Head Gasket Sealer

[Friartuck]

1) Is there a practical specification on how flat a cast iron head should be, e.g. 0.003 variation over the surface, and

2) best method for sealing a copper head gasket; greased or other sealant or compound?

 

[Owen_Dyneto]

I have used Permatex's copperized head gasket sealant for decades and recommend it highly, never a do-over.  It comes in aerosol so I hand the gasket by a hook and spray both sides just minutes before installing.

[Frank DuVal]

I second the copper spray. Spray all sides of gasket and the surfaces it is going to stick to.

 

Plenty of ideas on the web for flatness, most do thousandths per a certain length. Here is one:

 

http://www.enginebuildermag.com/2007/06/common-mistakes-to-avoid-when-resurfacing-cylinder-heads-blocks/

[Friartuck]

This is the spec I was hunting for:

Flatness specifications vary depending on the application, but on most pushrod engines with cast iron heads, up to .003″ (0.076 mm) out-of-flat lengthwise in V6 heads, .004″ (0.102 mm) in four cylinder or V8 heads, and .006″ (0.152 mm) in straight six cylinder heads is considered acceptable. Aluminum heads, on the other hand, should have no more than .002″ (.05 mm) out-of-flat in any direction. On a performance engine, the flatter the better.

 

Has anyone made their own head gaskets from Graphite sheet like Grafoil?

[cahartley]

Hylomar.

I've used it for years on head gaskets that still look serviceable.

An engine rebuilder friend of mine put me on to it.

I never had a leaker.

 

https://www.google.com/search?client=opera&q=hylomar&sourceid=opera&ie=UTF-8&oe=UTF-8

[Spinneyhill]

17 hours ago, cahartley said:

Hylomar.

I've used it for years on head gaskets that still look serviceable.

Um... which one? They make many products

http://hylomar.com/hylomar-product-range/

[Guest SaddleRider]

cyl.   head gasket sealing issue:

 

There is a reason why engine manufacturers do not use "gasket goop" when assembling engines.  It isn't necessary.   And makes for problems when it comes time for servicing.

 

If the machined surfaces are level,  and you use a technically correct gasket,  it wont leak.  

 

True -  if you are dealing with uneven surfaces, (for failure to do or insist on a proper machining job)  "gasket goop"  MIGHT get you by for a while.

 

My recommendation  - fix it right.

 

Why do I recommend that ?   Well.....if you don't have the time or money to do it right the first time,   think about the time and money to try and fix it again the second time.

[Ben Bruce aka First Born]

I have never used sealer on a head gasket. Never.

 

  Ben

[cahartley]

1 hour ago, Spinneyhill said:

Um... which one? They make many products

http://hylomar.com/hylomar-product-range/

 

Hylomar blue........the very high temperature one.

This one >>> http://www.ebay.com/itm/Hylomar-M-Universal-Blue-Non-Hardening-Gasket-Sealer-80ML-Jointing-Compound-/332338988598?vxp=mtr

[Bloo]

37 minutes ago, Spinneyhill said:

18 hours ago, cahartley said:

Hylomar.

I've used it for years on head gaskets that still look serviceable.

Um... which one? They make many products

http://hylomar.com/hylomar-product-range/

 

Don't you hate it when they do that? We live in a world where "liquid wrench", for instance, used to be a pretty competent diesel-like penetraing oil, and now they seem to make everything from beef jerky to warm socks. Similar for loctite. Once upon a time there were 5 common grades of loctite, mostly identifiable by color. Not anymore. I saw "Nikon" on something in the grocery checkout aisle the other day. I think it was a nylon laundry bag.

 

"Hylomar" is, or was, a specific product. It is a sticky, sticky goo, and is an anaerobic sealer, like loctite... err... oops... that stuff you put on bolt threads to keep them from rusting and or coming loose. It was transparent but also blue. Similar products could also be transparent, but could be any color. If you look in any Italian shop manual form the late 70s or 80s (Alfa Romeo, Ferrari, Fiat, Maserati etc.) you will see them specifying "Hylomar" in all sorts of places. I think in the USA Permatex was the source for it, but I cant remember for sure.

 

Hylomar's main purpose is sealing up aluminum on aluminum joints where gaskets are not used. Think about that little area on front cam cap of some overhead-cam engines that is not sealed by either the cam seal or the valve cover gasket.

 

 

It works great, amazing in fact. You can use it with gaskets, too. The downside is it only seems to hold up about 30k miles on a difficult spot like a cam tower. Many of the things I used it on were coming apart in 30k anyway at valve adjustment time.

 

There were some other similar products. Somewhere I have a huge tube of "Mopar" brand sealant I acquired from Dodge in the 90s. It looks, smells, feels and works like Hylomar. It is clear/red instead of clear/blue. This explains why I have not bought any for so long. This tube is so big it might become an heirloom.

 

Longer-living Hylomar substitutes appeared in the 90s or perhaps earlier. Probably silicone-based, but not quite like normal RTV silicone. Honda had something called "Hondabond". It will seal that little no mans land on a cam bearing cap, and most other aluminum on aluminum machined joints basically forever. The aftermarket substitute for Hondabond in the USA is "Permatex Ultra Gray". It isn't really the quite the same stuff as Hondabond, but it works.

 

Here is some Hylomar on aluminum:

 

[cahartley]

^ Yup......that's the stuff.

My engine builder friend swore by it and I do too.

If it's good enough for Rolls engines it's good enough for me.

Rolls would never have used it just because. 

[Spinneyhill]

42 minutes ago, cahartley said:

If it's good enough for Rolls engines it's good enough for me.

Rolls would never have used it just because. 

 

This sentence is from http://www.hylomarsealant.com/_resources/_html/products.html

 

"Hylomar Universal Blue was originally developed in the 1960's by Rolls-Royce Plc to help seal against synthetic lubricants that were used in early jet engines. "

[cahartley]

There has always been different schools of thought about putting or not putting some kind of sealant on head gaskets.

Some swear by copper spray, some aluminum spray paint, others grease and so on.

All I know is I have reused head gaskets on old (teens/twenties and newer) engines and never had a leak.

[Guest SaddleRider]

18 hours ago, cahartley said:

 

All I know is I have reused head gaskets on old (teens/twenties and newer) engines and never had a leak.

 

Wrong.  That is not "all you know".   Be honest -you also know how to insist on properly machined mating surfaces.  

[cahartley]

You are correct SaddleRider.

I certainly do!.......