Re: Bowman DC60-XCC Transmission Oil Cooler Failure; ZF Hurth ZF 25; Yanmar 4JH3-HTE #lessons

Colin - ex SV Island Pearl

Mark, congrats on a great post as the transmission oil cooler is particularly important learning for all new or existing SM and/or 54 owners. We had a similar experience on SM Island Pearl II (2001 build with Yanmar 75HP) when she had only approx 1400 engine hours, but was aged approx.10 years old from new. In our case, we had just completed a gentle 12nm motor sail and on coming into a safe anchorage after dropping anchor we noticed she would not engage reverse (or later fwd either) gear to pull back on the anchor. Fortunately, we noticed it just when it occurred so were able to immediately replace the part, and also immediate do 5-6 oil changes back-to-back, each with new transmission oil to be totally sure that absolutely all moisture was drained out ... and ..... for years later ... that transmission was absolutely perfect for a circumnavigation, and many more motoring years ahead. Remember the cost of oil is cheap compared to the hassel and expense of replacing that transmission.
Based on our experience, and what we saw on other Amels during our circumnavigation, I would personally always carry a spare oil cooler and replace this part every 7 years or 2000 hours, and also immediately if ever purchasing a 2nd hand 53 or 54 where the prior owner was not certain (with receipts) about when it was last replaced.

Losing your engine drive power can be extremely dangerous, and here is just one example ... 

In 2018 we were buddy sailing in the Indian Ocean with friends on a beautifully maintained late 2014 SM and, just 9 hours out to sea after leaving the very remote "Bally Bay" on the mid western horn of Madagascar to cross the notorious Mozambique Channel for Mozambique and Richards Bay, South Africa, they hailed us looking for an urgent boat to boat transfer of most of our spare transmission oil supply. After devising a cunning plan we successfully did the ship to ship transfer of oil at sea but the other captain was still sure his oil was just too low as his 100HP Yanmar was in excellent condition (still looked like new!) and so was intent on still proceeding down to South Africa with us despite our urgent suggestion that this could in fact be a failed oil cooler, and for them to rather turn immediately north, and safely down wind, directly for French based Mayotte Island where they could potentially safely sail almost all the way in to a large safe harbour without engine, and where a tow boat could be possible too, plus where that part could be freighted relatively quickly from Amel in France. 

After adding more oil and immediately losing it again, they eventually realised the gravity of their situation took our advice to head for Mayorette where two days later they did infact manage to sail safely in and have the part air freighted in from Amel too. 

As per Murphey's Law when at sea, this decision did indeed become a life-saver as there are absolutely no safe "sail in" anchorages along this section of the Mozambique coast before Maputo, and despite some very fast sailing on the latter third part of this leg, sometimes sitting on 10.5kts SOG pretty much for many hours on end with many peaks over 12kts!, we were still later faced with extreme conditions which our South African weather expert was repetitively calling "extreme life-threatening survival conditions ... divert immediately for Maputo!!..." with a huge unexpected SW gale coming up fast against the very fast moving southerly Augulas currents. In the end we decided to motor sail hard direct for Richards Bay with the last 150nm being extremely heavy going  as the wind against current conditions immediately lifted up what appeared to be huge mountainous waves and really nasty angry seas with winds shreeking through the rigging (I hope we will never see again!) and it was only thanks to having a good reliable motor pushing hard for many hours that we eventually safely got in safely behind the big concrete walls of the Richards Bay harbour just one hour before the real storm conditions really hit creating havoc and destruction along the coastline. We certainly could not have got back to safety without that engine and were so pleased that our friends decided not to press on direct for South Africa.

Moral of the story ... check your oil coolers ... and proactively replace them (they are not that expensive) as you never want to have this fail at the wrong time when you may really need it.

Colin Streeter
Brisbane, Australia
ex - Island Pearl II

On Thu, Aug 26, 2021 at 7:27 PM Mohammad Shirloo <mshirloo@...> wrote:

Hi Mark;


Thank you for sharing your experience. We removed and had all of the heat exchangers professionally cleaned in 2018. However, it is not possible to identify wear. Therefore I’d like to order a couple of the heat exchangers and replace ours and have one as spare. It is hard to read the part number on the cooler, without removing it.


Does anyone know if all A54s used the same part number too, or are there different parts for different hull numbers?





Mohammad and Aty

B&B Kokomo

Amel 54 #099


From: <> On Behalf Of Mark McGovern via
Sent: Thursday, August 26, 2021 12:41 AM
Subject: [Special] [AmelYachtOwners] Bowman DC60-XCC Transmission Oil Cooler Failure; ZF Hurth ZF 25; Yanmar 4JH3-HTE #lessons #lessons


In the spirit of Pat from Shenanigans "Lessons Learned" post a few week's back I thought I would share what I learned when my Bowman DC60-XCC oil cooler failed while motoring up the coast of Maine a few days ago.  Thankfully, we caught the failure relatively early in large part due to the fact that when cruising in Maine you have to remain hyper-aware at all times because of the lobster pots that are literally all over the place including in marked channels and anchorages. Because of that, both my wife and I were in the cockpit doing nothing but looking out for lobster pots and calling out their positions to whomever was at the helm. There were no podcasts, no music, no book reading, no headphone, just hyper-vigilance with two people, 4 eyes, and 4 ears on watch at all times. 

The first symptom we noticed was what sounded like a slight misfire of the engine.  It sounded like the RPM increased ever so slightly for just a second.  It was just a "blip" and was not large enough to actually even register on the tachometer.  After hearing it a few times, a minute or so apart, I asked my wife if she was hearing it. She said she was. My first thought was a clogged fuel filter despite the fact that my last fuel fill ups were from fairly busy harbors in Annapolis, MD and Onset, Massachusetts and that we had only ~60 hours on the Racor filter.  In addition, the RPMs of the engine seemed to increase not decrease like I would expect from fuel starvation from a clogged fuel filter.  In any case, I switched over to the second Racor but the occasional engine “blip” did not go away. In fact it got more frequent and it actually started to register on the tachometer just barely.  I put my head over the side to take a look at the engine exhaust.  I did not see any white or black smoke coming out of the engine exhaust.  However, I did see an oil slick trailing behind us the likes of which I have never seen before.  My immediate thought was that the engine oil cooler had failed and was leaking engine oil into the raw water system.  We had no choice but to shut the engine down ASAP.  There was only 6-7 knots of wind directly behind us but we also had a bit of favorable current so we just put out the main sail, turned off the engine and called Towboat US.  We are not at all familiar with this area and we did not see any decent anchorages looking at the charts. We were only 2 nm from our destination of Belfast, Maine and the Towboat captain said it would take him about an hour to meet us at the entrance to the harbor.  So we sailed at 1.5-2 knots with just the Main and met the Towboat captain at the entrance to the harbor where he towed us the last mile to our mooring ball where we still sit right now waiting for our replacement oil cooler to arrive from the UK.


Once we were safely moored, I went down to the engine room to check the oil in the Yanmar.  It was perfect.  Not a drop appeared to be missing.  After a brief “wtf?” moment, I checked the transmission dipstick.  The fluid level did not even register on the dipstick at all.  However, I could see that there was some ATF left in the transmission case.  That was a bit of a relief but not much.


All of this happened on a Saturday and I do not carry a spare oil cooler so I would have to wait until Monday to order a replacement.  First thing Monday morning I started to call all of the USA dealers for Bowman marine products listed on Bowman’s website.  Of those who actually answered the phone, none of them had the DC60-XCC in stock or even just the DC60 (oil cooler with no end caps). One actually told me that he didn't think DC60-XCC was a valid Bowman part number. I said “I’m looking at their catalog online right now.  It is.”


I then called Bowman in the UK and asked if they knew anyone in the USA who might have one of these in stock and they hesitated and said the only one who might have one is Tradewinds Power Corporation.  When I had previously called Tradewinds Power Corporation they said "our computer system is down right now" so we will need to call you back.  They never did.  

Luckily, I had also asked Bowman who in the UK would definitely have them in stock and would ship to the USA.  Without hesitation, they told me that Lancing Marine will definitely have it and they ship around the world.  So I called Lancing Marine ( and had a wonderful experience buying from them.  Not only were their prices the lowest by far that I had seen anywhere online (79 GBP/~109 USD including new couplers) but the ordering experience was fantastic despite it being phone order only.  The person I spoke to also obviously knows these transmissions well.  His name was Mike and I'm pretty sure he is the owner and founder of the company - founded in 1970!  He gave me his opinion on the state of my transmission (he thinks it’s probably fine) and advice on how to test it to see even before the replacement cooler arrives.  On top of all that, despite it being about 3pm their time when I called, the coolers (I ordered a spare) shipped out the same day.  Last, he said that if I do need to get the transmission rebuilt, that he would highly recommend a company in the lower Chesapeake Bay called Transatlantic Diesels. He says that they know these ZF transmissions better than anyone and he has done business with them for years.  It was really just a great overall buying experience that seems to be so rare in these days of anonymous Amazon purchases.


The moral of the story is that for ~$109 plus shipping and an hour of my time I should have replaced the transmission oil cooler PROACTIVELY soon after I bought the boat back in July 2017.  Especially given that I did not know the age of this critical part.  Or I should have replaced one of four times that I have replaced the transmission fluid.  At the bare minimum, I should have had a spare oil cooler already on board.  The engine, and I assume the oil cooler, just surpassed the 2000 hour mark.  Researching this site after the fact I found at least two other SM owners who had the same failure at around the 2000 hour mark. Both, I believe, lost their transmissions.  Hopefully, I have not. I will know in a few days time.


So in the spirit of the #lessonslearned, don’t be like me.  If you are not sure how old your transmission oil cooler is, replace it.  If it’s approaching 2000 hours, replace it.  At a minimum, get yourself a spare oil cooler.  And if you can’t find it locally, get it from the nice people at Lancing Marine in the UK so that we all have at least one place in the world that keeps these things in stock.


Mark McGovern
SM #440 Cara
Deale, MD USA

Colin Streeter
0411 016 445

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