Thermostat Replacement
01-05-2011, 01:13 PM
#31
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Are there any drawings or schematics that show the IMS bearing? I would like to see this arrangement just for my own education as to how this is lubricated.
I am not trying to be picky, or point out errors, or denigrate someone's post, but just so everyone knows, there is no such thing as a high viscosity grease. There are greases that have a higher viscosity oil in them than others, but greases are classified by their penetration number and not by the viscosity of the oil component. The higher the NLGI number, the "stiffer" the grease is, the viscosity of the oil is rarely a factor in determining the consistency of a grease. Maybe that was what Palmbeacher was referring with respect to packing the IMS bearing.
I am not trying to be picky, or point out errors, or denigrate someone's post, but just so everyone knows, there is no such thing as a high viscosity grease. There are greases that have a higher viscosity oil in them than others, but greases are classified by their penetration number and not by the viscosity of the oil component. The higher the NLGI number, the "stiffer" the grease is, the viscosity of the oil is rarely a factor in determining the consistency of a grease. Maybe that was what Palmbeacher was referring with respect to packing the IMS bearing.
01-06-2011, 09:45 AM
#33
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No, what I was referring to was the fact that grease is thicker than oil, and a bearing designed to be packed with grease will not ever be ideally lubricated by oil. I apologize for not putting it simplistically enough.
01-06-2011, 02:50 PM
#34
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See, the longer warm up time concerns me as does the lower average oil temperature. Longer warm up can translate into more cold start wear, and the oil is meant to operate within a range of temps at which it is most efficient. I am of two minds here. I know this may sound naieve, but if P wanted to run a different thermostat in this application why wouldn't they? They seem to have done it in different engines. I'll talk to Taso about this but he obviously was ok w it.
01-06-2011, 03:27 PM
#35
Most wear occurs during startup and the synthetics simply move through a cold engine and pressurize all areas sooner than mineral oils. Lubrication is therefore superior during this phaze ( first seconds and during warmup which is genrally 5 to 15 minutes). After that the oil is at operating temp and viscosity is basically the same as a -40 mineral oil.
01-06-2011, 07:11 PM
#36
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A grease is used to lubricate parts, mainly bearings, because there is no way to get oil to the part efficiently. However, it is the oil in the grease, which is usually about 85% of the total material in grease, with the other 15% being the carrier, normally a soap of some sort, that does the lubricating and the soap is just there to hold the oil so it can lubricate the part.
The thickness of the grease does not enter into the lubrication function one way or another other than it must allow the part to move freely through it. However, when making a recommendation for a greased lubricated part, one must consider, speed, load, temperature, environment, and how the grease will be applied. Sealed bearings are difficult because the grease must be able to be churned without any oil separation occurring and bleeding past the seals. Too much grease and the action of the part going through the grease will increase the heat and lead to problems. The same can be said for the thickness(consistency) of the grease. Too thick and the part cannot operate without increasing the heat as the part rotates or moves through the grease, too thin and the grease(actually the oil) gets by the seals and you have a loss of lubrication. Grease lubrication is always a compromise to oil lubrication even though it is the oil in the grease that does the actual lubricating. However, without grease it would be impossible to deliver the oil necessary to provide the required lubrication.
Not trying to be picky again, but a bearing designed to be lubricated by grease is actually lubricated by the oil in the grease, and if mechanically possible would always be oil lubricated in place of a grease.
The thickness of the grease does not enter into the lubrication function one way or another other than it must allow the part to move freely through it. However, when making a recommendation for a greased lubricated part, one must consider, speed, load, temperature, environment, and how the grease will be applied. Sealed bearings are difficult because the grease must be able to be churned without any oil separation occurring and bleeding past the seals. Too much grease and the action of the part going through the grease will increase the heat and lead to problems. The same can be said for the thickness(consistency) of the grease. Too thick and the part cannot operate without increasing the heat as the part rotates or moves through the grease, too thin and the grease(actually the oil) gets by the seals and you have a loss of lubrication. Grease lubrication is always a compromise to oil lubrication even though it is the oil in the grease that does the actual lubricating. However, without grease it would be impossible to deliver the oil necessary to provide the required lubrication.
Not trying to be picky again, but a bearing designed to be lubricated by grease is actually lubricated by the oil in the grease, and if mechanically possible would always be oil lubricated in place of a grease.
01-06-2011, 10:12 PM
#37
A grease is used to lubricate parts, mainly bearings, because there is no way to get oil to the part efficiently. However, it is the oil in the grease, which is usually about 85% of the total material in grease, with the other 15% being the carrier, normally a soap of some sort, that does the lubricating and the soap is just there to hold the oil so it can lubricate the part.
The thickness of the grease does not enter into the lubrication function one way or another other than it must allow the part to move freely through it. However, when making a recommendation for a greased lubricated part, one must consider, speed, load, temperature, environment, and how the grease will be applied. Sealed bearings are difficult because the grease must be able to be churned without any oil separation occurring and bleeding past the seals. Too much grease and the action of the part going through the grease will increase the heat and lead to problems. The same can be said for the thickness(consistency) of the grease. Too thick and the part cannot operate without increasing the heat as the part rotates or moves through the grease, too thin and the grease(actually the oil) gets by the seals and you have a loss of lubrication. Grease lubrication is always a compromise to oil lubrication even though it is the oil in the grease that does the actual lubricating. However, without grease it would be impossible to deliver the oil necessary to provide the required lubrication.
Not trying to be picky again, but a bearing designed to be lubricated by grease is actually lubricated by the oil in the grease, and if mechanically possible would always be oil lubricated in place of a grease.
The thickness of the grease does not enter into the lubrication function one way or another other than it must allow the part to move freely through it. However, when making a recommendation for a greased lubricated part, one must consider, speed, load, temperature, environment, and how the grease will be applied. Sealed bearings are difficult because the grease must be able to be churned without any oil separation occurring and bleeding past the seals. Too much grease and the action of the part going through the grease will increase the heat and lead to problems. The same can be said for the thickness(consistency) of the grease. Too thick and the part cannot operate without increasing the heat as the part rotates or moves through the grease, too thin and the grease(actually the oil) gets by the seals and you have a loss of lubrication. Grease lubrication is always a compromise to oil lubrication even though it is the oil in the grease that does the actual lubricating. However, without grease it would be impossible to deliver the oil necessary to provide the required lubrication.
Not trying to be picky again, but a bearing designed to be lubricated by grease is actually lubricated by the oil in the grease, and if mechanically possible would always be oil lubricated in place of a grease.
01-07-2011, 12:34 PM
#38
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LN makes a replacement bearing and spindle for the 996/997.1 and the Boxster equivalent motors. The bearing is ceramic and open from what I have seen. The spindle is more robust. The most cost effective time to do a replacement is when replacing the clutch since you are already there. Who wants to be the first on the block?
01-07-2011, 04:33 PM
#40
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Bearings, anti-friction, are not designed for for either grease or oil lubrication. Bearings are designed for conditions that have specific speed, load, and environmental conditions. A greased bearing does not have "more room inside" that an oiled bearing. The method of lubrication is a factor in the selection of a bearing only if the application for the bearing dictates it. Yes, some bearings are sealed for life with a grease as the lubricant, but the exact same bearing could be used in a oil(fluid) lubrication application as well if oil can be delivered to the bearing. Oil is always the preferred method for lubrication for anti- friction bearings. In fact, it is just the opposite as you state about grease and oil lubricated bearings. For instance, if the bearing life is calculated to be 1, with oil lubrication, that same bearing will have a life expectancy of something less than 1, somewhere between .75-.8 when grease lubricated.
Not ignoring or pontificating at all, just pointing out some misconceptions where the lubrication of bearings(anti-friction) is concerned in your posts. Sorry if you take exception with facts.
Not ignoring or pontificating at all, just pointing out some misconceptions where the lubrication of bearings(anti-friction) is concerned in your posts. Sorry if you take exception with facts.
01-07-2011, 04:47 PM
#41
We have gone far afield from a discussion about thermostats to the bearing used on the IMS. Perhaps starting a new thread on IMS failure would help Palmbeacher follow the conversation. As to the thermostat I remain unconvinced and am concerned that lowering operating temps to prevent a rare cylinder/piston failure may result in unnecessary wear. Note MichaelL (the only one to have this mod) indicating that it does take his car longer to reach normal running temps.
01-07-2011, 04:59 PM
#42
Bearings, anti-friction, are not designed for for either grease or oil lubrication. Bearings are designed for conditions that have specific speed, load, and environmental conditions. A greased bearing does not have "more room inside" that an oiled bearing. The method of lubrication is a factor in the selection of a bearing only if the application for the bearing dictates it. Yes, some bearings are sealed for life with a grease as the lubricant, but the exact same bearing could be used in a oil(fluid) lubrication application as well if oil can be delivered to the bearing. Oil is always the preferred method for lubrication for anti- friction bearings. In fact, it is just the opposite as you state about grease and oil lubricated bearings. For instance, if the bearing life is calculated to be 1, with oil lubrication, that same bearing will have a life expectancy of something less than 1, somewhere between .75-.8 when grease lubricated.
Not ignoring or pontificating at all, just pointing out some misconceptions where the lubrication of bearings(anti-friction) is concerned in your posts. Sorry if you take exception with facts.
Not ignoring or pontificating at all, just pointing out some misconceptions where the lubrication of bearings(anti-friction) is concerned in your posts. Sorry if you take exception with facts.
01-07-2011, 05:35 PM
#43
Whether it is a benefit for them or not is unclear. So far as I know nobody has had a failure on an LN-style rebuilt motor, but that doesn't prove it is much more reliable (and there are so many changes that you can't isolate the effects of one from another).
01-07-2011, 06:10 PM
#44
Bearings, anti-friction, are not designed for for either grease or oil lubrication. Bearings are designed for conditions that have specific speed, load, and environmental conditions. A greased bearing does not have "more room inside" that an oiled bearing. The method of lubrication is a factor in the selection of a bearing only if the application for the bearing dictates it. Yes, some bearings are sealed for life with a grease as the lubricant, but the exact same bearing could be used in a oil(fluid) lubrication application as well if oil can be delivered to the bearing. Oil is always the preferred method for lubrication for anti- friction bearings. In fact, it is just the opposite as you state about grease and oil lubricated bearings. For instance, if the bearing life is calculated to be 1, with oil lubrication, that same bearing will have a life expectancy of something less than 1, somewhere between .75-.8 when grease lubricated.
One of the wives tales (which may or may not be true) is that hard-driven tracked cars tend to have fewer IMS failures. The theory is that this is because they get more oil splashed up to the bearing.
01-07-2011, 06:19 PM
#45
That may be true for 997's but if you do some searching you can easily find lots of people with 996's and Boxsters that have this mod.
Whether it is a benefit for them or not is unclear. So far as I know nobody has had a failure on an LN-style rebuilt motor, but that doesn't prove it is much more reliable (and there are so many changes that you can't isolate the effects of one from another).
Whether it is a benefit for them or not is unclear. So far as I know nobody has had a failure on an LN-style rebuilt motor, but that doesn't prove it is much more reliable (and there are so many changes that you can't isolate the effects of one from another).