low compression in 1 cylinder after head gasket replacement

[koabi.brooks at gmail.com (Koabi Brooks)]

Is it possible that the improper installation of the cam cap somehow bent
the cam so the valve is sticking open?

On 11/2/07, T. Reed <tereed2@xxxxxxxxx> wrote:
>
> Hey guys,
>
> I changed the head gasket in my 16v during this past week. After getting
> it all put back together, I did a compression test.
>
> All cylinders were ~180 psi except for #3 which was zero (!). Actually, #1
> was zero as well the first 4 times I checked it, then it shot up to 180
> psi on the fifth check. I have no idea why. At first I thought the
> compression tester was faulty since it's new and its from Harbor Freight,
> but #3 consistently measured very low, and #1, #2, and #4 were ~180 psi,
> as I moved the tester back and forth between cylinders.
>
> I added some oil and #3 still came out as zero, but after I turned over
> the motor with the starter some more and tested again it went up to 35
> psi.
>
> The head was resurfaced before being reinstalled. The shop said they took
> 6/1000ths off. They also put one of my intake cam bearing caps on
> backwards.. I'm not very happy about that. I fixed it before re-installing
> the head.
>
> What could be causing this low compression? As I see it, its either valves
> not closing, or stuck rings. New head gasket, new bolts.. shop said my
> valves leak "a tiny amount" but nothing to worry about.
>
> The head gasket failure was between cylinder #3 and a coolant passage. It
> doesn't seem like a coincidence to me that this is the same cylinder
> giving me low compression. I searched around and found some people
> claiming a connection between a bad head gasket and stuck rings, due to
> coolant getting in to the cylinder. I don't know how to diagnose this, or
> how to solve it, though. Any tips would be appreciated.
>
> I scraped the carbon buildup off the top of the pistons in order to
> ensure valve clearance after the resurfacing, but I didn't do this to
> the cylinder in question (#3) because it was already shiny clean..
> probably from burning antifreeze.
>
> The head was jet washed before resurfacing, but this didn't take 100% of
> the carbon off the underside of the cylinders.. there were a couple of
> black patches left over. I suppose its possible that there's a similar
> deposit between a valve and the head, and its leaking there.
>
>
> Long story short, I decided to try starting it since if something is
> busted I'm sure I'll be unlucky enough to have to take it apart again
> anyway. I'm down on my car luck lately..
>
> It started right away and sounds strong except for the fact that its only
> going on 3 cylinders. If I pull the plug wire for cylinder #3, there is no
> change in the sound.
>
> Any ideas? This is my only vehicle. I've been bumming rides to and from
> work all week, and I'm really up a creek here if I can't get it driveable
> soon.
>
> -Toby
>
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