oil pressure

[Stewartb]

On the engine preheat subject:

Why the hell hasn't Tanis or Reiff made their heaters with a built in trickle charger and battery warmer for the battery? All off one 120 power plug. That'd be slick as ****. Surely the reason can't be they haven't thought of it? Be a huge sales advantage over their competior.

Because smart owners have converted to AGM batteries that work fine in the cold and don't need maintenance charging.

 

[jesse]

Because smart owners have converted to AGM batteries that work fine in the cold and don't need maintenance charging.

AGM batteries still self discharge plenty, and the colder the temperature, the worse it gets in a hurry. Capacity drops plenty as well.

Considering the prices of the damn heaters, and given the technology available now, I just don't see why they don't solve the battery problem as well.

 

[Stewartb]

If your bike battery is draining you have a ghost load, not a battery problem. I have a few fuel injected Polaris wheelers and those are battery eaters when parked. My carbureted Polaris has no such issue. The Odyssey PC625 on my 180's firewall has been spinning the 0-520 for 15 years without a maintenance charge including after some winters where I parked it and walked away til spring. Maybe your bike needs a master switch.

 

[jesse]

If your bike battery is draining you have a ghost load, not a battery problem. I have a few fuel injected Polaris wheelers and those are battery eaters when parked. The Odyssey PC625 on my 180's firewall has been spinning the 0-520 for 15+ years without a maintenance charge including after some winters where I parked it and walked away till spring. Maybe your bike needs a master switch.

Well yes it does have a load. Some airplanes do as well.

Anyways, see above, I edited/removed the part you're referring to after you saw it but before I noticed you saw it. I wouldn't say getting 15 years out of an AGM battery that often sits for months is normal.

 

[Stewartb]

advantages of living in a cool climate.

Longer storage life
Unlike conventional batteries that need a recharge every 6 to 12 weeks, a fully charged ODYSSEY battery can be stored for up to 2 years at 25°C (77°F) from a full state of charge. At lower temperatures, storage times will be even longer.

Superior cranking and fast charge capability
The cranking power of ODYSSEY batteries is double to triple that of equally sized conventional batteries, even when the temperature is as low as -40°C (-40oF). In addition, with simple constant voltage charging there is no need to limit the inrush current, allowing the battery to be rapidly charged. Please see the section titled Rapid charging of ODYSSEY batteries for more details on this feature.

http://www.odysseybattery.com/documents/US-ODY-TM-001_0411_000.pdf

 

[poadeleted20]

If the oil is cold enough to act as a solid as you're saying there is no chance in hell you would get that engine started without heat.

I didn't say it would solidify -- that's just Tom's take. However, it can get so viscous that it does not transmit pressure the same as normal, and you initially see a very low reading which doesn't last long.

 

[vintage cessna]

In order to get oil of the quality and SAE weights we use the oil would be require to be soaked in N2 over night. That some where south of -400 Degrees

could you get oil that cold, to do what you suggest, you would break the oil pump drive the first degree you turned the prop. but I doubt you could turn the engine at all.

I have seen 65 weight stored at cold bay Ak at temps below -40, poured out of a 5 gal can.

The only reason we pre-heat is to crank the engine, and vaporize the fuel for a quick start. The oil temp argument is simply an old wives tale, because the oil will pump or pour and lubricate at temps well below human's ability to exist.

Interesting. Mike Busch says one reason to pre heat is because of different expansion rates of the cylinders and pistons. Comment?

 

[Checkout_my_Six]

Interesting. Mike Busch says one reason to pre heat is because of different expansion rates of the cylinders and pistons. Comment?

This is the reason IMHO.....at temps below as low as 40 deg F there is a "possibility" for an interference fit in main journal bearing clearance and between the piston rings and cylinder choke location.

In most cases this doesn't mean a spun bearing.....but is does mean increased wear when starting cold.

 

[vintage cessna]

That brings up another question. I often see people say they would never start without pre hear below 40F.

Yet Continental says pre heat when the engine has been exposed to ambient temps of 20 F or lower for more than 2 hours. From an owner stand point this can get confusing.

 

[Henning]

If the oil is cold enough to act as a solid as you're saying there is no chance in hell you would get that engine started without heat.

You'll also break the oil pump drive with the starter motor.

 

[Henning]

That brings up another question. I often see people say they would never start without pre hear below 40F.

Yet Continental says pre heat when the engine has been exposed to ambient temps of 20 F or lower for more than 2 hours. From an owner stand point this can get confusing.

Many people are more conservative in hopes that it will extend the engines life/prevent repairs.

 

[vintage cessna]

Many people are more conservative in hopes that it will extend the engines life/prevent repairs.

What is the reality though? If you have to spend $30 for a pre heat are you wasting money if the temps never reached 20F ?

 

[poadeleted20]

That brings up another question. I often see people say they would never start without pre hear below 40F.

Yet Continental says pre heat when the engine has been exposed to ambient temps of 20 F or lower for more than 2 hours. From an owner stand point this can get confusing.

Some people will preheat at 40F, some at 32F, some at 20F. And I leave my warm air blower on all winter. IOW, it's dealer's choice, but Lycoming feels it's necessary only below 20F even though others recommend it at higher temps.

 

[Henning]

Anyone got the real temp that it will be required to solidify 50 weight?

Define solidify, at what dynamic viscosity are we calling it a solid?

The dynamic viscosity of 50wt oil at 0°C is 3.82. To give you reference the dynamic visosity of glass is 1x10*40th, the 50wt oil at 100°C is .015.

 

[Henning]

Does oil ever actually change phase to become a solid? I thought it was like glass and remained as a liquid, but never really studied it.

 

[vintage cessna]

Some people will preheat at 40F, some at 32F, some at 20F. And I leave my warm air blower on all winter. IOW, it's dealer's choice, but Lycoming feels it's necessary only below 20F even though others recommend it at higher temps.

Yes. But will pre heating above 20 F actually increase the longevity of anything, or is it just a feel good thing to do? If there was some increase of longevity for pre heating above 20 F why wouldn't the engine manufacturers say so? Or why wouldn't they just say pre heat 40 F and below?

 

[Henning]

What is the reality though? If you have to spend $30 for a pre heat are you wasting money if the temps never reached 20F ?

Depends how often you fly. If you fly frequently, it likely is not cost effective to preheat between 20&40°, one of the main factors being residual oil films still around with frequent use engines. If you don't fly much and will only encounter the question a few times a season, it's not going to break you even if it doesn't realize a result that you will never realize if it did or didn't.

The main thing about starting cold engines is controlling the initial rpm carefully and keep it between 1000&1200rpm until it has some time to get an initial heat soak into the heads and cylinders. You want to minimize the time it takes to get up to initial idle temp, but you don't want to run the engine too fast until all the oil has had a chance to circulate and pick up a bit of heat. It only usually takes 15-30 seconds regardless how cold it is, then lean back the engine to rough and richen back up a bit to approximately peak. This gives you the best heat without excessive fuel trying to wash out your rings. Once you get to this point, you can start to taxi. Avoid idling as much as possible.

 

[narchee]

The data sheet for Philips X/C 20W50 defines the pour point only below which the oil becomes a gel.

-27 F for this oil

 

[vintage cessna]

Depends how often you fly. If you fly frequently, it likely is not cost effective to preheat between 20&40°, one of the main factors being residual oil films still around with frequent use engines. If you don't fly much and will only encounter the question a few times a season, it's not going to break you even if it doesn't realize a result that you will never realize if it did or didn't.

My plane is outside, so when it is near 20 F I don't fly much. On the infrequent occasions I do fly at those temps I will have the plane put in a heated hangar overnight. So it is not that I'm not willing to spend the money if needed, but I hate spending money when there is no value.

 

[Henning]

My plane is outside, so when it is near 20 F I don't fly much. On the infrequent occasions I do fly at those temps I will have the plane put in a heated hangar overnight. So it is not that I'm not willing to spend the money if needed, but I hate spending money when there is no value.

The heated hangar provides value beyond the engine, gyros aren't particularly fond of the cold either. For infrequent use, I would go ahead, besides, it's always nicer to climb in a warm plane.

 

[vintage cessna]

The heated hangar provides value beyond the engine, gyros aren't particularly fond of the cold either. For infrequent use, I would go ahead, besides, it's always nicer to climb in a warm plane.

You are right about that. But, if the temps have been in the 30's I don't do anything special, no hangar, no pre heat. What I'm trying to get at is , am I damaging something or not.

You hear a lot of things. I usually rely on what the manufacture says on the assumption they would know the engine better than anyone else.

 

[Henning]

You are right about that. But, if the temps have been in the 30's I don't do anything special, no hangar, no pre heat. What I'm trying to get at is , am I damaging something or not.

You hear a lot of things. I usually rely on what the manufacture says on the assumption they would know the engine better than anyone else.

No, you'll be fine if you follow the starting protocol I gave you.

 

[Tom-D]

The data sheet for Philips X/C 20W50 defines the pour point only below which the oil becomes a gel.

-27 F for this oil

Pour point is a number at which a certain amount of oil will pass thru a calibrated orifice of a certain size. (a viscosity cup), as used by painters to measure the thickness of the paint they spray.

As we all know oil gets thicker (increases in viscosity) as it gets colder. the pour point is not the temp that it can no longer be pumped or can't be poured from the bottle.

 

[vintage cessna]

This is the reason IMHO.....at temps below as low as 40 deg F there is a "possibility" for an interference fit in main journal bearing clearance and between the piston rings and cylinder choke location.

In most cases this doesn't mean a spun bearing.....but is does mean increased wear when starting cold.

What I took away from the Mike Busch video on pre heating is you don't pre heat for the oil temp ( using multi viscosity oil after all) . But you pre heat becuase of dissimilar metals between the cylinders and pistons and so different expansion rates. In an auto engine you don't have the dissimilar metals, so no pre heat required.

He doesn't seem comfortable with manufacturers 20 F reccomendation either. I just can't resolve in my mind why mechanics would be more conservative than the manufacturer. Usually it is the other way around.

 

[jesse]

He doesn't seem comfortable with manufacturers 20 F reccomendation either. I just can't resolve in my mind why mechanics would be more conservative than the manufacturer. Usually it is the other way around.

Not really, many numbers given by a manufacturer should be thought of more as a limit .. not as a number that will lead to achieving long engine life and low maintenance.

Often times all a manufacturer cares about is setting limits that will keep things from breaking in the warranty period.

 

[Tom-D]

You are right about that. But, if the temps have been in the 30's I don't do anything special, no hangar, no pre heat. What I'm trying to get at is , am I damaging something or not.

You hear a lot of things. I usually rely on what the manufacture says on the assumption they would know the engine better than anyone else.

Lycoming recommended that the H2AD engine be pre-heated below 40 degrees, in hopes that would help with the cam failures the engine was plagued with in its early versions. They hoped the warm oil would get to the cam and lifters quicker, it didn't help, the failure rate continued.
This pretty much proved that preheating did not do much other than get the engine started quicker.

 

[vintage cessna]

Not really, many numbers given by a manufacturer should be thought of more as a limit .. not as a number that will lead to achieving long engine life and low maintenance.

I bought my airplane new. With it came a nice book and a DVD from Continental. These contained all sorts or reccomendations and tips for prolonging longevity. Not one single thing about pre heat above 20 F.

 

[Henning]

What I took away from the Mike Busch video on pre heating is you don't pre heat for the oil temp ( using multi viscosity oil after all) . But you pre heat becuase of dissimilar metals between the cylinders and pistons and so different expansion rates. In an auto engine you don't have the dissimilar metals, so no pre heat required.

He doesn't seem comfortable with manufacturers 20 F reccomendation either. I just can't resolve in my mind why mechanics would be more conservative than the manufacturer. Usually it is the other way around.

There are many dissimilar metals in auto engines including the Aluminum head, Iron block combination.

Manage the start up temp the way I told you and you'll be fine.

 

[Tom-D]

Not really, many numbers given by a manufacturer should be thought of more as a limit .. not as a number that will lead to achieving long engine life and low maintenance.

Often times all a manufacturer cares about is setting limits that will keep things from breaking in the warranty period.

Here is a question that relates to your answer.
Why do we see higher battery and starter failures during cold weather?
A. cold engines crank harder than hot engines, weak batteries will crank hot engines, they fail when the amperage goes up to crank a cold engine..

this is the major reason for the pre-heat. to be able to crank the engine within the ability of the battery / starter limits.

 

[vintage cessna]

Here is a question that relates to your answer.
Why do we see higher battery and starter failures during cold weather?
A. cold engines crank harder than hot engines, weak batteries will crank hot engines, they fail when the amperage goes up to crank a cold engine..

this is the major reason for the pre-heat. to be able to crank the engine within the ability of the battery / starter limits.

Given that we use multi viscosity oils, that sounds logical to me. What say you on Mike Buschs contention of the damage that could be caused by the different expansion rates between the cylinder and piston ?

 

[vintage cessna]

Pour point is a number at which a certain amount of oil will pass thru a calibrated orifice of a certain size. (a viscosity cup), as used by painters to measure the thickness of the paint they spray.

As we all know oil gets thicker (increases in viscosity) as it gets colder. the pour point is not the temp that it can no longer be pumped or can't be poured from the bottle.

I have an Odyssey battery that doesn't seem to have the cold temp issue that I use to experience with the Gill.

My POH says for cold weather start, to turn the prop ( backwards) several compressions as this will loosen the oil so the engine cranks more easily and use less battery power. Good procedure?

 

[Stewartb]

Lycoming recommends preheat below 10*F except for H series engines should pre-heat below 20*. TCM uses 20* without exception. TCM specifically says not to preheat continuously for more than 24 hours prior to flight. I've said I use 20* as my bottom temp but will use heat at 25* if convenient. 100% of my electricity at the airplane comes from a portable generator and always has. Going out early to start a generator isn't always convenient. Since TCM says 20 is okay, I'm comfortable with it.

I use Phillips 20-50 and have for many years. It's thick in single digit temps, I promise you. Simple experiment? Put a quart in your freezer overnight and pour it in the morning. Try it with W100 as well.

I've never preheated my cockpit. I park outdoors. Temps are often well into the preheat zone. Never a problem. I have no evidence that cold starting my gyros has hurt anything but I've only been doing it in this plane for 20 years.

Dissimilar metals. I don't understand why guys think there's some magic threshold for metals expansion at or near 32*. All these years of running high output air-cooled engines in snowmachines and never a thought about temperature. Other than oil viscosity, anyway. The cylinders and bearings are fine.

 

[Stewartb]

From what I've read the pour point test uses a beaker. The sample is cooled until it doesn't flow after being tipped on it's side for 5 seconds. At that point the temperature is raised 3* at a time until it does flow, and that's the pour point temp.

I've never seen a POH say to rotate the prop backwards. That's a surprise. When I rotate I do in the standard direction. If you want a real lesson in cold starting, priming, rotating the prop, etc? Hand prop to start a few times. It's interesting. you'll quickly zoom in on what your engine likes to minimize starting effort.

 

[vintage cessna]

Lycoming recommends preheat below 10*F except for H series engines should pre-heat below 20*. TCM uses 20* without exception. TCM specifically says not to preheat continuously for more than 24 hours prior to flight. I've said I use 20* as my bottom temp but will use heat at 25* if convenient. 100% of my electricity at the airplane comes from a portable generator and always has. Going out early to start a generator isn't always convenient. Since TCM says 20 is okay, I'm comfortable with it.

I use Phillips 20-50 and have for many years. It's thick in single digit temps, I promise you. Simple experiment? Put a quart in your freezer overnight and pour it in the morning. Try it with W100 as well.

I've never preheated my cockpit. I park outdoors. Temps are often well into the preheat zone. Never a problem. I have no evidence that cold starting my gyros has hurt anything but I've only been doing it in this plane for 20 years.

Dissimilar metals. I don't understand why guys think there's some magic threshold for metals expansion at or near 32*. All these years of running high output air-cooled engines in snowmachines and never a thought about temperature. Other than oil viscosity, anyway. The cylinders and bearings are fine.

As an operator of an engine but far from an engine expert I'm just trying to cut through the fog. Below 20 F even multi viscosity oils get to be a little too thick. I can see pre heat helping with fuel vaporization and battery power. But some others will say you will be taking a chance of trashing your engine without pre heat below 40 F.

For now, I think I will just stck to what Continental and my POH says. "Playing it safe" often equates to a waste of time and money. If I didn't visit these forums I probably would have never even questioned in my mind Continentals or my POH reccomendations.

 

[vintage cessna]

From what I've read the pour point test uses a beaker. The sample is cooled until it doesn't flow after being tipped on it's side for 5 seconds. At that point the temperature is raised 3* at a time until it does flow, and that's the pour point temp.

I've never seen a POH say to rotate the prop backwards. That's a surprise. When I rotate I do in the standard direction. If you want a real lesson in cold starting, priming, rotating the prop, etc? Hand prop to start a few times. It's interesting. you'll quickly zoom in on what your engine likes to minimize starting effort.

The POH says to rotate the prop backwards to prevent an accidental start. The aircraft is not equipped with a vacuum pump. I suppose the engine doesn't care which way it is rotated?

 

[Stewartb]

The primary items that I preheat for are the advantages of fast cranking speeds and quick cylinder firing. As temps drop into the lower 20s I can recognize a difference in those things. Cranking gets slower and the engine requires close attention to feed fuel to keep it running. Above those temps I can't recognize any difference.

 

[vintage cessna]

The primary items that I preheat for are the advantages of fast cranking speeds and quick cylinder firing. As temps drop into the lower 20s I can recognize a difference in those things. Cranking gets slower and the engine requires close attention to feed fuel to keep it running. Above those temps I can't recognize any difference.

What is your opinion of the reccomended cold WX start procedure in this video?

https://m.youtube.com/watch?v=GV1-CSxAGtA

 

[Henning]

The POH says to rotate the prop backwards to prevent an accidental start. The aircraft is not equipped with a vacuum pump. I suppose the engine doesn't care which way it is rotated?

Correct, with no vacuum pump, there's no real issue turning it backwards. It's the vanes in the vacuum pump that can give you problems when they get worn down.

 

[Checkout_my_Six]

Correct, with no vacuum pump, there's no real issue turning it backwards. It's the vanes in the vacuum pump that can give you problems when they get worn down.

negatory capitain....

 

[narchee]

Pour point is a number at which a certain amount of oil will pass thru a calibrated orifice of a certain size. (a viscosity cup), as used by painters to measure the thickness of the paint they spray.

As we all know oil gets thicker (increases in viscosity) as it gets colder. the pour point is not the temp that it can no longer be pumped or can't be poured from the bottle.

Kind of off topic since nobody is suggesting we shouldn't preheat at a temperature even close to the pour point of -27 F... but I cannot find any reference for pour point that describes it the way you have. Can you provide a reference?

A typical definition I've seen is:

"The low-temperature limit for starting an oil- lubricated machine is often specified by the pour point of the oil. This is the lowest temperature at which oil will flow when chilled under prescribed laboratory conditions (ASTM D97). With most mineral-based industrial oils (designated as turbine, hydraulic, industrial and machine oils), this pour point corresponds to the temperature that freezes the paraffin molecules of the oil into a white crystalline wax that will eventually immobilize the overall oil."

http://www.machinerylubrication.com/Read/1014/low-temperature-viscosity-limits