[RomperRu]

01 H6 Outback, just died last week. Nimrod chevy mechanic tore off crank cover: timing chains, guides and tensions look great, timing in sync. Ran compression tests in all 6 cyl, with cover off, got some pretty low numbers on the the driver side.
Buttoned it all back up, check plugs for fire; thier good.
Changed out fuel pump, didnt look too close at the O-ring (may have to pull it out again).
Engine will fire when the air intake is blocked (piece of cardboard over it), but not on all cyl and dies as soon as it gets air.
At only 180K I find it hard to believe that I threw a valve or a set of rings. I've been the only onwer and have been relgious on maintainence.
Any input or ideas would be appreciated.

 

[4wheeldog]

Blocking the air would not correct bent valves. Look for a big air leak (Intake manifold, loose throttle body, hose blown off etc.) or lack of fuel.

How low was the compression? Did you do the test with the throttle wide open? If not, the side with more compression is probably where your air leak is. Good luck.....

 

[1 Lucky Texan]

vacuum gauge test might help.

check fuel pressure and flow - maybe clogged fuel filter?

def. recheck the fuel pump cap.

some folks say the exhaust valves need adjustment around 200K, dunno if that could fit the symptoms though.

 

[RomperRu]

Fuel filter replaced too. Even with filter and pump replaced, still isnt spewing out fuel; will look at that O-ring again.
Yes compression checked with throttle open, got as low as 60 on #1 on driver side; again this was with the crank cover off. Attached 100psi air line too, could hear the air in the block, but didn't have the exhaust detached to check the manifold. Throttle body looks good, all vaccum lines look good as well.

 

[CNY_Dave]

Low compression can result if the cylinder has been flooded, the rings on this critter don't seal for crap w/o a little oil!

More than one person has diagnosed a bad set of rings due to a leaky injector.

 

[1 Lucky Texan]

^^^ good point, repeated non-start crankings will 'wash-down' the cylinder and yield low readings. Particularly worse when the engine is cold as the ECU assumes a cold-weather 'choke' setting for the injectors.

 

[4wheeldog]

Low compression can result if the cylinder has been flooded, the rings on this critter don't seal for crap w/o a little oil!

More than one person has diagnosed a bad set of rings due to a leaky injector.

Yeahbutt.......He says he DID get it running, although not well. The cylinders should have cleared, oil gotten back where it belongs, if it fired up. I am still putting my money on a hose getting blown off by a pop in the intake manifold.

 

[CNY_Dave]

I wasn't sure where in the sequence of events the compression test took place.

 

[RomperRu]

I haven't repeated compression tests with the block buttoned up (meaning crank case cover on and sealed:bolt sequence on that was a pain in itself)
I plan to recheck fuel pump components and will look to the manifold for leaks.
I'm guessing that I could use a bore scope through the plugs to visulize the rings verses pulling the heads correct?
I thank you all for your input and helping to steer me in my next steps.

 

[4wheeldog]

I haven't repeated compression tests with the block buttoned up (meaning crank case cover on and sealed:bolt sequence on that was a pain in itself)
I plan to recheck fuel pump components and will look to the manifold for leaks.
I'm guessing that I could use a bore scope through the plugs to visulize the rings verses pulling the heads correct?
I thank you all for your input and helping to steer me in my next steps.

A borescope will show you any damage broken rings have done to the cylinder walls, but you will not be able to see the rings themselves, nor be able to diagnose worn or failed rings.

Standard way to separate bad rings from leaky valves is to do a "Wet" compression test. (It doesn't work as well with a boxer). Shoot a couple of teaspoons of oil in the suspect cylinders, and do the compression check again. If it is valves, reading will only come up marginally. If it is rings, the oil will temporarily seal them, and you will get near normal readings.

The better test is to do a leak down test. A fitting is screwed in place of the spark plug, and 80 lbs of air is applied. Then, you can listen to the tailpipe/intake/oil fill and tell where the air is going.

But I am betting that the mechanicals are OK, and you have a huge source of air into the intake. Good luck.