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MG Midget and Sprite Technical - New oil leak

Good morning gentlemen
So far not much oil has been seeping out of the engine, only a few drops now and then. But recently I noticed more oil than usual on the workshop floor. Some oil has started to penetrate on the front LH side just under the exhaust manifold. I think it must be seeping out between the cylinder head and engine block. Not alarming, but why now, after approx. 5000 mls?
I gave the engine a Payen gasket when overhauling 1 3/4 years ago. I retorqued after running in at 500 mls.
Jan
Jan Kruber

Jan
That is the corner of the block where the oil feed goes up through the head gasket into the head casting to feed the rocker shaft. Oil seepage is not uncommon. If it is coming from the head gasket joint itself it probably needs a new head gasket, but it is worth just checking the torque on the head bolts. Sometimes a slight tweek of these is all that it needs. If it is only slight you may be able to just leave it, but I suspect that wouldn't satisfy your high standards.

But clean off the area around there carefully and inspect to see exactly where the oil starts from. The oil gallery in the head has a horizontal drilling from the outer corner of the head. This is sealed with a brass plug and these sometimes leak, but can often be tightened down and this would cure it. I cannot remember if the plug is threaded (Allen socket head) or if it is a press fit, drifted in. Someone will know.
GuyW

Guy,
This evening I took the valve cover off. I first checkec the valve clearances to see if the valve clearance over the this driving season, approx 3100 mls, had decreased. This was to confirm, what I believe, that my cylinder head is for lead free petrol and that it has hardened valve seats. The valves all are a little on the loose side, just as when I adjusted them last winter.
Then I checked the head nuts, they are still 50 ft/lbs or 6,9 kg/m. I gave the nuts a 1/4 turn.
After this retorque I checked the valve clearances again, they were the same.
So I guess I will have to give it a new gasket.
I don't think the oil is coming from the valve cover gasket. I use the silicone gasket glued in the cover and is very happy with it.
The area just under the valve cover gasket looks dry. But maybe it is cheating me, maybe the area around the exhaust manifold is so hot, that the oil runs quick pass the the area and further down on the head / block.
I still think the oil comes from the head gasket, but
I will keep the whole area under supervision next time the engine is warmed up
Jan Kruber

Dry the area off and brush talcum powder in and around the joint. Start the engine and the source of the weep should show pretty quickly,
f pollock

Jan,
Take a close look at the corner of the cylinder head, about 8mm up from the head gasket joint and on the front corner of the head. You will find a small round depression. This is the plugged end of the drilling for the oil gallery. The plug may be weeping, so check this first before removing the head. Wipe off any oil, take it for a drive and carefully check again. If there is oil on the side of the head above the gasket line, it could be this plug that is the problem
GuyW

The leak was increasing and it was seeping out in the front left corner. I retorqued the head, it was at it is supposed.
Today I removed the head and noticed, that allthough it was a Payen gasket, it did not have the "O-ring" surrounding the oil feed inserted, as the new Payen gasket has, photo attached, new gasket RH, off course.

Jan Kruber

I don't recall ever having a Payen head gasket with a moulded O ring for the oil feed, just the copper ring and have never had one leak.
David Billington

Ditto
Dave O'Neill 2

The new gasket is stamped AF470
Jan Kruber

My head hurts, this lot has twisted my eyes out of shape -

A-Series Spares
Payen AF470
Standard composite reinforced gasket used on all large bore engines, the Payen AF470 is an exceptionally good gasket. Asbestos free with special sealing ring for the oil feed. Compressed volume is 3.8cc. This A-Series head gasket has in some cases been proven over time to be superior to even the copper version, Payen AF470.
Payen BK450
Ideal for high compression road and race engine. Used on the Mini Miglia race cars. Standard composite reinforced gasket used on all large bore engines, the Genuine Payen BK450 is an exceptionally good gasket.

Mini Spares
(GUG702560HG) Payen stamped AF470
Standard composite reinforced gasket used on all large bore engines by Rover is an exceptionally good gasket. Asbestos free with special black sealing ring for the oil feed. Compressed volume is 4cc. This MINI head gasket has in some cases been proven over time to be superior to other version. The original number stamped on this gasket is LVL100380. For performance engines and 8 port alloy heads where you should not have the rocker feed sealing ring which can cause problems, use the original TAM1521 with 3.3cc compressed volume or GEG300 with 3.4cc compressed volume or composite type C-AHT189.
(TAM1521) Payen,stamped BK450
original standard composite reinforced gasket used on all large bore engines by Rover including Metro and MG Turbo and is an exceptionally good gasket.
Asbestos free with copper type sealing rings. Compressed volume is approx 3.3cc.
This original head gasket has now been superseded/replaced by the GUG702560HG which has a different black rubber type O ring fitted on the rocker supply gallery. Many customers prefer this original TAM1521 Payen gasket without the rubber seal which has been proven over time to be superior in competition use, even though these new black type have been known to act as a thermal barrier between head and block which can tend to increase engine temperature, hence why people are still using good copper gaskets, see GEG300.
Nigel Atkins

I think I've edited those together correctly -

Payen AF470 (GUG702560HG)
. standard composite reinforced gasket used on all large bore engines
. with special black sealing ring for the oil feed
. compressed volume is 3.8cc (?4cc)
. proven over time to be superior to even the copper version (to other version).


Payen BK450 (TAM1521)
. standard composite reinforced gasket used on all large bore engines
. superseded/replaced by the GUG702560HG
. ideal for high compression road and race engine
. without the rubber seal
. compressed volume is approx 3.3cc
. proven over time to be superior in competition use, even though these new black type have been known to act as a thermal barrier between head and block which can tend to increase engine temperature, hence why people are still using good copper gaskets, see GEG300.

Nigel Atkins

So which head gasket do I use then? Nigel thank you so much to raise the confusion to a higher level LOL
Jan Kruber

I'm just glad it's not just me that it confused.

IIRC your engine is fairly standard (within reason)(?) 1275 so I'd go with what the majority of knowledgeable owners suggest for your type of engine.

So that me out.
Nigel Atkins

And the majority is choosing ....... eh.....?
Well, I have the new uprated Payen AF470 here on the bench, and that's what I will use. The former Payen was in the engine for approx. 5000 mls before beginning the leaking. Perhaps the uprated Payen will last longer, who knows, if not, I'm mature to try a third type .....
:-)
Jan Kruber

This thread was discussed between 14/10/2018 and 01/11/2018

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