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+--- Thread: Replacing cylinderhead (/showthread.php?tid=3556)
RE: Replacing cylinderhead - Steve Jones - 05-12-2019
That appears to be me (and Alan) told off!
At least we tried!
Steve
RE: Replacing cylinderhead - Chris KC - 05-12-2019
Not at all Steve. But I do notice a tendency in these threads to bandy the term 'Loctite' around and I shudder to think what happens when a less well-informed reader slaps on the wrong 'Loctite' not realising that it comes in different flavours.
And I probably shouldn't have written that either!
RE: Replacing cylinderhead - Alan - 05-12-2019
Well thing is I said applied sparingly. A tube lasts ages. Mine says 5920.
RE: Replacing cylinderhead - Ian Williams - 05-12-2019
In my experience if the block and head faces are perfectly flat ( many blocks are low in the centre ) and you have water ways that are in good condition a smear of grease will usually suffice....certainly with copper asbestos gaskets, although some doubt exists with modern materials as I have discussed elsewhere here. However most times we are not dealing with perfect components and as a result water often seeps into the bores, especially on lightly used cars. I think that with regular (more than once a week) use a small amount of water seepage gets burnt off before it causes damage to the bores and valve seats, eventually the gasket seems to seal, probably from corrosion around the water ways and carbon build up on the flame ring. I believe it may be sensible in many cases to use a sealant such as described by Alan, Steve and others, but there appear to be issues with choosing the right sealant and quantity applied, too thick and it is blown out by compression exaggerating the problem. As I have said before at one time all I ever used was a thin smear of grease, but with the modern gasket materials I have tried a few solutions and the jury is still out on which is completely reliable. Some here still swear by coating the gasket Aluminium paint and I have seen this used successfully.
RE: Replacing cylinderhead - Ian Williams - 06-12-2019
Sorry to drag this back up but I was thinking about it again last night, and I have a question for Alan and Steve; Do you use the silicone Loctite product just as a light smear around the water passages or do you cover the entire gasket?
RE: Replacing cylinderhead - Alan - 06-12-2019
The whole gasket. But when I say sparingly, I mean sparingly
RE: Replacing cylinderhead - Steve Jones - 06-12-2019
A very light smear over the entire gasket for me, Ian. I've been using 5920/5990 on head gaskets on various engines since 2007. In that time as well as various touring engines, my main competition engines are my Trials Chummy and my Sprint/Hill Climb Ulster. The Trials Car has done 96 trials in that time, a lot of them at 5000+! The Ulster engine is from 2013 and has done 58 sprints and hill climbs, the majority double entered with my Grandson, so the equivalent of about 100 events. Neither car is the absolute best of the field but we're up there and we have a considerable collection of 'pots'. As a competitor you'll understand what level of use that is (and I hope I don't regret this) but no water leaks, no blown head gaskets. 100% reliability in that department. I use it on manifold and exhaust gaskets with the same results.
I first came across Copper/Silicone 5920/5990 in 2007 when I was having trouble sealing the head gasket on a Meadows 4ED engine. I good friend from the Frazer-Nash Club put me on to it and explained its story. It seems that General Motors commissioned Loctite to develop a sealant that could be used instead of a traditional head gasket. From a motor manufacturers point of view, that has to represent a considerable potential saving so it was a path worth researching. In the end, Loctite couldn't come up with a product that was sufficiently acceptable and that is why it says not to be used on a head gasket application on the 5920/5990 packaging. However, used in conjunction with a traditional head gasket it's a different matter and I'm a committed convert. I've lost count of the number of people I've recommended it to and they, too, have become converts. There are many ways of sealing high load gaskets, this is just one of them. Each to his own but this is what I do and it works for me.
I'm a firm believer that if such materials had been available in period then our Austins would have been glued together with them. If you look at your modern you'll find that similar high performance products are used throughout. My Skoda and my Wife's Fiat certainly are.
Steve
RE: Replacing cylinderhead - Malcolm Parker - 07-12-2019
I was converted by Steve many years ago and remain a dedicated follower!
RE: Replacing cylinderhead - Ian Williams - 08-12-2019
Thank you guys for your input, I have experimented with various products, Hylomar spray being one already mentioned, however I have not been entirely confident of the sutability in anything for all applications thus far. I have however not tried 5920/5990 so based on your comments that will be my next avenue, I would also like to clarify for anyone reading that I am discussing higher than normal compression ratios when stating I am not satisfied with some products, and on an LC head with GOOD faces and water passages a smear of grease seems reasonably satisfactory. There is though, no matter what anyone else says, more of an issue sealing modern gaskets than there used to be with traditional copper asbestos gaskets. I don't wish to scare monger but simply warn owners to beware, I have lost count of the number of engines which have been brought to me for work and once the head has been removed there is evidence of water damage to the bores and valves and seats.
RE: Replacing cylinderhead - Paul N-M - 08-12-2019
Could not get a gasket off the shelf that didn't overlap 57mm bores so made up this. Have used solid copper in several engines with very mixed results so not a great fan. However this idea certainly holds the compression (7.5:1) with a David Dye head. There were some initial dribbles at the manifold side which have now settled down. The clamping pressure on the Austin head just isn't that great. It was a new block so went to 25lbs.
One thing that has become apparent is the lack of good quality head gaskets that can also accomodate larger overbores. I did some investigation and could get modern black Payen style gaskets made with compression and water rings in all the right places. The price was not that bad, retailing at arround £40, but it would need time spent on prototyping and testing which I don't have, and though I think the price would be OK for something that worked way better than existing I wonder if most folks would still just buy the cheaper existing ones.