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Old 03-23-2013, 03:44 PM   #161
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Hi, late to this party with nothing especially useful.

Of course I enjoy reading the debate amongst the usual suspects. I recall way back in 1970 buying a manual called the idiots guide to VW maintenance or some such, where the author, John Muir, recommended warming up the engine whilst rolling a cigarette and getting a good draw going before putting the vehicle in gear. A practice I still adhere to today.

Synth v. Dino? I dunno, I use synth in all my motorcycles, but those are high rev engines. I suspect we could lubricate our FL120's with YAK fat.

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Old 03-23-2013, 06:12 PM   #162
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............. You can reduce the load on dry engine surfaces 10x by holding the engine fuel stop and crank the engine with out it starting for 20 seconds, . ..............
Yes, but at the risk of filling the muffler with water and ingesting it into your engine.
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Old 03-23-2013, 08:37 PM   #163
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Yes, but at the risk of filling the muffler with water and ingesting it into your engine.

That's a very good point on boats where the engine is close or below the water line < deep draft>, the water has to lift up to get out of the boat , At that point you would need to close the engine sea water valve to crank the engine, We use the rule never crank more than 3 / 20 second cranks with out closing the sea water valve or draining the lift muffler. On most small trawlers the exhaust elbow is well above the water line and the exhaust outlet is at or half way on the water line so a pre lube crank is safe , Its always smart to know the height of the exhaust hose in the boat just in case some one chose to run it high like under a deck coming rather then under the aft cabin floor, We re powered many a sail boat from over cranking.
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Old 03-23-2013, 08:39 PM   #164
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You can reduce the load on dry engine surfaces 10x by holding the engine fuel stop and crank the engine with out it starting for 20 seconds,
Over the years I have asked a number of people in the engine manufacturing industry about this because on the surface it would seem to make sense.

The reality, according to every one of these people I've talked to over a bunch of years, is that an engine-- gas or diesel-- will crap out to the point of needing a core overhaul for some other reason LONG before the wear caused by starting an engine without "pre-lubing" it with the starter becomes anything of a factor.

In fact, they all said, the primary benefit of pre-lubing with the starter is that it fattens the wallets of the people who sell and rebuild starters.

The only truly beneficial way to reduce startup wear, they all told me, is with a proper pre-lube system that brings the oil pressure up throughout the engine before the start button is even pressed.

I had the opportunity a number of years ago to go out on a training run on the RNLI 47' motor lifeboat William Street out of Fleetwood, England. These boats, some of them slipway-launched, are kept ready to go to full throttle the moment they get underway. To that end the engine coolant in their two diesels is kept at full-up operating temperature 24/7/365 and the engines' lube oil systems are brought up to full pressure automatically prior to the starters being energized.
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Old 03-23-2013, 09:08 PM   #165
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That's a very good point on boats where the engine is close or below the water line < deep draft>, the water has to lift up to get out of the boat , At that point you would need to close the engine sea water valve to crank the engine, We use the rule never crank more than 3 / 20 second cranks with out closing the sea water valve or draining the lift muffler. On most small trawlers the exhaust elbow is well above the water line and the exhaust outlet is at or half way on the water line so a pre lube crank is safe , Its always smart to know the height of the exhaust hose in the boat just in case some one chose to run it high like under a deck coming rather then under the aft cabin floor, We re powered many a sail boat from over cranking.
It's a warning in my boat's owners manual. The way my switch is set up, I can't be in the cranking and stop mode at the same time anyway. It's spring return to the right to start, spring return to the left to stop.

Of course I could add a separate stop switch but I don't think it's important on my boat.
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Old 03-23-2013, 09:28 PM   #166
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That's a very good point on boats where the engine is close or below the water line < deep draft>, the water has to lift up to get out of the boat , At that point you would need to close the engine sea water valve to crank the engine, We use the rule never crank more than 3 / 20 second cranks with out closing the sea water valve or draining the lift muffler. On most small trawlers the exhaust elbow is well above the water line and the exhaust outlet is at or half way on the water line so a pre lube crank is safe , Its always smart to know the height of the exhaust hose in the boat just in case some one chose to run it high like under a deck coming rather then under the aft cabin floor, We re powered many a sail boat from over cranking.

Not sure I would use the words "most" and safe....hate to see someone ruin their engine becasue they didn't investigate further if they agree with the pre-cranking theory.
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Old 03-23-2013, 09:51 PM   #167
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Over the years I have asked a number of people in the engine manufacturing industry about this because on the surface it would seem to make sense.

The reality, according to every one of these people I've talked to over a bunch of years, is that an engine-- gas or diesel-- will crap out to the point of needing a core overhaul for some other reason LONG before the wear caused by starting an engine without "pre-lubing" it with the starter becomes anything of a factor.

In fact, they all said, the primary benefit of pre-lubing with the starter is that it fattens the wallets of the people who sell and rebuild starters.

The only truly beneficial way to reduce startup wear, they all told me, is with a proper pre-lube system that brings the oil pressure up throughout the engine before the start button is even pressed.

I had the opportunity a number of years ago to go out on a training run on the RNLI 47' motor lifeboat William Street out of Fleetwood, England. These boats, some of them slipway-launched, are kept ready to go to full throttle the moment they get underway. To that end the engine coolant in their two diesels is kept at full-up operating temperature 24/7/365 and the engines' lube oil systems are brought up to full pressure automatically prior to the starters being energized.
Two things I'd like to mention; and, one I'd like to have:

1. When starter turning flywheel brings the engine oil pressure up – Pre Start - there is no pressure exerted on bearings or cam lobes or lifter bottoms or other items from down force created by ignition explosions in cylinders... therefore, no real pressure is applied to engine parts that require lubrication.
2. Due to engine reaching oil pressure by starter turns only the bearings, cam lobes, lifter bottoms, etc have had a lubrication barrier established prior to in cylinder ignition explosions bringing real pressures applied to engine parts that require lubrication barriers.
3. Wish I had a pressure system to bring each engine's oil pressure up and flood bearing surfaces without using the starter before ignition begins inside the cylinder presures!

Seeing as you say... "RNLI 47' motor lifeboat William Street out of Fleetwood, England." brings up oil pressure automatically... to me means it must be important to them. Cause, even if they very soon after launching start engines and accelerate to high power, with coolant also pre warmed, they must have at least a moment for the engine's own oil pressure to get established.

As you can tell, I too believe in pre lube before starting an engine.

Just sayen!
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Old 03-23-2013, 09:53 PM   #168
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Thanks Craig S for the detailed and very helpful post #160.

I understand a lot more than I did before and new knowledge is always good building blocks for more knowledge.

The only thing that is still unknown to me is the capacity of the oil filter. If I change every 100 hrs what percentage of the filter remains empty when I throw it away? One way to find out would be to measure oil flow and pressure over time until the flow and pressure starts to drop. I'll bet it would be many many oil changes before that happened. I'll bet the filter is only 1/20th or less full. But I may change my mind about skipping filter changes. I'd not give it good odds though.

Ron during my troubles w the fuel system last summer my mechanic cranked the engine A LOT w the sea cock open. I was very concerned but the capacity of the lift muffler seemed endless. Eventually we started the engine and pumped it all out and all was well.

Sunchaser you aways bring a blast of common sense and honest no nonsense guidelines to keeping things on track and observing what we need to know to go boating with great confidence and the knowledge that the right course has been taken. Thanks once again Tom.
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Old 03-23-2013, 09:55 PM   #169
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It's a warning in my boat's owners manual.
Mine too..........
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Old 03-23-2013, 10:15 PM   #170
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Not sure I would use the words "most" and safe....hate to see someone ruin their engine becasue they didn't investigate further if they agree with the pre-cranking theory.

Thanks for the heads up As stated in the previous sentence< We use the 3 / 20 second rule > For pre lube I would only crank once for 20 seconds. In the next sentence I stated that it was a good idea to know the height of the exhaust hose in the boat, We always install the exhaust run so it will drain at least 1/2 the volume of the muffler and if for some reason we cant make the system self drain we post a sign at the helm, I think its very important for boat owners to understand the basics of the installed machinery.
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Old 03-23-2013, 10:18 PM   #171
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Yes, but at the risk of filling the muffler with water and ingesting it into your engine.
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Originally Posted by Craig Schreck View Post
That's a very good point on boats where the engine is close or below the water line < deep draft>, the water has to lift up to get out of the boat , At that point you would need to close the engine sea water valve to crank the engine, We use the rule never crank more than 3 / 20 second cranks with out closing the sea water valve or draining the lift muffler. On most small trawlers the exhaust elbow is well above the water line and the exhaust outlet is at or half way on the water line so a pre lube crank is safe , Its always smart to know the height of the exhaust hose in the boat just in case some one chose to run it high like under a deck coming rather then under the aft cabin floor, We re powered many a sail boat from over cranking.
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Not sure I would use the words "most" and safe....hate to see someone ruin their engine becasue they didn't investigate further if they agree with the pre-cranking theory.
Well letís apply some math to the problem then.

I have a Volvo Penta D2-75 engine.

I have the following data points for my SW pump:
m≥/h @ RPM 1.6 @1200, 1.8@1400, 2.1@1600, 2.3@1800, 2.6@2000, 2.9@2200, 3.1@2400, 3.3@2600, 3.6@2800, 3.8@3000.

I have a data point of compression pressure of 2.95 MPa at 240rpm.

Iím going to make the assumption that this is cranking rpm (as it would be logical to test the compression pressure with the starter).

Iíll need to extrapolate backwards to get q (flow) at cranking rpm.

As it is fairly linear (and it should be as it is a positive displacement pump with slight variation due to flexible nature of the vanes and allow for some internal circulation losses), letís assume a value of .38 m≥/h at 240rpm. That is 380l/hr, 6.3l/min, or 105ml/sec. Seems reasonable based upon my observation.

I have a 90mm (3.5Ē) exhaust system with a Vetus NLP90 waterlock with a capacity of 10 liters. The water lock is in my keel pocket and I have approximately 70cm drop legs on the inlet from my elbow and the outlet to the slope towards the stern. This gives me a total capacity of ~18.9 liters. When draining my waterlock, I have measured ~5 liters remaining in the system when shut down, giving me a reserve capacity of 13.9 liters.

This would allow me to crank for ~132 seconds before I (theoretically) flooded my engine. ( In essence I really wouldnít, as my discharge leg from the waterlock is really shorter than the intake leg.)

A twenty second rule as stated would give me a safety factor of 6.6. I can live with that. If Craig were to come over and work on my engine with his rule, he wouldn't flood it either.
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Old 03-23-2013, 10:32 PM   #172
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Thanks Craig S for the detailed and very helpful post #160.

I understand a lot more than I did before and new knowledge is always good building blocks for more knowledge.

The only thing that is still unknown to me is the capacity of the oil filter. If I change every 100 hrs what percentage of the filter remains empty when I throw it away? One way to find out would be to measure oil flow and pressure over time until the flow and pressure starts to drop. I'll bet it would be many many oil changes before that happened. I'll bet the filter is only 1/20th or less full. But I may change my mind about skipping filter changes. I'd not give it good odds though.

Ron during my troubles w the fuel system last summer my mechanic cranked the engine A LOT w the sea cock open. I was very concerned but the capacity of the lift muffler seemed endless. Eventually we started the engine and pumped it all out and all was well.

Sunchaser you aways bring a blast of common sense and honest no nonsense guidelines to keeping things on track and observing what we need to know to go boating with great confidence and the knowledge that the right course has been taken. Thanks once again Tom.
Eric I think most small automotive type oil filters hold between 15 to 30 grams of trash, The only way to see the % of filter left would be to cut it open and weigh the filter media vs a new filter media that was wet with the same amount oil or just change the filter when you change your oil.
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Old 03-23-2013, 10:46 PM   #173
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Well letís apply some math to the problem then.

I have a Volvo Penta D2-75 engine.

I have the following data points for my SW pump:
m≥/h @ RPM 1.6 @1200, 1.8@1400, 2.1@1600, 2.3@1800, 2.6@2000, 2.9@2200, 3.1@2400, 3.3@2600, 3.6@2800, 3.8@3000.

I have a data point of compression pressure of 2.95 MPa at 240rpm.

Iím going to make the assumption that this is cranking rpm (as it would be logical to test the compression pressure with the starter).

Iíll need to extrapolate backwards to get q (flow) at cranking rpm.

As it is fairly linear (and it should be as it is a positive displacement pump with slight variation due to flexible nature of the vanes and allow for some internal circulation losses), letís assume a value of .38 m≥/h at 240rpm. That is 380l/hr, 6.3l/min, or 105ml/sec. Seems reasonable based upon my observation.

I have a 90mm (3.5Ē) exhaust system with a Vetus NLP90 waterlock with a capacity of 10 liters. The water lock is in my keel pocket and I have approximately 70cm drop legs on the inlet from my elbow and the outlet to the slope towards the stern. This gives me a total capacity of ~18.9 liters. When draining my waterlock, I have measured ~5 liters remaining in the system when shut down, giving me a reserve capacity of 13.9 liters.

This would allow me to crank for ~132 seconds before I (theoretically) flooded my engine. ( In essence I really wouldnít, as my discharge leg from the waterlock is really shorter than the intake leg.)

A twenty second rule as stated would give me a safety factor of 6.6. I can live with that. If Craig were to come over and work on my engine with his rule, he wouldn't flood it either.
Nice math fella But incomplete, you have to apply the compression pluses vs the weight of the column of water plus the lift height to see if the water will pulse drain
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Old 03-23-2013, 10:52 PM   #174
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1. When starter turning flywheel brings the engine oil pressure up – Pre Start - there is no pressure exerted on bearings or cam lobes or lifter bottoms or other items from down force created by ignition explosions in cylinders... therefore, no real pressure is applied to engine parts that require lubrication.

2. Due to engine reaching oil pressure by starter turns only the bearings, cam lobes, lifter bottoms, etc have had a lubrication barrier established prior to in cylinder ignition explosions bringing real pressures applied to engine parts that require lubrication barriers.

3. Wish I had a pressure system to bring each engine's oil pressure up and flood bearing surfaces without using the starter before ignition begins inside the cylinder presures!


As you can tell, I too believe in pre lube before starting an engine.
Load on a hydrostatic or hydroelastic oil film has very little to due with the bearing wear. Scuffing of a bearing occurs when there is no film.

I too believe in pre-lube. Much of the major rotating equipment I have operated and maintained uses pre-lube. However the pre-lube is used to lift the bearing while the equipment is static. Cranking an engine while not firing isn't really pre-lube.
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Old 03-23-2013, 10:58 PM   #175
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Nice math fella But incomplete, you have to apply the compression pluses vs the weight of the column of water plus the lift height to see if the water will pulse drain
Nah. Only solving for worst case scenario. System volume. But you are right, it would compressively drain. (It is a 2.2 liter engine if you feel like doing the math, and the salinity of the water where I live is ~30g/l)
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Old 03-23-2013, 11:25 PM   #176
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Seeing as you say... "RNLI 47' motor lifeboat William Street out of Fleetwood, England." brings up oil pressure automatically... to me means it must be important to them.
They let me drive the Street during part of the training mission and the crew commander told me that they operate the boats at just two power settings, Ike and max continuous power. And when they go out on a "shout" they are at max power the moment the boat comes off the slipway or leaves the pier.

Interestingly, I asked the boat's engineer about both the coolant heating and oil pre-lube systems after we got back, including the bit about why not simply turn the engines over with the starter before lighting them off. And I got the same answer I always have from people in the industry: it accomplishes pretty much nothing with regards to lengthening the service life of the engine but it makes life harder for the starter.

And don't forget, on these boats the coolant which is kept at full operating temperature keeps the engine blocks hot which keeps the oil hot, too. The engines are started as the boat is released down the slipway and when it hits the water just seconds later the engines are taken to full power. So, the engineer told me, anything that can lessen the shock of going to full power moments after startup is a good tjhing, hence the constant coolant heating and the automatic pre-lube system.

But comparing the needs of engines n this kind of service and the old clunker diesels in the boats most of us own is total apples and oranges. I very much doubt that anyone's Ford Lehman or Perkins in recreational boat service died a premature death because the operator didn't build oil pressure with the starter for the service life of the engine.
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Old 03-23-2013, 11:39 PM   #177
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Load on a hydrostatic or hydroelastic oil film has very little to due with the bearing wear. Scuffing of a bearing occurs when there is no film.

I too believe in pre-lube. Much of the major rotating equipment I have operated and maintained uses pre-lube. However the pre-lube is used to lift the bearing while the equipment is static. Cranking an engine while not firing isn't really pre-lube.
Thanks, NS...

In gasoline engines:

Oil pressure reached to have filled journals and coat bearing surfaces that have been long-term dormant by pre-start cranking an engine via starter alone, without severe ignition pressures from fired pistons, isn't a type of pre lube before starting a motor?

I know that if oil pressure is not first established by starter only and the engine immediately starts that there is notable difference in sound of internal parts upon start for the first two to three seconds before oil pressure is actually established... that can't be good - can it? I do not hear those internal sounds if the starter first established oil pressure, pre start. I find that to be true in each of my classic V8s. Marine, truck, car...
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Old 03-24-2013, 07:31 AM   #178
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3. Wish I had a pressure system to bring each engine's oil pressure up and flood bearing surfaces without using the starter before ignition begins inside the cylinder presures!

No problem, tho there are choices.

For a grand or two I'm sure a suitable electric pump systen can be found and installed.

Then there is the simpler way , home brew .

A DC selonoid valve that can handle 100PSI is cheap as is a used inverted propane tank as accumulator..

With a take off from any oil port (usually where the oil pressure sender is mounted) the accumulator is re filled after engine start.

To prelube the solenoid is switched to open , and the oil pressure is watched to see the pressure rise , then fall as the pressure tank is emptied.

Then the (now prelubed ) engine is started and kept to idle (700-800rpm).

When the oil pressure stabilizes in about a min the bottle will be refilled , the solenoid closed and your off to the races.


For the longest service life usually a block hearer will allow oil to the surfaces fast enough on most "cold" starts.
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Old 03-24-2013, 09:04 AM   #179
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............3. Wish I had a pressure system to bring each engine's oil pressure up and flood bearing surfaces without using the starter before ignition begins inside the cylinder presures!.................
Consider this: Few, if any recreational boat engines include this feature. Same for cars and trucks

From this, I can conclude that while it might make us feel better, it's not really needed.
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Old 03-24-2013, 10:22 AM   #180
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Consider this: Few, if any recreational boat engines include this feature. Same for cars and trucks

From this, I can conclude that while it might make us feel better, it's not really needed.
Yup. I would agree that is the case for most of the people on this forum. Same goes with the use of synthetic oil.

Hard to make a valid business case for either.
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