My Cooper S engine is leaking a little coolant from time to time at the point in front of No#1 cylinder, and only when under considerable load and/or temperature. Its very occasional, and is not significant enough to change the water level. I only know its there because of the dried coolant marks down the front of the blockt.

The engine has a Payen gasket, and is not sharing oil and water. The head was machined before fitting and the cylinder head nuts are torqued up fine. The cooling system has an overflow bottle as well.

My questions are, is it my gasket that's playing up from time to time, do the studs need a few more lb/feet of torque, or does my overflow bottle over-pressurise the coolant system?

_________________
SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I would retorque the head first.
What gasket? If a copper one this problem is common, I used to put a bead of silastic around the top and bottom edges before fitting.
I've never had this problem with a BK450 composition gasket.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Mine has been doing exactly the same thing for years , more noticable after a long run , (not sure what head gasket is on it ) , i have retorqued the head .

I asked the bloke that built the engine , and he said not to be too concerned about it , he has seen them do this before without dramas .

I keep a constant eye on it , but it hasn't got any worse , when it does , i'll rip the head off .

The gasket is the recommended Payen BK450.

I've retorqued the studs last time I did the gaps by backing off a little and bringing them back up.

If it happens from time to time, then I'm fine. If it's going to lead to a warped head and an overheated engine then I'll take the time to change it out.

_________________
SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I've had no less than 3 of these gaskets do that now. I'll never waste my money on them again.

_________________

What gasket do you use now then GT?
I'm about to buy my head VRS gasket set but don't want these issues, especially since the Payen BK450 have been the "one" to use!

Cheers Shane

_________________
If it's not a Cooper S, the mini was designed to be modified!

Yes there was a dodgy batch of Payen BK450 gaskets a while ago but lately I've not heard of problems. The last 3 or 4 I have fitted had no issues.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

The old style silver head gaskets seemed to always leak at the front. The later type with the metal rings around the water holes, BK450, seem to be much better and since I have fitted this type to my Cooper S I have not had any more water leaks.

_________________
1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

This gasket dates from 2009, and was ordered some time before that so it may have been part of the problem batch I suppose.

Its just not bad enough to lift the head however...but I reckon if I'm feeling a little OCD'ish I'll rip it off some time

cheers all

_________________
SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Mick, I did the head on mine a year or so ago.. same situation as yours - skimmed flat, properly torqued down, has an expansion tank, coolant level never really drops much but I see the evidence of dried coolant around the gasket line.

Mine's a smallbore with an ACL Monotorque gasket though...

_________________
Simon

The adventures of an owner builder in the Tallarook Ranges

It wouldnt be leaking from the temperature sender would it, then running down and along and then down just near number 1?

Just a sugestion..

_________________

Mine isn't - I just replaced the sender a couple of weeks ago, it wasn't leaking then and it ain't now

_________________
Simon

The adventures of an owner builder in the Tallarook Ranges

Nah, just the gasket

_________________
SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I recall someone saying that the only head gaskets that leak are on motors built by one particular engine builder.

It's the head gasket gnomes!

_________________
Simon

The adventures of an owner builder in the Tallarook Ranges