greatest contribution to wear reduction

[Gary Allan]

quote:

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Originally posted by TomJones76:
Thus, per Gary Allan's argument, we don't need an engine pre-luber.
What we need, ladies and gentlemen, is a heater under our hoods that keeps the engine at a constant 210 degrees!

---

Even that won't stop wear. It will reduce it ..but you can't simulate combustion temperature conditions for pistons other then having the combustion process occuring. You'll still have wear with all the warmers and preoilers you can hang on the thing. Unless you can have an engine running and pump the exhaust gas through the combustion chambers while it's not running ..then you're SOL.

 

[bonnie john]

my '92harley has a carburetor (c.v.)

it has 60,000 miles on it, 1 owner, original bore etc

no oval, no taper, no oil consumption, infamous 3000 mile oci

this was unheard of on bikes in years gone by (been riding 35 years on english mo'cycles)

quote:

---

Originally posted by Big Jim:
I still remember when you had to remove a ridge before removing pistons from the block. When common cylinder taper was between 5 and 10 thousands of an inch. Replacement rings were designed with forgiveness for such tolarences. An engine block with as little as 50,000 miles on it needed to be rebored when rebuilding it, and minimum oversize was 20 thousands of an inch.

What has changed? Certainly the materials are better. The oils are much better. But still to me the biggest improvement is that the oil isn't getting near the load of fuel dilution from the long outdated fuel control system, carbs. If we still had such heavy fuel dilution, even with all the rest of the improvements would not being doing much good. Compared with 30 or 40 years ago, we don't even know what sludge is. Sludge that was largly agrivated from fuel dilution.

---

 

[Black Bart]

The test that I revered to was a diesel.
When discussing bearing loads on dry startup you can't compare results from a engine with 22-1 C/R
to one that is 9-1 C/R

 

[jmacmaster]

quote:

---

Originally posted by 427Z06:
Some excerpts from one study I've read:

A cold start can cause between 200-1000 miles or wear (we normalized by the wear rate with fresh oil at highway speeds).

---

Lets take the mid-point of that 200-1,000 miles of wear per start up, which is 600 miles, and assume that you get the "wear-equivalent" of driving 600 miles with each cold start.

Then lets assume two cold starts per day (which I think is conservative for the average driver) over the period of a year, which equals 730 cold starts for the year.

Then multiply the 730 cold starts by 600 miles of wear. You get 438,000 miles. So the cold starts for that year caused as much engine wear as driving the car for 438,000 miles would have caused. So any new car's engine would be worn out long before the end of its first year.

This is patently absurd. I think that the amount of engine wear caused by cold starts is vastly overestimated.

 

[Audity]

Biomed, I think you mean Accusump, a pressure accumulator for the lube system.

Common in race cars. Primary purpose is to prevent momentary loss of oil pressure under high load (unporting the sump pickup in high-g corner, for instance). You see a lot of them in street-car based racers with high $$ engine enhancements.

However, they are also used to pressurize the lube system prior to starting, very relevent to what's being discussed here.

 

[Mitch Alsup]

"I would believe, just from common sense, that cold starts would contribute the significant amount of wear. Precise numbers, I could only guess at. But consider that when an engines starts it has to produce oil pressure to the main bearing, rod bearings, valve train and so on. It is the pressure that creates the "float" that keeps engine bearing surfaces from eroding."

This is incorrect, pressure mearly moves oil through the galleys and into and through the bearings. When a large force is applied to a rotating part in a journal bearing, a hydrodynamic wedge develops. This hydrodynamic wedge operates at thousands of PSI and is responsible for the vast majority of keeping the journal bearings and shafts from touching and incurring wear. There is simply no way for the oil pump (itself) to create such a sufficiently large force to keep the force of a piston at WOT from causing metal to bearing friction.

 

[badnews]

quote:

---

Originally posted by Gary Allan:
I think this perceverating on "startup" is totally misaligned with what wear we see in engines. That is, the wear has little to do with lubrication. It has mostly to do with ill fitting parts that have higher wear until they are warmed up. No oil is going to change that pattern of wear. We don't see much bearing wear in UOA from short run/short trip engines ..but according to the impressions that you seem to have ..a short trip car should be heavily laden with Pb in the UOA. In most that I've seen ..it's way down on the list compared to others.

Every reciprocating engine in existance eventually has oval cylinders. That's the wear that you cannot avoid and most of it occurs during startup (warm up). No oil is going to alter that wear much one way or another.

---

My thoughts exactly.

This start up wear ** is way overstated .

 

[Nebraskan]

Well, the race car engine builder I talked to today, affirmed the wear/bearing idea. They even crank the engine before allowing the ignition to fire, thus building up some oil pressure. There are even systems that are pressurized that keep the oil at a constant pressure even overnight.

He also said that the rattle sound you hear when you start up a car with lots of mileage on it is becuse of the excessive clearance in the rod bearings and you hear the rattle until the oil pump has "filled the gaps".

I stand with 427Z06 on this. He has stated a truth in the matter of wear. I think cars that were running with bypass sytstems, and left running constantly would exibit extremely small amounts of wear. Back in Nebraska we go into the grocery store or convenience store for just a few minutes, especially in the winter, and we leave the vehilces run. And ESPECIALLY if it's a diesel engine. I've heard it time an time again from mechanics from every class and age. The worst thing you can do to your vehicle is to start it.

 

[jmacmaster]

quote:

---

Originally posted by Nebraskan:
Well, the race car engine builder I talked to today, affirmed the wear/bearing idea.

I stand with 427Z06 on this. He has stated a truth in the matter of wear.

---

A race car engine is nothing like, is driven nothing like, and lasts only a few hundred or thousand miles, compared to the engine in what people use as a daily driver. You simply cannot compare the two, on anything.

More to the point, what's your answer to my post above, in which I point out the logical absurdity of the 427Z06 suggestion that each cold start creates as much wear on an engine as driving it
600 to 1,000 miles?

 

[Geoff]

1. Dirt (silicon) in the engine: single biggest wear agent I have seen. Change oil more often in dusty conditions, period. New designs are MUCH better sealed.

2. Fuel dilution. The silver lining in emission controls: modern cars operate with the water temp near boiling, much more precise fuel metering, variable valve timing, much stronger electrical systems to achieve clean burning.

3. Better base oil quality. Group II very common in dino practically kills synthetic requirements unless you go very long OCIs, but see #1.

4. Better additive packages. SL may have been the peak, but SM oils still in a different world than the older SD and earlier oils that would form sludge in just a couple thousand miles.

 

[jmacmaster]

One of the properties of oil is that it clings to things, and coninues to cling to them.
This is especially true of lubricating oils, which are formulated to enhance this (let us call it) "clingability" of the oil.

This is why people oil many things that do NOT have moving parts. The oil stays on those things and protects them, for a fair amount of time. Certainly longer than the time between the startups of a typical motor vehicle that sees typical use.

Oil applied to things that DO have moving parts does not completely, or all, drip off of those parts when the parts stop moving. This includes motor engine oil. When you shut off your engine, yes, most of the oil drips off of the engine and down into the oil pan. However, a thin film of the oil remains on the engine parts. Just as a film of oil remains on a tool with non-moving parts that you oil to preserve the surface of that tool. (This, by the way, is one reason why I prefer a 5w30 oil to a 5W-20 oil, because the 30 weight is thicker than the 20 weight and thus leaves a bit thicker film on the engine parts when you shut the engine off, thus, resulting in more protection of the engine parts on the next (cold) start.

When you start the engine of a motor vehicle, the oil pump immediately baths the engine in oil. This is oil in addition to the thin film of oil that continued to adher to the engine parts after you last shut off the engine.

A properly started engine is not revved up high on the start, so the engine is not turning over at high rpm's and working hard. This means that it does not experience much wear.

I say again that the amount of engine wear attributed to cold starts is vastly overrated, and as far as I can see, is not scientifically docmented on BITOG by those who claim that most engine wear, or a large percentage of the engine wear, comes from cold starts.

This idea of high engine wear from cold starts is a myth. Engine wear comes mainly from the total number of revolutions of the engine over its lifetime and the rpms at which the engine is run, which are minimal at startup. An engine wears out mainly from the revolutions that it experiences, and only minimaly from cold starts.

 

[427Z06]

quote:

---

Originally posted by jmacmaster:
Lets take the mid-point of that 200-1,000 miles of wear per start up, which is 600 miles, and assume that you get the "wear-equivalent" of driving 600 miles with each cold start.

Then lets assume two cold starts per day (which I think is conservative for the average driver) over the period of a year, which equals 730 cold starts for the year.

Then multiply the 730 cold starts by 600 miles of wear. You get 438,000 miles. So the cold starts for that year caused as much engine wear as driving the car for 438,000 miles would have caused. So any new car's engine would be worn out long before the end of its first year.

This is patently absurd. I think that the amount of engine wear caused by cold starts is vastly overestimated.

---

Well...math isn't your strong point I presume?

Seriously, you make the mistake of equating start-up wear miles as defined above with actual miles on a typical vehicle.

Recall that startup-wear miles are normalized to the wear rate with fresh oil at steady highway speeds. This means that the average engine, with average maintenance, in the average climate starts out with approximately 2 millions miles of life. Toyotas probably start off with 3-4 million miles.

Also, one has to define what worn out means. A worn out engine may still run, but one or more of the engine specifications are out of spec. This could be one or more of the following: bearing clearances, piston/ring clearances, bore taper, leakdown rate, chain stretch, etc, etc.

Your example above still gives you 5 years of starting a cold engine and running it up to temperature twice a day, everyday, before something is out of spec. And if you drove for 10 miles each start, 36,500 miles would be on the odometer.

I would say that average BITOGER is in the 200 miles of wear per start up range. And many are probably closer to the 100 miles of wear per start up range.

[ August 29, 2006, 12:25 AM: Message edited by: 427Z06 ]

 

[427Z06]

Let's look at another example. Assume a BITOGer who knows when his thermostat isn't working and replaces it shortly after failure. He also changes his oil religiously, and never runs it over the manufacturer's recommendations. Further, all maintenance, such as tune-ups, are done no later than the manufacturer's recommendations and all part failures are noticed and corrected in short order. He knows to not idle to warm, if he can avoid it, and the vehicle is used mainly for commuting and errands, not for auto-crossing or racing the kid down the block. His climate is average, meaning his vehicles see freezing temps half the year, and his wife has the garage loaded with a bunch of junk, so his car has to sit outside at night. This earns him a 200 mile start-up wear classification (YMMV). He's a NASCAR fan and likes Matt Kenseth so he drives a Ford.

200 mile(start-up) + 20 mile(commute) * 2 = 440 miles/day of wear

365 days * 440 miles/day = 160,600 miles per year of wear

13 years * 160,600 miles = 2,087,800 of wear

20 miles (commute) * 2 * 365 days * 13 years = 189,800 miles are on the odometer.

Although the car still starts and runs well, thanks to the computerized fuel injection and electronic ignition, you can bet there's at least a few parts that are close to or are slightly out of spec at this point.

 

[Nebraskan]

quote:

---

Originally posted by 427Z06:
He's a NASCAR fan and likes Matt Kenseth so he drives a Ford.

---

 

[Nebraskan]

Oil does have film property, but film alone won't keep you protected. When you first start that engine, your pistons begin to fire and transfer a LOT of pressure on the rod bearings. Film helps, and if it weren't for the film your bearings would not last very long at all. they are not the best for wear material, that's why they are composed of what they are. So, as soon as the oil pump builds some pressure the oil now becomes more than film, it becomes a hydrostatic fluid and your rod never even touches those bearings, but literally is cushioned by the oil pressure film. Now the engine is running fully protected. Before, it was in the process of becoming fully protected. Film alone can't give you much protection. Don't believe me? Just pull your oil filter, put in a restrictor in the flow going to the engine so that you have around 3 lbs of oil pressure, replace the oil filter, and find out exactly how great film is. 3 lbs of oil will give you film and will give you flow, but won't give you hydrostatic pressure and the "float" needed for bearing surface protection. BTW, this is NOT an advisable thing to do. But, it would demonstrate just how true that cold starts are on the overall damage to the engine.

It's true that race car engines do not represent the engines the consumer has in their cars. But, if this engine is only going to last a few thousand miles anyway, then why do they even go to the bother to crank the engine without firing until the oil pressure is built? Because they know better. *S*

 

[1sttruck]

Something's not right about the start up wear, as one would expect significant differences in engine life with such wear rates. Using a 200 mile commute instead of 20 miles with the example above one ends up with

800 miles per day of wear

292,000 miles per year

3,796,000 miles in 13 years

1,898,000 on the odometer in 13 years.

We don't see such mileage, so scaling back to a high 292,000 miles on the odometer in 2 years we only end up with 584,000 miles of wear.

Where did the other 1.5 million miles of wear go ?

If we use 7 years to get about 2 million miles of wear we end up with over a million miles on the odometer, just by commuting 200 miles a day. We should be seeing that on a common basis, but don't, so the start up wear needs to be scaled back.

 

[427Z06]

1struck, as usual, looks like you need help with math too.

200 mile(start-up) + 200 mile(commute) * 2 = 800 miles/day of wear

365 days * 800 miles/day = 292,000 miles per year of wear

7 years * 292,000 miles = 2,044,000 miles of wear

200 miles (commute) * 2 * 365 days * 7 years = 1,022,000 miles are on the odometer.

And it does happen:

http://www.theautochannel.com/news/2001/08/29/028398.html

http://www.prnewswire.com/news/inde...STORY=/www/story/08-29-2001/0001562942&EDATE=

 

[TooSlick]

427ZO6,

And you always try and make things too simple...

Actually I'd say it also depends on if you're talking about bearing and ring/cylinder wear or valvetrain wear. Since the bearings and rings/cylinder operate under hydrodynamic/full flow lubrication regimes, almost all their wear occurs on startup (unless you have abnormal liquid contamination). By contrast, valve train components function under boundary or mixed mode lubrication conditions, with intermittant metal to metal contact. So those components DO continue to wear under steady state driving conditions. This is particularly true if you have high silicon and/or soot levels.

How's that sound?...

TS

 

[friendly_jacek]

quote:

---

Originally posted by jmacmaster:

I say again that the amount of engine wear attributed to cold starts is vastly overrated, and as far as I can see, is not scientifically docmented on BITOG by those who claim that most engine wear, or a large percentage of the engine wear, comes from cold starts.

This idea of high engine wear from cold starts is a myth. Engine wear comes mainly from the total number of revolutions of the engine over its lifetime and the rpms at which the engine is run, which are minimal at startup. An engine wears out mainly from the revolutions that it experiences, and only minimaly from cold starts.

---

Sorry pal, but you are wrong. It's a scientific fact. Easy to find if you read scientific literature instead of forums.

It's simple and common sense if you realize that the "oil" in the ring/liner interface is not pure oil but a mixture of oil, unburn fuel, and combustion products.
During cold start it's mostly gas, water, and acids from combustions.

I hope this helps.

 

[Gary Allan]

There has to be a tapering off of startup wear. I don't think that it can be isolated to just the time between the turning of the key to 30 sec with nothing there on. I would think that your measured wear would be heavily weighted to the first half of the warmup cycle.