Turning engine over in winter - good/bad?

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MisterBen

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When visiting my boat in winter I have for many years turned the decompressed engine over fairly vigorously by hand, maybe a couple of dozen times, without thinking very deeply about it. It just seems the natural thing to do, to spread a bit of oil about and make sure nothing has seized.

In the pub the other night, a professional engineer said, "No, no, no! You are doing much more harm than good. There is no pressure so you are not spreading the oil, you are potentially damaging dry surfaces."

Is he right? Does it matter very much either way?
 
MisterBen said:
When visiting my boat in winter I have for many years turned the decompressed engine over fairly vigorously by hand, maybe a couple of dozen times, without thinking very deeply about it. It just seems the natural thing to do, to spread a bit of oil about and make sure nothing has seized.

In the pub the other night, a professional engineer said, "No, no, no! You are doing much more harm than good. There is no pressure so you are not spreading the oil, you are potentially damaging dry surfaces."

Is he right? Does it matter very much either way?
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At least you keep the valves moving
 
He is right, mind you at least you did not start it an let it tickover for 5 minites then stop it.

How ever it is no big deal either way. Think of all the diesels that get left to drain down overnight then are started fresh next day.

The diesels that last longest [ in terms of hours run] are the ones that are run almost continously, some courier vans and airport taxis run 24/7.

Worked with a midlands co running Peureot 505 and Siera diesels; 300,000 miles was common on the engines. and they would do this in 3 years. They would still be running ok if starting to get smoky and would be relegated to local work.
 
I think it's a good idea as long as you don't start it for 5 minutes and stop it. But make sure the cooling water inlet valve is closed as if not you can easily (in 15 seconds) fill the cylinders with water.
 
mitiempo said:
I think it's a good idea as long as you don't start it for 5 minutes and stop it. But make sure the cooling water inlet valve is closed as if not you can easily (in 15 seconds) fill the cylinders with water.
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As a newcomer to the world of marine diesels (it's only a Yanmar 1GM, but it's all I have) how does that happen?
 
orbister
As you turn over the engine, either by hand or with the starter, the water pump will pump water in. If the engine is not running there is no exhaust to push the cooling water out the stern so it backs up through the exhaust valve(s) into the cylinder(s). It's a good way toward an expensive repair.
 
Running a diesel engine

orbister said:
As a newcomer to the world of marine diesels (it's only a Yanmar 1GM, but it's all I have) how does that happen?
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As I understand it you need to get diesel engine up to temp and particularly the oil up to normal working temperature to evaporate water and acids that accumulate in the oil with cold startand or long period of inactivity. ??? olewill
 
Maybe not a good idea.The cam followers work under great pressure and will be dry.Most engine wear occurs on startup because there'll be very little oil where it matters.
 
cold engines

although maybe not answers the question, i worked for BMW a few yrs ago and they wouldnt let a engine sit running. for them, you drove the engine from cold, never let it sit there warming up.
they wantd the oils up around everything well before the engine got warm.
 
I agree that an engine has a tougher time of it when cold as far as lubrication goes and that is one reason to use a multiweight oil. It has more viscousity at a lower temperature which it will see at least half the year in northern climates. The attachment relates to cars but it's the same for boats, gas or diesel.
 
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MisterBen said:
When visiting my boat in winter I have for many years turned the decompressed engine over fairly vigorously by hand, maybe a couple of dozen times, without thinking very deeply about it. It just seems the natural thing to do, to spread a bit of oil about and make sure nothing has seized.

In the pub the other night, a professional engineer said, "No, no, no! You are doing much more harm than good. There is no pressure so you are not spreading the oil, you are potentially damaging dry surfaces."

Is he right? Does it matter very much either way?
Click to expand...

Always suspicious of "professional engineers", many of whom are mechanics. However, turning it over achieves nothing much but modern oils are such that the surfaces wont become dry. Hand turning is unlikely to cause much damage and it will prime the oil system but don't do what I did with a car in storage. Admittedly it was long term storage but I started the engine every 6 months for maybe 7 years and by the time it came to re-use the car, I had worn out the bearings in the bottom end.

Best thing is to change the engine oil and filters, spray the outside with WD40, drain off all raw water, and leave alone until the spring. Then crank by hand to get the oil system primed and start the engine up.
 
Firstly I am not a mechanic neither am I an engineer....Rules for prolonging a diesel engine/marine. 1) If the engine is started let it warm up 2) use it with a load ie in gear for a while. 3) after a minimum of approx half hour leave it to tick over for approx 10 mins, this is the cool down period. 4) switch off.. Job done= oil and diesel circulated engine expanded gear box oiled. .

Peter
 
MisterBen said:
.

In the pub the other night, a professional engineer said, "No, no, no! You are doing much more harm than good. There is no pressure so you are not spreading the oil, you are potentially damaging dry surfaces."

Is he right? Does it matter very much either way?
Click to expand...

He is right. The pistons and bores in most engines are lubricated by squirts of oil from the small end bearing, or possibly from the big-end, it varies. At starter motor cranking speeds with a cold engine there is insufficient flow for the oil to reach the bores, the oil will only squeeze out rather than spurting. The pistons will scrape along a dry bore, removing any oil that might be left there from when the engine was last run. Rings will partly scuff and the honing marks on the bores will be worn to some extent.

Some oil will probably reach the main, big-end and camshaft bearings but perhaps not the cams and tappets, dependent upon how efficiently your oil pump seals when the engine is stationary. As the latter are steel-on-steel and highly loaded they are likely to scuff.

Nothing good has been achieved, as the bearings are corrosion resistant anyway. If you absolutely have to run your engine it should be run for at least half an hour under load to prevent accumulations of the strong acids produced by the combustion process. It takes more like an hour for an engine to fully reach its working temperature.

By far the best way to treat your engine in winter, assuming it is laid up, is to leave it completely alone, after carrying out the recommended storage procedures trotted out by the mags every year.
 
There's a very good article on what happens in an engine that sees little use, and engine conservation, here: http://www.awm.gov.au/events/conference/bigstuff/papers/operating/corrosion.pdf

Having read that article, here's the NATO standard for diesel engine conservation. The article above should make it quite clear why it is important to get engine oil inside the cylinders and fuel system when laying up.

  • Drain engine sump and oil filter while engine is warm.
  • Change oil filter and add new oil.
  • The fuel system is treated with engine oil as follows:
    An extra fuel tank (jerrycan) is prepared so that it can be piped to the engine's fuel system (delivery and return pipe) with transparent plastic hose. Fill the jerrycan with a mixture of 2 parts diesel and 1 part engine oil.
  • Start the engine, using the regular fuel tank, and run until full operatinmg temperature has been reached. Drain the fuel filters.
  • Attach the prepared fuel tank and run the engine at 3/4 max RPM for approx 5 miutes.
  • Stop the engine.
  • Seal off the combustion air inlet with a sturdy lid or similar, rags must NOT be used. The lid must be able to withstand 1 bar of pressure with no deformation.
  • Set the fuel pump to max effect (full throttle), and turn the engine with the starter for 30 seconds. It is imperative that the air inlet is completely sealed or the engine may start and overrun. When the seal has been removed, the engine must NOT be turned over due to the danger of starting and overrunning.
  • The engine must NOT be run under heavy load when the conserving fuel mix is being used, since the high viscosity of the mix may damage the fuel pump due to higher working pressure.

Fuel tank:
  • If storing the vehicle (boat) with fuel in the tank, the tank must be full.
  • Do not add emulsifiers (alcohol) to the fuel since it promotes microbiological growth and may damage membrane type fuel pumps.

All that being said, I don't much bother with winter preserving the boat engine myself as long as the boat stays in the water. I do start it about once a month, and then let it run under load while still tied up at the dock, or simply go for a small trip. The point IMHO is to let the engine reach full operating temperature and then run it long enough to drive off any humidity that may be inside the engine.
 
castrol storage oil

Was the correct oil to use, you had to run the engine up to temp change the oil / filter, for the storage oil run it untill warmed up again and leave it was as simple as that re the lay up of the actual engine. The storage oil is to combat the acids present in the engine oil from degrading the bearings. I dont know if you can still buy the Castrol storage oil but that's what I was taught to use years ago when I did marine fitting, lol I had hair then maybe I should have bunged it on my head ;-)

cheers
Mick
 
Many thanks, Gents, for your very prompt and informative replies. Clearly, the concensus is that it is best to leave well alone - something which I will have to acknowledge to my pal in the pub when we next meet.

Best wishes to all - Ben.
 
I'd certainly go with the 'Less is More' consensus. Unless you're gonna give the engine a good workout under load, leave it be. You can always clean/lubricate ancillary components if you want to have a tinker. :)
 
May I just pass on a word of warning that has not been mentioned here and did in fact happen to me.

Turning over my diesel by hand on visits to the boat during the winter and then I found it would not start come spring fit out. This meant a visit from local diesel engineer who explained that my cranking the engine with out starting had added unburnt diesel fuel to the cylinders, which had accumulated over time. His answer was to remove air intake, hold a lighted paper to the intake as I turned the starter motor and with a gusto of a noise and smoke it burst into life.
So I would never do that again
 
Interesting thread. I've just bought a car that has been laid up for three years. "...but don't worry", said the previous owner, "I've religiously started her up for a few minutes every month"!

...So that would explain, when I took the cam covers off, the pint of "mayonaise" all over the top of the engine, the breather hoses and flame trap choked solid with the gungy stuff, and the patches of rust on the cam lobes...

As has been said, you get condensation in the oil that can't evaporate if the engine doesn't get up to temperature. You also get unbruned fuel that drips past the rings and can't evaporate of, so it dilutes the oil. Then there are the acids if you DO run it...

On the other hand, my boat engine is unusual in that it has no oil pump (everything is splash-lubricated) and it has roller bearings on the crank ratehr than shells. I sometimes just move the starting handle a smidgin in winter to move the piston rings on to a different place in the bore. Not sure whether that's a good idea but intuitively it seems so??
 
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