Reciprocating engines and lack of lubrication 4

[dicer]

I would like to hear some stories, and studies on this topic.
We've all seen the various ad's in the past of an engine running with out oil. I have also read some stories from aviators that had engines run out of oil, and the engine was saved from damage. I can even think back as a youngin when a friends vehicle ran low on oil and siezed the engine, rather than figure out how to tow it back home, I bought some oil, put it in, and of course the starter wouldn't budge it so I told him we will have to coast it to 35 and pop it into gear, it was a automatic. It started and was fine. I don't remember how long he drove it after that, and it may have ran low a few other times too and done the same thing.
I know very well what happens with no oil delivery to the bearings, I have had to repair many such failed engines.
Like a diesel engine that ran at idle for maybe 15 to 20 minutes before it seized.
How long can an engine run with little to no oil delivery and low power before bearing damage occurs?
I know of a fellow that ran a big radial engine mistakingly with very low oil level, its a dry sump, and 4 gallons maybe in the whole system if even that much I think it is meant to hold 20 or 30 gallons, it showed cranking oil pressure, and ran maybe 2 to 3 minutes, he doesn't remember checking oil pressure after it was running after initial start. My first guess is there was not even enough oil to scavenge any debris if there was any. So inspection of the filter would be worthless. The oil used is close to SAE 60.

 

[rmw]

I once had a motor scooter that after an overhaul was real tight would seize up when it got hot and I'd just have to sit on the curb and wait for it to cool off. When it did, I could crank it and drive it until it seized up again (which it did often until it got good and broke in. So excessive expansion of internal parts might be the culprit with seizing up rather than actual engine failure. That scooter went on to run for many years once it loosened up real good.

Other than that, low lubrication and no lubrication are two entirely different things. Lubricant capacity has an element of cooling involved as it sits in the 'storage' phase, so with low storage amounts, the danger is overheating of the lubricant, which the engine doesn't necessarily care about as long as something lubricates it, but the oil properties (additive depletion and viscosity indexer destruction) might. So an engine might run a long time with low amounts of oil and the only result would be trashed oil rather than a trashed engine, unless of course you operated it until the complete failure of the oil led to the complete failure of the engine.

These anecdotal tests where someone drops the oil out of an engine and runs it for "X" amount of time... well, let's just say I am from Missouri about all that. Without having seen what was really in there, or what was in there before the "miracle oil" was put in and then drained, well, I'd have to have lots more knowledge about the controls applied to such a test. Not that I don't believe the results, necessarily.

rmw

 

[JWaterstreet]

I have a personal experience to relate. In 1984, my Father in-law bought a used 1982 Toyota pickup with the 22R engine in it. It had about 20K miles at the time. From the day he bought it, the oil pressure warning light would take about 10-20 seconds to go off after you started the engine.

Over time, it got worse and worse. I was always after him to check it out, but he is totally non-technical and didn't seem to care. When it was taking a minute or two for it to go off, I told him it wouldn't be long for that engine to be toasted. In 1989, the light finally wouldn't go off at all, and it started to knock. It had 75K miles at the time. I bought it from him for $100. I drove it 500 miles from his house to mine & the whole time the oil pressure light was on that whole distance. When I pulled into my driveway, it was rattling pretty loudly.

I bought a 22R from a wrecked pickup that had about 80K miles. It had a different oil pan (4WD, mine was 2WD) so I had to take the pan off the trashed engine. When I pulled the pan and the oil pickup tube and screen, I immediately saw why it had no oil pressure. The oil pickup tube had a manufacturing defect, a large blob of weld on the flange where it met the flange on the block, and the gasket was gone around the blob of weld. It was sucking air from day one, and eventually quit pumping at all when the gasket fell away. I pulled a couple rod bearing caps for grins. The bearings were really worn, but weren't spun out. Cylinders didn't look too bad. Probably had enough splash to keep the cylinders in good shape, but the bearings suffered from little to no pressure.

I eventually sold that truck with 375K miles on that replacement engine. It still ran great, but the frame was rusted out....

 

[ivymike]

I've seen an engine that siezed in cold weather shortly after startup, because it was put under load while the oil was still too viscous to reach the undercrown gallery of the pistons. The engine was idled a few minutes, then taken to light load to slowly move a vehicle. In about 30 seconds the engine slowed then abruptly stopped. Significant damage to the pistons and liners was observed upon teardown (four-point scuffing of the crowns).

 

[BrianPetersen]

Two-strokes are notorious for cold-seizure like that.

 

[evelrod]

More anecdotal drivel?

In the early 80's I picked up a partial sponsorship from a local "Slick **" dealer for my SCCA GT-3. Part of the deal was to actually use the stuff in my car. At first we saw all sort of improvement (later determined as wishful thinking) and started using it in everything from my Goldwing to my lawnmower (it was free).

Now what all that has to do with the OP? It was SOP to have a small Briggs-Stratton mounted with a clear cover plate and running, sans oil, for hours around the paddock. (Like a puppy, vibrated all over the area). This was a standard line with the TV adds, running without oil. One such add included a driver test by a famous, very well known and retired pro driver (Willow Springs Raceway). The idea was to treat the vehicles with the product and then drain the oil out. Test was then to drive around the track for several laps. One of the test cars was a Dodge Viper. The pro lapped the track at moderate (for a Viper) speed for several laps. Zero oil pressure and all that. When oil was put in, no apparent problems. I was impressed, then at least, not so much today. No tear down so I'm suspicious. I suspect some tom-foolery. Also, I was supposed to do a "testimonial" and, may I assume GET PAID FOR IT----didn't happen. Eventually all the free stuff ran out and I never actually bought anymore. Hmmmmmm!

Rod

 

[izzmus]

And when I got tired of the leaking rear main seal in a 400 Chrysler, I drove it for two weeks with no oil in it. When it refused to die, I added five quarts and kept driving it.

Of course, the rear main leak went from "bad" to "smoking" after being run dry like that.

 

[patprimmer]

In my experience you might get away with running an old worn out engine at low output with no oil, but an engine in good condition will self destruct with things like melted bearings, scored journals, broken rings and stretched ring lands and skirts scuffed.

Regards
Pat
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[catserveng]

We did some pretty extensive testing for a CAT engine going into a special operations military application, two of the "possibly destructive" tests were,

1. under full load, generate a catastrophic loss of oil, allow engine protection system with programmed settings and delays to operate, stop the engine. Tear down and inspect.
The high speed low oil pressure setpoint was 45 PSI with a 10 second time delay. The testing was done on a dyno with the marine gear installed, dyno programmed to simulate a High speed moderate sea state run condition. A tee was brazed into the oil line going to the oil filter base (largest external line on the engine) with a full port valve, plumbed to a recovery tank. With engine at full load the valve was opened (then we got as far away from the engine as fast as we could, these were VERY high horsepower engines for the displacement). Engine protection stopped the engine, data logs recorded all parameters.
Results,
Turbo bearings siezed
Rod bearing starting to show adhesive wear and scuffing thru the LTO
Main bearings showed only minor scuffing
Cam bearing, fron (drive end) bearing badly scuffed and a local area of adhesive wear.
Piston pin bearings, all scuffed and discolored.
No other significant damage noted.

2. Drain oil from engine, let sit overnight. Start engine with dry sump, allow to run at idle until shutdown by protection. Restart and allow to shutdown again, repeat a third time. Stop test tear down and inspect. Engine used for this test had completed a 100 endurance test run at average 85% rated load in "sea state" or cyclic conditions. It had been disassembled, inspected and documented, then reassembled and run for 10 minutes at no load on the test stand. The low speed oil pressure setpoint was 15 PSI, the arming timer was set to 20 seconds and the low speed low oil pressure time delay was 10 seconds.
Only noted area of abnormal wear was the rear main bearing, all other areas of the engine.

This was the only time I purposely ran an engine without oil. Over the years did failure analysis on lots of failed engines. Older engines, with rectangular ring packs and either NA or low level turbocharging took lots of abuse. Newer high output engines, especially in pleasure (yachts and motorhomes), standby service and emergency vehicles (typically the highest commercial ratings) had very little tolerence for lube oil quality or quantity problems.

One of the best, a motorhome customer who "trained" his engine to run a gallon low on oil, came in four times the first year for turbo failures. Of course it was our crappy turbos. Got the factory to give me a flash file to use an unused analog input and installed an oil temp sensor, and did some logging with it, found running the engine a gallon low on oil caused a average 22 degree F rise in lube oil temp. And in that particular chassis it was hard enough to keep the oil temp below maximum anyway (we used 235 F as a maximum). Got him to start keeping the oil between ADD and FULL, just to humor me and he never came back.

 

[MikeHalloran]

At around 120,000 miles, my 95 Ford hightop van (5.0L V8) developed an odd symptom. The oil pressure 'gage' would drop to zero, then come back a few times, then drop to zero and stay there. Stop, check the dipstick, find the sump full, start the engine, and it would run normally, sometimes for days. I figured it was the 'gage'. ... but it kept getting worse.

One day it dropped while I was driving an invalid relative, and I wasn't real sure it would start again, so I got off the expressway at the first exit and went home by side roads to get another vehicle. Went maybe 20 miles with no oil pressure. It was clanking a little when I stopped it forever.

It wasn't the gage, which is not actually a gage, but a flag run by a switch.

The engine on that series van is pushed into what amounts to a big hole in the front crossmember, using a cherrypicker from the front. You have to remove both the top of the intake manifold and the oil pan to get it in or out. It will not come out from the top, or from the bottom; the frame encloses it almost completely, like a tube.

To get the oil pan out, you undo the bolts, drop it a little, unbolt the pickup and then the pump, and drop the pump into the pan, then rotate the crank to move the counterweights out of the way as you work the pan to the front. Only then can you get the engine out.
Factory assembly is the reverse of installation, and the pickup bolts were not loctited, so eventually, the pickup loosens enough to suck air, and it gets progressively worse.

It was a good engine; it had spent a lot of time in overdrive at 4000rpm/95mph, which is pretty good for a hightop van with a small engine.

I didn't have the tools to fix it in the driveway. The local Ford dealer gave me a good price to replace it with a rebuild, but the good price was more than half what the vehicle would bring if it was working, so I donated it instead. I always liked that van.

So, call it 20 miles or so.


Mike Halloran
Pembroke Pines, FL, USA

 

[JWaterstreet]

Well, another anecdote, prompted by the CAT engine story...

I went out diving in Grand Cayman with a group. Boat had a CAT diesel, no idea how big. On the way out, engine quit, had a low oil pressure automatic shutdown. Captain went into the bilge, found oil all over, plug had come out from oil pan. We went diving, when came back to the boat, they already had another boat ready to tow us back to shore.

Next day, went diving again, same boat, same captain. They simply put the plug back in, filled it up with oil, good to go. The weather had turned nasty, 8-10 foot swells, most people would not go out in this weather, I didn't care; once you are in the water, you have no idea what is going on "upstairs".

Motored out to the dive sites, Cat engine proceeded to throw a rod out the side of the block. Went diving anyway; but had to wait 2 hours once topside to get tow boat, most others in the boat were getting sick from the huge waves but it didn't bother me. Took an hour to tow back because of the waves, kept snapping the tow line.....

So I can confirm that by the time the Cat auto-shutdown feature shuts the engine down, the damage is already done....

 

[tbuelna]

dicer,

As one would expect, the likely failure mode for a typical recip engine run at length without lube oil flow would be rod bearing failure. But contrary to conventional wisdom, the lack of oil flow causes hydrodynamic journal bearings to fail due to overheating, and not because there is insufficient oil present to maintain the hydrodynamic oil film for supporting the bearing loads. It takes a surprisingly small amount of oil within the bearing gap to maintain an EHL oil film. But it takes lots of flow to keep the bearing shells from overheating.

Journal bearing oil flow rates are set to provide enough cooling such that the bearing materials are kept within their allowable temperatures for the surface compressive fatigue conditions they must endure. The rod bearings would likely fail before the mains, since their conductive heat transfer flow paths (out through the bearing shell back) are more thermally isolated than the mains, and thus they are more dependent upon heat transfer into the lube oil flows to prevent overheating.

As for how long a particular engine's journal bearings can run without adequate oil system pressure before suffering damage, that's a question that cannot really be answered accurately. There are lots of (low performance) journal bearing recip engines that are designed to run without any oil pressure feed to the bearings at all. Take a look at a B&S lawn mower engine or an old model T engine. They use "dippers" on the rod ends to splash oil up onto the rod bearings, and run happily for hundreds of hours.

If there is insufficient oil flow to prevent overheating, the overheated inner bearing surface will begin to lose strength and will suffer surface spalls/pitting caused by compressive fatigue failures. The pitted surface will be rougher (ie. have a greater average asperity height) which then will result in the surface contact condition becoming boundary instead of hydrodynamic. The higher friction of the resulting boundary contact will produce more friction heating, and the failure cycle due to the increased heat load into the bearing shell becomes self-perpetuating.

So, to make a long story short, starting and idling a journal bearing engine without adequate oil pressure would only be a problem if there was enough heat generated to cause thermal failure of the bearing shells. Most high performance journal bearings are "tri-metals", which means they have a steel backing with copper/nickel/babbit overlays. The steel backing provides excellent fatigue life; the bonded copper layer gives good heat transfer; the nickel plated intermediate layer provides a diffusion resistant barrier; and the tin/lead/indium babbit surface overlay provides a soft, sacrificial, conformal and embeddable surface to prevent damage to the mating case hardened journal surface during operation under marginal lubrication conditions.

Sorry for the long-winded reply, but there was not a short answer to your question.

Hope it helped anyway.
Terry

 

[franzh]

It is (was) common practice to do a hot engine oil change on irrigation engines. Up until it became common to use purpose built irrigation engine packages, it was accepted to take a junk yard engine, usually a Chrysler 413, Oldsmobile 394, a Ford 390, a Cadillac 500, or whatever large engine was floating around at the time, and adapt it to an in-out clutch.

It is not that easy to put an irrigation engine out of drive, shut it down, do a oil change, engage the clutch, and power the engine back up, there is a lot of water in that column. Many operators would install a ball valve in the oil pan and bring the engine down to a slow idle while keeping the water column primed, open the drain-cock, and drain the oil while the engine was running. A quick spin of the oil filter with a new one, and a refill of cheap motor oil, and bring the engine back to load, and all was well.

Many engines would have this done on an bi-annual basis, or whenever the farmer would feel like it. Spark plugs were installed when first commissioned and may never be replaced again (I saw one old Chrysler 392 Hemi engine with over 15 years of running on the same plugs, while on pipeline natural gas, running 24 hours a day at 1850 rpm and about 12" manifold vacuum).

Franz

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[dicer]

franzh,
interesting about the dynamic oil changes.
So were you one of the techs that did the oil changes or?

tbuelna ,
I agree, and temperature and viscosity breakdown are the main contributor.

catserveng ,
10 seconds? Wow I would think it would go much longer than that, even at full load. What viscosity oil?
Was it 3500 series or 3600? Are you sure that caused the turbo bearings to sieze? I guess they just don't build em like the good old D342 or D353 any more. Well and D398 and 99's, maybe not eco but good engines.

ivymike ,
Like artic cold?
I know that will turn SAE 30 into thick grease.
Must have been into the -30's or so.

 

[ivymike]

like Canada cold, eh...

 

[catserveng]

dicere,

The engines were 3126's rated VERY high for some special warfare boats, not much margin for any problems. Oil was CG-4 15W-40, Mobil product as I remember, oil was a premium blend and not felt to a part of the problem. Cylinder pressures and bearing loading was very high as measured in some of the first article test engines. The tough part was the cyclic loading, dyno testing simulated a deep lug followed by a high over-rev, like a boat going real fast in rough seas, digging in as it hit water and spinning up as it went airborne. The dyno test profile was built from actual at sea runs with some of the spec warfare guys, not sure they understood the concept of "part throttle".

The older CAT's, the 6.25 bores were tough, but liked to drink fuel and dirty by today's standards. The 3500's have had a good run, we'll see how the C175 does as a replacement.

 

[sartorbjk]

I would just like to make a comment that is oil will be replaced by ionic liquids. I already know some people who uses ionic liquids in their cars.


Best Regards,
Sartor

 

[patprimmer]

I would never use salt water in place of engine oil. ;-)

Regards
Pat
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[franzh]

Dicer:
I train field technicians working on both natural gas and propane powered industrial engines, plus help with design engineers on new adaptations.
One argument we have in the field is "why change what isnt broken?" often in reference to installing a new low emission engine to replace a junk yard engine.
These farmers and oil rig owners are tight with their pocket money and every cent counts, even when changing engine oil. The hour or so needed to bring an engine off line, cool down, change the oil, and refill, is counted as down time and frowned upon. Not every field tech does this, but quite a few of them have done it at least once in their career (grin!)

Franz

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[PJGD]

I will add a story:
Driving home from the pub late a night and still about 10 miles from home when I heard a slight change in engine note. Looked down at the instruments and was just in time to see the oil pressure gauge needle hit zero. Stopped, got out and looked under the bonnet [hood] and saw that the engine was washed with oil because the flex hose to the oil cooler had failed and emptied the sump all over the engine and road.

What to do? No option but to continue driving the 10 miles home. Did so but maintaining a relatively light throttle and made it home no problem. Next morning I replaced the hose, put in fresh oil and drove the 30 miles to work. The car seemed none the worse for the experience.

Why did it survive without apparent damage? Mainly I think because I drove relatively gently, but also perhaps because of the copper-lead-indium bearings, hardened crank and aluminium crankcase.

PJGD