Gutless, no power

[Nissanman]

Being a pushrod engine, it is not so traumatic to remove the head to ascertain the problem/s.
Disappointing I know, but methinks its not going to fix itself.
Removing the head and giving it a thorough inspection and/or repair will give you confidence in that area of the engine.

[Gregs672000]

What you're describing does not make any sense (air out #2 plug hole from #4 ONLY). Air can only escape through open or damaged valves or past piston rings. With the piston at top dead center or near and with both valves closed, applying compressed air to that cylinder will have air flowing out the carbs (bad intake valve), the exhaust (bad exhaust valve) or out the oil filler cap (rings, air into the crankcase). There's no way it can put air out the plug hole on #2 only... it has to be leaking into the crankcase that is then routing past that piston and out the hole, but if the rings are good in #2 then it shouldn't leak much. You need to do a leak down test which will give you a much better idea of the engines condition and where.

Check your valve lash first to make sure the valves are actually closing.

[Gregs672000]

If you have a screw in hose type of compression tester, you can unscrew and remove the Schrader valve with a pair of tweezers and use a fitting to adapt your compressed hose to that hose, then screw it into the spark plug hole to apply 20lbs of pressure to that cylinder with the valves closed and piston up, engine locked in place via the trans and parking brake. Listen for air leaking out as described above. Rotate the engine to the next piston position and repeat for each one.

[redroadster]

Walk me through it Red, why 15 lbs? assuming both valves closed? Pressurize and hold for how long? What am I expecting? As mentioned before, I can clearly hear the air coming through #2, should I have a spark plug in #2 or leave it open?

I put it back together, but that's no problem, fired it up just to see, noticed the new valve cover gasket isn't re-usable friendly.

I'll give anything a try.......

Wait ...you have 150lbs compression on #2 per your test , as do the rest or close but #4 has 0 compression
, Im, .. we're saying you can test to point to the problem with out tear down
A sticking/ slow valve is a posibility here
or fleck of carbon jamming the valve... Hyd lifter jammed
And low air pressure 15lbs you still hear the leak ...kind of a safety thing

[C.Costine]

Greg, for a good part of the time that the two valves of #4 are closed, Cylinder two would be on either intake or exhaust stroke with a valve open. While the air being blown into #4 is going into one of the manifolds, most would go out either the exhaust, unnoticed, or out the air cleaner, maybe slightly noticed. A lesser amount would come out the # 2 plug hole because of a wide open valve, and due to the proximity to the # 4 plug hole and Bob's face, even though in a far smaller quantity, I would say, be more noticeable.

[JT68]

There are no hyd lifters. Most likely it is a bent/burned valve in #4.

[Gregs672000]

There are no hyd lifters. Most likely it is a bent/burned valve in #4.

OR valve lash is way to tight and not allowing the valve to close... which may be burned now...

[bossbob]

Greg, for a good part of the time that the two valves of #4 are closed, Cylinder two would be on either intake or exhaust stroke with a valve open. While the air being blown into #4 is going into one of the manifolds, most would go out either the exhaust, unnoticed, or out the air cleaner, maybe slightly noticed. A lesser amount would come out the # 2 plug hole because of a wide open valve, and due to the proximity to the # 4 plug hole and Bob's face, even though in a far smaller quantity, I would say, be more noticeable.

Exactly what is happening. It is extremely noticed in the #2 cyl. not so much the intake manifold.

OR valve lash is way to tight and not allowing the valve to close... which may be burned now...
[/quote]

Rocker arm is not touching the valve stem, I have .018 - .019 gap, so only thing can be carbon holding the valve open or bent or broken valve. Right? I can push down on the valve spring retainer and see the valve open and close. The rocker arms open and close the valves during engine rotation, so eliminates a flat cam lobe?


[/quote]
Wait ...you have 150lbs compression on #2 per your test , as do the rest or close but #4 has 0 compression
, Im, .. we're saying you can test to point to the problem with out tear down
A sticking/ slow valve is a posibility here
or fleck of carbon jamming the valve... Hyd lifter jammed
And low air pressure 15lbs you still hear the leak ...kind of a safety thing
[/quote]

It's leaking straight out of #2, no question about it.

Also, my fresh oil is black, can't smell due to a cold, but it must be running rich. Plugs came out very sooty?
Thanks for all the input, looks like the head is coming off for sure. We'll see if I get motivated after the Steeler game.

[redroadster]

What is leaking straight out of #2 cyl. ?
And where exactly is it leaking from ?
coolant , oil. Sure cant be compression @150 psi

[bossbob]

What is leaking straight out of #2 cyl. ?
And where exactly is it leaking from ?
coolant , oil. Sure cant be compression @150 psi

Air from the spark plug hole.

When I add compressed air to the #4 cylinder, it leaks directly out of the #2 cylinder. Even though both valves on #4 are closed, the air is getting back into the intake manifold. So, best guess is a broken or bent valve, will have to remove the head and see what's going on below.