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Wind and Engine problems

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Interlude View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Interlude Quote  Post ReplyReply Direct Link To This Post Topic: Wind and Engine problems
    Posted: 10 November 2012 at 01:16
On my previous boat with a 1GM10 Yanmar, the exhaust port coked up with the nominally 25mm diameter reduced to about 10 mm before the engine misbehaved (after 10 years service with previous owner).  After I replaced the head and elbow, I read the part in the manual which advises you (when shutting down) to let the engine run at idle for 5 minutes, then take to full RPM four or five times to blow out the carbon.  I seem to be the only person I know who does this, although one knowledgeable marine mechanic (out of about 5 I have asked) agreed it was a good thing to do.  The other maintenance hint I follow is to flush vinegar through the sea water cooling circuit (via the strainer) every 6 month or so when shutting down the engine (knowing I will be sailing again in a week). 

So far so good with the 3YM20 after 8 years and about 550 hours.
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CharlesP View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CharlesP Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2012 at 12:06
Thank you for that information. I have never had a problem with the exhaust elbow on my previous boats. I have now done over 600 hours and was surprised to read that Yanmar say the elbow should be changed after 500 hours.

My normal procedure is to run the engine at high revs for a period like you. My boat is wintered ashore. At the end of each season I motor at high revs for half an hour, the boat is then lifted out. Before the engine can cool, I run it on the cradle with a fresh water supply by disconnecting the end of a suction hose from the raw water filter and putting it into a bucket of fresh water kept topped. The engine is run for about 15 minutes which cleans the tubes etc. After the 15 minutes, I put the end of the hose into a bucket of coolant and immediately this has been sucked through, turn off the engine. I've always thought that this regime helps keep the exhaust elbow and other tubes clear and helps prevent corrosion or freezing damage over winter.

I also put fresh water backwards from the raw water filter and into the saildrive and follow this with a glass of coolant.

Charles
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hawkeye View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote hawkeye Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2012 at 09:35
Hi Charles,
I don't have an answer for my Hanse because we have never had a problem yet. We only have about 400 hours on the engine so far.
The previous boat had a Nanni diesel and had done about 500 hours when it completely coked up the exhaust elbow. Did not need replacing, just cleaning. 
Hawkeye Wink
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CharlesP View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CharlesP Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2012 at 08:46
Good point Hawkeye. How many hours does your engine run before it requires the exhaust elbow to be changed?

Charles
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hawkeye View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote hawkeye Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2012 at 00:17
A common reason for the exhaust elbow to coke up is that diesels need to be run hard, but that  does not happen often enough in sailing yachts. Gentle running means exhaust temperatures are too low allowing the deposits to form. You should regularly run the engine for a good period of time at 80% of maximum revs to help minimise this. It will be a bit noisy and use more fuel, but should save problems and cost over time. We regularly run our 30kw (40hp) Yanmar at 3000+ RPM for 30 minutes, even though I normally cruise at about 2200 RPM. I had coking problems on my previous boat due to being too gentle on the throttle. No issues with my Hanse in more than 5 years since I took the mechanics advice.  
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holby View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote holby Quote  Post ReplyReply Direct Link To This Post Posted: 05 November 2012 at 18:58
Charles thanks for the note about the exhaust, I had  not even thought about inspection and cleaning....
It is now on my list.
All is well with my engine now, and it runs beter than it has ever done..........
Hanse 301, tiller steering, Volvo 2010 (10hp)
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CharlesP View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CharlesP Quote  Post ReplyReply Direct Link To This Post Posted: 04 November 2012 at 13:22
On my Yanmar, the oil filter is changed every 250 hours and the oil is changed every 150 hours and this operation is carried out with the engine hot. If this is being done, I find it difficult to believe that the filter would block. Sludge could form if the oil is contaminated with water, so that might block the oil filter. Fuel contamination would dilute the oil which would reduce pressure. Perhaps the oil pump is faulty.

The exhaust elbow should be inspected and cleaned at least every two years. Yanmar say it should be replaced every 500 hours.

Charles
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holby View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote holby Quote  Post ReplyReply Direct Link To This Post Posted: 25 October 2012 at 20:59
Well spotted, the engineer in Douglas, rebuilt the injectors and also found a bit of diesel bug in the tank.  With the increase of Biodiesel in our Marine diesel, and also having to use road diesel when in Scotland as the Marine diesel was hard to find, plus general use of the engine over the last 12 years, has created a build up of Carbon in the Exhaust, which also caused a problem....
But going back to the low oil pressure, I think thia was caused by the fact that the engineer, in Dougls, if the head comes of the engine, which he had to do to re grind the valves, then he should infact changed the oil and filter, and after the hard use it has had this year then, I think after speaking again to the Volvo penta people, it seems that it is likely the filter is blocked....
I must admit before I had this low oil pressure warning, the engine sounded better than when i bought the boat, it revs higher, and in fact it sound a lot happier....
 
Hanse 301, tiller steering, Volvo 2010 (10hp)
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H8jer View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote H8jer Quote  Post ReplyReply Direct Link To This Post Posted: 25 October 2012 at 10:30
Hi Holby

could it not be "Diesel bug"?

You had water in the fuelfilter (and therefore also in the tank)
The diesel bug will be visible in the oil, and can ultimately block a oil-filter.

There's Bio Protect 2 and another german product:

I've just changed the oil/filter through the bilge tupe on the bottom of the engine.
The manual say the engine contains 3.4 liter of oil.
After the operation I could only fill 2,75 liters of oil back. I don't think you can get it all out.
Castrol Engine flush is a good idea and used by experts in car-workshops working with old engines.

/H8jer

Hanse 370#487 30HP 3-cabin
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samuel View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote samuel Quote  Post ReplyReply Direct Link To This Post Posted: 25 October 2012 at 07:47
If a filter clogs there has to be a reason as oil changed so often should be clean
Are you sure that you are fully draining the sump each time?
I bet my engine gets a much use as yours & I only change the oil ready for each winter lay up to remove the old oil & the acid that would attack the engine. If you left some sludge in the sump each time it could possibly build up. Sucking oil out via the oil filler is not very good as some may be left behind. The best way is to get most out like this then drain the last bit out via the sump plug even if you run this last bit into the bilge under the engine & have to mop it up
I would suggest running some flushing oil through the engine next time you do a change

Edited by samuel - 25 October 2012 at 07:54
Daydream Believer- Hanse 311- No GBR9917T- Bradwell Essex
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