0 compression on #3

[grungeant (Anthony)]

My compression readings were
#1- 110 *115
#2- 105 *110
#3- 0     *0
#4- 105 *115
*After spraying WD-40 in the hole.

Everything looks clean and seems to move as it should under the left valve cover.






What's wrong, and what do I need to do to fix it?

[rich67vw]

Burnt valve, broken valve, valve not seating, even a a hole in ur piston.
Anything that allows air to escape. Most common is bad seating, but I'll defer to expert like JackWagen who is probably napping now **^bana0

[Bugaru "JAY"]

 Ant..
Can't see very well from your pics but looks like fresh threads on the #3 Exhaust adjuster screw.

Check to be sure that the push rod is seated into the lifter and not sitting on the outer lifter lip.
If it is your cause which I'm gueesing it very well maybe because Zero Compression is very uncommon.
This is a very common mistake unknowingly made when re-assembling the push rods end result is that the pushrod will hold the valve open thus Zero compression  :confused04:;

Check your adjuster screw and see if you can get any play at all on that push rod, if not I'd bet it's not seated correctly.
Hopefully it's not a bent valve.

[grungeant (Anthony)]

You know, I thought I saw the fresh threads in the picture too. I already put the valve cover back on.
Let me add this.
I've put a little over 10k on the bus, and it's only been running weak and using excessive oil for the last 2-3k.
It didn't just one day happen it progressively got weaker and weaker, and some days it would seem like it ran perfect and other days would not go over 55.
I emailed the previous owner and he said the motor has about 60-70k on it since being built.
I know the lifters are hydraulic. I've never had them adjusted.
The last few weeks of driving the bus I've been able to hear compression leaking near the left rear wheel.
When I turned the motor by hand with the valve cover off and all 4 plugs in I heard compression loudly. Is that normal?

Now all that being said should I still go back out there and look at stuff or does that pretty much say bent valve or cracked head or something?
I guess what I'm asking is it possible it would run fine that long if it was assembled incorrectly and decide to start acting up now?
My initial thought when it first started running weak and I was hearing the compression leaking while it was running was that it must be leaking from where the cylinder meets the head. Is that possible or would I still get something for compression even 5psi, or a flicker of the needle or something?

[Bugaru "JAY"]

 Ant.
Ohooo I had thought that you experienced your problems after doing engine work, tune up, valves etc?
Well if you didn't fool with the heads etc I wouldn't think you had the problem of a offset pushrod. So discount what I mentioned.

So if what you mentioned is true and the problem slowly showed as time and miles passed by.
Most likely the sound your hearing is a exhaust / compression leak escaping between cylinder and head.

With engine running That sound usually sounds like a whooshing sound as the piston pumps up and down.   

If so your hear the sound on the outwards side of the mating surface of head and cylinder..

Looks like your going to have to pull that Head to know more. If pistons and cylinders are good. Your probably looking at head gaskets, reseating the valves, and resurfacing the head mating surface. Might as well tackle both sides while your at it..

Regardless the troubles get her done time to enjoy the ride after the long-ggggggggg hard winter.

[grungeant (Anthony)]

Thanks Jay,
What you're saying sounds about right. It kind of sounds like an old washing machine.
Is it safe to say don't start the engine anymore?
Do you think the rings on #3 are probably in similar shape as the other 3 cylinders?
Should I have rings done too while I'm in there based on the mileage?

[rich67vw]

Back in the day, I would use a leak down tester to identify where the problem was. screw in a hose from the tester kit to the gauges, attach to a compressor, and pinpoint the leak, whether air whooshing from crankcase, cylinder head mating , throttle body, etc.

It avoided guesswork.  %$oldcit

[grungeant (Anthony)]

Ok, I think I can pull this off with what I have.
At the bottom of the hose for the compression tester hose there is a schrader valve. I'm assuming it is like a one way check valve.
there is also a schrader valve on the side of the gauge to release the pressure.
If I remove the valve at the bottom of the hose, and have someone hold the air chuck up to the valve by the gauge will this blow air into the cylinder?

I need to do this with both valve springs extended right?

Another question. Someone told me sounds like a burnt valve.
What things would I observe while running or driving would confirm or disprove this?
I don't have any backfiring. Wouldn't I have backfiring either through the intake or out the exhaust?

Is it possible I can just retorque the head bolts and be ok?

[Bob(Herbie)]

Does this motor have solid or hydraulic valves? If they are solids they may need to be adjusted? What does #3 spark plug look like? Is it black, wet, dry etc. Show us a picture if possible. If the engine was using oil, it is most likely a broken or badly worn piston ring or rings. It is possible that the head is leaking but, it would sound like an exhaust leak. When you hook up an air pressure adapter to the cylinder both valves must be closed. If the air leaks into the crank case the piston or rings are the problem. If the air comes from the exhaust, the exhaust valve is the culprit. If the air leaks into the intake manifold, the intake valve is the problem. Good luck!  %$oldcit

[grungeant (Anthony)]

I have hydraulic lifters.
#3 plug had some black ash on it.
It did sound like an exhaust leak, and I was also able to hear compression leaking.

I'm not home right now, but somewhere on here on one of my posts I put up pictures of my last set of plugs that came out. They all pretty much look the same.

[grungeant (Anthony)]

I put a torque wrench on the 2 head bolts I can get to without removing the rockers. Made one complete revolution with one and the wrench did not click. Made about 1/2 revolution with the other and the wrench didn't click.

I called George Gallagher. He assured me that even if it was just a case of the head bolts being loose, which he doubts, best case scenario I still need to pull the engine, take the head off and clean all the carbon out before retorquing everything.