Engine Warm-Up Discussion.

[OVERKILL]

Originally Posted By: Ducked
Originally Posted By: ReverendC
When I start my seldom used 1990 Chevy truck, I hate that 3 seconds of engine rattle knowing that lots of metal things aren't getting any oil.


If the paper I found is still current, the BPT (Borderline Pumping Temperature) is defined after a minute of cranking. Listening to that for a full minute would hurt.

I'd like to believe that this is a binary go/no go phenomenon, (oil pumps or it doesn't) and maybe it is, but its a bit of a stretch. The fact that it seems to be defined as a cutoff isn't very persuasive on its own, since that might just be for procedural convenience.


I believe we might have read the same publication and if that's the case what I found concerning was that the pumpability point for certain engines was different than with others. IE, one engine would pump a 60,000cP lube, but another wouldn't pump one that was 35,000cP. The limit used to be 30,000cP based on that same publication. It was found newer engines were able to pump the 60K cP lube but where does that leave the older engine crowd?

 

[BearZDefect]

Originally Posted By: datech
I remember reading a long time ago a magazine article that examined how long an engine could sit before bad things started happening. I think it said they started to find rust forming in the cylinder after 10 days.

...

I don't have the experience to comment specifically, but wouldn't environmental variables such as humidity, temperature, and corrosives like salt in the air make the number of days highly variable?

 

[Ducked]

Originally Posted By: BearZDefect
Originally Posted By: datech
I remember reading a long time ago a magazine article that examined how long an engine could sit before bad things started happening. I think it said they started to find rust forming in the cylinder after 10 days.

...

I don't have the experience to comment specifically, but wouldn't environmental variables such as humidity, temperature, and corrosives like salt in the air make the number of days highly variable?


There'll likely be engine variables as well. I THINK I vaguely recall hearing somewhere that particular cylinders on (Caterpillar?) diesels corrode more because the engine tends to stop with that exhaust valve open.

 

[CT8]

Originally Posted By: Ducked
Originally Posted By: BearZDefect
Originally Posted By: datech
I remember reading a long time ago a magazine article that examined how long an engine could sit before bad things started happening. I think it said they started to find rust forming in the cylinder after 10 days.

...

I don't have the experience to comment specifically, but wouldn't environmental variables such as humidity, temperature, and corrosives like salt in the air make the number of days highly variable?


There'll likely be engine variables as well. I THINK I vaguely recall hearing somewhere that particular cylinders on (Caterpillar?) diesels corrode more because the engine tends to stop with that exhaust valve open.
It is the same on all engines.

 

[Shannow]

Ducked,
I'm only up to page 42...
http://eprints.nottingham.ac.uk/13180/1/Thesis_JP.pdf

Interesting discussions in there about insulating bearings and the like....maybe 15W30 IS an answer.

 

[datech]

Originally Posted By: BearZDefect
Originally Posted By: datech
I remember reading a long time ago a magazine article that examined how long an engine could sit before bad things started happening. I think it said they started to find rust forming in the cylinder after 10 days.

...

I don't have the experience to comment specifically, but wouldn't environmental variables such as humidity, temperature, and corrosives like salt in the air make the number of days highly variable?


Yes that makes sense. Probably the type of oil, too. Good thing we have magnetic oil available.

 

[Ducked]

Originally Posted By: CT8
Originally Posted By: Ducked
Originally Posted By: BearZDefect
Originally Posted By: datech
I remember reading a long time ago a magazine article that examined how long an engine could sit before bad things started happening. I think it said they started to find rust forming in the cylinder after 10 days.

...

I don't have the experience to comment specifically, but wouldn't environmental variables such as humidity, temperature, and corrosives like salt in the air make the number of days highly variable?


There'll likely be engine variables as well. I THINK I vaguely recall hearing somewhere that particular cylinders on (Caterpillar?) diesels corrode more because the engine tends to stop with that exhaust valve open.
It is the same on all engines.


Don't have any data on that, but it seems pretty unlikely.

For example, the condensation and oil drain-down pattern on, say, a horizontally opposed engine is likely to be quite different to a V or vertical, then there's aluminium versus cast iron blocks, fuel injection versus carbs (more oil wash-off/dilution with the latter) differences in crankcase scavenging systems, and EGR, all of which are engine design variables which seem likely to influence corrosion rates.

Apparently its a particular problem with light aircraft engines (due to the intermittent use rather than design). I've seen straight weight mineral oils recommended for them in preference to multi-grades, interpreted as less-drain down, and/or light varnishing giving better protection when parked-up.

 

[Ducked]

Originally Posted By: Shannow
Ducked,
I'm only up to page 42...
http://eprints.nottingham.ac.uk/13180/1/Thesis_JP.pdf

Interesting discussions in there about insulating bearings and the like....maybe 15W30 IS an answer.


I got to 55, but I skipped the simulation and maths stuff.

Tis interesting, but, from my quick scan, the focus is on improving fuel economy through the reduction in friction achieved by shortening oil warm up time.

That's obviously of the greatest general interest, but the focus of our discussion (or perhaps just my bit of it) was on wear, which only gets passing mention in the thesis. My impression is that most of the "friction" being discussed is due to internal shear of the oil in the bearings which isn't directly wear-related.

My focus is on wear because I have an old vehicle with limited remaining lifespan, which doesn't use a lot of fuel, which I don't drive much, and which is putting a lot of ferrous metal in the oil, probably from the cams. Seems to me that the best way to combat this would be to use thicker oil, perhaps/ideally in combination with a prelube system.

I havn't seen anything in this discussion or this thesis (apart from your disagreement, which I don't discount, but which you havn't explained) to negate this conclusion.

Preheat/faster heatup would also probably have wear-reducing benefits through additive activation, though I might expect them to be less. A preheat system would, however, probably be easier to improvise than a prelube, but before I get into that (which I'm not likely to have time for anyway) I should probably just check my thermostat.

 

[Ducked]

Originally Posted By: OVERKILL
Originally Posted By: Ducked
Originally Posted By: ReverendC
When I start my seldom used 1990 Chevy truck, I hate that 3 seconds of engine rattle knowing that lots of metal things aren't getting any oil.


If the paper I found is still current, the BPT (Borderline Pumping Temperature) is defined after a minute of cranking. Listening to that for a full minute would hurt.

I'd like to believe that this is a binary go/no go phenomenon, (oil pumps or it doesn't) and maybe it is, but its a bit of a stretch. The fact that it seems to be defined as a cutoff isn't very persuasive on its own, since that might just be for procedural convenience.


I believe we might have read the same publication and if that's the case what I found concerning was that the pumpability point for certain engines was different than with others. IE, one engine would pump a 60,000cP lube, but another wouldn't pump one that was 35,000cP. The limit used to be 30,000cP based on that same publication. It was found newer engines were able to pump the 60K cP lube but where does that leave the older engine crowd?


Out in the cold, I'd have thought.

Aside from basic backward-compatibility testing, (and "boutique" products), I don't think older engines are of much concern to oil companies, since they are a small and shrinking market.

Car companies, and governments, are actively hostile, as in the UK where you can get a substantial govt payment, matched by the car companies, if you scrap a 10 year old car and buy a new one.

This is justified by the govt on environmental grounds. Possibly some people actually believe that.

 

[Olas]

The Government scrappage scheme only ran for one year and it finished in 2011 or 2012. The majority of cars that were scrapped for the subsidy were ill maintained and rusty, fortunately hardly any niche/classic cars were entered into the scheme


Car companies, and governments, are actively hostile, as in the UK where you can get a substantial govt payment, matched by the car companies, if you scrap a 10 year old car and buy a new one.

This is justified by the govt on environmental grounds. Possibly some people actually believe that.

 

[Ducked]

Originally Posted By: Olas


The Government scrappage scheme only ran for one year and it finished in 2011 or 2012.


Yes, "can" should have been "could" (past tense), my bad, though there's talk of a revival, specifically for diesels, presumably so you can get a new one with a DPF system that'll wreck your engine.

Originally Posted By: Olas


The majority of cars that were scrapped for the subsidy were ill maintained and rusty, fortunately hardly any niche/classic cars were entered into the scheme


Many, many reported exceptions to that generalised allegation, the most astonishing being a Morgan. Plus todays "banger" is potentially tomorrows classic, if it survives long enough.

http://www.topgear.com/uk/photos/20-saddest-scrappage-scheme-victims-2014-09-30

http://www.mirror.co.uk/news/uk-news/thousands-classic-cars-destroyed-part-4353320

Very few un-crashed cars in any scrapyard I've ever visited have looked worse than any of mine, but mine had to pass the UK's fairly picky annual inspection, so they were basically OK.

 

[SteveSRT8]

Originally Posted By: Olas
This is is justified by the govt on environmental grounds. Possibly some people actually believe that.


Indeed. An older car can easily emit thousands of times more pollutants than a new one, and then there's the safety issues as well.

But regardless the "cash for clunkers" program here was a huge waste of decent cars as well as a blow to parts scroungers working the junkyards...

 

[Garak]

Originally Posted By: Shannow
What OVERKILL is saying is that provided the oil isn't started at temperatures that it won't pump at, it will pump and move through the engine.

Exactly. As I mentioned some time ago in another thread, some of us see temperatures where oil will not pump. Some of us also have engines with carbs and good batteries that will start the engine when the oil is far, far from up to the task.

 

[Shannow]

Originally Posted By: Shannow
Ducked,
I'm only up to page 42...
http://eprints.nottingham.ac.uk/13180/1/Thesis_JP.pdf


Quote:
Having validated the model, the authors went on to do a parametric study investigating the effect of engine running condition, combustion chamber wall thickness, together with coolant and lubricant volumes, on the engine’s warm-up characteristic. Operating the engine at the same power, but at double the engine speed of the baseline condition resulted in quicker heating of the oil. The lighter load condition led to a lower mean gas temperature and hence decreased cylinder head and liner temperatures. This suggests that heat input to the oil from friction dissipation generally outweighs heat exchange from hot engine surfaces.


This week, on my commute I trialed leaving the Caprice in "2", while traversing town, and not using "D" until at the highway.

The extra revs and work done on the oil during this process mean that the temperature gauge reads normal temp when I hit the highway, when under lower revs, it's not at the normal lever for a few ks on the highway.

 

[demarpaint]

Originally Posted By: Shannow
Originally Posted By: Shannow
Ducked,
I'm only up to page 42...
http://eprints.nottingham.ac.uk/13180/1/Thesis_JP.pdf


Quote:
Having validated the model, the authors went on to do a parametric study investigating the effect of engine running condition, combustion chamber wall thickness, together with coolant and lubricant volumes, on the engine’s warm-up characteristic. Operating the engine at the same power, but at double the engine speed of the baseline condition resulted in quicker heating of the oil. The lighter load condition led to a lower mean gas temperature and hence decreased cylinder head and liner temperatures. This suggests that heat input to the oil from friction dissipation generally outweighs heat exchange from hot engine surfaces.


This week, on my commute I trialed leaving the Caprice in "2", while traversing town, and not using "D" until at the highway.

The extra revs and work done on the oil during this process mean that the temperature gauge reads normal temp when I hit the highway, when under lower revs, it's not at the normal lever for a few ks on the highway.


I've considered exactly what you tried. I have about a .8 mile ride to the highway, with three lights. The acceleration ramp is long, and never requires flooring it to get on the highway. I opted out of leaving it in second until I get to the highway. What bothers me is the torque converter won't lock up until about 2-3 miles into the trip if the weather is cold. I'd rather the engine rev lower on the highway until it reaches operating temps, but the automaker believes otherwise.

 

[Jetronic]

it's the transmission design and temperature that dictates when lock-up starts to work. nothing to do with engine temperature.

Some only require 15C, others want 50+

 

[demarpaint]

Originally Posted By: Jetronic
it's the transmission design and temperature that dictates when lock-up starts to work. nothing to do with engine temperature.

Some only require 15C, others want 50+


I thought it designed to operate that way to facilitate engine warm up by letting the engine rev higher?

 

[Jetronic]

I doubt it as quick engine warm up becomes more and more important to meat emmisions demands, but the transmissions themselves lock sooner with every generation, and in lower gears aswell.

 

[ragtoplvr]

about 20 years ago I worked with a former GM engineer that had done time at the hot and cold weather testing facilities. One of the cold tests was to start the cold soaked car and then let it idle for hours with the heater on. then cold soak again and repeat.

Another test was to start the cold soaked car, turn the heater fan on high, and floor it, looping on the heated track until good and hot, then repeat.

On tear down, the idled engines always had much more wear.

Some even had minor scoring.

The wide open cars usually did well. If a car did not pass the test, they had to make it where it would.

Rod

 

[Shannow]

Rod, a good and interesting data point.

Thanks