Diesel engine warm-up

[Fiddler]

Hi,

 

I'm trying to figure out what's the best practice for warming up a marine diesel engine? For how long? At what revs? Especially when you don't have a temperature gauge...

 

Thanks!

@

[Sir Nibble]

The best practice for warming a marine diesel is the same as for any other engine, start it up and use it. The faster the warm up the better, and an engine will warm up quicker under load.

[Athy]

That may work for some engines but not for mine. It needs warming up on about half throttle for a good 10 minutes or quarter of an hour, otherwise when you put it into gear it won't go much over tickover speed.

[NB Alnwick]

The best practice for warming a marine diesel is the same as for any other engine, start it up and use it. The faster the warm up the better, and an engine will warm up quicker under load.

 

That is what I have always believed. Running a 'cold' engine off-load for long periods may cause expensive and unnecessary wear.

[Fiddler]

That is what I have always believed. Running a 'cold' engine off-load for long periods may cause expensive and unnecessary wear.

 

I also prefer this explanation, but I've heard that some engines (Volvo Penta?) have dedicated governor that will not let you go unless the operating temperature is reached. That's why I got confused.

[nb Innisfree]

That is what I have always believed. Running a 'cold' engine off-load for long periods may cause expensive and unnecessary wear.

 

Engine whether diesel or petrol take in the region of 1 hr to reach full operating temp. it's not just temp gauge to consider but oil temp too which takes longer. In the winter we preheat to 60c with our Mikuni, starts without any glowplugs (Lister Petter 4cyl Alpha) and dramatically reduces time to max temp. research has shown that over 90% of engine wear takes place in the warmup period. Don't know if we use more fuel overall using this method, takes about 1 hr pre-heating in the winter with this method.

I think running offload for a couple of mins before loading is best

Edited July 1, 2009 by nb Innisfree

[Tony Brooks]

That may work for some engines but not for mine. It needs warming up on about half throttle for a good 10 minutes or quarter of an hour, otherwise when you put it into gear it won't go much over tickover speed.

 

 

Might you by any chance have a traditional, slow revving engine with a large engine to alternator pulley ratio? If so a slightly lower (say 3;1 instead of 4:1 - only for clarification of what I mean) ratio may be all that is required to allow you to rev it straight away. If the ratio is too high all the engine power goes into charging so none is left to increase the revs - just a thought.

[Proper Job]

Start it up and use it.

 

Putting it on to full load straight away - maybe not. But for average canal/river work normal running should be instantly achievable.

 

The main thing during 'warm up' is not to use excessive throttle. Increase revs slowly and at not one spin of the wheel/push of the lever. Constant revs are better.

[WJM]

With any petrol/diesel engine, you should give it several bursts of acceleration immediately after it fires up. This is to ensure the top of the engine is flooded with lubrication. Firing up and letting it immediately settle to low revs can leave the various high-up bearings dry because the oil is still very thick and the oil pump will not be providing much pressure to drive the oil around. So splash your engine with oil the second it fires up!

[mykaskin]

With any petrol/diesel engine, you should give it several bursts of acceleration immediately after it fires up. This is to ensure the top of the engine is flooded with lubrication. Firing up and letting it immediately settle to low revs can leave the various high-up bearings dry because the oil is still very thick and the oil pump will not be providing much pressure to drive the oil around. So splash your engine with oil the second it fires up!

 

So when I rev up the JP2 to get the alternator to start charging is a good thing then? Good.

 

Mike

[Fiddler]

With any petrol/diesel engine, you should give it several bursts of acceleration immediately after it fires up. This is to ensure the top of the engine is flooded with lubrication. Firing up and letting it immediately settle to low revs can leave the various high-up bearings dry because the oil is still very thick and the oil pump will not be providing much pressure to drive the oil around. So splash your engine with oil the second it fires up!

 

The answers are getting really interesting, and contradicting. So far my conclusion:

 

Start the engine, let it run for 2-3 minutes, then sail away with a gentle speed.

 

I haven't yet reached the conclusion regarding the revs.

 

 

Further theoretical interest: can anyone point me to the right resource on explaining the physics of engine wear in the warm-up period?

[mayalld]

The answers are getting really interesting, and contradicting. So far my conclusion:

 

Start the engine, let it run for 2-3 minutes, then sail away with a gentle speed.

 

I haven't yet reached the conclusion regarding the revs.

 

 

Further theoretical interest: can anyone point me to the right resource on explaining the physics of engine wear in the warm-up period?

 

The problem is that you think it is a science.

 

It is actually a black art.

[Fiddler]

The problem is that you think it is a science.

 

It is actually a black art.

 

Yes, that's what I suspected... being a scientist myself..

 

Still it is worth reviewing the state of the (black) art.

[Sir Nibble]

Further theoretical interest: can anyone point me to the right resource on explaining the physics of engine wear in the warm-up period?

There are two factors at work.

!. The oil will flow better at working temperature and not provide quite such good lubrication when cold.

2. The individual components of the engine simply do not fit properly and present their designed bearing surfaces until thermal expansion has taken place.

 

It is for these two reasons that almost all engine wear takes place before operating temperature is reached. There are other factors such as fuel dilution of the oil which is more particular to petrol engines on choke but that really is about the size of it.

[WJM]

Yip - That is why you have to throw that oil all over the place as soon as possible, wet the thing before it swarfs itself!

[Yoda]

There's a lot of tosh written about this subject so here is an answer from the aircraft industry.

 

Start up and its wear on surfaces is more dependent on the engine temperature and the type of oil. Air cooled engines have larger tolerances than liquid cooled. Air cooled also use oil to help with the cooling and therefore need it splashing around more.

 

Thermal shock is what kills engines and trying to produce high power levels from cold. So bearing in mind how many different types of canal boat engine there are, here is my advice.

 

Start the engine normally to idle and check for oil pressure. Engage the alternator to get power. Run the engine normally at low to reasonable power levels what ever the ambient temperature is. This advice is given that the engine has the correct oil specification contained within. Do not turn the engine off whilst still cold. All engines need to heat soak. Engines should be left running rather than turning them off and on, as this is where the greatest stress is.

 

I hope this will help.

[Sir Nibble]

Spot on reply for a Bristol Hercules on a round trip to Berlin.

The advice for road/industrial units is.... Start it up, use it.

[WJM]

"the aircraft industry"

 

Aircraft engines have very short service intervals, a very high rate of component replacement, very high quality components - and the whole thrust of their operation is against failure in use. I am not sure their strategy applies universally to boat engines.

[Yoda]

"the aircraft industry"

 

Aircraft engines have very short service intervals, a very high rate of component replacement, very high quality components - and the whole thrust of their operation is against failure in use. I am not sure their strategy applies universally to boat engines.

 

You just answered the question yourself.

 

The operation of all aircraft engines is to ensure that they work properly and produce their maximum power all through their lives. That is why they are 'looked after'. Their operation is still the same as any other piston engine powerplant.

 

All boat engines must start and not fail, basically so that people are not lost.

[MoominPapa]

"the aircraft industry"

 

Aircraft engines have very short service intervals, a very high rate of component replacement, very high quality components - and the whole thrust of their operation is against failure in use. I am not sure their strategy applies universally to boat engines.

"to save you money, this rainbear 737 is powered by a couple of BMC 1.8 power units bought second hand from boats moored on the GU. The APU is a knackered Honda EU10" - argh, run away!

 

MP.

[WJM]

Nope - aircraft engines are all about 100% total reliability with absolutely no reference to cost. Marine engines are quite different. With a piston aircraft engine, after X number of hours there is literally nothing left of the original engine, save some core structural parts. The same cannot be said for a marine engine. Because it is known that the components of an aircraft engine will never be used beyond a very low number of hours then the care-taking of that engine will not be concerned with long term wear and tear - unlike...

[nb Innisfree]

"to save you money, this rainbear 737 is powered by a couple of BMC 1.8 power units bought second hand from boats moored on the GU. The APU is a knackered Honda EU10" - argh, run away!

 

MP.

 

Does you co-steerer put their hand over yours on the throttles during lock approach?

[WJM]

No - A second set of throttle levers at the engineer's station - narrowboating is a traditional sport!

Edited July 1, 2009 by WJM

[Athy]

Might you by any chance have a traditional, slow revving engine with a large engine to alternator pulley ratio? If so a slightly lower (say 3;1 instead of 4:1 - only for clarification of what I mean) ratio may be all that is required to allow you to rev it straight away. If the ratio is too high all the engine power goes into charging so none is left to increase the revs - just a thought.

Well deducted, Sherlock Brooks! Yes, the engine is a Gardner. I haven't a clue what the pulley ratio is all about; but because I know that I will have to wait 15 minutes between starting from cold and driving away, it doen't worry me.

[MoominPapa]

Does you co-steerer put their hand over yours on the throttles during lock approach?

Since I have a trad stern, so we're both jammed onto the back step, we have come to know each other quite well!

 

MP.

 

 

Might you by any chance have a traditional, slow revving engine with a large engine to alternator pulley ratio? If so a slightly lower (say 3;1 instead of 4:1 - only for clarification of what I mean) ratio may be all that is required to allow you to rev it straight away. If the ratio is too high all the engine power goes into charging so none is left to increase the revs - just a thought.

This is why I've kept the split charge diodes. I have a switch to disables the Adverc and instantly cuts the charge current dramatically even with very discharged batteries. I let the engine warm up with the Adverc shut off, and only when it's good and warm I switch the Adverc on.

 

MP.