GMT
We also had a coolant leak. After much searching it was the coolant filler cap which was not completely closing. There's also a much discussed issue with the overflow/high pressure bypass small hose attached to the filler neck just below the filler cap. That can leak but it appears that the cap itself is leaking. We had that issue and I solved by cutting off the end 1 inch, cleaning the pipe and then reattaching the hose. Also, we had the cap itself leak, That was finally resolved by taking off the cap and carefully cleaning the top of the assembly with metal polish - removing any burrs and such. Then the cap washer was cleaned - end result; no leak. Tom, Alchemyst, 45DS #312
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Post by mesteve on Aug 28, 2021 1:00:32 GMT
I need to get in there with a bright light and some paper towel, I just have not had the time and unfortunately it keeps getting bumped by learning something else that affects liveability, like where the water tank vents are…
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Post by fakinx on Aug 28, 2021 17:22:08 GMT
We had very small crack on the filler neck just above cooler. Our mechanic made some brass ring over it and sealed with something (wasn’t there). Leackege stopped and never returned since.
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Post by bitsailor on Sept 3, 2021 19:11:45 GMT
Check the freeze plugs - we had some coolant leaking out of one of the freeze plugs on the side of the engine.
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Post by rxc on Sept 12, 2021 16:44:09 GMT
Definitely check the alternator bracket mounting bolt. I also had a leak from there, and it drips down onto the engine mounts and causes them to rust and make a mess.
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Post by mesteve on Sept 12, 2021 19:19:39 GMT
And what seals that bolt?
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Post by rxc on Sept 14, 2021 16:44:12 GMT
There is a special spring washer between the head of the mounting bolt and the alternator bracket. You won't see it from the drawings, but that bolt mounting point on the frechwater pump is open to the interior of the pump. When you remove the bolt, water will come out. It is very weird for them to do something like this - I wonder whether they might have had thermal expansion problems with the hole without drilling all the way thru. Following images are from the Yanmar spare parts manual for the 4JH3-TE engine Part No. 6 on the drawing is the one you need to replace. I think the surface of the alternator bracket and the water pump mounting point are machined flat to get a good seal. Following are photos of the bolt on my engine The part number is 22217-080000 You can see the bits of red rust around the bolt head. I want to thank you for bringing up this issue, because it looks like I have to renew the gasket on my boat. The boat has been used only a tiny bit since the start of the COVID situation, and the level of fluid in the expansion tank is down from where it normally should be. So, it is time for me to deal with this. I think I will likely also replace the alternator belt and SW pump impeller while I am at it. I have a good Yanmar dealer nearby, and will pay him a visit this week.
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Post by mesteve on Sept 14, 2021 17:53:14 GMT
Ok, that makes sense; I was think of the lower mounting point for some reason.
I finally found where my leak is.
It was the lower hose going to the front of the heat exchanger. Looks like the clamp used was a serrated type (as all from Yanmar appear to be) and it had put a small cut in the upper end of the hose.
I cleaned up both barns and have the hose on order. Also replacing with solid clamps on reassembly.
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