Cometic MHG problems

[Suprafast0422]

So I finaly got my cometic mhg and I layed it ontop of the block last night just to see how everything lined up and all.

Well, the first thing I noticed apon taking the mhg out of its plastic is that there is no coating on it. Cometics directions say to install the gasket dry but ive read on here about using a sealer or some brake quiet spray on mhg's.

The second thing I noticed was the coolant channels on the intake side dont line up with the mhg very well. The gasket covers up some of the passage.

The third thing I noticed is that the rivet on the front exhaust side of the mhg looks as if its not going to stick over the edge of the block and get sandwiched between the block and the head, which I know will not work.

 

[shaeff]

The rivet problem is well documented. Remove it.

 

[Neal]

I didn't have any rivet problems they all lined up but i did put some hylomer on mine, you could use the spray on hylomer as well but i chose to use the brush.

 

[bluemk3]

cometic gaskets have a very thin layer of coating on them and you arent to use additional sealer or any metal head gasket you are to prep the sufaces to the recomended smoothness grade

 

[Neal]

bluemk3: You are right, i personaly like hylomer, never had any issues and should have stated that, its entirely up to the individual to use a sealant or not.

 

[Rennat]

I bought an HKS 3mm MHG... and i just swapped it out with a Titan (cometic) 1.4mm... and they looked IDENTICAL. The coating was even the same color... both were covered in it, the only issue i saw was that i had to remove two rivets from the titan and only one from the HKS...

so far i havent had any unexpected issues... so we'll see.

 

[Neal]

What was the 3mm like?

 

[gaboonviper85]

What was the 3mm like?

It's like a 3mm version of the 1.4mm.....

Just so you know...you determine headgasket thickness only by how much metal you removed from the block and head...picking a random thickness is retarded and can ruin your motor in the long run....you are to keep the stock piston to head clearance which is done with the headgasket after machining!

Some people on this forum don't understand that...

 

[KMinAF]

How can you determine the correct thickness if the milling specs are unknown? i.e. I bought the engine in a "basket" from someone who couldn't complete the project. The block and timing cover were milled as well as the cylinder head, nice machine work but no way to aquire the measurements.

 

[jdub]

Sure there is
Stock head height = 116mm deck to cam cover surface
Stock block height = 198.5mm deck to crank journal saddle

A couple of you guys mught want to read this concerning using a sealer on a new MHG:
http://www.supramania.com/forums/showthread.php?t=29335

 

[Rennat]

It's like a 3mm version of the 1.4mm.....

Just so you know...you determine headgasket thickness only by how much metal you removed from the block and head...picking a random thickness is retarded and can ruin your motor in the long run....you are to keep the stock piston to head clearance which is done with the headgasket after machining!

Some people on this forum don't understand that...

I only bought it because it was $200, and i had the thinking "lower compression means i can run more boost"... and i also thought "lower compression wont be that bad"... yeah... well i wasted my money.


but i have a question for you jdub, theoretically, could i remove the rivets, and take out the two steel pieces which make my hks 3mm so thick, and make it a thinner MHG? it has like 5 of the thin black pieces, and 2 thick pieces... i was just thinking you could get a nice "custom" head gasket thickness but the the materials of the HKS.

 

[Suprafast0422]

Thanks for all the replies, id never heard of the rivet problem before. but what about the coolant passageways being blocked partially on the intake side?

 

[jdub]

but i have a question for you jdub, theoretically, could i remove the rivets, and take out the two steel pieces which make my hks 3mm so thick, and make it a thinner MHG? it has like 5 of the thin black pieces, and 2 thick pieces... i was just thinking you could get a nice "custom" head gasket thickness but the the materials of the HKS.

I've never done that, but don't see why it would not work...when you re-use a MHG, you do exactly the same thing. You remove the rivets, clean all the old viton off to bare metal, and re-spray with copper sealant to replace the viton.

You would want to remove center layers of the MHG, making sure the top/bottom layers are oriented correctly. Since this MHG is new, it should have a viton coating on the layers as well...no sealer needed. Place it on the block index pins to line it up. The block/deck surfaces still need to have a very smooth RA and be flat for it to seal correctly.

Can you get a couple pics of the coolant passages you're talking about?

 

[Suprafast0422]

Pics are np, ill put some up when i get home tonight.

 

[Poodles]

The rivet on the exhaust side is fine if the block/head hasn't been decked to the point where that part is level with the gasket surface.