Cracked head or cracked block? Technical advice anyone?
02-25-2007, 05:43 PM
#1
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Cracked head or cracked block? Technical advice anyone?
Here's the quick rundown of the situation:
The car is missing on cold start (3rd cyl) and under heavy boost and it's losing coolant out the exhaust (smoke/steam). It had gotten to the point where coolant needed to be topped up every 45 minutes of driving or so and the 3rd cyl's spark plug was slightly dis-colored from the rest. A compression test showed low results, but all relatively even across all 5 cylinders. In the intake runner (within the head) to the 3rd cyl there was a lot of black gunk built up. All spark and fuel related issues have been positively eliminated. The head has been removed and pressure tested/dye tested, but it came up clean. The headgasket didn't look so hot when the head was removed, but not especially bad around the 3rd cylinder.
Does anyone have some thoughts/suggestions/tests?<ul><li><a href="http://www.motorgeek.com/phpBB2/viewtopic.php?p=171774#171774">http://www.motorgeek.com/phpBB2/viewtopic.php?p=171774#171774</a</li></ul>
The car is missing on cold start (3rd cyl) and under heavy boost and it's losing coolant out the exhaust (smoke/steam). It had gotten to the point where coolant needed to be topped up every 45 minutes of driving or so and the 3rd cyl's spark plug was slightly dis-colored from the rest. A compression test showed low results, but all relatively even across all 5 cylinders. In the intake runner (within the head) to the 3rd cyl there was a lot of black gunk built up. All spark and fuel related issues have been positively eliminated. The head has been removed and pressure tested/dye tested, but it came up clean. The headgasket didn't look so hot when the head was removed, but not especially bad around the 3rd cylinder.
Does anyone have some thoughts/suggestions/tests?<ul><li><a href="http://www.motorgeek.com/phpBB2/viewtopic.php?p=171774#171774">http://www.motorgeek.com/phpBB2/viewtopic.php?p=171774#171774</a</li></ul>
^^^
02-25-2007, 11:10 PM
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Re: ^^^ Nicest **** on these boards. :) ^^^
Thanks Corey, that's just how people are in this community, (as least all I've met) I just know the spot you're in right now...it is no fun 
02-26-2007, 04:09 AM
#6
Oh ! Just occured to me - did you re-torque the Head after installing ARP Studs ?
I see you have a multi-layer metal and ARP studs - from 034 right ?
They do loosen after heat cycle and you have to re-torque them or they loosen and eventually back-out -> leaks
I did mine a couple of times
They do loosen after heat cycle and you have to re-torque them or they loosen and eventually back-out -> leaks
I did mine a couple of times
02-26-2007, 05:04 AM
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We actually haven't reinstalled the head w/ the new gasket and studs yet.
The car will miss on the 3rd cyl on cold start and it also misses in high boost. After a period of a minute or so, the car will start running on all 5 cyl's (until you start getting the boost up there).
We didn't want to reinstall the head (yet) without making sure it was crack free/good to use. I don't know why it or the block would've cracked... but without having any other reason for that black gunk buildup in the 3rd cyl's intake runner (in the head), I don't know what else it could be.
We didn't want to reinstall the head (yet) without making sure it was crack free/good to use. I don't know why it or the block would've cracked... but without having any other reason for that black gunk buildup in the 3rd cyl's intake runner (in the head), I don't know what else it could be.
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02-26-2007, 08:06 AM
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So I talked it over today and took a look at the gasket in person...
Right now I'm thinking that the gas mixed with the coolant while the cylinder was mis-firing on cold start, causing the buildup of coolant/gas to "splash" within the cylinder and in turn go into the intake runner of the head, which is where I think the browny/black crap (just as Steve posted) all of the runner is coming from. After seeing the headgasket in person, it does look possible that it was the cause of the coolant leak into that cyl... so I think I'm just going to have my current head built up and rebuilt and take a good close look at the cylinder walls... if all checks out, replace the headgasket with the CP reducing one and cross my fingers. (I'm going to regret this choice later, aren't I Tom...)