MMO -- Coincidence? Perhaps.

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CCI

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I used MMO and Sea-Foam in a couple of Shovelhead motors over the past year, one was an 89" Sidewinder with just a very few thousand miles, the other was a 74" that has so many miles on it you wouldn't believe me if I told you. Both ran strong and were not having any problems.

I just thought maybe with the bad gas these days this might help the motors.

Both motors suffered serious damage to the top end shortly thereafter from massive carbon build-up just above the top ring. Bad noise from the top end, cylinder scoring, piston damage, I mean bad. Upon disassembly nothing else was wrong. Just a lot of carbon and a lot of damage.

I'm not offering a post hoc ergo propter hoc argument, but I probably won't ever put that stuff in a Harley again, either.
 
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The question I would ask about the motors you're referring to would be: did you inspect the pistons and bores before you added the MMO/ Seafoam, or did you just assume they were responsible for the cylinder scoring/ piston damage/ carbon build-up above the top rings problem you described?

My experience: I have now run about 80 consecutive tank fillups with the recommended doseage of MMO in my 2001 Silverado HD with 6.0 liter V-8. That's about 22k miles since I started doing it, and now nearly 120k miles total on the odometer. Seems like the medium and heavy throttle pinging are gone, idle is perfectly smooth, injectors and fuel pump are eery quiet, and the original fuel filter appears squeeky clean. Gas mileage is a little better than before I started. Spark plugs that came out 14k miles ago had very little carbon or ash buildup. A 10k mile OCI UOA that Blackstone tested suggested I should try at least 2k miles more on the next OCI.

And a quart of MMO in the crankcase oil for the last 800 miles of an OCI reduced the oil consumption from 1 quart per 1800 miles to 1 quart per 4500 miles (most likely from unsticking the oil control rings).

Coincidence? I don't think so - for me it's been a really good product for its intended purpose.
 
I think the late Garry Alan did some experiments with huge doses of MMO to see what might happen.

As I recall, there were no ill effects.

Why did you use two products? Together??

What were you trying to fix?
 
Originally Posted By: CCI
I used MMO and Sea-Foam in a couple of Shovelhead motors over the past year, one was an 89" Sidewinder with just a very few thousand miles, the other was a 74" that has so many miles on it you wouldn't believe me if I told you. Both ran strong and were not having any problems.

I just thought maybe with the bad gas these days this might help the motors.

Both motors suffered serious damage to the top end shortly thereafter from massive carbon build-up just above the top ring. Bad noise from the top end, cylinder scoring, piston damage, I mean bad. Upon disassembly nothing else was wrong. Just a lot of carbon and a lot of damage.

I'm not offering a post hoc ergo propter hoc argument, but I probably won't ever put that stuff in a Harley again, either.



As the quote says "live and learn".
 
Good point -- thank you for asking and allow me to clarify.

I did not add anything to the oil. I don't typically use oil additives anyhow, and after hanging out here, I'm less inclined to do so than ever before.

I'm third-generation Harley rider, and I'm guessing the worst oil I've ever put in these bikes is probably better than the best oil my grandfather ever used. Maybe not, but the OHV big twin motors from the mid 1940s to the mid-1970s are essentially unchanged in terms of their lubrication requirements, and my motors seemed to be holding up quite well until I tried this.

I used it in the fuel.

Gasoline just seems to keep getting worse and worse, and bad gas is tough on the top end of air cooled motors, especially those with somewhat, ah, shall we say, "unsophisticated" metallurgy.

I've built a lot of motors, and I built both of these. The '79 in question here was a 10:1 big bore, fresh, less than 2,000 miles since assembly, absolutely minimal oil consumption, well below factory spec and then some. This was (on paper) a 139 mph Shovelhead that started on one or two kicks and did not smoke.

The '77 was coming right up on 30 years old on this crank and 23 years on those pistons with a recent head gasket change. At the head gasket change (again, under 2,000 miles ago) the heads were somewhat carboned, the pistons were not bad at all. Yes, both bikes had received fairly recent (within less than two thousand miles) visual inspection, however inadvertent. This one had no rational reason why it still ran. Very low compression, rear exhaust guide was providing steady puffs of smoke at an idle, check the gas, fill the oil, and it never missed a lick. 75 mph all day for days at a time was simply not a problem.

Heavily carboned Shovelheads won't do that.

Now I have two motors in identical failure modes that couldn't have been much more different. Scored pistons above the top ring, ridiculous amounts of carbon, and they both made the same noise when it happened.

I'm not telling anyone else what they should or shouldn't do, and as I mentioned in the first post, this story doesn't prove a thing.

But I certainly won't be putting this stuff in my motorcycles anymore.
 
MMO certainly didn't cause any of the damage you cited on either bike. If anything, MMO would have prevented the carbon deposits from developing in the first place or slowly begun to break up the deposits you already had. I'm. It sure what caused this damage, but there definitely sounds like there may be more to this story.
 
CCI, I think what you are getting at is that these were very different motors ... but the one thing they had in common was the gas additives. Makes sense.

(By the way, this thread should be moved as this particular sub-forum is for oil adds)

Can you describe your treat rate? If it was really heavy, and the engines tend to run rich, I could see a potential for excess carbon formation.

I run MMO in OPE (not a SeaFoam fan) and have for about 2 decades. I haven't run into any problems except the liquid-cooled Honda tractor would stumble a bit if the treat rate was too heavy and I ran it it 2-3 consecutive tankfuls. Easily rectified with one tank of plain fresh fuel

My current piece of OPE is a snowblower that is under-engined. Current plant is a 250cc B&S OHV motor when it should have at least 300cc or even 350cc like my Dad's (both Ariens). I put this engine under heavy loads and run MMO, Lucas UCL or TCW3 every other tankful at a treat rate of 100:1 to 200:1.

Engine runs great (there's simply not ENOUGH engine) however, it only has something like 30 hours on it despite being 4+ years old.
 
Originally Posted By: Bror Jace
CCI, I think what you are getting at is that these were very different motors ... but the one thing they had in common was the gas additives. Makes sense.

(By the way, this thread should be moved as this particular sub-forum is for oil adds)

Can you describe your treat rate? If it was really heavy, and the engines tend to run rich, I could see a potential for excess carbon formation.





You're right -- I put this in the wrong sub-forum. How do I move it?

I also think you understand the question, the circumstances, what I was trying to describe, and I think you might be on to an answer.

Old HD motors with cast iron cylinders and valve guides that are not sealed are designed to use oil. New from the factory it would not be unheard of for them to use a quart every 500 miles.

Again, your point is well taken -- one of the motors in question was working at easily half that and the other was double that.

They also run very slightly rich by modern standards, especially at high rpm for extended periods of time -- and the motor usually lasts longer if they do.

I must confess that I did not accurately measure the amount of additives I put in, and it's entirely possible (likely) that I used too much.

Particularly given the long-term success so many people have had, it seems to me that your hypothesis is entirely plausible.
 
CCI,
Contact a moderator to have this thread moved (I think they can).

"I also think you understand the question, the circumstances, what I was trying to describe, and I think you might be on to an answer."

Your original observations were reasonable and I thought it was worthy of specific follow-up, without snark or heavily biased jabs. I just wish more exchanges on the internet were similarly respectful.

It serves as a warning to UCL users that for heavy treat rates in certain applications, there can be dire consequences.
 
Never used MMO, but I have been using seafoam in all my OPE and motorcycles fuel systems for 20 years.
 
Originally Posted By: Bror Jace
CCI,

Your original observations were reasonable and I thought it was worthy of specific follow-up, without snark or heavily biased jabs. I just wish more exchanges on the internet were similarly respectful.




I very much appreciate that and thank you.
 
Originally Posted By: Skittles
Never used MMO, but I have been using seafoam in all my OPE and motorcycles fuel systems for 20 years.
Heh heh, I've only used Seafoam once. All my OPE gets a dose of MMO at every fill up. Stuck with E 10 gas and MMO -ed fuel gives the carbs less grief when stored. I used Seafoam to hot soak an engine with 220 K on it. Results were inconclusive, but the smoke was awesome
grin2.gif
 
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