Cometic HG Failure

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project-c2
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Post by project-c2 »

Totally had the same problem TWICE. It also blew between the cylinder 1 and 2. Went Felpro, never had a problem.
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Post by TryingToTurbo »

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Mine did this on 3 and 4. 4 was the worst but still not nearly as bad as yours.
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Rick
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Post by Rick »

I ran an o-ringed block with a stock HG for quite a long time. It wasnt until I replaced the stock HG for another stock HG that I started having problems. I traced it back to the fire ring in the stock HG seemingly was getting made out of harder metal than previously and the o-ring wouldnt bite into it. I ended up filing the o-ring down, and using a Cometic HG with ARP studs and never had an issue again.

Just my 2 cents.

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Post by kacam24det »

Where I live there is a car builder Troy Trepainer. His business is call Rad Rides by Troy runs twin turbo motors pushing 35 psi in ls6 and ls7 and ls9 all using cometic HG. I called them to see if they would set my block and head up for a o-ring and copper HG he said to me, I run 35 psi on an ls7 for over two years with no issues. If he is making that happen with no problems I think something happened during assembly or something of that sort. Or contamination IDK just my opinion.
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Post by supakat »

It is most likely when the head lifts, this happens.
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TryingToTurbo
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Post by TryingToTurbo »

supakat wrote:It is most likely when the head lifts, this happens.
Agreed.
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Post by CINCYS13 »

Well I guess Ill welcome myself to the group of fu*k you cometic. car was on the road a solid 5 days almost 900 miles conservative tune 330whp on 9lbs. started to notice smoke coming through the air vents under boost. so Being i have a jeep thats known for blowing out heater cores I think I know whats going on.. Well I then thought there isnt any residue on the windows from the coolant. 2 days go by and i noticed the car is running lean and not holding boost, I check the oil and everything is fine there thinking im gonna see water in the oil, I then look over at my over flow and see the coolant isnt that bright green anymore either, I then start to come to the thought is it possible the gasket really popped already? I look at the back of the motor turbo side and see the top of the block is wet. I put my hand back at the valve cover hoping it to be wet and just bad. Nope starts at the bottom of the head and when it cooled down and I looked in the Radiator you could see the oil in there also. ugh ok im done venting Ill keep you guys updated. gonna order a cosworth and I guess try out the ARP 202-4304 head bolts supposed to be a little more bite then the standard 10mm

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kacam24det
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Post by kacam24det »

I am super surprised that there are so many problems with these HG. Did you guys use the copper spray?....Is the block and the head machined to a polished finish the only cometic I have blown was due to me blowing a coolant hose. I just am having a hard time understanding it.
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Post by airman »

I haven't chimed in on this yet but I had a similar failure with my Cometic. I attributed it to debris from blown rings but it looks just like what supakat and TTT have posted. I had both block and head decked to the right polish and used copper spray.
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Post by kacam24det »

well looks like im selling my cometic and heading over to cosworth i have had good luck with them but now I am expecting the worst. I've used them on ls1 motors that were turboed so many times. But i dont want to risk my new motor for an extra 100 bucks ill use the cosworth now
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Post by TryingToTurbo »

airman wrote:I haven't chimed in on this yet but I had a similar failure with my Cometic. I attributed it to debris from blown rings but it looks just like what supakat and TTT have posted. I had both block and head decked to the right polish and used copper spray.
I had everything machined to the proper roughness, including the timing covers. Also used copper spray.
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kacam24det
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Post by kacam24det »

So you guys are all going cosworth here is my question I can only find 90.5mm bore HG and my motor is only a 89.5mm bore is this just what you run for all setups?....And what about thickness
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Post by jholman05 »

I really wish I would have saw this earlier... as I was trying to find some information on recommended torque specs for the Cosworth head gasket I ran across a promotion cosworth is doing. I ran through there cart all the way to the payment and it was still just

$110 Shipped for a Cosworth head gasket!

:shock:

Wish I would have saw this a month or so ago, I would have saved $50.

Unfortunetly this was a scam, sorry everybody.
Last edited by jholman05 on Tue Apr 30, 2013 6:39 pm, edited 1 time in total.
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2012 - S14 KA, Nismotronic, GTi-R T28 12psi, Meth, PSM HMIC, DW550cc, N62, S15 HLSD, Spec 3, Fidanza = 12.4 @ 110
2013 - 9.0 Wiseco/Manley, Nismotronic, GT2876R 23psi, Meth, PSM HMIC, 850cc, N62, S15 HLSD, Z32 Spec 3, D21 Fidanza = ??.? @ ??? 440whp/380wtq
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airman
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Post by airman »

Hot damn. Just ordered a 1.5mm gasket. 90.5mm but I figured that's the only size they got. I won't need it until next year probably haha but figured I'd get it before they get gone especially if they stop distributing in the US like they say.
R.I.P. 1990 Red Hatch - DOHC 5 speed // CP 9:1 - Eagle Rods - Clevite - ARP // Holset HX35 - 20psi daily - MSPNP2
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Post by jholman05 »

Good deal! They have all three sizes listed there, 1.1 and 1.5 are $110, 1.8 is $116.

Hope this helps some others.
Image
2012 - S14 KA, Nismotronic, GTi-R T28 12psi, Meth, PSM HMIC, DW550cc, N62, S15 HLSD, Spec 3, Fidanza = 12.4 @ 110
2013 - 9.0 Wiseco/Manley, Nismotronic, GT2876R 23psi, Meth, PSM HMIC, 850cc, N62, S15 HLSD, Z32 Spec 3, D21 Fidanza = ??.? @ ??? 440whp/380wtq
YouTube Channel -> http://goo.gl/MZ5EE
mewantkouki
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Post by mewantkouki »

^ That is a credit card fraud scam. I tried to buy one and got a charge for $350 to radioshack.com from a nigerian... Did anyone even get a HG or was it just me that got *****?
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Post by adamky »

I placed an order and got screwed as well. Tried to charge me $350 on kroger.com, or something like that. Luckily my bank caught it.
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jholman05
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Post by jholman05 »

****... looked legit, I'm going to edit out that link then. Sorry guys :cry:
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2012 - S14 KA, Nismotronic, GTi-R T28 12psi, Meth, PSM HMIC, DW550cc, N62, S15 HLSD, Spec 3, Fidanza = 12.4 @ 110
2013 - 9.0 Wiseco/Manley, Nismotronic, GT2876R 23psi, Meth, PSM HMIC, 850cc, N62, S15 HLSD, Z32 Spec 3, D21 Fidanza = ??.? @ ??? 440whp/380wtq
YouTube Channel -> http://goo.gl/MZ5EE
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Post by adamky »

It's all good. It sure looked legit. Several other people posted it other than you.
Wiseco/Eagle, JWT S1 cams, BC valve springs, PT5857, ID1700 injectors, SR20DET ECU w/ Nismotronic, COP conversion with LS ignition coils, etc, etc...
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Post by Kamilitaryman »

I wish I could catch the culprit, choke him until his eyes popped out of his ***** sockets. ***** scumbags.
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chillmieste
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Re: Cometic HG Failure

Post by chillmieste »

so supa which route did you end up going?? did u have to machine your block and head again? use copper spray? was the cosworth 90.5mm work ok, if u used that one? just curious ready to put mine on just unsure of which route to go
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Re: Cometic HG Failure

Post by supakat »

Cosworth. I did not machine the head or block. No copper spray. Yes, 90.5 was what I used. 1.1mm thickness.
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