Sump gaskets (no, seriously, GASKETS this time)

[Fingolfin]

Evening (or I guess morning) all,

I'm trying to rectify some major oil leaks from Mog's sump (because last time I didn't do it right). I've cleaned it thoroughly, removed all traces of the last gaskets and cork seals, carefully inserted new cork seals coated in a thin smear of grease, cut the cork seals to between 1/8" and 3/16" proud either side, and applied grease to the top faces of the sump for the card gaskets. But -- always a but -- the new gaskets overlap the cork seals where they stand proud.
[frame][/frame]
I know I can't cut the cork seals flush. Should I trim the card gaskets so they don't overlap? Should I leave the gaskets to overlap the cork seals?

(You may be pleased to know that I have already addressed the oil pump leak, which was the bigger problem.)

[MarkyB]

Leave the gaskets to overlap the cork seals.
Is the other side sticking out by the same amount? They both need to be equal.
Hard to tell from the picture but the cut looks quite rough, a stanley knife or other sharp blade would make a better job.

[bmcecosse]

And the protrusion looks too much - perhaps it has sprung up. Oil pump leak???? Was it loose ? There is a drain hole just below the pump - if there is excessive crankcase pressure, then of course fume and oil will be forced out of that hole . and can then run down the backplate. Are you sure this isn't the cause of your many leaks?? Sump gaskets are easy to seal - they are rarely the cause of leaks - unless the screw hole threads are stripped - and the screws can't be tightened??

[alexmcguffie]

Best to use Wellseal to seal gaskets, fantastic stuff probably easier to find it on eBay these days. I've never had a leak using it on an A series or leak prone Lotus twin cam. Don't use it on head gaskets tho.

[bmcecosse]

There is absolutely NO need to use bodger seal on any A series gaskets. BMC never used it - why should we now? Clean surfaces and correctly torqued screws are all that is necessary.

[Fingolfin]

Yes, I'm quite certain a large portion of the leakage was from the oil pump; the backplate gasket was soaked and some oil had forced its way around the backplate bolts. This was in part due to poor oil pump gasketing on my part and in part due to crankcase pressure, which has since been somewhat alleviated by my shiny PCV setup.

However, I am also quite sure I had sump seal leakage (the cork seals, not the gaskets), because there has been plentiful evidence of leakage down both front and rear of the sump. Also, a former owner had lost many of the sump bolt flat and spring washers, which surely didn't help; this time I ordered a replacement bolt and washer kit.

I have been very careful about cutting the cork. The proudness is fairly even all around, and the cuts are clean, since I did in fact use a razor knife to begin with. Having remeasured and trimmed a tiny bit, I can say all the cork protrudes by precisely 3/16"; possibly this looks like a lot because of the camera zoom. Should I trim them closer to 1/8"?

I shall leave the gaskets to overlap, and report back with results in a few days. Fingers crossed. Further input is always welcome, of course...

[alexmcguffie]

Hi Fingolfin,

Have you checked that any of the bolt holes haven't 'pulled', creating a local high point on any of the mating surfaces? This can easily be fixed.

Also, Wellseal isn't used by bodgers. It was developed by Rolls Royce and used by then, Bentley, Triumph etc until the development of more modern silicone based gasket sealers. It is a world renowned proven product.

[Fingolfin]

All the bolt holes on the sump seem to be quite flat and smooth, but I will double-check with a straightedge. I haven't had a close look at the block surface, except to scrape off the remnants of the old gaskets, but surely the block shouldn't have high points.

In any event, folks, Wellseal isn't a product sold in the States! I can order it from the British eBay, but if I'm going to use an aftermarket sealant, I'll just go get some high-temperature Permatex (that is, Formagasket), which is readily available.

[alexmcguffie]

Hi Fingolfin,

Pulled threads would cause more of a problem with your oil pump than the sump as it uses a thinner paper gasket.

I believe Permatex is a modern aviation based equivalent to Wellseal, non-hardening etc.

Alex

[philthehill]

I am with bmc on this one. There is no need to use a proprietary sealant on the sump cork seals or gaskets if fitted properly.
If you cover the cork seals in grease, fit and centralise them in the sump cork seal carriers/groove letting them protrude (1/8" -3.2mm) above the end of the carrier/groove each side, Trim if necessary. Grease the sump gaskets and fit to the block flanges (the grease will hold the gaskets in place), offer up the sump and fit the bolts and washers, tighten up progressively diagonally around the sump until tight and you will have no problems. Attached is the extract (Section AA.34) from the BMC Minor wksp manual[frame][/frame]

[bmcecosse]

Seriously guys - NO sealant - it IS for bodgers.... Yes - later sealants have been developed INSTEAD of gaskets (and are applied by robots). No need for both......

[Matt Tomkins]

Seriously guys - NO sealant - it IS for bodgers.... Yes - later sealants have been developed INSTEAD of gaskets (and are applied by robots). No need for both......

riiiigggghhht, so that's why some of the top race engine builders in the country who i have visited with a b series engine for the motorsport club car, all use paper gaskets with a tiny smear of flange sealant.

[bmcecosse]

If the mating faces are good - no need for bodger seal.....

[philthehill]

Matt
The sump gasket arrangement is totally different to the Minor. The front and rear main bearing caps are recessed into the block and so present a annular flat surface for fitting the one piece sump gasket. There are seals (Pt No: 12H1638 or 12H1476 engine 18v on) fitted to the front and back main bearing caps and seal against the front and back engine plates.
Over the years I have rebuilt/reconditioned quite a few 'B' engines and I never had to resort to using a proprietary additional sealing medium.
I have just had the head and sump off my Suzuki wagon 'R' and yes in certain areas I had to use a propriety sealant as that was used as OE and so no gaskets were manufactured.
But there again on a similar subject when I worked for REME (many years ago) all copper asbestos cylinder head gaskets had to be smeared with Blue Hylomar before fitting because that was what the REME engineering regulations (EMER's) required but I never considered it necessary to use it myself on any of my vehicles and I doubt there would be many advocating its use for that purpose on this forum. So yes there are arguments fore and against using additional propriety sealants so if the MGB tuners want to use a propriety sealer good for them. The use of a propriety sealer is a personal choice but I would not use it out of choice.

[Fingolfin]

Goodness...can of worms... Phil, I'd already looked at that page. My question was about the overlap, which the BMC manual doesn't address. But it seems that it'll be all right. I'll trim a bit more off the cork seals to be safe, since the manual indicates 1/8", and then go ahead and bolt up -- if I still have leaks, next time I'll try sealant!

[Boomlander]

A 1/8" protrusion of the cork seals will allow the seal to be compressed under the side gaskets without distortion.
Any longer and you risk the sump not seating correctly and leaking.

[philthehill]

Fingolfin
Although not directly stated the Minor wksp manual does address the relationship between the two cork seals and the two sump side gaskets. If you read the wksp manual page above it says fit the two side gaskets first and then offer up the sump. It says nothing about trimming the side gaskets only trimming the corks seals to suit so the corks WILL press against the end of the side gasket. It is all about how you read it and your mechanical experience. You have to remember that the Minor wksp manual was written in the main for mechanics who had served an apprenticeship and understood things without having to be told directly.
Anyway good luck with an oil leak free fitting and wishing you a Very Happy New Year.
Phil

[bmcecosse]

The important thing is to have good screws - with the elongated flat washers - correctly torqued up. If there is any doubt about that - drill and retap the block to next size up. This is done as a matter of course on Minis - but that is mainly to make sure the gearbox is securely gripped to the block - rather than to prevent oil leaks.

[alexmcguffie]

Thinking back a good few years I seem to remember a rubberized alternative to the cork gasket was available, not sure if they still are. This was designed to avoid any cutting, trimming and uncertainty.

Rather than tapping the sump bolt holes to a larger size you'd be better off having a machine shop fit helicoils. It would look much better to the purist

[Declan_Burns]

Fin,
And if all that does not work-try the rubber seals. I use them and many others and I have never had a leak since.
Regards
Declan