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cadye · 23-03-2006, 10:17

I am wondering what precaution/procedure might be prudent for start up of Yanmar 44 hp after two year storage period.It has been inside heated storage, tank was topped up before lay up.I was thinking just cranking for a period to get the oil up would be all that is needed.Anyone tell me how long this should take?Any other suggestions?
I do not have a lot of experience,(yet) and want to avoid the bad ones as much as possible.

**Alan Wheeler** · 23-03-2006, 11:27

If you can, placce a socket on the crank pulley bolt and rock the motor a fraction, to ensure all is free. Then with the starter, cranking over for about 15 seconds. If you have the beauty of a decompression lever, engage that so as the engine is under no compression load. It doesn't take much to get the oiul up and around the engine. The major concern is the cam shaft running dry for a few seconds. You can spray a generouse amount of WD40 or similar into the oil filling hole on the top of the rocker cover. This will help with a little lubrication on the cam lug's till the oil gets there. The WD40 will not will not adversly affect the main lubricating oil.
If the engine doesn't start right away, go through a fuel bleed proceedure to ensure there is no air in the injector system. The engine should roar into life.
Now allow about 30sec's for the oil to get around the engine and with the engine at idle, engage drive. Allow the boat to pull on the lines tied to the dock and every minute, raise the RPM just a little. After the temp indicator has started to move up, raise the RPM upto halfway. As the engine reaches full temp, take it all the way up to full RPM. Of course, you can be going for a short trip doing all this, you don't have to be tied to the dock. But what ever, make sure the engine gets under loads as soon as you can.

NEVER allow a diesel to warm up under no load.

Sandero · 14-04-2006, 04:30

What exactly is the deal about no load running being harmful to diesel engines? I have heard this many times and I can't understand what the reasoning is. Please explain.

Are you advocating, for example, when you fire up your diesel at anchor you need to be in reverse?

Jef
sv Shiva
Contest 36s

**GordMay** · 14-04-2006, 05:01

This subject has been extensively discussed on the CruisersForum, and a search should reveal more detailed information.

Excessive (more than 5 minutes*) Diesel Engine idling can cause:
~ Cylinder glazing & low compression
~ Timing gear backlash & increased wear
~ Low operating temperature, carbon accumulation, and accelerated wear

* Yanmar specifies 5 minutes maximum idling time.

General engine operating rules:
- Start engine, run in neutral at a speed just above low idle for no longer than 5 minutes.
- Engage transmission into gear, and get underway, while warming up the engine under light load (about 1/2 max rpm)
- When temp gauge approaches operating temp (about 180 Deg F for Fresh-water cooled, and about 140F for Salt-water cooled), run at normal cruise rpm (about 3/4 of max)

When shutting down, run at reduced rpm (just above low idle) for 5 min, then shut down.
Some engine makers suggest to give a final shot of fuel and then immediately shut down (clears excess fuel & carbon from the cylinders).

Sandero · 14-04-2006, 05:11

I am curious how these "problems" are manifest by no loading. Why does loading prevent glazing for example?

With all due respect all you have cited is more detailed information about what happens (supposedly).

Does this apply to all diesels? I see many buses and trucks idling their diesels. One would presume that owners of fleets of diesels would be very careful about these matters.

Can anyone explain what happens when you idle an unloaded engine?

Sandero · 14-04-2006, 05:46

How about some citations in literature about this "problem"?

Admittedly use equals wear and running an engine is using up its life span... but idling as a cause for destroying it? Sounds a bit fishy.

Yes... you DO waste fuel and your DO pollute the environment...

How much of this problem is a myth and how much is fact?

**GordMay** · 14-04-2006, 05:58

It appears that you’re not satisfied with a description of what happens when you idle a diesel engine excessively, but desire a detailed description of the mechanisms by which these things happen. A four-year engineering course might be a more appropriate (and assured) forum for that level of expertise.

References:
~ Any diesel engine manufacturer's manual.
~ Online search - Diesel +Idling

FWIW:
An idling diesel engine is running cooler (temperature) than designed for. Cooler operating temperatures prevent the piston rings from expanding (as intended), allowing them to hydroplane over the cylinder wall. Lubrication oil is thus left on the cylinder, allowing it to be exposed to the cylinder combustion. The oil film will then partially burn on the cylinder leaving a residue that will build up and oxidize over time. Eventually this leaves a hard deposit (glazing) on the cylinder wall. Low firing temperatures also allow unburned fuel oil to migrate to the lube oil sump, reducing the lubrication properties of the lube oil, and presenting an explosion hazard due to fuel oil vapours in the sump.

Sandero · 14-04-2006, 06:10

Gord,

Are you referring to idling at low revs? or just no load? I don't know how accurate the temp gauge on my engine is, but I don't see it dropping if the engine idles.

I accept that an engine operating outside it's design temperature range CAN be harmful to the engine. But how does a load... say at idle speed change the way the engine works, then when there is no load at the same RPM?

I don't understand how this works and I am asking to be educated.

I am not trying to be argumentative. But as I have heard this many times, I am now wanting to completely understand the mechanisms at work.

I don't believe I need a 4 year course in diesel engines to understand... 6 years of architecture enducation should suffice to give me the skills to comprehend what happens in a diesel engine.

I did search for the past hour for articles about this "problem" on the web and found no hits.

Jef
sv Shiva
Contest 36s

Sandero · 14-04-2006, 06:29

Cute story... and completely irrelevant.

I am not going to defend architect, lawyers, doctors, engineers... They are all full of hot air at times.

My point was simply that I have enough education to understand a reasoned argument.

Patiently waiting for that argument.

Jef
sv Shiva
Contest 36s

Dman · 14-04-2006, 06:57

The situation to me goes somthing like this.The rings need to be hot enough to expand to keep the cylinder wall from building up an oil film that will begin to half burn and glaze.If the engine is under load the engine will burn more fuel which makes more heat thus keeping the rings tight enough against the wall to prevent glazing.I thought i would add,if you try and idle a diesel under load this is also not a good thing"lugging".Bottom line don`t do it,however i`ve seen diesel trucks idle all night at the big truckstops to just throw the monkey wrench in there.However under further thought the injection systems on todays gear is electronic so the computor should be able to put enough fuel in to prevent damage.

BC Mike · 14-04-2006, 08:07

Direct from the Yanmar manual.
Warm up the engine for more than 5 minutes. Prior to stopping engine, idle for about five minutes, after five minutes raise rpm to 2500 to blow out any burnt gas in cylinders, set the engine to lowest speed and stop.
I used to go fishing with my 2QM15 Yanmar and it would idle all day, but the motor only lasted about 22 years before it needed rings. Will fire it up today and run to charge the batteries.
I think dead slow idle is not a good idea, but 7 to 800 revs should be okay, but that is just my opinion. Other motors may react differently.
These things only run at about 60C. My Ford tractor did not have a thermostat when new, and they run a bit cold in the winter. Oil froth seems to be the biggest problem, so most of us put a 160F thermostat in the radiator hose. These tractors are run at just above idle often. Maybe it will develop problems after more use, it is only 65 years old.
Michael

Sandero · 14-04-2006, 08:42

What I am understanding is that diesel engines which are running when cold are not doing themselves a favor. Fine... how does load figure into this equation? Does a higher reving engine run hotter or cooler? If cool is a bad thing then why not idle at higher revs?

Dman · 14-04-2006, 09:24

It is my understanding that a diesel will dump in extra fuel when the load is placed on the engine,extra fuel more heat,rings working properly.What would be the purpose of idling at a high rpm to do nothing with the engine in the first place?Answer me this.If a fly sits on a 20 inch Ibeam, does it bend?