Just for the halibut, give each cylinder a few squirts of oil and see if the numbers improve, #6 could have been a bad reading (you hope). Bob
I know nothing other than the number given to me by phone. It's the zero that bugs me most. Just going to have to couch them along with the usual things to do.
What did the other bank test out at ? I had similar readings on a sbc one time, one cylinder was also zero. Turned out the motor was running way rich and the valves were carboned up so bad they were not seating. Do the oil into the cylinder routine, at least that will tell you if it is rings or not. Don
The readings are there Don. I had them separated but they got bunched up on the posting. I do like the carbon build up. Will see.
The best way to find the problem is to use a leak down test. that will tell you where the problem is on the first try; valves, rings, gasket. It is not as easy to do as a compression test. and it usually requires a second person to help. It is the best troubleshooting tool for that problem.
on #6 you can just put compressed air in the cylinder and listen for where the air goes, make sure both valves are closed.
Ya, like in, it's not my car, I've never seen it, only that these are the readings they got from a repair shop.
Like AZbent said ......get a dual gage leakdown tester. Make sure both valves are on their seats (closed) air up the cylinder to, say 100 psi on the inlet side. Read your leakage on the other side if it reads 90, thats 10% leakage if it reads 25, thats 75% leakage. Anything over 10% is not good, although if they are all at 10% its still a decent used engine. A decent used engine will show pretty consistent readings on all cyls. (only varying by a few percent).
i would still pop off a valve cover and look at the rockers/valves. with 0 PSI i bet a valve is stuck open
Kinda like a flow bench...an 8 cyl one. just hold on to that crankshaft when putting the air to it...
That's where you come in. By the way, Thanks everyone for all possible things it can be. Back to the ? You listen in these places. Bad intake valve.....You will hear air go by either at the carb or if intake is off the intake runner. Bad exhaust valve.....You will hear air coming out the tail pipe or if ex. manifold is off, the ex. runner. Ring's or hole in Piston.....You will hear air coming from the crank case either oil filler tube or any opening that you can get at that's open to the crank case.
My guess its and exhaust valve not moveing,bad push rod,bad cam,anybody with a compreesion gauge should be able to remove valve cover.
If you do the cylinder leak test be sure to remove the radiator cap and cover the filler neck with a fender cover or an old blanket! If you've got a head gasket problem you'll end up pressurizing the cooling sytem well beyond it's normal operating range. No sense in splitting a hose or radiator tank or heater core and maybe taking an anti-freeze bath. Especially if the coolant is HOT!
Hence the second guy. For some reason I thought it was going to be more scientific! Good luck, I agree (and hope) that 0 pressure seems like a stuck valve. Even with a badly burnt exhaust valve on a flattie I was getting 30lbs.
If you are going to do a leak down compression check then be careful. Each cylinder that you are testing must be on TDC compression. This means both valves are closed. Now the part than nobody mentioned. When you pump 80 or more PSI into that cylinder, the piston is going to be shot down the cylinder bore. Thus, turning the crankshaft, fan and so on. Exact TDC is not reliable. Easy way to lose a finger or worse. Oh, yeah, make sure it's out of gear too. Get a friend, a strong friend, to hold the crankshaft nut with a breaker bar. It can turn either way. And, by slightly moving the crank one way of another a few degrees. The numbers will go up and down. Pick the highest and that's the reading for that cylinder.
Actually I do mine in gear with a wheel chock in front of the tire. The leak down pressure remains at it's setting minus what ever is leaking despite changes in chamber CCs
has this motor been sitting or has it been running and started to fail? if it has been sitting get it running, let it run a while then test it.
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