Cutting open oil filters

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Post by gasax » Sun Nov 01, 2009 6:55 pm

Nice one Brian - you hooked me!

Given a C90 I tend to agree with you - there is little in the engine which is likely to make metal - unless there is a component failing. That is really where filter opening is concerned. But with a C90 there is not much likely to do that.

As you note a Rotax is more highly stressed and so opening the filter is a sensible precaution.

Having said that if I ran a Lycoming I would do the same - the camshaft issues make having a filter and opening pretty much compulsory......
Pete Morris

Simon Clifton
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Post by Simon Clifton » Wed Nov 04, 2009 10:03 am

Just to finish this off, I have decided to invest in a custom filter cutter.

It is from a motor factor, so the fact that it is 'billet' made is apparantly a very good thing.

Simon C

Rob Swain
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Post by Rob Swain » Thu Nov 05, 2009 4:21 pm

gasax wrote:Given a C90 I tend to agree with you - there is little in the engine which is likely to make metal - unless there is a component failing.
I thought small Continentals were noted for shedding lumps of starter gears. Come to that, I've seen a couple of really 'orrible generator gears too (admittedly in 'rogues galleries').

Or are we talking -8 (non electric) engines here?

I'd not thought of going to a motor factors for a can opener. Thanks for that, I'll take a look.
Rob Swain
If the good Lord had intended man to fly, He would have given him more money.

Bill McCarthy
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Post by Bill McCarthy » Thu Nov 05, 2009 7:06 pm

Simon, don't forget to follow up with your findings, and by the way, if you are just going to have a look see for "bits" you could also invest in a 30 X magnification pocket microscope from a RS outlet.
For your inspection you could dilute a small sample of sediment in surgical alcohol and catch the solids in a filter paper. That way you will see a combination of perhaps carbon, joint material and hopefully not too much metalic particles.

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Post by flyer.jones » Thu Nov 26, 2009 9:17 pm

Hi all,

an effective oil filter cutter for the smaller filters used on Rotax Jabiru and the UL260i engine is the Draper 40100 exhaust pipe cutter tool with a slight modification.

If the pivot holes for the arms are moved further out by drilling two new holes then this tool cuts the oil filter in a few turns easily and can be bought on the internet for about £16.00.

This is what we intend to use on our shared UL260i in our escapade.


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Post by mikehallam » Sat Dec 05, 2009 12:20 am

I've studied the picture of the Draper exhaust cutter on the web but can't see either how it opens to admit the pipe or how one applies pressure to the cutting rollers ?
Thus where & in which two (?) arms one drills new pivot holes for adapting to the Rotax 912 oil filter dia. is equally obscure.
Could you elucidate pls. as it would be neat to have one at the strip -we have three 912 planes.

A difficult qu. I realise as the LAA site has no direct provision for J-pegs.


Dave Moore
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Post by Dave Moore » Sat Dec 05, 2009 11:55 am


Here's what I did:

Remove the flat, rectangular pivot plate from the arms.

Tap out the roll pin to remove the handle from the pivot plate.

Cut a new notch for the handle and drill a new hole for the roll pin on the opposite edge of the pivot plate - dimensions as the originals.

Drill two new pivot bolt holes for the arms closer to the outer edges of the pivot plate than the original holes, at the same distance up from the new notched edge of the plate. i.e. simply turning the plate around, with new holes which are further apart.

The holes I drilled were 6 mm diameter, centered 7 mm in from the outer edge of the plate.

Replace the handle & roll pin into the new notch & hole. Reassemble with the arms bolted via the new holes.

Hey Presto, it worked.....! It'll also still work in its original configuration, with a bit of minor reassembly.

Thank you for the idea, "Flyer.Jones"

Ian Melville
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Post by Ian Melville » Sat Dec 05, 2009 7:19 pm

Sounds like a project worthy of a page or two in Light Aviation

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Post by JohnStrong » Thu Dec 24, 2009 9:05 pm

For anyone following this thread, the February issue of Kitplanes magazine has an article on Oil filter cutters if anybody is particularly interested in the performance of commercial cutters (requires either subscription or article purchase).

The article refers to this link which looks at oil filter contents and analysis methods:

Merry Christmas to all

John Strong

Matt Dovey
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Post by Matt Dovey » Sun Jan 10, 2010 12:12 pm

Just thought I would add my own thoughts on opening filters.Having worked for a large flying school and a couple of light aircraft maintenance companys,myself and my work mates would open filters for inspection on every oil change on customer and school aircraft.We would find that most would turn up nothing except carbon.But some times you would find metal.The worst case I can remember was a customer 152 on a 50hr check.Engine running fine,changed the oil cut open the filter found it full of rather large peaces of metal.Ended up pulling all four cyclinders and finding all of the piston skirts braking up.This was with no reported engine problems and with the filter having been "inspected" 50 hrs before.
Also opening the filter will give you an idea of what happening inside your engine,or whats about to happen.You may have changed the oil over the entire life of your engine and found nothing.Its the one time you do do it and find something that stops you from flying with a defective engine and saves yours or somebodys life.In my view its not worth the chance.A filter cutter doesnt cost alot.Cutting open a filter doesnt take long.
The link that JohnStrong provided above is very helpful.The piston pin (Gugeon pin)
plugs is another problem we would find often.

Matthew Dovey

Rob Swain
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Post by Rob Swain » Wed May 26, 2010 2:43 pm

I'll resurrect this thread with what has turned out to be a non-event.

Started the old Lycosaur in the RV the other day. Seemed sluggish to start but it was a warm day so put it down to that.
Taxied out, warming the old girl as I went. Did the mag checks. Coughs and splutters from both mags when run individually. Hmmmm! Well I had a missed approach last time out so ended up doing a couple of circuits fully rich and forgot to lean after landing so it must be lead fouling.
Lean it back, run it up, keeping an eye on the EGT. That should clear it. Let's try again. Same story!

Much cussing and swearing ensues.

Back to the hangar. Cowlings off. Plugs out. Check engine log - might as well change the oil as well as it's nearly due.
Round to maintenance and clean all the plugs on the pukka Champion plug cleaning and testing machine (Thanks, Pete). Check gaps. First 6 fine. Last 2 have ugly arc lumps in the centre electrode that prevent proper gapping. When tested sparks look really ill. One plug is from one mag, one from the other.

Hmmmm, again!

Peeeete? Got a pair of plugs I can buy? Yes? Thanks! How much? Ouch!

So why are my plugs expiring all of a sudden, after only 150 hours? Bits of ring getting in them? Or bits of piston? Shavings from loose gudgeon pin plugs?
Worry ensues! Expense looms! Thoughts of long 'character building' hours with the RV in the hangar begin.

Remember the oil change happening at the same time? Retrieve the filter, back to Uncle Pete and open the critter up. Nothing! Oil, carbon, a couple of tiny shiny bits which I'm assured by Pete (licensed engineer and my inspector) are nowt to worry about.

Basically what I'm saying here is the filter can contain peace of mind as well as metal, doom and despondency, so I'll always be opening them in future. I'll try and find an opener of my own to avoid pestering Pete in future, though.

And yes, she runs fine now!
Rob Swain
If the good Lord had intended man to fly, He would have given him more money.

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