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S/V/C zero compression cylinder 1

S

swiggy

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Joined
Jan 13, 2011
Location
Victoria, BC
Kind of cross-posted from OT, need to make this a proper maintenance question now.

So I bought a 1998 V70, N/A. The car ran great for 3 days, then I kind of beat on it a bit on the highway, nothing crazy but I definitely put my foot down, wanted to see what it could do.. It seemed to lose a bit of power, then when I pulled off the highway it was idling pretty rough, I thought it was running on 4 cylinders, and it was, pulling the first plug wire made no difference. Check engine light was flashing away at me. Scanned it (I got a scanner for $30 from princess auto) and it just had p0301, cylinder 1 misfire, which I knew already. It already had codes for EVAP and the secondary air system bull**** that everyone deletes.

It has zero compression on cylinder 1. Completely zero. I knew it was zero before I even read the gauge, I had all the plugs out and it was just freewheeling. Cylinder 2 hit 180 after 3 strokes, throttle closed. I ran out of time to do the rest, but based on the way it runs on 4 cylinders I guess they are fine, its surprisingly quick still. It seems like bubbles are coming up in the coolant overflow tank, and I have sprung a fairly big coolant leak somewhere around the power steering pump area. No evidence of blowby, the oil cap sucks closed with engine idling, i.e. there is crankcase vacuum.

I know its not a redblock but damn. I had it 3 days and probably burned a valve, or at least blew a HG. Bad luck or are these motors really that delicate? Its not even turbo, "beating on it" consisted of 5 mins above 4k rpm. I do still only have $400 into it, I can probably part it out and start again with something with a few less issues, I don't really want to sink lots of money into a non-turbo auto trans car..

I might just drive it on 4 cylinders for a while, it doesn't run that bad with the injector unplugged.

How bad is replacing a valve on these motors? Head gasket looks like a bit of a pain but I can deal with that, I don't want to throw $hundreds at a machine shop though, is it possible to replace valves yourself? I know its a common problem so somebody must have done it.
 
You are not helping anything. If yiu want to trash the engine even more it's your money down the drain :e-shrug:
 
I unplugged that injector, its not dumping fuel into the cat or washing down the cylinders, I don't see how driving it a little while on 4 cylinders is going to screw it up that much, seems to be a few people driving with a burnt valve for a while over on volvospeed from my googling. I was joking with the 100mph comment, I wouldn't admit to speeding on public roads on the internet...

I've found some valves locally, and also found a volvo enthusiast here who has replaced valves on whiteblocks themselves for guidance. So I think I'm going to have a crack at fixing it. Half the reason I am still driving it is because I wasn't convinced whether it was worth fixing a $400 car, or just buying another less roached example
 
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If it has 0, not even a bump, I would check for a seized lifter or broken valve spring. A burned valve or blown HG would at least bump a little usually.

Got my wagon for that very reason...diagnosis by the shop was blown HG. My test showed absolutely 0 bump on #2. Pulled the VC and found a custom 2-piece valve spring, but the retainer was still on it so no valve contact with the piston.
 
Yeah its dead zero. Gauge doesn't move. I hear a very tiny puff of air when I hit the reset button on the gauge, but it doesn't even move my gauge to 5 psi, I can blow with that much pressure. Pulling the valve cover is easy enough, thanks for the tip.
 
gsellstr said:
If it has 0, not even a bump, I would check for a seized lifter or broken valve spring. A burned valve or blown HG would at least bump a little usually.

Got my wagon for that very reason...diagnosis by the shop was blown HG. My test showed absolutely 0 bump on #2. Pulled the VC and found a custom 2-piece valve spring, but the retainer was still on it so no valve contact with the piston.
Click to expand...

I agree. Probably pumped up a "lash adjuster" while playing with the rev limiter.
 
swiggy said:
I would hear it if it had dropped a valve into the piston right? No nasty noises coming from it..
Click to expand...

Yeah, that would be a whole different story. It would sound awful.

My guess is that the valve stem seals have been leaking for a while so there's some carbon built up on the back of the exhaust valves. Sometimes that crud prevents a valve from sealing right and if something causes detonation and/or high EGTs it'll cause a piece of the valve to chip off. It wouldn't hurt to check the valvetrain but sudden, constant misfire codes and zero compression on whiteblocks is almost always a symptom of a burnt/chipped valve.
 
Stop driving the car. Fix the problem. You can only make things worse by beating on a motor with a dead cyl.
 
How ugly does it look when you pull the oil filler cap? Can you see bare aluminum, or is it coked with years of abuse and lack of oil changes/poor oil?

If it's coked up, I'd still vote for a seized lash adjuster which isn't uncommon on these things. Seafoam in the crankcase or the old ATF trick may loosen it back up.

Definitely quite beating on it though until you figure out what the issue is and resolve it.
 
The 850 engines I've worked on with burned valves still had some compression, it wasn't at 0. If it did burn a valve check for tears in the intake boot after the AMM, incorrect a/f ratio will burn a valve up in those motors.
 
^^^^ is my thinking regarding a burned valve as well, unless it took out a huge chunk. Hell, pull the spark plug, put some compressed air in, and see if it all leaks out thru the intake or the exhaust for a starting point. If it comes out the intake, pull the intake manifold, see if both valves are open or just one. Just one is spring or HLA, both open with the cam up, well, something else ain't right and the cam cover should come off.
 
I'd run a leak down test first- determine where all the pressure is leaking to.

My xc90 ingested its PCV valve last weekend. It bent all of the valves on the #3 cylinder, but I still had 60PSI pressure in that cylinder.

Leak down test- see whats happening. Then go from there.

Also, any damage is likely already done. Disconnecting the fuel and running it is unlikely to cause further damage.

Jordan
 
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