Head gasket question.

[Childnurse]

My son and I have just replaced the head gasket on the 1275 engine (Marina) fitted in our 1971 Traveller and when we refilled with coolant we noticed that it is steadily dripping from a point on the joint at the front corner, just above the engine number plate below plug no. 1. There are no leaks from anywhere else.

The car has been under restoration and has just come back from Woodies in Sussex, having had a completely new wood frame fitted. The only reason we replaced the gasket was that the engine oil appeared to be emulsified with water and there were rust spots on some parts of the rocker gear. There was also a lot of gunk in the rocker cover. Taking advice from a local mechanic, we went ahead and carried out the gasket change.

In removing the head we were careful to follow the sequence described in the manual and have replaced it the same way, torqued down to the recommended 40 lb ft. There seemed to be contradictory advice about whether the new gasket should have a smear of oil or grease before fitting, so we decided to fit the gasket, which seemed to be made of some sort of fibre material, 'dry'.

We are reluctant to run the engine in this condition. Does this very localised leak indicate that the head needs skimming, or is there something I can do to stop the leak without having it skimmed?

Never had to change a head gasket on a car engine before, so maybe I've missed something.

[minor65]

The same thing happened to me once. I would retorque it to 42 lbf after the first heat cycle.

[bmcecosse]

You should have used a copper faced gasket - yes thin wipe of grease both sides, and torque to 44 ft lbf. And again after the first heat cycle. It's not going to heal up - so pull the head and check for flatness of head and block surfaces - and spotlessly clean of course.

[dalebrignall]

ive had this happen with a cooper gasket , im using composite now and no more leaks

[Childnurse]

Thanks for the info. Might just replace with a copper gasket. That's next weekend lined-up, then!

[bmcecosse]

No harm in trying cranking this one down to 44 ft lbf - but I doubt it will help.

[philthehill]

Pre 1975 1275cc engines - the cylinder head torque is 40/42 ft/lb.
Post 1975 1275cc engines - improved cylinder head studs with better flanged based nuts were fitted to the 1275cc Marina/Ital and the studs can be identified as such as they have either a pointed/cone top end, a dimpled end or stamped with a 'Y' on the end - if they are they should be torqued to 50 lb/ft.
If the studs fitted are as above torque to 50 ft/lb before doing anything and see what happens. That extra torque may just cure the problem.
There is nothing wrong in using a fibre composite head gasket if fitted correctly and torqued down to the correct torque and tightened in the correct sequence.
Some fibre/composite gaskets should not be greased - you should look to the fitting instructions for the head gasket for advice as to grease or not.
My preference is not to grease fibre/composite head gaskets (or copper type for that matter) and just fit/use dry.
Phil

[bmcecosse]

I wouldn't grease a fibre gasket either - but then I wouldn't use one in the first place !

[Childnurse]

Pre 1975 1275cc engines - the cylinder head torque is 40/42 ft/lb.
Post 1975 1275cc engines - improved cylinder head studs with better flanged based nuts were fitted to the 1275cc Marina/Ital and the studs can be identified as such as they have either a pointed/cone top end, a dimpled end or stamped with a 'Y' on the end - if they are they should be torqued to 50 lb/ft.
If the studs fitted are as above torque to 50 ft/lb before doing anything and see what happens. That extra torque may just cure the problem.
There is nothing wrong in using a fibre composite head gasket if fitted correctly and torqued down to the correct torque and tightened in the correct sequence.
Some fibre/composite gaskets should not be greased - you should look to the fitting instructions for the head gasket for advice as to grease or not.
My preference is not to grease fibre/composite head gaskets (or copper type for that matter) and just fit/use dry.
Phil

Thank you. It's too dim in my garage to clearly work on the engine on winter evenings, but I will have a close look at the weekend.

[philthehill]

Whilst studs are on the agenda - the improved cylinder head studs fitted to the 1275cc MG Midget/Sprite are stamped with a No: 22 on their tops and they should also be torqued to 50 lb/ft.

[bmcecosse]

I would be wary of cranking down more than 44 ft lbf. Remember - the studs rely on 3/8 UNC threads in the cast block,and these can sometimes be a 'bit loose' on older blocks, and it may be that the later A+ blocks had a bit more metal to grip the studs. Certainly the 1275 blocks are taller and possibly thicker. There may be a risk of pulling a stud out of the earlier 'small bore' blocks. Take care!

[philthehill]

Whilst I agree that care should be taken when torqueing down the head if the studs and nuts are as described above there will be no problem with 50 lb/ft - but I would recommend that the nuts are torqued down to 50 lb/ft progressively and not all in one go.
The fitment of the studs and nuts as described above was (and still is) a recommended upgrade to those engines not so fitted; and was the way to go before the availability of ARP studs/bolts.
I have used the studs and nuts as described above on 948cc/998cc engine and 1275cc/1380cc & 1400cc engines and all set to 50 lb/ft with no problems encountered.
There is more than enough metal in the top of the block on the 948cc/998cc/1275cc engines whether they be 'A' or 'A' Plus.
My 1380cc 'A' Plus block has been seriously decked and fitted with ARP studs (with the same length UNC threads) at a similar torque.
If you do take the head off - take the studs out and chamfer the edges of the holes in the block as per the diagram below.
Make sure that the head studs are screwed fully into the head. I always run a used (slightly blunt) 3/8" UNC bottom/3rd tap down the threads to clean the threads. If a tap is unavailable use a 3/8" UNC stud with a small flat or vertical 'V' slot filed on and the length of the UNC threads. Make sure to clean out any resulting crud from the stud holes.[frame][/frame]