| stevep | -- 10-23-2009 @ 4:04 PM |
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I think I have a stuck valve. The engine is making a tapping sound, backfired thru exhaust once and idles rough. I started the car in my garage and after about 3 minutes the tapping sound started. Does anyone have an easy fix for this problem?
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| tierod | -- 10-23-2009 @ 6:10 PM |
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If it is a hung up valve what has worked for me is a dose of Marvel Mystery Oil down the carb with engine running. Good luck.
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| 51f1 | -- 10-24-2009 @ 5:16 AM |
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Many years ago, I freed up a valve in a Navy surplus (WW II) Kohler engine with Marvel Mystery Oil. The engine had been in storage for 20 years. I probably added it to the gasoline. Marvel Mystery Oil is one of the old wives tales that actually works. Richard This message was edited by 51f1 on 10-29-09 @ 5:44 PM
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| TomO | -- 10-24-2009 @ 8:50 AM |
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MMO is the answer. Pour some down the carburetor and smoke up the neighborhood. The add 1 quart to the oil and drive the car about 50 miles. Drain the oil and refill it with fresh oil. Then add some MMO to your gas for a few tankfuls. Some people add it to every tankful. Tom
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| supereal | -- 10-24-2009 @ 10:05 AM |
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I'd run a compression test to see what is happening. While a stuck valve isn't completely rare, it can be from another cause, and running the engine can cause a lot of damage. About a month ago, a customer brought in an 8BA engine to be rebuilt. We found that a valve seat had come loose and broke, with the pieces dropped into the cylinder. It battered the piston and ruined the cylinder wall. We may be able to sleeve it and save the block, but time will tell. We occasionally find that a valve seat has been "staked" into place after the pocket was made too large. With good flathead blocks bringing big bucks, it is worth determining which cylinder is at fault, and pulling the head to inspect the cause. It could be a broken valve spring or other problem, too.
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| 37RAGTOPMAN | -- 10-24-2009 @ 4:12 PM |
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HI pull the spark plug in that cylinder, see if you can look in the cylinder and see if both valves are going up and down, if it looks like only one valve is going up and down, try pushing down on the valve that is not moving,have a helper crank the engine by hand,using a starter crank wrench, also us a good grade of rust buster, like PB BLASTER cheap penterating lubes usually are not that good, this should free up the valves, put plug back in when you have compression back in that cylinder, removing all the spark plugs make it easier to turn the engine over. and a little top oil [ MARVEL MYSTERY OIL ] will keep this from happening, is car stored in a damp place ? LETS HEAR HOW YOU MADE OUT,!!!!!!! hope this helps 37RAGTOPMAN
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| supereal | -- 10-26-2009 @ 9:27 AM |
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Marvel Mystery Oil (MMO) is often recommended both as a preventative and as a cure. Just be aware that if overused, it can, and will, foul spark plugs.
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| stevep | -- 10-29-2009 @ 10:12 AM |
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Still having problem. I tried everything suggested but no luck. I have no compression on number four cylinder, but the exhaust valve is moving up and down what appears to be full length of travel. I can't see the intake valve. I think the only thing left to do is pull the head and intake. Anyone got a better idea?
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| 37RAGTOPMAN | -- 10-29-2009 @ 4:52 PM |
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HI STEVE if you had a old spark plug and a air hose connector you could make a leak down tester, by taking the spark plug apart and welding the air line connector,together, know you can screw the adapter into the cylinder,and using the air regulator, starting with low pressure start letting the air into the cylinder, be sure to put at top dead center, and lock the engine, either by putting into gear, jack up one rear wheel, now if it leaks into the radiator the head casket could be bad, if it leak out the exhaust, the exhaust valve is leaking, or a broken valve spring, if it leak up into the carb it could be the exhaust valve or bad valve spring could be broken, or in extreme cases it could be a problem with the vaalve seats, especially if some engine work was done, do some more checking and let hear how you made out, together with some help from others ,I am sure you can get in back on the road hope this helps 37RAGTOPMAN
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| supereal | -- 10-30-2009 @ 6:36 AM |
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To construct a useful leak down tool, you will need to have a valve and a gauge. The valve isolates the air supply, and the gauge allows you to see how rapidly the pressure declines. The tricky part is being sure that the cylinder under inspection is truly at the top of the compression stroke. In the case of a large loss of compression, there is no practical substitute for pulling the head and intake to see what is happening, as correction will require it to be done, anyway. Large compression loss can indicate internal damage that may ruin the engine if left uncorrected. We have an 8BA engine in our shop currently that lost compression on one cylinder because the valve seat came loose. Continued operation caused the seat to shatter and heavily damaged the piston and cylinder wall. We hope to save the block, but it will not be cheap.
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| TomO | -- 10-30-2009 @ 7:45 AM |
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I agree with Supereal, pull the head and examine the cylinder and valves for damage. If you do have a stuck valve, replace it and the guide. Lap the new valve in and clean every trace of the lapping compound from the valve and seat. When a valve sticks so bad that it cannot be freed with MMO, just freeing it up and cleaning it will not prevent it from sticking again in the future. If you want a cylinder leak down tester for home use, Harbor Freight has one at a reasonable cost. As Supereal said you need a gauge to tell you the pressure that you are applying and another gauge to tell you the leak down rate. Tom
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| stevep | -- 11-02-2009 @ 1:27 PM |
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I pulled the head and intake today. I found a broken valve spring.The cylinder,pistons,head and other valve parts look ok. The car has 42,000 documented orginal miles. The valves have the ford logo on them so I am resonable sure the engine has never been apart. The car is used on summer weekend rides and local shows. Maybe 1,000 miles per year. Do I need to just replace the valve assy. in the affected cylinder or go thru the engine and do a complete overhaul. Compression was a little low in other cylinders. No smoke, good oil pressure etc..
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| BrianCT | -- 11-03-2009 @ 5:39 AM |
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Does the valve move freely. If yes, I would just replace the spring and drive it.
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| TomO | -- 11-03-2009 @ 7:20 AM |
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If you were satisfied with the performance of the engine before the spring broke, just order a new spring and replace it. Tom
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| supereal | -- 11-03-2009 @ 9:10 AM |
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Broken valve springs are common if the springs were not replaced the last time the engine was opened for repair. Valve springs fail when the anti-corrosion coating wears off, and pits are opened on the spring. At only about three bucks each, replacement is cheap insurance. Same is true of the retainer forks and keepers. It is also a good idea to turn the engine a bit now and then when in storage to lessen valve spring "set" from constant compression of the spring.
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