Cometics are leaking
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Cometics are leaking I filled my car up with coolant wednesday evening and pushed it back under the garage. I went back out thursady for the initial cranking and noticed a small puddle under each of the headers and a few drips of coolant hanging from the header. I figured it was just a loose hose and I would find it when the system pressurized. The car fired up with no problems and I let it run for a few minutes. Then retired it for the evening. Today I brought home a cap pressure tester from work and pressurized the system to 15lbs. After dropping the headers, I found both sides to be leaking between the middle cylinders where the block meets the head. Both the block and the heads were brand new, and I took all precautionary measures when installing because I've heard the horror stories before. I'm not even sure if re-torquing will help because it's leaking with 0 pressure on the system. It seems that something would have to be surfaced wrong since it is in the same place on both sides. I wondering if the block or the heads have bad spots in them? I used ARP studs and cometic gaskets with no extra sealent and torqued to ARP spec with there lube. Any idea on what might have caused it? 
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The motor is brand new, so there was no water in the holes. I'm now thinking that it is either the block surface or the head surface that is out of line. Even if the heads were torqued complete off sequence, which they weren't, they shouldn't leak at 0psi. I was thorughly meticulus in this process of installing the studs and gaskets. I had read to many posts about someone doing something wrong. I probably took more time and was way more thourough than any proffesional would have been. Looks like it's gunna be off with the heads tommorow.
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Verdad Gallardo Dude, try the sealant tabs, or "cadillac pills" as they are sometimes called. My cometics leaked as soon as I put water in, and just like you this was a complete new motor. I added the seal tabs and no leaks, almost 2 years now. What do you have to lose? This is actually a very common problem and cure.
It might be related to the finish left on the block and/or head deck....It is very critical with Cometic gaskets to have a smooth finish. If your nail can grab anything pulling it across the finish you are sunk....they will leak. Cometics are not like a Felpro which has a lot more conformability. When we mill the AFR LS heads here at the factory we use a slow pass at the end and only remove a few thou of material to leave a very smooth last cut. Surface finish is just as critical on the block if for some reason you had it decked. Barring that, you probaby have a slightly warped head or block deck that might need truing up....
Good luck....bummer you have to pull the heads again.
Tony M.
Good luck....bummer you have to pull the heads again.
Tony M.
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TS6, what is a sealant tab? Is it something like a stop leak that you run through the radiator? Tony, thanks for the info. It's because of post like that that I was so careful when installing them. The Block was brand new, so I doubt it was decked. The heads I assume were finished at TEA and not AFR since they were bought as bare castings. If the system wasn't leaking at zero psi, I might try the sealent tabs, but I could just see my first pass on the 200 shot. I don't think it would be pretty. I already have half of the drivers side apart from looking, so it should take me about another hour and a half to get the head off. I'm going to assume that whatever is wrong on one side is wrong on the other since they are both leaking in the same spot. I'll report back in a bit..........
i'm getting ready to do this also cometics and new heads.after i scrape the graphite off is it ok to finish up with a scotchbrite pad to the block surface?
Last edited by Z06 Steve; May 7, 2005 at 01:47 PM.
Ive had a rough cut set of heads before, and as Tony mentioned, if its not as smooth as the factory finish, it will leak.
Dont use a ceramic "block sealant" or something of that nature as it will cause you more of a headache later on down the road. Just look for some radiator stopleak, and that should solve it.
Dont use a ceramic "block sealant" or something of that nature as it will cause you more of a headache later on down the road. Just look for some radiator stopleak, and that should solve it.
Stop leak might solve it, but if your **** like I am you will want to fix it for piece of mind at least. I had no problems with ARP's an Cometics on mine, but I feel your pain, it sucks to pull it all apart just when you think your all done..
Dan
Dan
Originally Posted by jrp
did you install the gaskets with the little tabs the right side up or down per the directions.
My Grand National runs cometics, block and heads were surfaced properly, and as soon as I put water in it leaked, even before the car was started. I thought I was sunk too, but after hearing many people having the exact same problem and using the seal tabs with good luck, I tried it, and its been working fine. I assure you, you will never put the stress on the head gaskets like my Gn does at 27 psi, don't even worry about it.
The tabs I speak of are made by GM, any dealer will have them, and they are only a couple bucks. I'd put 2 tabs in and check it out after running a bit. You're only out $2 and a few minutes if it doesn't work. I'm telling you, this is more common than you think. You might take it all back apart and have the heads and or block resurfaced and still have this problem. Then you will be more pissed!
The tabs I speak of are made by GM, any dealer will have them, and they are only a couple bucks. I'd put 2 tabs in and check it out after running a bit. You're only out $2 and a few minutes if it doesn't work. I'm telling you, this is more common than you think. You might take it all back apart and have the heads and or block resurfaced and still have this problem. Then you will be more pissed!
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Well, I pulled it apart and didn't find anything. Both the heads and the block look perfect. As far as the gaskets being upside down, they are the same on both sides, so how could one way or the other hurt? I could understand if the rivets made there way inbetween the block and head, but they weren't, so that shouldn't be of concern. Anyone with instuctions care to fill me in on if there is a right side up or down on these? Other than that, all i can do is put it back together and try these seal tabs from the dealer.
my cometics and arps leaked like a siv.. i put it together,started it up and it was leaking..i was so pissed..i followed all the correct procedures..i just yanked the heads off in anger.. bought some stocker gaskets,cinched them up and havent had a bit of problems since, nitrous and all 