Had a set of gaskets that were leaking, they sent a new set and I returned mine. They said they didn't see anything defective in the gasket, but gave me the benefit of the doubt and are refunding my money for the new ones. Basically, the old ones leaked, the new ones don't, so there is something there. He did say it looked like one of the surfaces is a little too rough, one face of each gasket showed signs of this. The heads were fresh from MTI, and I gently used a razor blade and carb cleaner on the block. Both seemed very smooth after, but who knows. It seems to be sealing fine now, so hopefully if something is a tad too rough it won't rear its ugly head again. I guess if I decide to S/C this year I'll find out!

It is great to see some companies still put the customer first!

-Dave

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 1dirtyZ:
<strong> make sure you torque them down well ! </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I was very ****, with arp studs (in the Helms order):

First pass to 20lbs
Second pass to 40lbs
Third pass to 70lbs
4th pass to 70 again
5th pass to 70 again.

No budging on the final pass. Hoping it holds!

-Dave

 

We had to do the last car 5 times to get them to seal.We let it sit for 15-20 minutes in between torqing.

 

make sure you torque them down well !

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Slowhawk:
<strong> We had to do the last car 5 times to get them to seal.We let it sit for 15-20 minutes in between torqing. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yeah I actually made a 6th pass the next morning, but they didn't budge at that point at all. Cometic says both the block and head have to be ultra-smooth for them to seal well, hopefully mine are good enough, the heads are surfaced from MTI and I cleaned the block up pretty well. Don't appear to have any leaks, oil cap is dry as a bone and coolant level hasn't budged in about 300 miles.

-Dave

 

Excellent <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

 

Try the stock multilayer head gaskets. I'm not sure why you are praising cometic. You had freshly resurfaced heads, did a proper install, and they leaked.

 

The Cometic gaskets are horribly designed and will leak 90% of the time regardless of how well you surface the heads and/or use a sealant spray.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by NastyC5:
<strong> The Cometic gaskets are horribly designed and will leak 90% of the time regardless of how well you surface the heads and/or use a sealant spray. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">They said they can guarantee they'll leak if you use a sealant spray, it stops the gasket from slight movements when necessary. I used the cometics because I plan to add a blower next year, haven't heard any yays or nays about the GM MLS ones.... if I have more problems I won't be sticking with cometic, but I appreciate them standing behind the product regardless.

-Dave

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 2001 LS1 SS:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by NastyC5:
<strong> The Cometic gaskets are horribly designed and will leak 90% of the time regardless of how well you surface the heads and/or use a sealant spray. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">They said they can guarantee they'll leak if you use a sealant spray, it stops the gasket from slight movements when necessary. I used the cometics because I plan to add a blower next year, haven't heard any yays or nays about the GM MLS ones.... if I have more problems I won't be sticking with cometic, but I appreciate them standing behind the product regardless.

-Dave </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Trust me, they'll leak even if you don't use the spray. I have a buddy who installed these on his C5 with his H/C setup and he took the heads off about 5 times due to a leak, did the spray, all the of the things the tuner told him and it still leaked. He measured the Cometics and the way they are designed/made, they'll never seal. Let me get the link for you explaining it all.

 

Here's what my buddy, Buckshot, found:

"Be careful with the Cometics. I put a set on with my 5.3l heads along with the ARP studs (thank goodness for studs!). I won't go into all the dtails here but one of the Cometics had a persistent leak (3 times) - even after swapping the gasket on the chance that the first was bad. The leak was on the outside-front passenger head.

After a LOT of work and analysis, I discovered that the perimeter-sealing configuration of the gasket would not work on my passenger-side head. The Cometic counts on the rough cast shape of the head on the corner to conform to a .090" raised land along the perimeter to seal. No go. I even tried K&W Copper-Coat sealant on the advice of the tuner I bought the h/c and gaskets from. The gasket stuck out .118 from the head at the corner with both Cometics I tried.

The first 2 leaks I had were coolant. The third was oil. That's another thing - the oil drain galleys in the heads are not sealed off like in the stock gaskets so the sealant stopped the coolant but allowed oil through.

It was a frustrating but educational process. Ultimately I went with '97-'00 composite gaskets due to the relief in the head at the #6 cylinder, although I would have gone with the newer MLS stockers if I could have - they appear to be quite good.

The Cometics are beautiful and I'm sure quite good when no sealing issues like mine exist. But I'm getting credit back for them from the tuner and we put stockers on my buddy's also when we did his h/c last weekend because of this potential problem. He's returning his unopened."

YOu can refer to this link: https://ls1tech.com/ubb/cgi-bin/ulti...c;f=1;t=009639

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by NastyC5:
<strong> Here's what my buddy, Buckshot, found:

"Be careful with the Cometics. I put a set on with my 5.3l heads along with the ARP studs (thank goodness for studs!). I won't go into all the dtails here but one of the Cometics had a persistent leak (3 times) - even after swapping the gasket on the chance that the first was bad. The leak was on the outside-front passenger head.

After a LOT of work and analysis, I discovered that the perimeter-sealing configuration of the gasket would not work on my passenger-side head. The Cometic counts on the rough cast shape of the head on the corner to conform to a .090" raised land along the perimeter to seal. No go. I even tried K&W Copper-Coat sealant on the advice of the tuner I bought the h/c and gaskets from. The gasket stuck out .118 from the head at the corner with both Cometics I tried.

The first 2 leaks I had were coolant. The third was oil. That's another thing - the oil drain galleys in the heads are not sealed off like in the stock gaskets so the sealant stopped the coolant but allowed oil through.

It was a frustrating but educational process. Ultimately I went with '97-'00 composite gaskets due to the relief in the head at the #6 cylinder, although I would have gone with the newer MLS stockers if I could have - they appear to be quite good.

The Cometics are beautiful and I'm sure quite good when no sealing issues like mine exist. But I'm getting credit back for them from the tuner and we put stockers on my buddy's also when we did his h/c last weekend because of this potential problem. He's returning his unopened."

YOu can refer to this link: https://ls1tech.com/ubb/cgi-bin/ulti...c;f=1;t=009639 </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">That sounds like an incompatibility, they have a list of heads and years that the gaskets won't work with, most of them have a "notch" that interferes with the gasket. I'm using same year 5.7L heads. My leak was internal, not external. Time will tell I guess.

-Dave