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Oil filter seal leaking / loss of torque

rjcthree

Well Known Member
I’m a little stumped. It’s not like I’m new to spin on filters.

I discovered oil leaking from the oil filter seal this morning following a finding of a mess on the belly of the AC. The first hint was during preflight when the oil level was 1/4 qt lower than yesterday’s flight, (I admit to cleaning the bugs off yesterday, but didn’t look under). After removing the cowling to inspect and clean, I was able to reach over and turn it a little less than 1/4 turn tighter with one hand, and almost 1/3 turn total with the torque wrench. I torqued this one accurately when first installed about 10 hours ago, and it was still wired and marked. The oil leak flow path is clear, it was easy to identify. It’s also messy.

This is the second time this has happened this year, same order of Tempest EZ turn filters sourced from Aircraft Spruce. The first time I attributed it to maybe my torquing effort being obstructed, as it’s tight in there, but with a stubby wrench offset I don’t have that issue anymore. The first time was about 15 hours in from an oil change, tightening to spec stopped the leak. I retightened this time too (and wired and marked), we’ll see what happens. In both cases, I did intentionally pre alloy oil or DC4 to the gasket, the steel interface of the gasket was wiped dry and clean with a dry wipe.

Engine is an H2, oil is aero shell w15w50 with camguard, oil pressure is 55/65-70/95 psi idle/cruise/max, oil temps in cruise 165F-190F depending on phase of flight, OAT and leaning. The filter is a Tempest AA48103-2.

Any ideas would be helpful.
 
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Was a film of oil applied to the "O" ring before installing? You can also achieve the proper torque by installing the filter to seal contact then mark the top of the filter and then tighten another 3/4 of a turn with a band wrench.

If it was properly wired, was the wire still tight when you found it leaking?
 
Shrinking gasket? Could you measure a used one compared to new and post results?
 
Oil or no oil on gasket

Not at the hangar but do I recall that on my Tempest filters it states to NOT oil the gasket???
I use them on the Cessna and never had issues...
 
After reading several such tales of woe about the Tempest EZ Turn filters I opted to go back to my old technique of applying a thin wipe of DC4 compound to the gasket.

I honestly think that we should be filing Service Difficulty Reports with the FAA for these gasket problems. Tempest is manufacturing under PMA. They made a design change. The new design does not seem to be as reliable as the old design. The FAA needs to know so they can follow up with Tempest.
 
No pre oil.

I updated my IP with the detail, but I did not pre oil, everything was clean and dry when assembling per spec.

It was wired and the wire was tight, I also marked it and it hadn’t moved.

David, while I’m unwilling to buy one just to do a chem test, I do have the previous one. Doing some exposure testing might prove interesting.

The picture shows how far I was able to turn it one handed and how loose the safety wire got when doing so. Again, a casual one handed grab and twist, no real straining, a little less than a quarter turn. The yellow dots matched when torqued at installation, and still aligned in it’s leaking condition this morning. Actual retorquing got it to almost 1/3 turn.
 

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Wow! My aircraft consumed over a hundred of filters every brand available and never leaked never came loose. Thanks for reporting Rick.
 
That’s the weird thing….

Vlad, It never moved, it leaked and retained very little torque, as in it was easy to continue turning. I KNOW it was right on installation this time, no excuses.

I might stick with the tempests, just oiling the gasket and planning a retorque after a few hours going forward. It’s kind of a PITA, as since I installed electronic ignition, this has been the only reason I’ve had to pull the cowl between oil changes and condition inspections.

Airplanes……
 
Vlad, It never moved, it leaked and retained very little torque, as in it was easy to continue turning. I KNOW it was right on installation this time, no excuses.

I might stick with the tempests, just oiling the gasket and planning a retorque after a few hours going forward. It’s kind of a PITA, as since I installed electronic ignition, this has been the only reason I’ve had to pull the cowl between oil changes and condition inspections.

Airplanes……
I use the Tempest EZ-Turn, and I’m always having to wrench the filter off the adapter.
Good to know if there is a suspected defect, as I just replaced mine this week. I’ll be looking at this very close on preflight(s).
 
Outside the box

Thinking outside the proverbial box here...
Could the oil filter flange and/or its threads on the engine (and not the filter itself) be partly or entirely responsible for your issue???
 
The first "why" of five.

I mark and rotate my filter, I use 3/4 min or torque which ever come last.

There is only one of two things that have caused your leak. Fundamentally it was not tight - rotation not torque, or the top plate of the filter has deformed, bent. Note I did not say it was overpressure, but deformed. You should take that filter and put a straight edge over the top (no gasket) and compare to a new one.

The plate is the most highly stressed part of the filter and typically the most expensive single part (hint hint).

Everything else should be considered after these two things.

Edit:The gasket is also included in that joint. I would agree with the OP to investigate the possibility creep allowing a loosening joint. But - - the compression of that gasket at 3/4 turn should be quantified on a bench. Just a block with the top plate and the center "stud". Does the plate make contact and limit compression of the gasket? Are the threads clean, or could they have interfered with the rotation? Will the filter w/o gasket easily thread to a stop? What stops it? These questions are some of the many that need quantification to reach a unambiguous root cause.
 
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I believe the filter torque is maintained by force generated by the compressed rubber gasket, just like a lock washer. I suspect there could be a manufacturing flaw with the rubber or whatever synthetic compound is being used, allowing it to go flat instead of resisting the force and pushing back. It sounds like this is some unique filter type that is using an exotic compound instead of rubber. When you pull the filter, measure the thickness of the rubber ring and compare it to new. It should be about the same. If thinner, deformation of the gasket is the problem.

Food for thought.

Larry
 
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Rick-
At some point in it's life, your H2 engine was probably converted to a spin-on filter from a cannister type filter. Champion sold a kit to accomplish this:
CH48922 kit comprising of a stud, base plate & gasket. Refer to Champion Aviation Service Manual AV6-R, page 22.
Would be good to review this & see if the stud/plate are loosening off and fouling up your filter torquing results, as your loose filter issues are a (relatively) recent development.
 
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I pulled out a few filters to see if there was any difference between them. Granted, 2 of them are not the same pt# as the 103-2 (different mounting stud size), but I am looking at the sealing ring which are the same dimensions in the two applications.

Champion CH48109-1 - o-ring width 0.180", crush depth to metal retaining plate 0.10", o-ring material silicon infused rubber (per Champion pamphlet), o-ring rubber feels softer than Tempest filters (so narrower & softer), slight waxy or similar on the o-ring surface when lightly scraped with my thumb nail.

Tempest AA48109 "The Original" - o-ring width 0.225", crush depth to metal retaining ring 0.080", o-ring material unknown but feels more like a neoprene type material, will compress when pushed in with thumb nail but is harder than the Champion filter, slight waxy film when scraped with nail.

Tempest AA48103-2 "SpinEZ" - o-ring dimensions same as the Tempest 109 filter, 0.225 wide / 0.080 crush depth, can't tell if material is different but o-ring has about the same hardness as the Tempest 109 filter, no waxy film on the o-ring.

Instructions on both of the 109 filters call for pre-lubing the o-ring before installation, all call for 16 - 18 ft/lbs torque, but the SpinEZ states Do Not Lubricate. I can deduce that same torque values between the two different manufactures & product models would produce different crush depths so the 3/4 turn method will result with different final torque results because of the o-ring difference of width & stiffness.

I also note that both Tempest and Champion have specific oil filter torque wrenches available, might be a tool I'll be investing in instead of falling back to older methods as I now see there IS a difference between the 2 product lines.

Just more food for thought...
 
Flatness, OE parts vs Champion.

I overhauled it, and I have the logbooks since it was zeroed by lycoming in ‘78 or ‘79, when it also became an H mod. I don’t remember. My lycoming parts manual tells me the spin on was original for this engine. At the last oil change, I checked the stud and it was secure - I had the same thought. There is another ring seal between the mating plate and housing, and while it could leak, when the stud is tight, I the mating plate bottoms on aluminum. I haven’t figured out how the stud could loosen but the filter not move versus the housing. Since I didn’t find the stud loose, I dropped that angle.

This is the seventh filter on the engine. The first five did not do this. The latest two, both ez turns, did. Past were not ez turns, but regulars and one champion in the mix.

At the moment, I’m leaning toward a seal chemical interaction. The company I work for manufactures a few million spin ons a year. Since I have the previous end plate/daseplate/seal, I may spend some time in the lab. Although it’s not a slab or button, I can probably get a comparative durometer as I work through exposure scenarios. The exposure profile is pretty simple, oil, camguard, heat. If I can lunch off another test, I can do a heat set test, comparatively at least.
 
tempest oil filter leaks

ive used tempest oil filters for a number of years and never had a problem. changed the oil and filter recently and had a leak after about two hours flying.oil on the firewall and the belly.removed the filter and it was hand tight and easy to remove even thoughi had tightened it 3/4 turn and saftety wired. when i installed it i put a light coat of clean oil on the gasket like ive always done.noted after removal directions on filter said clean no lube oops.new filter no lube will fly soon, hope this fixes the leak
 
I'm surprised this thread has gone silent.

It would appear there is some number of defective Tempest oil filters in circulation.

Has anyone that has experienced the problem contacted them? If so, please share.
 
One data point...

Just my experience, others may vary;
I've removed and replaced more than 30 filters so far this year. Both Champion and Tempest. None have come loose during service, and the torque required for removal is always greater than the 16 lbs-ft I use for installation.
You might look at a different technique for safety wiring, also. The wire should limit loosening to no more than 1/8 turn, and loosening a properly installed filter to the point of seal yield should be much more than that.
Maybe there is something to the seal shrinkage hypothesis, but I haven't seen it.
Best of luck figuring this out.
 
oil filter seal leaking

changed tempest oil filter, flew to petit jean and back ,did my condition inspection,no leaks,no lube on filter gasket per instructions.
 
Tempest oil filter losing seal

Just installed two Tempest 108s (RV7A, IO360) --- two-hand tight plus 1/2 turn with wrench --- after approx two hours of flight, both filters loose and leaking, a lot!. Safety wire still tight! NEVER had this issue before in 70yrs of flying/maintaining airplanes.

I have been using Tempest over several years on RVs and certified aircraft. I did have one that was leaking at the crimp, but long time ago.

Do you think the gasket is shrinking from heat, or other cause?
 
Defective Tempest Oil Filters

I work part time for a pipeline patrol company. We use hundreds of Tempest filters on our Lycomings and this is rare, but we've had a few that were assembled wrong. When you spin them on you can see a marked runout (wobble) on the flange. We never even got to the "leak check" stage so I don't know if they leaked. Warranty recovery was no problem. I should've filed an SDR but didn't.
 
Calling Tempest tomorrow - just checked gaskets against new

It appears that the gaskets on the two leaking filters have taken a "set" and have lost their elasticity? -- compared to a new one the gaskets have compressed about half and are not at all pliable.

I just checked one I put on a Cherokee about 6 hrs ago and it is fine, but, it came from two year-old stock.

Will let you know if Tempest has any comments.

Ron
 
Tempest is interested in seeing the filters

So, they will be shipped to them for their review --- meanwhile, we will continue to monitor our oil filter installations.

Ron
 
I’m sure it’s sacrilege but I was taught by an old auto mechanic the following procedure many years ago:

Lightly oil gasket with old or new oil
Hand tighten oil filter until snug
Turn with wrench another quarter turn

Never ever had any leaks on airplanes boats or cars with this method. To include a very high HP V8.

This sounds like it may be some issue with the gasket on that particular filter. Especially since you torqued it and used safety wire. I’m sure you made sure the safety wire is snug and won’t jump a “lug” on the back of the filter by the nut?
 
I have read about this exact same issue with Tempest oil filters on another well know forum for certified aircraft. I can assure you they are not leaking because of poor installation methods.
 
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