3.0 cylinder base gaskets, use sealant or not

[Luke M]

I've just installed all of the cylinders on a 3.0 . I had to use two different thickness cylinder base shims to get the cylinder deck height correct. My question is, should I use sealant on these shims prior to installing the heads/cam towers ? I would use the loctite 574 sealant on these.


TIA

[Tyson Schmidt]

I'm sure you'll get many answers, but I'll put in my two cents.

I use a very thin layer of Curil-T on both sides of the copper gasket. But it's perfectly acceptable to install them dry.

I would NOT use 574, as it harden. With all the expanding and contracting going on there, that can lead to cracking and flaking of the hardened 574 down the road. I've seen it on motors I've disassembled.

[Trackrash]

Dry is fine, as long as everything is perfectly flat, clean and smooth.

A thin layer of Yamaha bond or similar would not hurt.

[Eagledriver]

Using different thickness gaskets sends up a red flag. If you mean one thickness on the left bank and another on the right, then that’s ok. If you used different thickness on cylinders next to each other, then you will have a problem with not putting the cams in a bind when you put the heads and cam towers on. Tyson as usual offers spot on advice.

-Andy

[Alan L]

You can do them dry, I have used some loctite master gasket on them. They are only sealing the crankcase pressure - but you don't want any weepage. PITA. So I use a bit of gasket gunk as insurance.
But as stated above - you better clarify about using different gasket mixes on cylinders.
Alan

[Luke M]

[QUOTE=Tyson Schmidt;9968532]I'm sure you'll get many answers, but I'll put in my two cents.

I use a very thin layer of Curil-T on both sides of the copper gasket. But it's perfectly acceptable to install them dry.

I would NOT use 574, as it harden. With all the expanding and contracting going on there, that can lead to cracking and flaking of the hardened 574 down the road. I've seen it on motors I've disassembled.


I forgot the 574 hardens so I'll use the Curil-T which I have on hand.
Both sides of the engine got the same thickness/amount of cylinder gaskets/shims.
I would hate to have a cylinder base gasket leak that's why I asked the question.
IIRC, when I did my 2.7 I ended up installing them dry but only used one base gasket on that build.

Thanks,

[lvporschepilot]

IF you must use some sort of Loctite product on them, 515 has more flexibility and tensile strength than 574, and 515 smells and looks like grape jelly (added bonus). Use 515 if you're bent on using something of that nature that 'cures', otherwise a bit of Curil-T is how I'd go. Curil-T never dries, just expands and contracts with the copper base gaskets.

[Trackrash]

Curl T is great for gaskets that will be changed occasionally. It won't last as long as the motor between overhauls. AHIK

[Luke M]

Originally Posted by lvporschepilot

IF you must use some sort of Loctite product on them, 515 has more flexibility and tensile strength than 574, and 515 smells and looks like grape jelly (added bonus). Use 515 if you're bent on using something of that nature that 'cures', otherwise a bit of Curil-T is how I'd go. Curil-T never dries, just expands and contracts with the copper base gaskets.

I'm Not set on using a Loctite product but I do have some 515 on hand too.
Just want to use a product that lasts a while. This is not a race motor so I plan to get as many miles out of it as I can. I'm gonna try to get this work done next week so I have a few days to figure this out.

[Eagledriver]

Don’t use sealants that harden here. You can’t get the heads and cam towers all tightened up before it sets so you end up with the cylinders at different heights. Also as Tyson said, the sealant will be damaged when you torque the heads.

-Andy

[Jeff Alton]

We use Curil T as well on all of our builds, never had a leak.

Cheers

[Trackrash]

Originally Posted by Eagledriver

Don’t use sealants that harden here. You can’t get the heads and cam towers all tightened up before it sets so you end up with the cylinders at different heights. Also as Tyson said, the sealant will be damaged when you torque the heads.

-Andy

What I have done with success is to put a very thin coating of Yamaha bond on both sides of the gasket. As soon as I install the cylinder I use nuts to tightly hold the cylinder in place. What I want the sealant to do is fill any small imperfections in the case, gaskets or cylinders.

I agree if you put a lot of sealant there, you are wasting your time.

BTW, once upon a time I followed an experienced Porsche mechanic who recommended CurlT on my rebuild. It eventually seeped in all the places where it didn't also have a fiber gasket. YMMV.

[lvporschepilot]

Originally Posted by Luke M

I'm Not set on using a Loctite product but I do have some 515 on hand too.
Just want to use a product that lasts a while. This is not a race motor so I plan to get as many miles out of it as I can. I'm gonna try to get this work done next week so I have a few days to figure this out.

In the end there remain many different methods from several very experienced mechanics, who all swear by their way as being the only way. The guys at Mittelmotor use nothing on these base rings and absolutely swear by it, and they build more RSR stuff than anyone on the planet not to mention holding the record for most bhp from a naturally aspirated 3L 911 motor. Quite literally, to each their own.

[Jeff Alton]

^^^^^ This.... When a shop/builder finds a system that yields repeatable results in sealing, they generally don't try other solutions unless an issue arises. This means there are many good solutions out there as noted above.

Years ago we started with nothing and never had an issue. Then after lots of research decided a little Curil T would be good insurance. The base gasket, by design, is malleable enough to compensate for minor irregularity in the sealing surfaces.

Cheers

[VFR750]

Just pulled my cylinders off after two years and 6000 miles. And the Curil-T was still there, and I did not have any leaks. I think it acts as a second barrier. Will use it again.

[billybek]

Curious as to why you are tearing down after only 6000 miles? Race motor?

[VFR750]

Bigger cam. Just for the fun of it.