Oil filter housing o-ring
 

I changed the oil in the XJ a couple weeks ago. When I removed the old oil filter, I noticed a thin, large diamter o-ring in a groove on the housing. I chucked it out, thinking it had stuck on there and had belonged to the old oil filter.

Here's the thing. I'm not sure it did. I think it might be meant to be there as an additional seal

Now there's an oil leak between the oil filter and adaptor housing (this is not the oil leak between the adaptor and block - I put a new Mopar o-ring kit in at the same time). I've tried tightening the oil filter (Ryco Z89A). That's not it.

Does anyone know where you could get a new o-ring locally? I don't think it'll be something Supercheap carries. I've been changing oil in my cars for more than 30 years. A bloody rookie error :wall:

EDIT: Now I'm not so sure that what I did was wrong. If you look at a pic of the oil filter housing, there'a groove for the seal on the engine side of the adaptor, not the oil filter side. Could it be a dodgy Ryco oil filter? I have not ever had an oil filter leak before.

Bummer...Wreckers ...?
Otherwise no Idea!
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Screw your new filter off & look at the mounting face on the adaptor, it should be a nice flat machined surface. Clean the surface with brake cleaner or similar, run some fine emery paper around it lightly & clean it again. Look at o-ring on filter, is it distorted out of shape? if it is get the o-ring out of the old filter, smear a little oil on it & put it in your new filter. Before you screw it back on, look at thread in filter & adaptor to be sure it wasn't cross threaded. If all looks good screw it on till it touches then about another quarter turn, too tight can distort the o-ring then start up & look for leak. If you still have a leak you'll have to try another filter. I've only had one refuse to seal (ryco z9) & took it back to repco, they replaced it without question. Repco seem pretty good like that, I got tailgate gas struts for wifes focus from them, gas pressure was so high she couldn't close the tailgate. Went to repco in the car & asked counter bloke to come out & have a look, he came out with a new set & fitted them without even checking the one's I'd just fitted.

Thanks mate, really appreciate it. It's such a basic job, one that I have never had a problem with. Maybe I've become too blase about it. I tried tightening the oil filter a little more on the w/end, but it was already tight enough. It still leaks. I'll back it off a bit and see how that goes, but I think really I need to take the filter off to see what's going on. I'm sure it isn't cross-threaded.

Like you said maybe the mounting surface was not entirely smooth or the Ryco filter gasket was faulty. I've thrown out the old filter so I can't use that gasket.

I thought you were talking about a O ring in the oil filter adapter? not a crappy filter you can get a O ring kit off rockauto for about $5 plus shipping prob about $20 all up
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I did replace the 3 filter adaptor o-rings while I was there as the adaptor-to-block join was leaking. But this is something else, the adaptor-to-oil filter join that's leaking. I took off the filter today and checked everything. It all looks normal to me. Cleaned it all up anyway, fresh smear of oil and tightned the filter back to just less than 3/4 turn from gasket meeting the adaptor body. I think it's still leaking, well, weeping at least. I'll check again tomorrow but the only thing left i to replace the filter...
It's a strange one. Maybe I have just been lucky but I have replaced an oil filter a year, roughly on average, since about 1981 and have never struck this before.

you said " I changed the oil in the XJ a couple weeks ago. When I removed the old oil filter, I noticed a thin, large diamter o-ring in a groove on the housing. I chucked it out, thinking it had stuck on there and had belonged to the old oil filter. " the O ring kit consists of some small ones and a big one that fits in the groove on the oil filter mateing surface was it in place when you took the filter off?

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l_---l_l__l---[ ]llllll[ ]
_.(o)_)__(o)_)--o-)_)