Main Agents Overtightening Oil Filters, Why?

[Baldchap]

Serviced my nephew's Fiesta Ecoboost over the weekend and chucked a new set of pads on it, and whilst everything was nice and simple, the oil filter had clearly been done up using a breaker bar or something.

I literally destroyed the filter getting it off. Absolute nightmare. All done and the new filter appropriately tight, but it left me wondering why the main agent (the last service was a local Ford dealer) would do a filter up so bloody tight. It's not the first time I've experienced this from previously dealer-serviced cars, either.

Anyway, rant over.

[acricha3]

I have had oil filters go particularly tight even though I've used a freshly calibrated torque wrench, lubed the seal etc to install the previous one!

Given how many times the rubber seal gets heat cycled and general exposed to elements you have to expect they will become more difficult to remove. It always feels to me that the seal gets stuck and you get that elastic feeling where you have to stretch the seal longitudinally before the filter start moving!

For the dealer its most likely a combination of lack of lubrication on the seal on install, time, weathering and a previous install by using the "good swing on the ratchet method" that's contributed.

[drmotorsport]

If they're spin on metal type, then yes they're frequently a pain to remove. I've done plenty of filter changes over the years and only hand tighten with some oil on the seal as per instructions, still a year later at service time i'm swearing at it.

[donkmeister]

The only time I changed a filter that had been installed at the factory, it was very tight.

The gasket is responsible, generally. Do it up by hand yet still need a cup or strap to remove it.

[andybracing]

you would soon be complaining if it came loose at 80 miles an hour

[GreenV8S]

I think it's because of the way the O ring distorts as the filter is spun on. When it shears that tends to reduce the height. The clamping pressure of the filter prevents it springing back to its normal height so it is stuck in shear and acts as a sort of ratchet. In order to unscrew it you have to force it back over that shear 'hump' but that takes much more torque that it took to apply it in the first place. It's similar to the way Nordloc washers work.

[SturdyHSV]

GreenV8S said:

I think it's because of the way the O ring distorts as the filter is spun on. When it shears that tends to reduce the height. The clamping pressure of the filter prevents it springing back to its normal height so it is stuck in shear and acts as a sort of ratchet. In order to unscrew it you have to force it back over that shear 'hump' but that takes much more torque that it took to apply it in the first place. It's similar to the way Nordloc washers work.

That's a shockingly sensible bit of reasoning. Are you on the right forum?

[GreenV8S]

SturdyHSV said:

Are you on the right forum?

Who the :bleep: do you think you are to question what forum I should be on?

[rewild]

Ah, normality is restored.

(I too think that's a cracking bit of logic.)