Yanmar 3YM Problems

[benjy1966]

Ahoy All,

If you're thinking about buying a new Yanmar 3YM engine think again. This engine has issues and I'm not alone.

In just 4 years it has let me down once a year on average. Two heat exchangers that started leaking. Yanmar said that my experience was unique but a quick search on line will show that others have had similar problems. The problem is because Yanmar keep cutting corners and using manufacturing techniques that are cheap, such as pressing in a tube rather than making a thread. At least with a threaded pipe, it can be removed and re sealed but once a pressed in pipe starts leaking you need to change the entire heat exchanger. Cost about £2000.

The cast iron exhaust risers come from a 40 year old Yanmar engine and are so restrictive that it blocked with soot after just three years and had to be replaced. Cost £500. I was lucky, one chap I read about had to pay £5000 to have the engine completely rebuilt as the increased back pressure sent carbon into his oil which acted like cutting paste.

The latest problem concerns the Johnson Seawater Pump which started leaking so badly the engine was rendered unusable. Just the shaft and seal cost another £200. So all in all, including unscheduled stops in marinas and parts I've had to buy I would say that this engine has cost me well over £3000 in just 4 years. Not to mention the stress trying to get any sense out of Yanmar.

The worst of it is Yanmar's attitude which is lamentable. They just don't care. I won't be buying another Yanmar that's for sure. It's my belief that have cut too many corners trying to be competitive. More fool them.

Benjy Yanmar 3YM20

 

[christopherc]

3YM Problems

That sounds a bit alarming. I have one year old 3YM30, I thought it was going to be an improvement over Volvo in previous boat. No sign of any problems yet, but I shall have a close look when I'm aboard this weekend. Provided I can shake off the flu!!

 

[Searush]

I too have a 3ym30, about 4 years old (with 3 seasons' light use plus 1 winter in commission) no problems so far, it starts & runs beautifully. I have even been complimented on how quiet and smooth it sounds as I glide along the river.

 

[matt1]

I have a 3YM20 and the only problem was an exhaust elbow exchanged FOC by the local agent. None of the other problems you mention and am generally pretty happy with it. However your post is somewhat alarming so I will keep a closer eye on it

 

[CAPTAIN FANTASTIC]

I think you are unlucky. I have had tho Yanmars on previous boats; the 1 cylinder and the 3 cylinder. I was very impressed with both engines, especially with the 3 cylinder which was lighter and smoother than my Volvo MD11c which I have on my present boat.

 

[PaulR]

interesting as my experience over several boats has left me singing the praises of yanmar engines - both our current 3gm and previous 1gm have been superb - not the same for the preceeding volvo 2000 series engines - having said that you do point out that it is a new engine and perhaps their standards have changed but based on our experience yanmars good , volvos less so

 

[jwilson]

Not perfect but not that bad!

I have a 2004/5 early build 3YM30, now with approaching 1000 hours. Early overheating problems sorted by an under warranty change to a different and bigger heat exchanger. Since then changed several impellers, water pump seals, and stop switch. Exhaust elbow probably to be changed next year: these went on old 3GMs as well. But the engine runs very smoothly and not too noisily and starts instantly even from cold.

If your exhaust is blocked with soot maybe you are running it too lightly. I run at 2,800/3,000 rpm as a cruise against a rated 3,400 max, and I do give it 5-10 min bursts of full throttle every few hours. The boat also gets chartered out and most users don't use nearly enough throttle - several have told me they cruise at about 2,000 to 2,200, which I regard as vandalising the engine, so I like to make up for it with a bit of proper work when I am using the boat.

 

[jason -and the arguenauts]

Sympathise with your problems Benjy but I've had both Volvo anf Yanmar in 4 different boats and had problems with every one of them - including a replacement block on one Yanmar (polished bores that wouldnt hone), one replacement engine, knackered heat exchanger on Volvo. internal corrosion on Volvo etc etc. And as far as I can tell from my own club, small marine diesels are all a bit like that.

The most reliable was the simplest - a !gm raw water cooled.

 

[charles_reed]

No such thing as a perfect engine - I suspect it has more to do with servicing.

My 3YM20 has done 1068 hrs in 30 months, needed one impeller, one alternator belt and nothing else except normal service ancillaries. The alternator is a 100amp Magnetti-Maréchal, instead of the puny Hitachi fitted as standard.

Contrary to another poster's opinion, mine is used mainly in the rpm range of 1400-2400r pm and averages a mean fuel consumption of 1.3litres/hr.

The exhaust elbow is supposed to be cleaned every 1000 hrs - when I looked at mine it was reasonably clean and really didn't need to be taken off.

 

[benjy1966]

3YM engine problems

Ahoy All,

I am glad you lot have such reliable engines. Sadly I am not alone and despite what Yanmar would have me believe, none of my problems are unique and are in fact a lot more common than you might think. I too have owned Yanmars before and that is why I was happy to have one again but of late, in an attempt to try and remain competitive Yanmar have been cutting corners and it is starting to show.

There are plenty of other people out there with problems even worse than mine, just try a few searches on Google and see for yourself.

People have had pistons coming out the side of the crank, engines have been destroyed by carbon getting into the oil from too much back pressure thanks to the Mickey Mouse cast iron riser that Yanmar see fit to supply to those of us who have engines below the water line. Heat exchangers leaking and engines overheating are common as are the Johnson water pump issues.

I'm sure that the majority of these engines are excellent and work fine for most people but there seems to be a significant number out there with quite serious problems. Mine is number 000399 so it was one of the very first. Maybe Yanmar are addressing these problems. I hope so, this is the main reason why I brought it up.

What annoys me the most is Yanmar Marine themselves. They just couldn't care less, and that's not just my experience either.

Just for the record my engine is serviced regularly and run correctly with a correctly pitched prop and plenty of revs. It is through no fault of mine that the engine has failed me so often.

I sincerely hope that you continue to have such good fortune with your Yanmar engines, I wish I was one of the luckyy ones.

One thing I can tell you is that I for one will not be buying a Yanmar again. There are plenty of other good engines out there.

Fair winds

Benjy

 

[jonno45]

Hi Benjy
Are you refering to the pressure cap fitting on the heat exchanger?
You can replace this instead of the heat exchanger. The filler assy slots into the heat exchanger and a copper sleeve is then inserted to spread out the fitting to seal. You can buy all the parts to complete the job easily.
As for the exhaust, regardless what it is it should never block with soot. I would look at the way the boat is propped as soot build-up is usually down to overloading. Or that gas oil is being used instead of diesel. Send me a PM and i will email you some info.

 

[benjy1966]

Exchanger and soot issues

Ahoy Jonno,

The problem is not that simple. In an attempt to save costs, Yanmar now press in the lower pipe in the casting of the heat exchanger (they used to thread it so at least if it started leaking it could removed and repaired) and so if there is a leak the exchanger must be replaced which it was. Twice, though very reluctantly under warranty after months of harassment, by Yanmar. In the end I had it welded in place since that was the only way to stop it happening again!

As for the soot, perhaps I did not explain myself very well. There is no problem with the standard (as supplied with the engine) exhaust riser, although the inner tubes can rot out in time and cause water to get into the engine. I digress. On engines that are fitted below the water line, Yanmar supply a cast iron riser which in fact is a very old design that has a very restrictive interior design. The hole for the exhaust gases is about one third of the diameter of the exhaust tube! It is no wonder that it soots up here. My engine runs beautifully when it's not leaking and it never smokes. The prop, a Kiwi is perfectly set up and I can manage 3600rpm no problem which suggests the pitch and prop are well matched to the engine. I was amazed too, but after just three years it blocked so completely that the engine would not run!

This cast iron riser is a 40 year old design that should simply not be fitted to these engines. I have since managed to find a bronze version with a much freer interior and hope that I have at least managed to solve this problem.

Regards

Benjy

 

[jonno45]

Hi Benjy
Sorry for that i was assuming. What coolant are you using?
As for the high rise elbow, i know its ancient ( QM,GM,JH) but it does the job, I presume you fitted the bronze elbow EPY625 to replace it? I would be worried about the soot build up as I have worked on Yanmars for 17years and have never experienced that under normal use. Question: How long do you run the engine before hoisting the sails?
Cheers

 

[benjy1966]

Soot and stuff

Ahoy Jonno,

The coolant was supplied by the local Yanmar dealer and fulfils all criteria etc. that was one of the first things I looked into.

I got the bronze elbow from Cellar Marine, don't know what model it is. I had to laugh, when you asked how long I run the engine before switching off. I'm in the Med! The engine gets a good work out down here! Sometimes it runs for days at a time! This is not the problem.

I agree that to soot up like that is wrong but the engine starts fine, never smokes, is never overloaded, always serviced properly. I have even had the injectors tested. I have just fitted the new bronze riser and was amazed to see that the cast iron riser that I had to fit last year, just 100 hrs ago, was starting to clog. It's not really surprising though, the hole in the cast iron riser is tiny. Rest of the exhaust is spotless.

I maintain that the cast iron risers internal dia. is simply too small for a 21hp engine with 3 cylinders. We'll see how the bronze one fares but already I can report that the engine revs freer and quicker than before. I always felt it was sluggish to rev.

Thanks for your input!

Benjy

 

[Wightman]

I have a 3YM 20 with 2 issues: 1. A leak where the cooling water hose joins the exhaust elbow, this is directly above where the starter motor joins the bell housing, salt water contaminated the the starter mechanism & seized it also corroded the studs attaching the end cap to the heat exchanger. Starter motor was easily repaired, dismantle , wire brush & grease. 2. Considerable difficulty removing HE end cap, replaced studs with SS ones then went to Yanmar dealer to replace O ring was then shown a parts diagram which showed 2 O rings with a spacer in between, I was then advised that there no spacers available in Australia & that it would take 2 weeks to import at a cost of $60. 2 weeks later reassembled, start up to find not a leak but a squirt from the end cap joint. Did a internet search to check the assembly & found 3 different versions of HE for a 3YM20. Inquired with Yanmar & received NO reply. Returned to dealer & verified this was the correct configuration according to their book. I believe the book is incorrect & that there should be only one O ring. Summing up, don't waste your time looking for help from Yanmar & make sure you have long deep pockets to afford any replacement parts. Help & advice greatly appreciated with this matter.
Wightman