Warming diesel engines

[nicho]

Why do so many owners (both sail and Mobo) deem it necessary to start their engines and leave them running in neutral for 10 minutes or so before casting off, filling the whole area with smoke??

Owners of cars don't do this (unless to warm up the heater in winter, or cool the airconditioning on hot days), neither to lorries, buses or most other forms of diesel powered vehicles. They simply start up and go.

I was always taught that allowing diesels to idle from cold, with no loading, did more harm than good, yet people leave them smoking away for a 10 minutes or so before finally moving off. They will surely heat up quicker, and do less damage, when under way??

Nearly as annoying as asking CG for a radio check.

I just don't get it.

<hr width=100% size=1>

 

[boatless]

Completely agree, have heard some say mobo gearboxs need warming, but I've never found that on any I've used.

I believe that a upcoming 'Confessional' touches on this though.

<hr width=100% size=1>my opinion is complete rubbish, probably.

 

[Robin]

Hear hear. Our engine is started only when all redundant lines are already off. We were behind a HR on Sunday where the engine was left running whilst the crew apparently all went ashore for showers. We had previously questioned on mobochat if this was necessary having been one one occasion behind a Trader 41 + something who smoked us (straight into our cabin) for over 30 minutes before they eventually left (not an anti mobo call, we had been talking with them earlier and they were ex raggies). Surely the gentle run out of the harbour gives plenty of time for warming up? Do big trucks run their engines for ages before leaving?

<hr width=100% size=1>

 

[dieselhead]

i have always been taught to let the engine come up to norlal temp before engaing the turbo, and keeping the engine just in gear when you have finished for the day to cool teh turbo down. reasond being that a boat diesel has to stay at high revs for long periods unlike a car???

<hr width=100% size=1>

 

[Oldhand]

Surely your departure and return to harbour are done at speeds at which diesel turbos are hardly spinning if not at all? It is certainly the case with my yacht auxiliary and there is no need for extended warming up or cooling down in the berth.

<hr width=100% size=1>

 

[Twister_Ken]

Exception...

...seems to be diesel trains where the engines run continously even in terminus stations. Also Red Jet ferries don't shut dowm while loading unloading.

<hr width=100% size=1><A target="_blank" HREF=http://www.writeforweb.com/twister1>Let's Twist Again</A>

 

[longjohnsilver]

Oh dear here I am again on the dark side and agreeing wholeheartedly. Not only is it unnecessary but does the engine no good at all. Start up and move off asap.

Now I need to go and lie down with a cold flannel or more preferably a wet nurse.

<hr width=100% size=1>

 

[blackbeard]

Usual advice seems to be to let the engine run at idle or slow speed until warmed up, before actually using it for propulsion; once motive power is no longer needed, to let the engine run slowly for a while to allow any hot spots to resolve.

I'm very unconvinced, especially since engine usually will not be required to give anything like full power until some time after the boat has left its berth. Similarly, when berthing, the engine will have been run slowly while approaching the berth (at least, one might hope so).

It seems to me that, with modern multigrade oils, and assuming we are going to treat the engine gently until we reach open water, there just isn't any point in idling the engine for any longer than it takes the oil to circulate to all the bearing surfaces, and to check that the engine is running sweetly and that the gearbox is OK - which shouldn't take long. However, this seems to be against the advice in the maker's handbook. Is the maker's advice simply a hangover from the days of non-multigrade oils?

<hr width=100% size=1>

 

[Mike21]

Don't know about others , but did find when very cold on previous boat with EDC controls that they were bit unresponsive unless engines left to warm up a little.
Not problem with present boat so case of start engines and go

<hr width=100% size=1>

 

[BlueSkyNick]

Sorry, Nicho, but if I start up from cold, and immediately put her into gear, my manky old engine will die which can be embarrassing if the lines have already been let go.

So I like to let her run for about 5 minutes on the first start of the day, so she is not stone cold. I will try to give you some warning, so you can close the flaps on your cockpit conservatory in time!

(It that motor launch behind you which is the biggest culprit!)

<hr width=100% size=1>As one bar of soap said to another - "That's Life Boy"

 

[nicho]

Nick - it's not such a problem with yacht engines, but you will no doubt have also suffered from the miriad of 600hp motor cruisers around us. Once started, most diesel engines should not stall in that way, perhaps there's a small problem in the injection system?? (I'm no expert by the way!)

<hr width=100% size=1>

 

[nicho]

Over 50% of new cars registered these days are powered by turbo diesel engines. I know they are a long way from the rather agricultural marine diesels still being put into new boats, but car handbooks never tell you to ensure the engine is fully up to temperature before you apply enough throttle to get the turbo spinning.

<hr width=100% size=1>

 

[TonyD]

If there was any possible reason for allowing the engine to warm up after starting, Volvo would be sure to advise you to do it in their manual (if only so that they could claim you hadn't done it when you make a warranty claim). They do not, so you can be sure it isn't necessary - see <A target="_blank" HREF=http://www.stationr.org/water/S2/Volvo2000p3.htm>here</A>.

Many (most?) of the smokey marine diesels have glazed bores from too much idling.

<hr width=100% size=1>

 

[[2068]]

Anybody that does this is just glazing their bores and covering their combustion chambers and piston crowns with carbon, causing even more smoke the next time they start.

Unfortunately, when cold, our KAD32 does chuck out some smoke, so we start and leave the slip as soon as we can. Once the block temp comes up even a little (from proceeding in gear) the smoke disappears until the next day. Under load, the smoke clears within 60 seconds. At idle, it would take 5-8 mins (cough, splutter, ahem)...

What these people are maybe getting confused with, is that it isn't a smart move to get planing (i.e. full throttle, turbos at full boost, superchargers etc.) until mostly warmed up. This can take 5-10 mins, but again, should be under load, not adding diesel dressing to your neighbours salad in the marina. It's also a good reason for proceeding along the channel at a respectably slow pace until you hit the deep blue stuff.

dave.

 

[dieselhead]

my mercruiser manual says you have to warm up

<hr width=100% size=1>

 

[TheBoatman]

Couldn't agree more a couple of minutes is more than enough.

<hr width=100% size=1>

 

[cliff]

I let my engine idle for a few minutes before casting off simply to make sure all is OK having had a bad experience once when I cast off immediately, was motoring out og the marina when the engine died. Fortunately there was one empty finger near the end of thepontoon that I managed to turn / drift into. Engine refused to start so started checking it over. Eventually bled the system and she fired first turn.
Now I let the engine run for a few minutes while I remove springers, sail covers etc. Perhaps I am paranoid, but.......

<hr width=100% size=1>

 

[Evadne]

Not paranoid

It's perfectly normal to want to make sure the engine is actually running, and not going to conk out, before casting off. Especially if you've got an old and cantankerous one. I've suffered from diesel bug in the past and the usual symptom is that after about 5 minutes of running the engine cuts out and won't restart. Idling for 5 minutes gives me the confidence to set off down the winding creek. Since I have to floor the throttle of my 1GM7 to get it to push the boat around anyway, I am sure I'll burn off any glaze before it has time to set.


<hr width=100% size=1>

 

[qsiv]

Not what Sabre told me when I ran a Nelson 44 - they advised me to moor facing the harbour exit, single up all lines, start engines, check water coolant, slip lines and leave. By the time the marina entrance was reached the engines and gearboxes would be warmed up. In an ideal world they suggested that at that point the throttles be advanced to cruising revs - just like all commercial fishing boats seem to do!

All operations below crusing revs should be minimised - save a cool down period for turbos, unless there was a harbour speedlimit which would dave the same purpose.

<hr width=100% size=1>

 

[drawp]

I've just been looking at some blurb from Nanni Diesel. I quote
"You usually have to be patient to start a diesel engine - but not a NANNI DIESEL! (Their capitals - not mine). ...... You also need to be able to call on the engine's full power immediately. especially during manoeuvres in harbour and all models in the NANNI range respond instanteously as needed."
I guess that means Start up and go (for a modern engine, anyway)

<hr width=100% size=1>