Which head gasket?

[robbyasti]

I have always used cooper head gaskets in the past. I have recently been told that composite are better.
Is one better than the other or it is just important to buy good quality?

Thanks

[Vegard]

BK450 every time

[robbyasti]

BK450 every time

Is there an equivalent for an 850?

[CooperTune]

There was but not any more as I understand. Steve (CTR)

[Spider]

These are really good

http://mgspareparts.com.au/index.php/en ... que-detail

be quick though as they stopped making them a while back, so what ever is on the shelves is it.

As an alternative, if it's a fairly standard engine, these are also very good;-

http://mgspareparts.com.au/index.php/en ... ite-detail

not sure who in the UK might stock a similar one though.

[Rich997]

No doubt the technical wizards on the forum will identify precisely which one to buy.

My belief was and still is, would be to revert to only OE spec parts.

I purchased a copper head gasket for my 997, along with new high tensile studs, for a complete engine rebuild.

There is a thread on the site which recounts problems with head gaskets leaking (water), when the bolts come loose / the gasket fails by a water gallery.

Anyway, the salient point is, when stripping the head to discover why my head was leaking water / pressure in the jacket, I found 2 things wrong:

1. Head gasket hadn't compressed properly by the water galleries (gasket had alloy rings formed around the galleries)
2. Several of the studs had worked loose

The learning is to make certain your copper head gasket is of the best quality ie. PAYEN

I also recommend checking the quality of the head studs, I measured mine and found the course thread to be significantly undersized, hence wasn't a tight fit in the block.

The alternative set I bought from Minispares (their best quality non comp spec) was much better.

Some say the composite gaskets are more forgiving, or the MLS type (very expensive) is helpful in overcoming tolerance issues.

True to say that if the surfaces are properly prepared and flat, then a good quality copper gasket will be very capable.

Cheers

[ianh1968]

<SNIP>2. Several of the studs had worked loose
<SNIP>I measured mine and found the course thread to be significantly undersized,
hence wasn't a tight fit in the block.

There is no requirement for the studs to be "tight" in the block...
The fact that when undoing the nuts, it loosens off the studs undo is of no consequence.

As Rich has also said, good quality studs that don't stretch and decent surface preparation
will go along way to providing the best results.

As far as which gasket is concerned, it's a never ending story!

viewtopic.php?f=3&t=9463
viewtopic.php?f=3&t=12681

Ian

[Rich997]

Fair point Ian, 'tight' isn't the correct adjective.

The poor quality studs measured significantly undersize (thread dia) and waggled about in the block.

Minispares best grade studs measured fine and turned nicely in the block.

Pressurising the water jacket obviously means water can be forced up via the head studs.

Having read many sources of advice on how best to build up the head and what torque to apply, I found Keith Calver's advice to be the most comprehensive.

No surprise, KC is indeed a genuine font of A Series knowledge.

Cheers

[robbyasti]

No doubt the technical wizards on the forum will identify precisely which one to buy.

My belief was and still is, would be to revert to only OE spec parts.

I purchased a copper head gasket for my 997, along with new high tensile studs, for a complete engine rebuild.

There is a thread on the site which recounts problems with head gaskets leaking (water), when the bolts come loose / the gasket fails by a water gallery.

Anyway, the salient point is, when stripping the head to discover why my head was leaking water / pressure in the jacket, I found 2 things wrong:

1. Head gasket hadn't compressed properly by the water galleries (gasket had alloy rings formed around the galleries)
2. Several of the studs had worked loose

The learning is to make certain your copper head gasket is of the best quality ie. PAYEN

I also recommend checking the quality of the head studs, I measured mine and found the course thread to be significantly undersized, hence wasn't a tight fit in the block.

The alternative set I bought from Minispares (their best quality non comp spec) was much better.

Some say the composite gaskets are more forgiving, or the MLS type (very expensive) is helpful in overcoming tolerance issues.

True to say that if the surfaces are properly prepared and flat, then a good quality copper gasket will be very capable.

Cheers

Thanks Rich. As per usual, you have been a great help. I couldn't understand why my hg was leaking. I checked my studs, after reading your post and I found several studs to be very loose that I could turn them without any effort. It was no surprise to see that the leak was exactly around that area. I looked at the underside of the hg and again the head gasket was marked around the area of the loose studs. My fault, I obviously loosened off the studs at the the last hg change. Torqued up the bolts which in time just loosened off and water started seeping from the hg.

I have now tightened up the studs and will fit a Payen af070 copper hg. I was tempted by the FAI composite hg but I am not sure of the quality.

[robbyasti]

Do the rear head studs actually enter into the water jacket (1969 850)?

[Ronnie]

Do the rear head studs actually enter into the water jacket (1969 850)?

I dont think so? Only the bolt on the Cooper S

[ianh1968]

I checked my studs, after reading your post and I found several studs to be very loose that I could turn them without any effort.

THIS IS MY OPINION:
Given that I only ever put my studs in finger tight, in other words, not tight at all,
I am struggling with this concept of "studs working loose"...

I have run engines of up to 13:1 compression ratio and have never
had gasket problems other than them "going" between No2 and No3
cylinder. This is the hottest part of the head, and is also the area of
the head where there is the least metal to soak the heat away.

These engines also have a very thin wall between the bores as despite
asking for this to be done, the bores were not offset. This is bad enough
at 73.5mm and even worse at 74mm. It has nothing to do with the
clamping ability of the nuts/studs...

I would ask:
How do you conclude that the studs were "loose"?
If they undo easily either whilst you are undoing the nuts, or else
after you have removed the nuts, this does not mean that they
were "too loose".

If it takes virtually no effort to undo the NUTS, then yes, there is
something amiss... If the nuts were still tight, it is entirely likely
that there is no problem with the studs.

Imagine a bolt going through two sheets of metal and then having
a nut on the threaded end. The bolt is not "tight" in the hole, it can
spin around of its own accord and this is of no consequence.

If I had a leaking gasket, I would be considering these things:
1) Is the head face and block deck spotlessly clean?
2) Is the head face and block deck flat with no high spots around the studs?
3) Is the gasket damaged prior to fitment?
(I was once supplied with a gasket with a "crease" in it).
4) Is the correct sequence of tightening being used for the nuts?
5) Are soft/damaged washers being used that will crush up?
6) Does the head foul up on the top of the water pump?
(When things have been skimmed, this can stop the head
sitting on the block correctly).
7) Does the head have the original "ally" rocker pillars which ae known
to collapse easily?
8) Are any of the brass plugs in the head sunken?
9) Have any of the waterways in the head grown substantially and are
now outside the gasket?
10) Is it actually the right gasket?
(If you use a large bore gasket on a small bore engine, things don't line
up very well sometimes).
11) GOO - This does not magically disappear when you torque down
the head. It is still there, possibly contributing to an uneven fittment
of the head.

The gasket will always get "marked" around the stud holes, but if this
is over a large area, I would suggest that there is a high spot around
the stud hole. If there is a high spot on the deck around the stud hole,
this will cause the gasket to crush up substantially in the immediate
area of the stud, but much less so outside of this area, thus possibly
leading to water sealing and other problems.

Ian

[robbyasti]

I checked my studs, after reading your post and I found several studs to be very loose that I could turn them without any effort.

THIS IS MY OPINION:
Given that I only ever put my studs in finger tight, in other words, not tight at all,
I am struggling with this concept of "studs working loose"...

I have run engines of up to 13:1 compression ratio and have never
had gasket problems other than them "going" between No2 and No3
cylinder. This is the hottest part of the head, and is also the area of
the head where there is the least metal to soak the heat away.

These engines also have a very thin wall between the bores as despite
asking for this to be done, the bores were not offset. This is bad enough
at 73.5mm and even worse at 74mm. It has nothing to do with the
clamping ability of the nuts/studs...

I would ask:
How do you conclude that the studs were "loose"?
If they undo easily either whilst you are undoing the nuts, or else
after you have removed the nuts, this does not mean that they
were "too loose".

If it takes virtually no effort to undo the NUTS, then yes, there is
something amiss... If the nuts were still tight, it is entirely likely
that there is no problem with the studs.

Imagine a bolt going through two sheets of metal and then having
a nut on the threaded end. The bolt is not "tight" in the hole, it can
spin around of its own accord and this is of no consequence.

If I had a leaking gasket, I would be considering these things:
1) Is the head face and block deck spotlessly clean?
2) Is the head face and block deck flat with no high spots around the studs?
3) Is the gasket damaged prior to fitment?
(I was once supplied with a gasket with a "crease" in it).
4) Is the correct sequence of tightening being used for the nuts?
5) Are soft/damaged washers being used that will crush up?
6) Does the head foul up on the top of the water pump?
(When things have been skimmed, this can stop the head
sitting on the block correctly).
7) Does the head have the original "ally" rocker pillars which ae known
to collapse easily?
8) Are any of the brass plugs in the head sunken?
9) Have any of the waterways in the head grown substantially and are
now outside the gasket?
10) Is it actually the right gasket?
(If you use a large bore gasket on a small bore engine, things don't line
up very well sometimes).
11) GOO - This does not magically disappear when you torque down
the head. It is still there, possibly contributing to an uneven fittment
of the head.

The gasket will always get "marked" around the stud holes, but if this
is over a large area, I would suggest that there is a high spot around
the stud hole. If there is a high spot on the deck around the stud hole,
this will cause the gasket to crush up substantially in the immediate
area of the stud, but much less so outside of this area, thus possibly
leading to water sealing and other problems.

Ian

Thanks for that Ian. Certainly a thorough and complete list of tips on fitting a hg.

[ianh1968]

Top Tip:

Please don't re-quote the whole message for each reply.
It can get a bit repetitititive after a while.

If there is anything specific that you are commenting on,
you can slice out most of the post and just leave these bits...

If you are refering to the whole post, you can just refer to
"your post above" and people will always find it.

It is quite easy to wear out the scroll bar or end up with RSI
if every message is displayed several times within a thread.
I noticed that this happened quite a lot on "another" forum and
personally found this quite tedious to read as a result.


How have you worked out that the studs are "too loose"?
If the nuts weren't loose, the studs were "tight" enough...

Ian

[Rich997]

Hi Ian,

The disappointing aspects I found with the parts I sourced were:

Copper head gasket didn't compress properly / uniformly around the water galleries. Genuine PAYEN gaskets don't have the 'alloy' rings visible around the holes.
Measuring my 'failed' gasket showed that the alloy rings were proud of the gasket face, in spite of correct torque sequence.

New studs used on first rebuild were a poor fit in the threads, which is verified by micrometer. Measuring the 'best' quality MS high tensile studs shows very fine tolerances, giving a much better fit in the block.

I appreciate you shouldn't need to gorilla the studs into the block, nor overtorque in an attempt to compensate for poorly seated gasket or contaminated face.

In summary, I suffered due to poor quality components, with the unfortunate combination of dodgy head gasket then pressurising the water jacket ...

Typically I follow factory standards and don't risk over torquing, in spite of many articles or threads advocating up to 50 !!! pounds for head nuts (I stick at 42 max).

Having spent some time with a historic race team of good repute, some years ago, I recall they had only two torque settings for any job ie. 'Tight' or 'F@cking tight!!!'

[robbyasti]

New Payen gasket fitted today. I have only driven for about 70 miles but for now all is good, no leaks, good compression.
I am sure that the problem was due to an inferior quality head gasket and loose bolts.