Head bolt leak.

[Graham Honnor]

Thank you for that, if it blows again I will definitely try the 5990.
The nuts and washers came from one of our normal suppliers so hopefully 
they are tried and tested.
Many thanks again
Graham

[dickie65]

Hi Folks,
I have had this issue over the years, including a stud which was slowly pulling out of the block.
My bodge fix has been to undo the offending nut dry, off and put red hermatite on the stud and washer and do up again.
This has lasted me a couple of years in some cases.
Helicoils in the block can give you another leak path up the stud.

[Charles Levien]

When replacing head gaskets we use Loctite 5990 a silicone copper gasket sealant applied thinly to both sides works on race engines its stocked in Halfords.

Me too.

Steve

I used to have problems with head gaskets on a 37 head but seem to have found a solution. Basically it is very important to tighten the three middle nuts first - I take them up quite a bit before touching the other nuts. That spreads the head and gives you a fair chance of sealing between 2 and 3.
I also use spray-on blue hylomar and coat all four surfaces before putting the head on.

Charles

[Ian Williams]

This is an interesting thread for me, when I first got involved with sevens I only ever fitted head gaskets with a very light smear of grease, never with any problems. More recently I have been experiencing issues with failures between 2 and 3 as well as water seepage into the bores, I should add that some of these are gaskets fitted by others. There are two issues being discussed here, the first is leaking studs, a cure for that is always fit new studs with a sealant, I know some suggest loctite, I found success with a good pipe thread sealant. The other issue is water seeping across the gasket from waterways, this is a real problem if it goes unnoticed and water is getting into the bores, a lot of damage can occur throughout corrosion. I have suspected that the modern gaskets we get use a different composite to those from 30 or 40 years ago and that possibly this fails to compress as well under our modest torque settings. It is also vital that the head and block faces are completely flat, many blocks seem to have sunk slightly where they get extremely hot between 2 and 3. I have tried a few things to seal the gaskets but Hylomar spray has been the most successful for me. Now I fit a fair number of gaskets, however no where near as many as a well known contributor here who's opinion I trust, he tells me that he only ever fits gaskets with copper slip with complete success. It would be informative to hear from other's about success or failures.

[Michael]

Thinking about water...I wonder...there used to be a legend that antifreeze being particularly bad for white metal. Any truth in this?

[Graham Honnor]

Many thanks to all of you who have be kind enough to offer your valued advice and opinions in my hour of need.
I've yet to have the time to test my findings but will report back when I have.
Like you Ian, I have a lot of respect for Ruairidh, and if he is willing to offer me any help I will always gratefully accept 
and act on it.
I do not believe that there is any problem with using the copperslip, I do however think that I was wrong in not rechecking the head nut torque values after another long run.
As Andy suggested earlier, I will now religiously check them on a far more frequent basis.
At the end of the day however, if I do have to remove the head again for any reason, then with the presence of copperslip 
on the gasket and studs at least it should come of easily! (Not on the threads however.)
Once again, thank you to all.
Graham.

[Andy Bennett]

Just to answer Ian's question from a very inexperienced contributor.

My head and block are definitely not flat in that they have not been skimmed in my 9 year ownership and show signs of 'rounding off' around holes. All of which has led to my decision to put together a new top end.

I have had 2 head gaskets go after about 1000 miles (both between 2 and 3). The second one went a few weeks ago, before which I noticed some bubbling around 2 studs, (not around 2-3).

On this second replacement I have taken more care to prepare and check. I added penetrating locktite stud sealer to the bubbling studs (they would nor move with reasonable force and i did not want to risk breakage) in case the water was coming up rather than tracking along the head.

On replacing the gasket I used blue hylomar on both sides. I torgued up, left overnight, torgued again, ran hot and torgued again. I then rechecked torque after 50 or so miles and found that I could tighten by about a quarter of a turn across the head.

Today, after 300 miles I torqued again and strangely 1,2 and 3 all took a further 1/8 turn to 20lb, all others were fine and took no more.

Not sure what that says but to note I do consider this to be a very tired top end and I just hope I have my replacement sorted out before it goes again.

Andy

[Nick Lettington]

After replacing my head, I had a few issues with popping back through the carb and assumed that 2 and 3 were having a bit of sport between them. My cousin (also a bodger) suggested wellseal... It certainly does. Not looking forward to taking it to bits again though!

[Nick Turley]

Thank you for that Andy.
My gasket went between 2 and 3 also.
Initially I had covered several thousand trouble free miles (engine wise at least) and then snapped 2 crankcase studs
which meant me stripping the engine down and therefore replaced the head gasket on rebuild.
This has only lasted approximately 800 miles and then blew on a local club run a few weeks ago.
Having a bit more time I decided to have a minimal amount skimmed off the head this time by a local firm who are very 
used to pre-war cars and bought new nuts and washers.
I lightly greased the gasket on both sides and brushed a tiny amount on the plain part of the head studs as well.
I was surprised at how much the nuts needed torquing down again for the third time and will definitely follow your 
advice and keep rechecking over the next few months.
It wouldn't surprise me that if I had done this last time I may have avoided the gasket blowing so quickly last time.
You live and learn, even at my age.
Many thanks again
Graham.

Since Steve Jones recommended the Copper silicone to me I have used it since and not had any kind of leak. It is great stuff.

[Speedex750]

Hi,

A few engines back I took a lot of care to get both the block and aluminium head machined flat, reassembled dry and torqued down. The gasket blew very quickly and I was not amused. I read on here about Loctite 5990 (is that what others are calling coppaslip on here? That's something else) and reassembling that engine, with the slightly used gasket coated in 5990, well torqued gave a gas, oil and water tight seal. Since when I've used nothing else.

When I was in industry we did have problems when asbestos jointing was finally banned in the 1990's. The replacement gasketing materials weren't as forgiving as CAF. The new material isn't as resilient as asbestos, it doesn't spring back after it's compressed taking up a permanent set and the expansion and contraction from heating can reduce the clamping pressure. Correct tightening and following up were vital parts to avoid a blow out.

My advice follows others on here; 5990 and regularly keep torqueing to 20lbft until the nuts no longer rotate.

Dave