Manufacturers do push them, at least over here in the colonies, Freightliner, International, Mack, Paccar, Western Star and Volvo offer these heaters from the factory.
I know all about oil structures and viscosity, but testing and numbers, even my own oil analysis tell me much less than the Mk1 eardrum. From a cold start my engines sound awful, once warm, they sound much better. Quite simple really.
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newmercman:
There’s a simple reason I like to warm things up, the sound of the engine, when it’s cold it sounds like a washing machine full of nuts and bolts, a bit of heat in it and it sounds much smoother, I’m assuming that the metal parts haven’t changed in size as the temperature difference is minimal, but that the oil has thinned out and is cushioning the blow of metal to metal contact, which is another way of saying lubrication.Sent from my SM-G930W8 using Tapatalk
Nothing to do with the oil thinning, its due to thermal expansion (in laymans terms taking up the slack) as engine parts heat up. If the oil pressure is good there wont actually be any ‘metal to metal’ contact. The temperature im assuming you refer to is coolant temperature which will show as a minimal increase on a guage especially in very low ambient temps at idle…
I’ve said I’m doing it right and have evidence to back up my claims, I have never said doing it the other way is wrong, it’s just my preference, an opinion if you like.
Yet here we are with post after post of people trying to change the way things are done to their way of thinking. No new posters, just the same few going on and on and on trying to prove that they’re right and everyone else is wrong.
It’s boring.
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Its simple if it aint in the manufacturing book then there is no need to do it, and if you do you are wasting you own time for no reason, its the past you all are talking about, like warming the plugs before starting.
Rjan:
I’m led to believe cold engines tend to be a bit clattery because the temperature affects the timing and behaviour of combustion, causing noise in two ways, firstly by affecting the timing of ignition itself, and secondly because the whole engine is tighter and less efficient when cold which requires slightly more fuel to be burnt to get it to turn over against its own internal resistance (making it noisier relative to the set idle speed). And of course there are various auxiliary systems where rubber belts, pulleys, and gaskets will be a bit stiff and less accomodating, plastic covers are a little bit more rigid and resonant, bearings and shafts which are a little bit tighter than when warm, and so on, and the noise properties of the engine are of course finely tuned to be best at normal operating temperature (if it were tuned to be most quiet when cold, it would become slightly noisier when at operating temperature). None of it necessarily indicates that anything is out of order or suffering undue wear due to inadequate lubrication.
That seems to totally overlook piston slap at least to a greater or lesser degree and which applies more in the case of a cold engine than a warm one.So we know for a fact that a cold the piston is rocking relatively more within the bore than when it’s warm.So why would you want to apply load to it in that case thereby creating more shock loading on the rings and possibly even piston scuffing ?.
conforg.fr/cfadaga2004/maste … 000327.pdf
On that note where do you get the notion that clearances are tighter when an engine is cold. 
When we know that bore to piston clearances for one and valve to camshaft clearances are wider when cold.Resulting in more scope for more shock loadings and excessive rocking regarding pistons at least if subjected to load/speed when cold.
The only thing that expands when cold is water, everything else shrinks, go for a ■■■■ at -20c, there’s all the proof you need.
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newmercman:
Manufacturers do push them, at least over here in the colonies, Freightliner, International, Mack, Paccar, Western Star and Volvo offer these heaters from the factory.I know all about oil structures and viscosity, but testing and numbers, even my own oil analysis tell me much less than the Mk1 eardrum. From a cold start my engines sound awful, once warm, they sound much better. Quite simple really.
Is there anything in the bay between those Mk1 eardrums however? 
Carryfast:
On that note where do you get the notion that clearances are tighter when an engine is cold.
I don’t know, I keep struggling with the issue. Usually things enlarge slightly when they are heated, but when you’re talking about parts in which one is hollow and contains the other, is the expansion of the outer part completely outwards or does the outer part also expand into its hollows slightly to fill the internal space? I suspect the shape and strength of the parts may have a bearing on the answer - as of course may any difference in material/alloy between the two parts. And then of course there is the separate question of the thermal mass of the parts and whether they heat up equally with one another. Suffice to say I don’t know enough to be confident on an answer either way.
Rjan:
newmercman:
Manufacturers do push them, at least over here in the colonies, Freightliner, International, Mack, Paccar, Western Star and Volvo offer these heaters from the factory.I know all about oil structures and viscosity, but testing and numbers, even my own oil analysis tell me much less than the Mk1 eardrum. From a cold start my engines sound awful, once warm, they sound much better. Quite simple really.
Is there anything in the bay between those Mk1 eardrums however? [emoji38]
That depends who you’re listening to, if it’s me, the answer will be yes, not quite so sure what others will tell you though. [emoji23][emoji23]
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Rjan:
Carryfast:
On that note where do you get the notion that clearances are tighter when an engine is cold.I don’t know, I keep struggling with the issue. Usually things enlarge slightly when they are heated, but when you’re talking about parts in which one is hollow and contains the other, is the expansion of the outer part completely outwards or does the outer part also expand into its hollows slightly to fill the internal space? I suspect the shape and strength of the parts may have a bearing on the answer - as of course may any difference in material/alloy between the two parts. And then of course there is the separate question of the thermal mass of the parts and whether they heat up equally with one another. Suffice to say I don’t know enough to be confident on an answer either way.
To be fair steel pistons at least predictably seem to be far less of an issue than aluminium in regard to thermal clearance issues.Steel rightly seeming to be the material of choice for heavy truck engines and obviously now finding its way into lighter applications.I’d guess that given steel,cam ground,pistons and modern synthetic wide range grade oils the issue is realistically a case of take your pick and make your choice.There’s probably not much in it either way.But things were/are certainly obviously different in the case of the potential for piston slap issues at least,caused by thermal clearance allowance issues,involving aluminium pistons v iron or steel bores.I’d guess that’s maybe where at least some of the old school ideas originated from IE generations raised on old cast iron block or steel liner light vehicle engines using the old school ally Hepolite pistons in which a relatively loose fit in the bore when cold was obviously essential.
Although that still leaves other obviously temperature sensitive component chains such as in the valve train and possibly engine bearing assemblies and differing expansion rates of head,block,crankcase and sump in which warm it up slowly is probably better than quickly and don’t put it all under load while it’s doing it. 
Rjan:
Carryfast:
On that note where do you get the notion that clearances are tighter when an engine is cold.I don’t know, I keep struggling with the issue. Usually things enlarge slightly when they are heated, but when you’re talking about parts in which one is hollow and contains the other, is the expansion of the outer part completely outwards or does the outer part also expand into its hollows slightly to fill the internal space? I suspect the shape and strength of the parts may have a bearing on the answer - as of course may any difference in material/alloy between the two parts. And then of course there is the separate question of the thermal mass of the parts and whether they heat up equally with one another. Suffice to say I don’t know enough to be confident on an answer either way.
Engine parts have tolerances to to take into account thermal expansion. When an engine is designed the expansion of various types of metals, ie cast iron / ally/forged ect are all taken into account and the tolerances applied as required.
A diesel in general will sound louder when cold due to an excess of unburnt fuel in the cylinder until the combustion chamber heats up to allow it to burn efficiently…
AndrewG:
Rjan:
Carryfast:
On that note where do you get the notion that clearances are tighter when an engine is cold.I don’t know, I keep struggling with the issue. Usually things enlarge slightly when they are heated, but when you’re talking about parts in which one is hollow and contains the other, is the expansion of the outer part completely outwards or does the outer part also expand into its hollows slightly to fill the internal space? I suspect the shape and strength of the parts may have a bearing on the answer - as of course may any difference in material/alloy between the two parts. And then of course there is the separate question of the thermal mass of the parts and whether they heat up equally with one another. Suffice to say I don’t know enough to be confident on an answer either way.
Engine parts have tolerances to to take into account thermal expansion. When an engine is designed the expansion of various types of metals, ie cast iron / ally/forged ect are all taken into account and the tolerances applied as required.
But the question is how do the tolerances change with temperature?
A diesel in general will sound louder when cold due to an excess of unburnt fuel in the cylinder until the combustion chamber heats up to allow it to burn efficiently…
Agreed.
So if the noise is produced because the engine is not burning fuel efficiently because of cold temperatures, doesn’t that mean that running at reduced load until warm will only exacerbate that inefficiency?
As I said in an earlier post, I think this is a situation of six and 2x3, my oil analysis results, mainly the oxidation and nitration readings, confirm that a 15min warm up is doing the oil no harm, wear metal levels are below acceptable readings for the mileage on the oil, ergo it’s not harming the metal parts either. I recently had the DPF cleaned on the Volvo and that was also in good shape, which confirms idling isn’t producing harmful (to the emission system) soot levels either.
Or poodling along slowly bringing things up to temperature gradually, what are the effects of this? It is probably exactly the same as idling up to temperature, it could actually be a better bet in the short term, as the gearbox and differential will come up to temperature along with the engine, although the gearbox and differential operate very differently to an engine, being an oil bath with all the components in one place, rather than an engine with moving parts all over the place.
As far as I can see, the only difference will be fuel usage, will the inefficiency of combustion at lower temperature use less fuel than idling? I don’t know, the only way to tell for sure would be to pull an engine out of a truck and perform a simulated test using both methods and measure the fuel used in both examples.
I’m guessing that the difference would be too small to make any significant difference to my operation, maybe if I had a few hundred trucks it would be different, but I don’t, so I guess I’ll just carry in doing what I do and not worry about micromanaging things to the point where I lose sight of the big picture.
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newmercman:
So if the noise is produced because the engine is not burning fuel efficiently because of cold temperatures, doesn’t that mean that running at reduced load until warm will only exacerbate that inefficiency?
Re wet stacking, it’s interesting, because your point is almost identical to CFs response to Bking.
Wet stacking occurs due to incomplete combustion of fuel due to insufficient combustion temperatures.
Converse to incorrect view of “washing more oil off” - increasing revs:-
(Below are excerpts from an article on wet stacking)
An engine will normally operate at a somewhat higher temperature at higher engine speeds than at low idle because of the added fuel requirement. Atomisation of fuel improves at higher revs due injection rate and chamber turbulence increasing with higher engine speed. The tendency for fuel particles to overpenetrate and impinge on cylinder surfaces is reduced at higher engine speeds.
This isn’t me trying to dictate to you, just to answer your point re wet stacking. Increasing revs on a cold engine causing more dilution of bore face oil is a myth CF also subscribes to. So thought it interesting to share some actual gen.
Freight Dog:
newmercman:
So if the noise is produced because the engine is not burning fuel efficiently because of cold temperatures, doesn’t that mean that running at reduced load until warm will only exacerbate that inefficiency?Re wet stacking, it’s interesting, because your point is almost identical to CFs response to Bking.
Wet stacking occurs due to incomplete combustion of fuel due to insufficient combustion temperatures.
Converse to incorrect view of “washing more oil off” - increasing revs:-
(Below are excerpts from an article on wet stacking)
An engine will normally operate at a somewhat higher temperature at higher engine speeds than at low idle because of the added fuel requirement. Atomisation of fuel improves at higher revs due injection rate and chamber turbulence increasing with higher engine speed. The tendency for fuel particles to overpenetrate and impinge on cylinder surfaces is reduced at higher engine speeds.This isn’t me trying to dictate to you, just to answer your point re wet stacking. Increasing revs on a cold engine causing more dilution of bore face oil is a myth CF also subscribes to. So thought it interesting to share some actual gen.
I was actually referring to the issue of ‘load’ = more fuel put into the same cold cylinder as the idling engine example.IE you’ve got the catch 22,of using ‘load’ not just speed to supposedly warm up a cylinder ‘quicker’,working against you.Because you’re obviously pushing in a lot more of the fuel,that you’re worried about regarding fuel wash,while it’s doing it.You can obviously also add the arguable issue of piston slap to that with a cold piston in a cold bore.Although obviously less of an issue in the case of steel cam ground pistons.
While surely if it’s just engine ‘speed’ that we want then high idle,thereby creating beneficial engine speed,under no load thereby minimising harmful fuel input and other arguable cold/warm up stress issues on components and oil,wins ?.
Freightdog, I was only thinking about the actual fuel use itself, as in, how much fuel is burned from starting until reaching cruising speed using both methods?
The inefficient combustion of a cold engine using as much fuel as idling and then setting off when combustion is at peak efficiency. That was my question.
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newmercman:
Freightdog, I was only thinking about the actual fuel use itself, as in, how much fuel is burned from starting until reaching cruising speed using both methods?The inefficient combustion of a cold engine using as much fuel as idling and then setting off when combustion is at peak efficiency. That was my question.
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I beg your pardon. I’m with you. Mm, don’t know. I’d be guessing either way. Aside from fuel use, from what I can reason, it would take a very long time, if at all to take a Diesel engine to a position of peak efficiency through idling cold.
I have a very strong conviction that the prime reason many diesel manufacturers discourage cold idling is to mitigate wet stacking, glazing and bore scoring maladies.
I think I may need to define what I consider idling, I’m referring to a gradual increase in rpms as oil pressure comes down, starting at a dead idle and rising to 1,000rpm or more. On my CAT engine anyway, the Volvo won’t idle at over 700rpm without a PTO setting in the programming. The Volvo does do some magic as it idles though, I don’t know what or how specifically, but it does put itself under load during an overnight idle, it may be something the VGT does, closing the vanes or some other kind of witchcraft and sorcery, but it does it to keep coolant temperature up to 180deg.
That in itself is confusing, it gives an argument for both sides, first that the engine needs a gentle load to operate efficiently, secondly that it needs a bit of heat in it to operate efficiently. Like I’ve said, it’s six and 2x3.
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Carryfast:
Freight Dog:
newmercman:
So if the noise is produced because the engine is not burning fuel efficiently because of cold temperatures, doesn’t that mean that running at reduced load until warm will only exacerbate that inefficiency?Re wet stacking, it’s interesting, because your point is almost identical to CFs response to Bking.
Wet stacking occurs due to incomplete combustion of fuel due to insufficient combustion temperatures.
Converse to incorrect view of “washing more oil off” - increasing revs:-
(Below are excerpts from an article on wet stacking)
An engine will normally operate at a somewhat higher temperature at higher engine speeds than at low idle because of the added fuel requirement. Atomisation of fuel improves at higher revs due injection rate and chamber turbulence increasing with higher engine speed. The tendency for fuel particles to overpenetrate and impinge on cylinder surfaces is reduced at higher engine speeds.This isn’t me trying to dictate to you, just to answer your point re wet stacking. Increasing revs on a cold engine causing more dilution of bore face oil is a myth CF also subscribes to. So thought it interesting to share some actual gen.
I was actually referring to the issue of ‘load’ = more fuel put into the same cold cylinder as the idling engine example.IE you’ve got the catch 22,of using ‘load’ not just speed to supposedly warm up a cylinder ‘quicker’,working against you.Because you’re obviously pushing in a lot more of the fuel,that you’re worried about regarding fuel wash,while it’s doing it.You can obviously also add the arguable issue of piston slap to that with a cold piston in a cold bore.Although obviously less of an issue in the case of steel cam ground pistons.
While surely if it’s just engine ‘speed’ that we want then high idle,thereby creating beneficial engine speed,under no load thereby minimising harmful fuel input and other arguable cold/warm up stress issues on components and oil,wins ?.
From what I can understand operating diesel engines at light loads maintains combustion temperatures adequate to support full combustion. The temperature is influence by engine design such as compression ratio and environment like intake temp. A light load does actually aid an increase of combustion temps.
Re piston slap and bore scoring. Under load this will generally take place on the thrust side of the bore face. From what I can read if you’ve an engine that has been idling at sub prime combustion temps for a while, perhaps under wet stacking conditions, the oil dilution would have been taking place. Thereafter when a load is placed upon the engine, bore scoring is a risk. A piston will always be “looser” at moderate speeds (otherwise it would sieze at full throttle). The lubricant is required to mitigate this. Sitting under wet stacking conditions prior to load is probably a bad idea from reading the research.
I know on certain Porsche engines (m96), fatal bore scoring can take place in mere seconds for very different reasons when flooring the throttle from low revs from traffic lights. If you’re interested anyway. It’s not related to idle warming. The reason is multi faceted. The coolant flow rate across the cylinder is at its lowest at idle. The sudden load on the thrust face coupled with a huge temp increase (by flooring it at very low revs) causes a localised heat spot on cylinder bank 2. The coolant flow rate, unable to catch up, allows the hotspot to raise the oil temp enough that viscosity fatally drops on the thrust side only, the piston face and skirt, under huge load, scores against the locasil liners causing some of the microscopic crystals to dislodge and rub against the liner.
I’ll remember that when I’m buying my next Porsche… if only…
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