| carguy | -- 08-26-2010 @ 1:33 PM |
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I suspect based on poor engine performance, backfiring, and a ticking sound that sounds like a sticking valve that I, in fact, do have a sticking valve. I did a search on sticking valves and most suggestions were to put Marvel Mystery Oil in the fuel tank and crankcase and hope that this solves the problem. I tend to be skeptical of "mechanic in a can" fixes and suspect that the way to fix it right is to remove the intake and heads and pull the valves and guides. Comments/suggestions will be appreciated.
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| oldford2 | -- 08-26-2010 @ 1:51 PM |
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Well, if you are sure it is a sticking valve then dribble MMO down your carb and smoke up the neighborhood. Pretty easy/cheap way to test the effects of MMO. I think you will be surprised. A lot of folks swear by it. Putting it in your tank is more a preventative action so it won't happen again. Let us know. John
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| bobs36 | -- 08-26-2010 @ 1:57 PM |
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i had the sme situation, actually took a small squirt bottle and put some MMO in it and took out the plugs and squirted it into each chamber (8),started it back up went around the block and its been perfect ever since. i also now put a bit in the carb and the gas tank. good luck.
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| supereal | -- 08-26-2010 @ 1:57 PM |
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The only reliable way to determine if you are having a "sticky" valve is to do a compression test. On each cylinder, check the compression with the piston on the top of the compression cycle, then insert some oil into the cylinder and retake the test. If the compression increases, the problem is Worn or broken piston rings. If it stays about the same, one or both of the valves are leaking. It is also possible you have a broken or weak valve spring. Clicking sounds are difficult to assess. A sticking valve often doesn't make a noise, but shows up as a miss or acceleration or a hard pull. I share your skepticism about relying on additives to cure mechanical problems. Sticking valves are mostly due to deposits on the stem, which an additive won't usually remove. The most recent job we did for a click turned out to be a loose valve seat that someone tried to fix by staking the rim with a chisel!
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| MG | -- 08-26-2010 @ 3:31 PM |
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A compression check as "supereal" suggested should be your first step in trouble shooting your engines problem. I had the same "noise" problem in my '37 last year. I pulled the intake manifold and inspected the valve galley. I found that I had three broken valve springs. Pulling the intake is easy - not very labor intensive.
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| 37RAGTOPMAN | -- 08-26-2010 @ 5:13 PM |
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Was the engine sitting for a long period of time? or miss started while you were driving? Were is it backfiring from, carb or exhaust ? intake valve or exhaust valve ? while it is running,disconnect one plug wire at a time, when you disconnect one and it still runs the same,this is the were your problem lies. take a compression test,see what you get, trying MMO is easiest to do before you tear the whole thing apart,AND IT JUST MIGHT work it would not be the first time it would have done so. use a hand sprayer creating a mist,and spray in the carb while running,very little at a time hope this helps 37 RAGTOPMAN an KEEP ON TRUCKIN,,,!!! if you take a compression test, and get low comp or none,after using MMO, PULL THE INTAKE and check the valve train over and see if you have any broken valve springs,
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| TomO | -- 08-27-2010 @ 7:13 AM |
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MMO works to cure a sticking valve by cleaning off some of the varnish on the valve stem and guide. It is a high detergent penetrating oil. I would not pull the heads and replace one sticking valve until I had tried MMO. I would do a compression check first and then try the MMO. If it did not cure the problem, then I would pull the intake manifold and inspect the valve springs and keeper (horseshoe clip) to make sure that the problem could be resolved without pulling the head. If everything looked OK, then I would pull the head and replace the valve, guide and spring. If you have several valves sticking, it is probably a good time to do a valve job. Tom
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| carguy | -- 08-27-2010 @ 9:34 AM |
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OK Guys, thanks so much for your responses. I am on vacation at this time and I'll be trying the MMO "fix" when I get back home. I'll let everyone know what happens. Thanks again.
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| TomO | -- 08-28-2010 @ 8:17 AM |
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I should have added a vacuum gauge will also show a stuck valve. Tom
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| supereal | -- 08-28-2010 @ 3:27 PM |
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It always amazes me that the "old school" tests and equipment are usually the best diagnosis tools, such as the vacuum gauge and analog VOM meter, for old cars. Too often we seem to ignore the obvious in favor of the exotic causes. I only wish it were so simple today. We spend big bucks on code readers and computerized shop manuals. If you don't have a vacuum gauge chart, I am attaching one.
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