Sticking Valve?

[atkinson40]

Still chassing my #3 cylinder miss. 

 

I've adjusted the valve lash a couple of times, but still hear a clickety click noise.

 

I hooked up a vacumm gauge to the intake manifold and and it hops around between 14-15 in/Hg.

 

If I rev it. it drops and then pops back to over this range.  How can I tell if I have a sticking valve?

 

Thanks kevin

[racerx]

I think vacuum should be about 17-22 in/Hg.  You may have a vacuum leak at that low. Also go on line and see how the gauges should act like when you have sticking valves and vacuum leaks.

[atkinson40]

I think vacuum should be about 17-22 in/Hg.  You may have a vacuum leak at that low. Also go on line and see how the gauges should act like when you have sticking valves and vacuum leaks.

 

Thanks SR,

 

Before I posted, I had this from the interwebs.

 

1. NORMAL READING: Needle between 51-74 kPa (15-22 in-Hg) and holding steady.

 

2. NORMAL READING DURING RAPID ACCELERATION AND DECELERATION: When engine is rapidly accelerated (dotted needle), needle will drop to a low (not to zero) reading. When throttle is suddenly released, the needle will snap back up to a higher than normal figure.

 

3. NORMAL FOR HIGH-LIFT CAMSHAFT WITH LARGE OVERLAP: Needle will register as low as 51 kPa (15 in-Hg) but will be relatively steady. Some oscillation is normal.

 

4. WORN RINGS OR DILUTED OIL: When engine is accelerated (dotted needle), needle drops to 0 kPa (0 in-Hg). Upon deceleration, needle runs slightly above 74 kPa (22 in-Hg).

 

5. STICKING VALVES: When the needle (dotted) remains steady at a normal vacuum but occasionally flicks (sharp, fast movement) down and back about 13 kPa (4 in-Hg), one or more valves may be sticking.

 

6. BURNED OR WARPED VALVES: A regular, evenly-spaced, downscale flicking of the needle indicates one or more burned or warped valves. Insufficient hydraulic valve tappet clearance will also cause this reaction.

 

7. POOR VALVE SEATING: A small but regular downscale flicking can mean one or more valves are not seating.

 

8. WORN VALVE GUIDES: When the needle oscillates (swings back and forth), over about a 13 kPa (4 in-Hg) range at idle speed, the valve guides could be worn. As engine speed increases, needle will become steady if guides are responsible.

 

9. WEAK VALVE SPRINGS: When the needle oscillation becomes more violent as engine rpm is increased, weak valve springs (6513) are indicated. The reading at idle could be relatively steady.

 

10. LATE VALVE TIMING: A steady but low reading could be caused by late valve timing.

 

11. IGNITION TIMING RETARDING: Retarded ignition timing will produce a steady but somewhat low reading.

 

12. INSUFFICIENT SPARK PLUG GAP: When plugs are gapped too close, a regular, small pulsation of the needle can occur.

 

13. INTAKE LEAK: A low, steady reading which can be caused by an intake manifold or throttle body mounting flange gasket leak.

 

14. BLOWN HEAD GASKET: A regular drop of fair magnitude can be caused by a blown head gasket (6051) or warped head-to-block surface.

 

15. RESTRICTED EXHAUST SYSTEM: When the engine is first started and is idling, the reading may be normal but as the engine rpm is increased, the back pressure caused by a clogged muffler (5230), kinked tail pipe or other concerns, will cause the needle to slowly drop to zero. The needle then may slowly rise. Excessive exhaust clogging will cause the needle to drop to a low point even if the engine is only idling.

 

When vacuum leaks are indicated, pinpoint and correct the cause. Excess air leaking into the system will upset the fuel mixture and cause concerns such as rough idle, missing on acceleration or burned valves. If the leak exists in the power brake, the system will not function correctly. ALWAYS FIX VACUUM LEAKS.

 

I also found this site.

 

http://www.imperialclub.com/Repair/Fuel/VacuumGauge/

 

I see that the vacumm is a bit low, but am not real sure of the accuracy of my old gauge. 

 

I was wondering if there was a way to inspect/test the valve manually w/o removing the head to see if it was bent or sticking.

 

I also saw on line where you can feed a peice of rope in the spark plug hole to keep the valve from falling as you take off the spring.

 

Just wondering if there was someone that had been down that path before.  I need to find a way to compress the spring and then I think the rope in the hole trick and spin the valve by hand, or I'm not quite sure what else, to see if it's OK.

 

Thanks kevin

[racerx]

I like that Imperial Web page one.  Yeh, heard about the rope trick, too..but never tried it.  Hopefully someone tried this before and can chime in..good luck.

[MikeRL411]

The "rope trick" has been around since the first over head valve engines appeared on the market.  "L head" engines obviously didn't need any voodo since the valves sat flush with the block.

 

If you need to ask "what's an L head engine" think WW2 Jeep  ]Willys or Ford version].

[datzenmike]

I've never used air (never had a compressor before)

 

Use rope and....

 

You don't have to finish before bed time. Hell you can leave it till nest week!

You don't have to worry if you paid the hydro bill

Your cousin Billy-Bob from over at sixtoe county doesn't have to pass out from blowin' in that hose.

[atkinson40]

I've never used air (never had a compressor before)

 

Use rope and....

 

You don't have to finish before bed time. Hell you can leave it till nest week!

You don't have to worry if you paid the hydro bill

Your cousin Billy-Bob from over at sixtoe county doesn't have to pass out from blowin' in that hose.

 

OK Thanks Mike, Guess there's an inside joke there soemwhere.

 

I used the rope.  No bent or sticking valves.  Rechecked the clearances - OK.

 

The clickety clack gets louder as it warms up so I'm going to check the clearances hot. 

 

Need to get a new vacumm gauge and recheck the manifold vacumm.

 

Thanks Kevin

[datzenmike]

OK Thanks Mike, Guess there's an inside joke there soemwhere.

 

My point was you could use a hunk of rope or extension cord or cloth's line or bailing wire... almost anything and do it 30 miles up a logging road on the side of a mountain far from any compressor or electricity.  :lol: