Sump gaskets (no, seriously, GASKETS this time)

[bmcecosse]

But there is no need! My cork seals don't leak - not a drop! I can't see a 'machine shop' lying under the car fitting tiny helicoils to a Minor block...easy to run a drill through followed by a 5/16 UNF tap. Use Allen cap screws to avoid any 'head size' limitations within the sump rim.

[alexmcguffie]

Tapping over size sounds like a bodge to me

[bmcecosse]

Not all - it's an improvement!

[alexmcguffie]

So bigger bolts is over kill but an improvement? Much like using gasket sealer to guarantee a leak free engine?

[bmcecosse]

No -you don't need any sealer - BMC didn't use it - and their engines didn't leak. The larger bolt is to replace a stripped out thread - and improves the grip. As earlier - done as a matter of course on powerful Mini engines - indeed -they often add extra screws - but that is to try to stop the gearbox ripping away from the block and in some way to brace the block too... Can't see a pressed steel minor sump doing much bracing...so not really suggesting it as a matter of course upgrade for a Minor.

[Matt Tomkins]

done as a matter of course on powerful Mini engines -

As per my previous comment about flange sealant being used as a belt and braces measure along with the paper gaskets by top race engine builders.

[Fingolfin]

Phil, I suppose that's fair -- mechanical experience is something I am lacking. This Minor is my first restoration, and though the resto is essentially complete (insofar as I now have a running car), I have made many tremendous mistakes that I've had to rectify. This whole charade is an example! But I'm learning, slowly, and that's what counts.

Viewed through the tiny aperture in the backplate, the cork seals do not appear to be spreading, but have not yet compressed sufficiently for the gasket to seal effectively -- there's maybe a millimeter to go. Perhaps another few days of sitting there will compress them enough. I rechecked the torque on the four corners bolts, and they're correct.

[bmcecosse]

You need to pull up ALL the screws- round and round - not just the corners. We are not using paper gaskets - Minor gaskets are relatively thick cardboard! Seriously - throw the sealant away - and take pride in doing the job properly......

[les]

Just to add my bit! Helicoils are used to replace bad threads if you want to retain the original size and form, if you want to go bigger, for whatever reason, and have the surrounding metal to allow it, it's better to tap a new larger thread direct. Regarding using 5/16 screws for the mini gearbox, I've always been dubious of this because there is a trade off between giving more strength and weakening the box flange by opening out the holes thus leaving less metal around the edge. Much the same as happens when opening out the holes in the Minor uprights when fitting discs. The sealant issue also got me thinking. There is no harm in doing the job properly Roy and still using a thin film sealant, admittedly buckets full looks terrible. I think I go ott when rebuilding stuff but I'm not above a little insurance! The point being it does no harm and it's a second line of defence against that elusive (possible) leak.

[Fingolfin]

Roy, I had tightened all the bolts to the correct torque -- it was just the corner ones I double-checked. And I am using no sealant, yet. Good thoughts, Les.

[bmcecosse]

[MikeNash]

Dear Fingolfin,
Yours is an old problem and you might like to see this.
http://www.mmoc.org.uk/search.php?keywo ... mit=Search

There're other old posts but I can't recover them - just as well I printed them off! Regards, MikeN.

[Fingolfin]

I'm doing it again! It didn't work. In fact the leak was worse.

Here's a simple question: which direction do the cork seals fit in? They're rectangular in profile; do they sit into the groove the "thin" way or the "thick" way?

(If I can't get it with the cork seals this time, I'll try the rubber ones. I'm doing the cork way again because I've got them spare.)

[Declan_Burns]

Fin,
In my opinion the rubber seals are much better. They need to be cut back slightly with a hacksaw and then filed as there is a metal re-inforcing wire ring moulded in. Use plenty of high temperature silicone and only fully tighten the sump after the silicone has cured. Then you can bin the cork seals!
Regards
Declan

[Fingolfin]

Thanks Declan, I'm keeping that in mind. But I very much want to see if I can meet the Cork Challenge, as it were. And since I've already got brand-new cork ones at hand, I may as well play with them! So -- thin or thick?

[philthehill]

Fingolfin
To determine whether it is thick or thin side up measure the gap between the cork seal retaining walls and that will indicate which way up it goes - on the 1275cc engine it is thin side up.
Going back to your original photograph there seems to be very little cork seal protruding above the cork seal retaining walls. It should protrude well above those retaining walls!!!!!!!
Thankfully I have never had any problems with either fitting sump gaskets/seals or oil leaks from the sump gaskets/seals so I must be doing something right and that is without using a propriety gasket seal.

[Fingolfin]

The trouble has been that the cork seals don't fit snugly when sat in the channels the "thin" way - though they're too wide the "thick" way. But I will try the "thin" way this time...this pair of seals seems to be thicker, such that they're almost snug the "thin" way.

[philthehill]

I have just checked the dimensions of two sump cork seals I have and they are different.
One is 5.1mm x 10.2mm x 154mm (untrimmed) and 7mm x 10mm x 147mm (trimmed).
The cork seal should be a snug fit in the seal carrier and protrude well above the walls of the carrier.
Just spotted on an old spare sump that I have that the rear wall of the cork seal carrier has partially come adrift (a couple of spot welds failed) from the sump proper. This would allow oil to weep down the back of the sump. I would advise that you check that yours is still intact.

[Fingolfin]

Thanks for that, Phil -- I'm quite sure now that I had been placing the cork seals in the wrong direction, and that they are supposed to sit the "thin" way. Earlier I must have been using those 5mm ones, and the new ones must be 7mm. I've detected no loss of structural integrity in any part of the sump, but that's a good thought, and if I still have leaks I'll give that a check.

Anyhow, the sump is back on now. I used some proprietary RTV sealant, a small smear around the sump flange and larger dabs where the gaskets meet the cork seals, and more smears on the cork seals themselves. Also, as mentioned, I put the seals in the "thin" way, different from before. Bolts all torqued down, and I'm letting the sealant cure overnight before retorquing and filling with oil.

[bmcecosse]

Thin is wrong - as is RTV sealant! Seriously - this is not a difficult job....are you sure the oil is escaping at the cork seals - and not from the crankshaft tail and the timing case seal at the front??