Oil filter loosening info.

[Ryland3210]

I recently purchased a Purolator filter with the same basic specs as the UFI 2328700 which came with my '04 Cafe Sport.

 

It was interesting to find significant differences in the gasket dimensions.

The UFI measured 0.22 wide by 0.250 thick.

The Purolator measured 0.16 wide by 0.255 thick.

The UFI stood 0.067 proud of the metal can.

The Purolator stood 0.080 proud. All measurements in inches.

 

Since the thread pitch is 1/16", the UFI would bottom out in 1.07 turns past contact, assuming negligible deflection of the metal base of the filter.

The Purolator would bottom on in 1.28 turns.

 

If both filters are tightened the same number of turns, the Purolator's gasket will develop 37.5% higher contact pressure with the block, assuming the same durometer elastomer is used.

If both filters are tightened until they bottom out on the can, the Purolator will develop

69% squeeze, whereas the UFI will develop 73%.

 

Conclusion: Assuming both gaskets are of the same durometer, in all three cases,,regardless of whether tightening is by turns or torque or until bottomed out, the UFI gasket develops lower sealing pressure.

Moreover, the prevailing torque generated by the gasket preventing loosening in the case of tightening until bottoming out is less in the case of the UFI design.

If the UFI uses a higher durometer material (I have not compared the two yet), if tightened using the torque method, all other things being equal, it will still generate 37% lower sealing pressure because it has a higher projected area. It might generate higher prevailing torque and sealing pressure than the Purolator, but that would require a considerably harder material than the fairly stiff Purolator filter.

 

I expect to change my filter shortly, and I'll compare the durometers when that happens. I didn't meaure that when I inspected the UFI filter. My recollection is that it was pretty soft, but I won't be sure until I check it again.

 

I'd be interested if anyone out there knows the durometer of the UFI gasket and/or Purolator's standard.

[Guest ratchethack]

Nice work, John. With all the recent oil filter/pressure failure phenomena, I reckon you very well could be right on track here. If this one proves valid on the durometer scale and then proves itself in field trials, you'll most certainly have more than earned your place in the Guzzi Hall of Famous Solutions to Very Serious, but Admittedly Esoteric Problems -- right next to Skeeve for his Famous Seat Latch/Idle Advance Spring Swap!

[helicopterjim R.I.P.]

 

I'd be interested if anyone out there knows the durometer of the UFI gasket and/or Purolator's standard.

 

Just curious but are you referring to the Shore hardness measured with a durometer?

 

I am very intrigued to here about any results in this matter!

 

Cheers

Jim

[DeBenGuzzi]

Nice work, John. With all the recent oil filter/pressure failure phenomena, I reckon you very well could be right on track here. If this one proves valid on the durometer scale and then proves itself in field trials, you'll most certainly have more than earned your place in the Guzzi Hall of Famous Solutions to Very Serious, but Admittedly Esoteric Problems -- right next to Skeeve for his Famous Seat Latch/Idle Advance Spring Swap!

I'd say he's up for a Guzzi Gearhead award, what do you think alex?

[Ryland3210]

Just curious but are you referring to the Shore hardness measured with a durometer?

 

I am very intrigued to here about any results in this matter!

 

Cheers

Jim

 

Yes, the Shore A scale is used on softer rubbers. There are other scales for plastics.

 

Elastomers come in various degrees of hardness. I am most familiar with O-rings. Typically, manufacturers will offer 70 durometer for most applications, and 90 durometer (harder) for high pressure applications.

 

Today, I changed the filter on my wife's Jeep. It was also a Purolator. The cross section of the gasket was the same as the filter I reported on before, and so was the distance it protruded above the metal base. On the can, it said to tighten it between 3/4 and 1 turn. I found that it takes quite a bit of muscle to get to 1 turn, even though I used a foot long ratchet on it and the gasket was lubricated with engine oil. Given the pitch of the thread, it would not be bottoming out until just over 1-1/4 turns. My guess is that the 1-1/4 turn limit is intended to prevent crushing the gasket by an overzealous installer.

 

If the filter is bottomed out, there is no gap for the gasket to extrude though under high pressure conditions. If it is not bottomed out, the geometry of the gasket's cross section and its hardness determine the max pressure it will contain. It seems to me that if the gasket is not under sufficient compression and/or is not hard enough to prevent leakage, there could be condition where a thin film of oil is squeezing out between the gasket and block. At that point, only the friction of the thread prevents the filter from loosening, as the gasket "floats" on the oil film.

 

John

[Ryland3210]

Among the manufacturers who actually specify an "X" turns past contact, the number varies from manufacturer to manufacturer. They may have an intended level of compression by design but they don't always seem to get the numbers out to the users. I don't know of any application where bottoming out is desireable. (Oil filters that is!)

 

In high pressure applications, for example hydraulic systems with system pressure of 3,000 psi, elimination of the extrusion gap is desirable. At 6,000 psi, it is essential when using O-rings of 70 or 90 durometer. Of course, oil filters for these applications are a far cry from sheet metal cans used at 50-100 psi.

 

Whether bottoming out is desirable or necessary depends on the filter base design. I find it interesting the in the case of the UFI and Purolator filters I've measured, bottoming out the UFI would require slightly over 1 turn, quite close to the 3/4 to 1 turn spec'd by Purolator.

 

Based on what I know so far, I plan on tightening up the next UFI filter I use (if I ever do) to bottom it out at 1.07 turns. I should be able to feel the sudden increase in torque required. At that point, I know I'm not crushing the gasket any farther, so any additional turning will preload the metal base and increase prevailing torque, which I view as a good thing. There will also be no extrusion gap.

 

Incidentally, when installing the Purolator, I was surprised to see some metal chips in its female thread. This is on the outlet side of the filter, which goes right into the engine. I cleaned it out with a cloth, and recommend checking filters for this, no matter what make they are.

[docc]

Sounds like torquing the UFI to a metal to metal contact ( especially if the surfaces were dry) might account for why some factory installed filters have been reported to be so impossible to remove.

 

Getting that one full turn on the UFI is a piece of cake. It's getting that next 0.07 that could get tricky.

[Crooz]

Dude !!! I'm gona go out on a limb here and guess that you don't work at the Jiffy Lube?

 

 

I bet you also have been know to wear a pocket protector!

[Ryland3210]

Sounds like torquing the UFI to a metal to metal contact ( especially if the surfaces were dry) might account for why some factory installed filters have been reported to be so impossible to remove.

 

Getting that one full turn on the UFI is a piece of cake. It's getting that next 0.07 that could get tricky.

 

I wasn't suggesting tightening .07 turns past metal to metal contact. The measurements indicate that 1.07 turns are required to reach that point.

[stormsedge]

Man, what am I going to do when I run out of the filters in the bottom drawer of my tool box...this is all getting very complicated!! k

[Ryland3210]

High pressure hydraulic applications may require bottoming but in low pressure it is not required or desireable. Overtightening can distort filter internals preventing them from working as designed. The factory specs should be sought and followed.

 

The surfaces need to be lubricated with engine oil, never grease.

 

Don't worry in the least about a thin film of oil working under the face of the seal. A minimum of contact is all that is required to acheive a positive seal. The seal used is actually self energizing. The hydraulic pressure working against the inside actually increases the pressure on the face of the seal. As long as extrusion is controlled the seal will not leak.

 

Spin on filters rated for upwards of 3000 PSI would be a much stronger design than the 1 to 2 MM thick drawn steel or extruded aluminum cans used with engine oil systems. A totally different animal. Most hydraulic spin on filters were in the lower pressure sump return or bypass line. High pressure filters are pretty costly devices, designers generally favor the low pressure side when possible.

 

Ah yes, self energizing is useful, so long as there is no extrusion. That's where having any gap between the metal faces small enough (not necessarily zero, unless one is at 6,000 psi) is vital.

 

I'm certainly not advocating torqueing beyond metal to metal contact to the point of causing serious distortion of the internal parts. Nor do I advocate compression to gap elimination if a gasket stands proud of the filter base so far that doing so would cause compression failure of the seal. In the case of the filters I have measured so far, that is not a concern.

 

I'm not familiar with spin on filters in the 3,000 psi range. The one's I've designed into systems have a screwed in heavy wall thickness machined filter container that has an O-ring seal to the housing. Low pressure return line filtration keeps contamination from getting back into the sump. Pump inlet filters are often nothing more than screens or cartridge filter rated at 100 -125 microns to avoid cavitating the pumps. On better systems, especially where proportional or servo valves are used, high pressure, non-bypass filters rated at as fine as 3 micron absolute protect expensive components from damage. In the machine tool industry, reputable machine builders always include high pressure filtration along with coarse filtration on pump inlets, but not always return line filtration. Over the last several years, more and more add low pressure auxiliary filtration loops recirculating the reservoir fluid constantly through relatively large disposable filters rated at 3-10 micron. It's well understood and accepted today that 6 micron (nominal) or better filtration is required for long term life. In comparison, typical filters used in automotive applications are usually 15 micron (nominal) or even coarser.

 

On balance, I place somewhat more credibility on the filter maker's recommendations than I do the motor's. One exception to this is the torque spec on the UFI filters, which I consider surprisingly low. When I read about all the problems with them coming loose, I got interested. It's generally risky or even dangerous in my view to accept anything on authority unless it seems consistent with common sense, experience, and the laws of physics. One of the things I enjoy is in understanding why things fail or work. I'll sometimes spend a ridiculous amount of time researching, calculating, and analyzing, especially if it will save the life of a machine I depend on or consider a "friend".

 

Regarding: "Don't worry in the least about a thin film of oil working under the face of the seal. A minimum of contact is all that is required to acheive a positive seal." Maybe so, in an application where pressure is always maintained, but what if pressure cycles from zero to perhaps 75 psi on startup and back to zero when the engine is shut down. I can't help but feel the consequent squeezing and relaxation of the seal does it no good. I've personally seen plenty of seals fail for that reason if the extrusion gap was too large or the seal was not sufficiently squeezed mechanically due to faulty installation or design.

[Guest Mattress]

Interesting thread. The fact that the Guzzi has an oil filter you cant observe while the engine is running lends itself to suspicion I am gathering. At least when something is wrong on your car's filter joint you will know pretty quick.

 

As for me, next oil change I'll be putting on a constant tension hose clamp on the filter. Why not? Some have issues with that, but I don't. If things can't vibrate themselves loose on a big twin, then racing organizations shouldn't require us to safety wire things.

[Ryland3210]

Interesting thread. The fact that the Guzzi has an oil filter you cant observe while the engine is running lends itself to suspicion I am gathering. At least when something is wrong on your car's filter joint you will know pretty quick.

 

As for me, next oil change I'll be putting on a constant tension hose clamp on the filter. Why not? Some have issues with that, but I don't. If things can't vibrate themselves loose on a big twin, then racing organizations shouldn't require us to safety wire things.

 

Well, you can't see the filter from inside a car either. Nothing wrong with belts and suspenders on something so critical.

 

I'll be looking for a way to elegantly connect up a pressure guage.

 

Here's one for the books: Once, and only once, it happened that the gasket stuck to the block. I didn't notice that because of where it was located. Nor did I notice it missing on the used filter taken off, probably because it never happened to me before in decades of changing filters, and because it was covered with dirty oil. Started the car, and made sure the pressure built up OK, as always. Next morning, we took off up the road. I have a habit of checking the pressure guage frequently, especially after an oil change. After driving about 1200 feet, pressure dropped off. Stopped the car immediately. I found that the double gaskets had held pressure for a while, about 800 feet, then extruded out, and emptied most of the sump in a matter of seconds. Interestingly the guage told the story while the idiot light stayed off until I shut down the engine.

 

Since then, I check every filter I take off to make sure the gasket comes with it!

[jrt]

I'll be looking for a way to elegantly connect up a pressure guage.

 

This might be useful for ideas-Greg Bender put on on his Ambassador.

[Guest Gary Cheek]

Quote

 

"Here's one for the books: Once, and only once, it happened that the gasket stuck to the block. I didn't notice that because of where it was located. Nor did I notice it missing on the used filter taken off,"

 

 

 

And this is exactly the cause of "seal extrusions" when referenced to spin on engine oil filters. If the filter is tightened within the broadest limits of the proper range the seal will not, cannot extrude under normal operating pressure ranges. In most situations when there are pressure extremes the filter can will burst before the seal extrudes and fails. The pressure must be extremely high usually from a defective relief valve or very cold, viscous oil.

 

This is a very common problem where the operator neglects actually checking the sealing surfaces. It's the same as "I didn't see the biker"." Didn't see" = didn't look. Working carefully is the key.

 

When using gauges I personally use electrical gauges on motorcycles. Try to avoid the commonly used 1/8 inch nylon line.