2.5DT oil filter leak

The filters that I have been using, all from different manufacturers, only have 1 large O ring and 2 very small O rings in the kits. The 2 small rings go on the bottom part of the plastic cap and the large O ring goes to the top to make the seal. There is another O ring near the top of the cap which goes between the threaded part but that ring doesn't come with the new kit. I did source one of those locally and fitted it. I just think that the O rings that come with the kits aren't thick enough to make a proper seal. Thanks for the advice.

defender300td1 said:

What kit wammers? I've the plastic type mine ever only comes with three o rings two for the spike and a large one for cap ?? What's the differance between the metal type and plastic I've always thought the differance is in length they have differant part numbers I seen a diagram somewhere showing one to be longer ??

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Can't remember to be honest. You are possibly correct. They do have different numbers, but seem to recall when i got my last kit (later) one, it had two large O rings one thinner than the other. Have a new kit in garage will have a look later when the bloody snow stops. Plastic top is STC3351.

wammers said:

Can't remember to be honest. You are possibly correct. They do have different numbers, but seem to recall when i got my last kit (later) one, it had two large O rings one thinner than the other. Have a new kit in garage will have a look later when the bloody snow stops.

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Thank you


Cosy try a rubber band on first before the o ring as a temp repair

Ok to Clarify

Early type L 150mm W 90 mm larger top o ring metal ends on filter

Late type L 160mm W 84 smaller top o ring fibre ends so basically you can not get it wrong

Thanks for all the info guys, but I reckon now that maybe if I can source a rubber seal that is a snug fit round the plastic cap and is flat in section like a washer and about 5mm thick that should make an oil tight seal and it shouldn't distort when tightened up, unlike the crap O rings do. What do you think?

I know this thread is a little old but i think i've just worked out the problem (because i've been having the same problem and its been driving me around the bend). There's a little seat about 1 thread from the top and when you seat the 'o' ring in that it seems to go inside the housing rather than sit between the 2 surfaces. Was a little cautious at first because it didnt seem right but i've been checking for a few days and all appears dry. Can anyone confirm if this is right

Yes the O ring should site in a groove if thats what you mean.

ragsyrandell said:

I know this thread is a little old but i think i've just worked out the problem (because i've been having the same problem and its been driving me around the bend). There's a little seat about 1 thread from the top and when you seat the 'o' ring in that it seems to go inside the housing rather than sit between the 2 surfaces. Was a little cautious at first because it didnt seem right but i've been checking for a few days and all appears dry. Can anyone confirm if this is right

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That is what it is supposed to do. Fit in the O'ring recess and fit inside the housing. If you have been putting it under the top lip no wonder it's been leaking.

cammo45 said:

Good idea Cossie David, I did try some ptf plumbers tape round the threads at the top of the casing but oil eventually leaked past it but strong thread looks like a good solution.

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Plumbing PTFE tape isnt man enough for the job, try Gas PTFE tape (yellow case) its 10x thicker. Dont wind it round the thread loads, just 1 1/2 turns is enough.

Baiman said:

Plumbing PTFE tape isnt man enough for the job, try Gas PTFE tape (yellow case) its 10x thicker. Dont wind it round the thread loads, just 1 1/2 turns is enough.

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Bit late to the party @Baiman but no need for ptfe tape, the problem is down to the thickness of the large O ring just a few thou thinner ring on some filter kits is the difference between leak and no leak, been there done that.

kds said:

Bit late to the party @Baiman but no need for ptfe tape, the problem is down to the thickness of the large O ring just a few thou thinner ring on some filter kits is the difference between leak and no leak, been there done that.

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+1. Always keep the old O ring if it seals as you can then re-use it if the new one leaks.

cammo45 said:

Thanks fellas, I hadn't thought about the plastic caps going out of shape, though I'll try a bit more plumbers tape round the threads in the meantime and if oil still keeps leaking out, I'll probably go and part with more cash and get a new one ££££. Once again thanks for the info.

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I take it you only live in Yorkshire and were not born there, the way your threatening to spend money gives it away.

kds said:

Bit late to the party @Baiman but no need for ptfe tape, the problem is down to the thickness of the large O ring just a few thou thinner ring on some filter kits is the difference between leak and no leak, been there done that.

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That's two of us late to the party, must learn to check the post date.

Contributions to threads that died a while ago are still potentially usefull to those who come after, as too are further hints and observations etc. I only fell accross this 10 year old thread because it is still relevant to diagnosing my oil leak today. I really dont see an issue with commenting on an otherwise dead thread, especially if its potentially of practical use to someone else at somepoint.