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MG MGB Technical - Spin On Oil Filter Bracket Adapter Leak

I have a slight oil leak coming from the spin on oil filter adaptor bracket on my 18v engine. It appears to be coming from where the adaptor meets the block and I have had this sort of leak before and cured it by just slightly nipping up the adaptor mounting bolt.

I've had a look for torque values for the bolt, but can only find one for a "Oil filter center bolt" of 15 lbft. I suspect that this value is for the earlier type of filter. Does anybody have a torque setting for the later type adaptor bolt? I'm reluctant to overtighten the bolt and ruin the block sealing ring.
If the ring does need replacing - any tips on how to do it?

Thanks

Andy
Andy Robinson

Andy,
it might, or might not, be the particular oil fitter you are using as a lot of the cross-referencing tables for oil filters contain errors that are compounded and repeated with mergers of data bases.

What adapter to exactly which actual oil filter (wots on the tin, the label) are you using?

The oil filter itself will have something like hand tight plus a half/quarter/threequarters/wotever turn.
Nigel Atkins

Andy if I understand your leak is coming from between the adaptor and the block, not the adaptor and the filter?

I assume you replaced the seal in the block when fitting the adaptor?

If not you must fit a new seal. Stick a sharp pointed 'thing' into the rubber and prise it out.

I dont think there is a torque value for the big bolt. You just tighten it up! Mechanic tight!!

Colin
Colin Parkinson

Apologises I totally misread (not for the first or last time) ignore me.
Nigel Atkins

Thanks Colin, l have never fitted a new seal in the 10 years that l have owned the car. It's a 18V engine and has the spin on filter adaptor as standard.

If the seal needs to be changed then l won't be surprised as it's probably been in there for 45 years.

Andy


Andy Robinson

Andy, check John Twist videos. He has one on stopping oil leaks on MGB . Specifically mentions
oil filter adaptor o ring. He may mention torque.
A bit of useless info. This bolt is the only one on a MGB.
Craig M Harvey

Andy shame on you!!!

Oil seal is changed every time you do a filter change!!
Colin Parkinson

Not on an 18V Colin, it's just a spin on filter replacement ,the housing doesn't need touching normally to change the filter
Andy ,when you do replace the O ring in there, it's not a bad idea to replace the washer/seal on the bolt while you're going, it's the same size as the drain plug washer and the plastic/nylon drain plug washers seal up really well there, where the copper washers can weep a bit
The original O ring is a square section ring so just be aware if someone is trying to sell you a round section ring that it will be wrong
It's easy to do just remove the centre bolt and the housing will move enough for you to get a scriber or seal pic up in there to flick the old ring out , feed the new one in and bolt it back together-
I haven't seen a spec for the bolt torque but the old cartridge filter that bolted up to that hole using the same O ring was 15ft/lb so that should be close
Other thing is are you sure that's where it's leaking, it could be the bolt or the filter or the oil pipe banjo or the o ring --a good wash and check where the weep is starting from

willy
William Revit

Seal part no 8G619.
We have seen the odd car with a leak there caused by fitting a new seal ..... because the fitter thought the old one was out due to it being so hard! Not enough groove to stack two, so a leak was inevitable.
Paul Walbran

Thanks Willy and All for your advice. The weep has only become evident after a good run on Saturday. The oil and filter were changed a month ago, so I will also have a good look at the seal between the spin on filter and the adaptor. There is lots of info about this on Paul Hunts website (thanks Paul!).

http://www.mgb-stuff.org.uk/enginetext.htm#filter

When I replaced the filter there was a slight movement of the adaptor when I undid the filter, so I'm suspecting that is most likely where the weep is coming from. Interesting point about using a sump drain plug washer for the mounting bolt Willy. I'll have a look at that and may give it a try as I've have a good stock of them.

I've ordered a new O ring, and washer and fan belt as it's got to be easier to remove the alternator to replace the O ring. I assume it's best to completely drain the engine oil?

Andy
Andy Robinson

no need to drain the engine oil but probably best to take the filter off to stop the oil from it siphoning out all over where you're working-
William Revit

I had to replace the adapter as it warped and the filter didn't seal. I didn't fancy starting to dig out the old block seal which had probably been there for getting on for 50 years as once you start you have to finish. I was lucky, the new adapter sealed.

Have you tried slackening the adapter bolt just a little to make sure it's not siezed or very stiff? If that is tight but the adapter moves then it could be, or the bolt may have bottomed. First off I'd try taking the adapter off and making sure it isn't cracked and check the bolt. If those are good then you probably will have to replace the seal.

Quite a big bolt as I recall - 5/16", 3/8" thread? Standard torque for those sizes is 18 and 30 ft lb respectively. I suspect the lower value for the earlier type is more about not damaging the container. You are unlikely to damage the seal as it is (or should be) in a channel so will squash out to fill that.
paulh4

Willy there is a seal on 18V as well! 8G619.

It is fitted on all the engines.

That is where I am sure Andy has the problem. But they do get forgotten and get very hard and very difficult to remove. Particularly standing on your head with the engine in the car!

Colin
Colin Parkinson

As Colin says, these are not easy to fit , especially lying down under the car reaching up. It helps if you have the car sitting squarely on 4 axle stands rather than just raising the front.
You can then also see if the adaptor is sitting in the middle of the large rubber block seal ( i note you will be using a new copper sealing washer).
Cheers,
Charles
Charles9

Colin, yes that(8G619) is the correct square section ring, but you don't need to replace it every time you change the filter as it doesn't get disturbed---Normally they last for several years and only leak when they get rock hard-
They're not hard to replace, just pick it out and poke the new one in, I just use a good light and a mirror and do it from above, the housing will move sideways enough to get at it without pulling half the car apart
Paul, yep it is a larger bolt with a big head,but that's where you can get caught over tensioning it, it only needs to be about as tight as you can get it with about a 6" long spanner by hand--

willy
William Revit

The leak is fixed. When I got the bolt and adaptor out it was no surprise that it was weeping. The bolt only had a fibre washer to make the seal with the adaptor and that had pretty much disintegrated - see picture. There was also lots of red hermatite smeared around where the adaptor fits with the block.

The old O ring was easy enough to get out with a pic, but it was a bit of a challenge getting the new one to stay in. A smear of grease on the outside of the O ring fixed that. I've fitted a new bolt, copper washer and O ring and tightened it up to 15ftlb and all is fine.

Thanks Willy for your advice about using a mirror when replacing the O ring, which is really essential to see what you are doing and saves you having to crawl under the car.

Andy


Andy Robinson

Nice one Andy, It's a good feeling when you set out to fix something and it works out-
That fibre washer looks a bit sad-
Congrats on your effort
willy
William Revit

Well done Andy. Just for info I like to use bonded seals as per the pic, instead of a copper or fibre washer.

Colin

Colin Parkinson

This thread was discussed between 30/05/2021 and 05/06/2021

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