Engine Tapping Noise....Marvel Mystery Oil?
Thread Starter
Melting Slicks
Joined: Jan 2003
Posts: 2,714
Likes: 32
From: Shreveport LA
LA Events Coordinator
Engine Tapping Noise....Marvel Mystery Oil?
Heard a loud tapping noise coming from the front/passenger valve cover this afternoon. 
Checked the oil...about 1/2 quart low. A friend of mine said that a lifter was sticking and to put some Marvel Mystery Oil in the crankcase (to the full mark) and the rest, slowly, down the carb with the engine running. I did just that...1/2 quart in the crankcase and the rest down the carb...when I poured it down the carb, it looked like I was laying a smoke screen for the troops to attack!!! People thought the car was on fire!! Anyway, after doing all that, I drove it on the interstate for about 10 miles....now the engine is QUIET!!! 
No more tapping sound! WHAT HAPPENED AND WHY???? Is this a temporary fix or should I go and have something adjusted???
Checked the oil...about 1/2 quart low. A friend of mine said that a lifter was sticking and to put some Marvel Mystery Oil in the crankcase (to the full mark) and the rest, slowly, down the carb with the engine running. I did just that...1/2 quart in the crankcase and the rest down the carb...when I poured it down the carb, it looked like I was laying a smoke screen for the troops to attack!!! People thought the car was on fire!! Anyway, after doing all that, I drove it on the interstate for about 10 miles....now the engine is QUIET!!! No more tapping sound! WHAT HAPPENED AND WHY???? Is this a temporary fix or should I go and have something adjusted???
Last edited by vetteguy75; Mar 13, 2005 at 08:48 PM.
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
If you run really low on oil there is not enough pressure to pump up the lifters and they click. Only 1/2 quart low is not low enough to cause this. The two problems are probably unrelated. The lifter stuck and the oil was low, but one did not cause the other.
Drive it for a few days and change the oil. Keep an eye on the level and make sure it doesn't get low again.
You didn't really need to pour MMO down the carb, although it probably wasn't a bad idea if the engine has a lot of miles on it. MMO down the carb cleans out the combustion chamber. Your plugs may be fouled now from the crap getting loosened up so you may want to stick a new set of plugs in it.
The MMO in the oil is what freed the lifter. I've done it myself on one of my cars and it works great.
Drive it for a few days and change the oil. Keep an eye on the level and make sure it doesn't get low again.
You didn't really need to pour MMO down the carb, although it probably wasn't a bad idea if the engine has a lot of miles on it. MMO down the carb cleans out the combustion chamber. Your plugs may be fouled now from the crap getting loosened up so you may want to stick a new set of plugs in it.
The MMO in the oil is what freed the lifter. I've done it myself on one of my cars and it works great.
Melting Slicks
Joined: Jul 2004
Posts: 2,577
Likes: 2
From: Long Island New York
Originally Posted by zwede
If you run really low on oil there is not enough pressure to pump up the lifters and they click. Only 1/2 quart low is not low enough to cause this. The two problems are probably unrelated. The lifter stuck and the oil was low, but one did not cause the other.
Drive it for a few days and change the oil. Keep an eye on the level and make sure it doesn't get low again.
You didn't really need to pour MMO down the carb, although it probably wasn't a bad idea if the engine has a lot of miles on it. MMO down the carb cleans out the combustion chamber. Your plugs may be fouled now from the crap getting loosened up so you may want to stick a new set of plugs in it.
The MMO in the oil is what freed the lifter. I've done it myself on one of my cars and it works great.
Drive it for a few days and change the oil. Keep an eye on the level and make sure it doesn't get low again.
You didn't really need to pour MMO down the carb, although it probably wasn't a bad idea if the engine has a lot of miles on it. MMO down the carb cleans out the combustion chamber. Your plugs may be fouled now from the crap getting loosened up so you may want to stick a new set of plugs in it.
The MMO in the oil is what freed the lifter. I've done it myself on one of my cars and it works great.
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
Originally Posted by vetteguy75
Heard a loud tapping noise coming from the front/passenger valve cover this afternoon. Checked the oil...about 1/2 quart low. A friend of mine said that a lifter was sticking and to put some Marvel Mystery Oil in the crankcase (to the full mark) and the rest, slowly, down the carb with the engine running. I did just that...1/2 quart in the crankcase and the rest down the carb...when I poured it down the carb, it looked like I was laying a smoke screen for the troops to attack!!! People thought the car was on fire!! Anyway, after doing all that, I drove it on the interstate for about 10 miles....now the engine is QUIET!!! No more tapping sound! WHAT HAPPENED AND WHY???? Is this a temporary fix or should I go and have something adjusted???
Checked the oil...about 1/2 quart low. A friend of mine said that a lifter was sticking and to put some Marvel Mystery Oil in the crankcase (to the full mark) and the rest, slowly, down the carb with the engine running. I did just that...1/2 quart in the crankcase and the rest down the carb...when I poured it down the carb, it looked like I was laying a smoke screen for the troops to attack!!! People thought the car was on fire!! Anyway, after doing all that, I drove it on the interstate for about 10 miles....now the engine is QUIET!!! No more tapping sound! WHAT HAPPENED AND WHY???? Is this a temporary fix or should I go and have something adjusted??? 
Pro
Joined: Aug 2002
Posts: 560
Likes: 0
From: The Valley of The Sun AZ
MMO is a solvent, light oil and flavoring. The MSDS sheet is out there so it's no longer a mystery. It also contains TPP which is a lead scavenger, so if you are running leaded fuel it will attach itself to the lead and blow it out the exhaust. In the crankcase it will dissolve carbon, lead, and other contaminants that are causing sticking and added to the fuel it will lubricate the top end and unstick valves by dissolving crud buildup in the valve guides. It is also used to free siezed pistons and valves by letting them soak in the stuff over a period of time.
JB, if you are adding TEL and MMO, you are wasting some money since MMO helps scavenge the TEL out of the fuel
One or the other I would think would be better.
JB, if you are adding TEL and MMO, you are wasting some money since MMO helps scavenge the TEL out of the fuel
One or the other I would think would be better.
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
Trivia: MMO was originally developed during WW2 for use in piston engine aircraft. These engines had problems with lead fouled plugs during runway taxing. Adding MMO to the fuel prevented the plugs from fouling.
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Instructor
Joined: Jan 2003
Posts: 188
Likes: 2
From: Flowermound Tx
When you all add MMO, do you first drain an equal amount out of the crankcase ? I've got 6 quarts of 1 month old in the case now, would adding 16 ozs of MMO create an overfill problem ? Kind of paranoid about going beyond the full mark. I currently have a sticking lifter. Would 16 oz be enough or should I just drain out a quart and replace it with MMO?
Thanks for your thoughts,
Scott
Thanks for your thoughts,
Scott
Burning Brakes
Joined: Jan 2000
Posts: 904
Likes: 0
From: Seymour Indiana
I learned about Marvel Mystery Oil when working with my dad on the pipeline during the summers in high school. They had lots of small engine items (water pumps, generators) etc. that they would treat like utter crap, let them run low on oil..everything else. A little MMO would get them going most times..
Most recent experience was with a 1972 Cadillac Hearse we bought to promote the charity haunted house I produce, had a terrible sound in the motor...some in the crankcase, some down the carb...good as gold.
MMO is awesome.
Most recent experience was with a 1972 Cadillac Hearse we bought to promote the charity haunted house I produce, had a terrible sound in the motor...some in the crankcase, some down the carb...good as gold.
MMO is awesome.
Racer
Joined: Apr 2004
Posts: 370
Likes: 0
New England Events Coordinator
Originally Posted by bhays
I learned about Marvel Mystery Oil when working with my dad on the pipeline during the summers in high school. They had lots of small engine items (water pumps, generators) etc. that they would treat like utter crap, let them run low on oil..everything else. A little MMO would get them going most times..
Most recent experience was with a 1972 Cadillac Hearse we bought to promote the charity haunted house I produce, had a terrible sound in the motor...some in the crankcase, some down the carb...good as gold.
MMO is awesome.
Most recent experience was with a 1972 Cadillac Hearse we bought to promote the charity haunted house I produce, had a terrible sound in the motor...some in the crankcase, some down the carb...good as gold.
MMO is awesome.
