Leaking Sump Seals

[Longdog]

Are you ensuring that the transition between the seals and gasket are seating properly? I found it necessary to trim the gaskets slightly to ensure the seal made contact with the block in the journal area, thus not making a step where the seal compresses up to the block. If there is an overlap this could cause a problem.

[bmcecosse]

If the sump flanges are dented - that won't be helping. The screws should have thick oval washers to spread the load - these bend with time and I usually turn them over. There should also be anti-shake washers on each screw. If all else fails - you can use liberal quantities of black silicon sealer - but try to keep it as neat as possible! I doubt Hylomar will do much - it's just a thin gasket sealer - it can't hope to cover up and significant gaps..........

[daveyl]

... but then it appeared that it may be due to crankcase pressure. So I sorted out the crankcase pressure issue by fitting a rocker top with a breather pipe outlet and connected that to the carb. The seals still leaked....

I presume you are running a 1300 engine as they usually only have a breather outlet attached to the timing chain cover. I thought only the 'small' bore engines (803, 948,1098) had a rocker cover breather pipe + the one out of the tappet chest..
If so, is it recommended to fit an extra 'breather' on a 1300? I'll try it myself if that is the case.

[swithland]

Mine is a 1098 standard set up with the breather through the rocker cover top to the air filter housing. I may buy a recon carb with the suction for the breather pipe on the side and see if that improves things as tthat would certainly increase the amount of suction from the crankcase. When i remove the plastic rocker cap, there is no smoke or anything from it. Im wondering now if I change to a metal cap if that would improve things ? Those plastic ones dont seem to seal at all....not only that but the cap rattles too !!

[bmcecosse]

If there is no smoke from the oil filler when you rev up, the engine is in good order and pressure is not the problem. The plastic cap should be fine - but it may need a rocker cover that was 'designed' for it in order to be secure? 1275 engines ALWAYS need additional breathing - you can't have too much. I have no idea why they discontinued the rocker-with-breather, it's the best thing you can add!

[DaisyMayFozz]

Just replaced mine today, and well ITS STILL LEAKING ! there was good seals and I used blue hylomar on it, which i have had no problems with before. Standard 1098 and its leaking at the back. (sorry to hijack the thread swithland)

[alainmoran]

I've always used the cork seals, but I soak them before I put them in ... could that be the difference?

That said ... my attitude towards oil-leaks is that it's a healthy throughput of oil & I paint the underside of the car regularly with old engine oil so any leaks are just saving me part of the job

[chrisryder]

soak them in what?

i'm planning on changing my sump gasket soon! it's definately the sump, and it's well ventilated, i think i trimmed the cork too much last time

speaking of which, should you trim the cork at all? if not, how much do you take off?

[alainmoran]

diesel works best, but engine oil will work too.

[Declan_Burns]

I am convinced the rubber seals are better-if fitted as I've described so many times. This is the first time I've heard that it hasn't worked. Something wrong somewhere!
Regards
Declan

[swithland]

Thanks for everyones comments. I took the sump off again last Friday and inspected. There was defintely a leak from the back sump oil seal and a small one from the front.

There was also a tiny blob of oil hanging from the bottom of the timing chain cover, so I nipped up those bolts. If the timing chain cover still has a tiny drip, then I will have the radiator out and reaseal the cover. Even though the engine has only done 1100 miles since full reconditioning, the timing chain can be heard, so I will stick a duplex chain in if I do have to fix the drip from the cover.

I soaked some new cork seals in oil and fitted them with a 3mm overhang on both ends according to the Moggie book. Then I used new sump gaskets and sealed the whole lot up with blue hylomar. Seamed like a really good seal.

Then I put new oil in, changed the oil filter and whilst feeling energetic, changed the gearbox oil too. I went for a brisk spin and guess what......it still leaks ...... arghhhhh !! I am now of the view this will never be fixed and will have to live with it. Very annoying when the rest of the car is almost perfect.

I have kept the rubber seals just in case for the future, but it is obvious to me that Rubber or Cork.....they are just the same when it comes down to it.

Whilst under the car, ive spotted a tiny drip of what appears to be brake fluid from the hole in the chassis leg under the master cylinder although there appears to be no drop in the remote fluid reservoir. I didnt bother to check if it was brake fluid as it was getting a bit late at night. Will investigate further in the week......

[swithland]

Just replaced mine today, and well ITS STILL LEAKING ! there was good seals and I used blue hylomar on it, which i have had no problems with before. Standard 1098 and its leaking at the back. (sorry to hijack the thread swithland)

I think we both have to live with it

[Declan_Burns]

Thanks for everyones comments. I took the sump off again last Friday and inspected. There was defintely a leak from the back sump oil seal and a small one from the front.

There was also a tiny blob of oil hanging from the bottom of the timing chain cover, so I nipped up those bolts. If the timing chain cover still has a tiny drip, then I will have the radiator out and reaseal the cover. Even though the engine has only done 1100 miles since full reconditioning, the timing chain can be heard, so I will stick a duplex chain in if I do have to fix the drip from the cover.

I soaked some new cork seals in oil and fitted them with a 3mm overhang on both ends according to the Moggie book. Then I used new sump gaskets and sealed the whole lot up with blue hylomar. Seamed like a really good seal.

Then I put new oil in, changed the oil filter and whilst feeling energetic, changed the gearbox oil too. I went for a brisk spin and guess what......it still leaks ...... arghhhhh !! I am now of the view this will never be fixed and will have to live with it. Very annoying when the rest of the car is almost perfect.

I have kept the rubber seals just in case for the future, but it is obvious to me that Rubber or Cork.....they are just the same when it comes down to it.

Whilst under the car, ive spotted a tiny drip of what appears to be brake fluid from the hole in the chassis leg under the master cylinder although there appears to be no drop in the remote fluid reservoir. I didnt bother to check if it was brake fluid as it was getting a bit late at night. Will investigate further in the week......

Try it again with the rubber and use the high temperature silicone allowing it to cure before tightening the bolts-then run a seam on the outside and allow to cure. Then start the engine.
Regards
Declan

[swithland]

OK, will give it a wizz this weekend, and let you know the result. Will need to leave it 24 hrs before tightening up i suppose ??

[David53]

I think they all leak, it's just a fact of life. Put it down to a design flaw with the sump mountings. I have tried three times with three new gaskets and cork seal sets and still have a drip or two which is definitely coming from the back seal of the sump. Have a drip tray on your driveway and carry an old baking tray in the boot for when you're out! All part of the charm of an old car!

[swithland]

I think they all leak, it's just a fact of life. Put it down to a design flaw with the sump mountings. I have tried three times with three new gaskets and cork seal sets and still have a drip or two which is definitely coming from the back seal of the sump. Have a drip tray on your driveway and carry an old baking tray in the boot for when you're out! All part of the charm of an old car!

I suppose it also comes down to how the car is driven. Over here in Hong Kong, there are some steep hills and the engine revs quite highly in 2nd gear going up many of them. Thats got to slosh a load of oil around the bottom end of the engine....and if there are any weaknesses, the oil will find a way out !! Ive lost the enthusiasm to redo the seal again having done it about 6 times thus far without success. Im going to live with the drips, a lump of cardboard and of course, her indoors !!