Stuck Valves?

M

mustang8

Senior Member
Read on another post that a little marvel mystery oil down the plug holes would help free up stuck valves. Not sure if any of mine are stuck but last time the motor ran for a very short period 2 years ago there was quite a bit of popping and back splash out of the carb. I think it was maybe a plug wire issue so it has all new plugs, wires, coil, etc. But while im going through it i might as well try the marvel mystery for a week or two before i dump the oil and change it. Sound like a desent idea?
 
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The belt i took off was about 57" and with the new alternator on instead of the generator this one is too short. I figured it would need to be between 58-60". But when i measured the width it looked like about 9/16", but my guess is it calls for 5/8"
 
All the wireing you need is the battery, solenoid and starter + cables. The OEM metal solenoid should have a push button on the bottom, or else just use a jumper wire to activate the sol. You may need a helper and/or a third hand to do this. I have a remote starter button from Mac Tools that clips to the batt and sol with 4 foot of wire, quite handy. RooDog

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Pouring MMO down the plug holes or the carb seldom cures sticking valves. Pull the intake manifold and directly inspect the valves and springs. If the engine was properly rebuilt before sitting for a couple of years, it is unlikely deposits on the valve train are at fault. If the engine had been run before storage, it will depend on how clean the engine was. Run a dry/wet compression test to verify where the problem is. Old valve springs can take a "set" when compressed for long times, as well.
 
MMO works best when added to the oil and gas, add 4 oz of MMO to 10 gallons of gas, it may take 50 to 75 miles of running for the MMO to start to work
 
supereal said:
Pouring MMO down the plug holes or the carb seldom cures sticking valves. Pull the intake manifold and directly inspect the valves and springs. If the engine was properly rebuilt before sitting for a couple of years, it is unlikely deposits on the valve train are at fault. If the engine had been run before storage, it will depend on how clean the engine was. Run a dry/wet compression test to verify where the problem is. Old valve springs can take a "set" when compressed for long times, as well.
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I'll have to disagree that MMO don't free most cases of sticky valves. I have used it for 65 years and could post cures on here that would take several days to read. There is a white residue that forms on the valve stems that cause the valves to stick. Mostly they still open and almost close. This is noticed in the 45 MPH range by a slight miss. It is more noticed when in high gear and the car is slowed to 10 MPH and slowly press the gas pedal and as it picks up speed the engine bucks. Drizzle some MMO down both sides of the carb while running and a 1/2 qt in the gas tank, drive 10 to 15 miles and the miss go's away every time. If you have dual exhaust you can hear the duals before the treatment going boom, boom, bip, boom, boom, bip. After the treatment and the 10 mile drive listen and you here boom, boom, boom with no bips. If the MMO isn't added to the gas after 2 tanks of gas the miss comes back. G.M.
 
the intake valve is the ones that usually stick, the fuel being drawn into the cylinder washes of the oil off the valve stem, making it run dry, the MMO provides constent lubrication to the valve stem from the gas going into the cylinder
 
Get your wiring straight then run it for a while. Drizzle some mmo down the carb till you almost choke it out. Then run the engine a few 100 miles. If the valves are still stuck then they need attention.
 
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Tinker said:
Get your wiring straight then run it for a while. Drizzle some mmo down the carb till you almost choke it out. Then run the engine a few 100 miles. If the valves are still stuck then they need attention.
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Tinker you got the first part but you also need a good load of MMO in the gas tank to work on them while driving. G.M.
 
One more suggestion? Pull the oil pan. When I got my '36 pickup, a running/driving vehicle, I went about a year before pulling the pan to fix the cork seal at the back-I was shocked at the amount of sludge sitting in the bottom!

Adam
 
Once you get to know these engines you can pick up the sound of a cylinder with stuck valves just spinning it with the starter. The dead cylinder wil be quite noticeable. When I started on my 52 Merc last fall I think it had 7 dead cylinders. You can turn those engines by hand with a wrench on the nut holding the crank pulley. 7/8 or 13/16 wrench I think. Also a jumper wire on the solenoid allows you to bypass the starter button and do the compression test without an assistant.
 
The L-head V8 engine will easily stick valves from corrosion (sitting too long) or from carbon build up. When they are stuck hard, I would recommend pulling the manifold and the heads to work them free. I've seen valve stems pushed through the top of cam followers where folks tried to free them by pulling the vehicle to turn the engine. I guess most folks are reserved about pulling the heads but it's a way lot easier than pulling overhead valve types and you can clean the crap out & inspect better to boot. Getting the MMO where gravity can help you free a valve stem is better that trying to get it in there from the bottom up. All it will cost is a set of top end gaskets unless you twist off a head bolt. If it is so rusted up that the bolts won't come out right then it probably needs an overhaul anyway.
 
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