Don't use gasket maker silicone on cylinder head!

[Stelios_Rjk]

Why? Because of thermal conductivity.

I had my silver century cylinder not well sealed with the cylinder head. When outboard runs I could see water drops appear at the point of the copper gasket. I decided to replace the copper gasket with one of permanite. But this gasket was harmed by the water. I decide to apply one layer of red gasket maker silicone (permatex) to each side of the the permanite gasket. The sealing was outstanding. No leak in or out. But silicone does not transfer the heat to the cooling water so the cylinder head started heating up. I realised the problem in time so there was no damage. Now I am looking for a material that that seals like silicone and transfer the heat as the copper. Or just a new copper gasket would do the job. The old one was not much used so I am wondering if copper is not too flexible to seal like silicone.

[Charles uk]

Stelios I use silicon RTV compound all the time, I always use Seagull copper head gaskets & RTV on my racing Seagulls that run at much higher temperature & pressures than you will get in a stock Seagull, with no problem at all.

Seagulls with removable cylinder heads have fins on them to assist with head cooling but is only a small part of the cylinder cooling team, the other parts being, conduction through the cast iron cylinder walls into the coolant in the water jacket, heat used in vaporising the petrol in the atomised mix in the fresh charge from the transfer port, cooling the head, cylinder walls & piston crown but the major source of heat loss is in the exhaust gas which as it exits the exhaust port is somwhere between 400 & 500 degrees C.

You might be better off with a copper Seagull head gasket.

[Stelios_Rjk]

Now the problem is far more viewable. The exceeding RTV create a thick layer in the holes where the coolant water flows. I believe this did not allow thermal exchange between the water and the cylinder head. If I place RTV in small amount and only on the block and not on the cylinder head, I will avoid exceeding RTV block waterways?

[david]

Stelios...what you need is a thin smear, the stuff will get everywhere otherwise!
Apply it careully, no problem!

[Stelios_Rjk]

Thank you guys!

Can I get the desired result only by using RTV in thin smear and without using the copper gasket? I believe the copper one does not seals too good as RTV.

[Charles uk]

The distance between the piston & the cylinder head is critical, you are about to move them closer by nearly 1mm, this will decrease the combustion chamber volume by 2.5 cc, depending on your current combustion chamber volume, you will increase the compression ratio quite considerably!

If you think your engines running hot now, without the head gasket it will run hotter, that's if the piston doesn't hit the head, please remember that the piston & conrod will expand at normal running temperature & that with the increased temperature from the increased compression & extra loading on the bearings both of these components will run hotter & expand more you will run a greater risk of a piston seize or a piston / head coming together.

If you want to run without a gasket lap, the head onto the cylinder & you might have to shorten the head where it projects into the cylinder if it bottoms out, & check the clearance between the ends of the piston deflector & the cylinder head!

[Stelios_Rjk]

OK. No way to run it without copper gasket. If I add thin smear of RTV would things be better? Am I supposed to smear RTV on the cylinder head, on the block or both?

[Bluecloud]

Scrape the gasket clean with a razor blade then the thinnest, meanest smear of Red Goo on either side should, if you will excuse the pun, seal the deal.

[Collector Inspector]

Interesting Post, my 10 cents worth.........

I do not use silicon on barrels or heads, I use either a cleaned and annealed old gasket or a new one (New ones are cheap).

I make sure that all surfaces are clean and flat.

I use this, just a very light spray on the copper gasket, both sides and let set for a few minutes and assemble. You do not need much, just a light blue coat with the gasket colour showing through.

Silicon sealer in large, or maybe any, amount is not a good idea, previous comments as above for silicon but I do not understand the need ever. Just me being picky maybe.

Silicon can never seal pressures and will not have any heat transfer properties when used as " Solution" for a problem.

http://www.hylomar.com/

http://www.youtube.com/watch?v=yXiVZIBoHL0

The video uses a bit too much for our application. Just enough to cover with a slight Blue etc.

Hope this helps.

B[/color]

[Stelios_Rjk]

Interesting product. Good to have more than one solutions. I tried with a thin layer of RTV applied only on the block. I believe it didn't go into the holes where the water flows. I will try run it in a week to see the result.

It was beneficial that petrol removes RTV, so if temperature go up I will know how to remove it.

[Collector Inspector]

"It was beneficial that petrol removes RTV"

Another reason not to go there aye?

B

[Stelios_Rjk]

Sorry, I don't totally follow you because of my poor English. Just say what you have in mind.