Does Moly "plate up" on aluminum cylinder walls?

Messages
3,202
Location
Far North East Texas
I've read the entire Moly & AW additive tutorials on the home page, and searched & read through much of BITOG forums & molakule's section, and *still* can't find a definitive answer. The one thing I found refers to how Moly plates up, then qualifies it by saying something about "...at least on ferrous metals...". Will it plate & protect well on the aluminum cyl wall of a new air-cooled Honda OHC lawn mower engine? Or will the zinc compounds have to do the lion's share of the work? Now, I know this is splitting hairs. With all those 20 to 30+ yr old Briggs engines still running out there, I'm sure any decent oil will be more than good enough. Still, I'm curious. [Big Grin] All help appreciated. [Cheers!]
 

UncleS2

Thread starter
Messages
3,202
Location
Far North East Texas
That's one heckuva good question, & I have no idea. [I dont know] The manual said nothing about having a cast iron sleeve(probably safe to omit that one! [Big Grin] ) or any types of coatings. The Honda engines seem to have such a good reputation that it wouldn't surprise me at all if there *was* some type of hard coating or near-miracle anodizing on the cyl walls. Still, that wouldn't be ferrous metal. I've also been warned by those in-the-know that my first oil drain will look like a "silver soup" from all the specks of metal in the oil. As Pablo said, they tend to "shed a lot of metal" when new. [Big Grin] Probably mostly from the piston, but *some* might be from the cyl wall, just dunno.
 
Messages
2,364
Location
sebring, florida
its just a bare aluminum cylinder on the smaller honda engines. some of the medium and larger ones have iron sleeves, plated, etc. most small engines, including briggs, honda, etc even chainsaws and line trimmers use bare aluminum cylinders. its kind of the normal thing.
 
Messages
882
Location
North Carolina
Could be Nikasil plated or Alusil. A lot of small 2 cycle engines use Nikasil. Porsche and BMW use Nikasil in auto engines too. Maybe the moly would attach itself to the nickel component in Nikasil if present.
 
Messages
3,593
Location
Outside smalltown, IL
quote:
Originally posted by Master ACiD: its just a bare aluminum cylinder on the smaller honda engines. some of the medium and larger ones have iron sleeves, plated, etc. most small engines, including briggs, honda, etc even chainsaws and line trimmers use bare aluminum cylinders. its kind of the normal thing.
I know some of the Briggs engines are that way, but they're disposable engines. I just wasn't aware that Honda had gone that route too.
 
Messages
3,478
Location
Millbrae, CA
Moly disulfide does not plate to anything it is a solid that will "burnish" into the surface roughness or small pits and cratches. It Will not add to dimensions. Will Burnish into plastic aswell as metals. bruce
 
Messages
537
Location
California
If the Honda cylinder seems to have "bare" cylinder walls, then it is a special type of aluminum casting that has silicon "precipitate" to the cylinder wall during the casting phase. They made quite a few Civic engines this way, I forget when they stopped. The extra silicon makes the cylinder wall very hard. I believe the old Chevy Vega used a similar approach.
 
Messages
4,478
Location
Southern California
The idea for longevity is dissimilar metals making up sliding parts. One way to accomplish that in aluminum engines is a cast-iron cylinder liner. But, it's not the only way. B&S and Tecumseh both use flash chromed pistons and cast-iron piston rings in their entry-level engines. For a good read about which automanufacturers have abandoned cylinder liners in their aluminum engine cylinder blocks go to Ward's Light Vehicle Engine Specifications. [Wink]
 
Messages
267
Location
Idaho
quote:
Originally posted by Stuart Hughes: Chevy Vega?! [Eek!] I hope it's a lot better than a Vega- "Fill up the oil & check the gas!"
Not a very encouraging thought, is it? I, too, owned a Vega. Ran great after I put a block with steel sleeves in it! The Vega used a high silicone aluminum bore and the pistons had an iron flash coating applied over the aluminum. Apparently the iron coating wore more rapidly than expected. This left aluminum piston material rubbing on a too similar aluminum bore, which lead to galling which caused poor ring seal.... [Mad] Obviuosly something went awry between testing and production. Joe
 

UncleS2

Thread starter
Messages
3,202
Location
Far North East Texas
Chevy Vega?! [Eek!] I hope it's a lot better than a Vega- "Fill up the oil & check the gas!" About the Moly- I'm referring to the modern soluble moly compounds that stay suspended in motor oil, such as used by Schaeffer, Pennzoil, Havoline & some others- *not* the old black powdered MoS2 that would settle out of oil. Thanks for all the input, but: does anyone know if soluble Moly will work on a non-ferrous aluminum cylinder wall? [Big Grin]
 
Messages
8,937
Location
SC
The Vega engine was another example of GM's reach exceeding their grasp. In other words, the technology was sound, but their ability to put said technology into production wasn't. Merecedes (and later Porsche) used the same technology, i.e., high silicon aluminum block with the cylinder bores micro etched to make the hard silicon stand just slightly proud of the surrounding aluminum. There are plenty of aluminum block Mercedes V8s with 250,000+ miles on them that don't smoke or consume inordinate amounts of oil. (Which is something you can't say about a Vega.)
 
Messages
3,593
Location
Outside smalltown, IL
Nice link but I wish they'd have given more details. What we can't really tell from the link is how many use a plated or otherwise coated aluminum cylinder and how many use some form of bare aluminum alloy.
 
Messages
8,937
Location
SC
quote:
Originally posted by Ray H: Apparently Mercedes hedges its bets with a pressed in aluminum-silica liner for rebuildability. See my link above.
They may do that now, but their first aluminum block V8s, which began with the SOHC 5.0 first seen in the late 70s in the 450SLC 5.0, and entered regular production in 1980 in 3.8 and 5.0 liter version, did not use any sort of cylinder liner.
 
Messages
2,364
Location
sebring, florida
as i said most small engines use bare aluminum cylinders. it they have a plating like nikasyl or a cast iron liner then they are advertised as being industrial/commercal and usually list the feature which makes them that way. 99% of the time they have aluminum cylinder, aluminum piston, and iron ring that has chrome plating on the ring. no other special coatings are used (under normal circumstances for most small engines that is) the reason for this whole thing is, small engines just dont have the stress per part of a large automotive engine. its the same theory as to why an ant, if elnarged to the size of a human, wouldnt be able to support its own weight much less carry a washing machine on its back like they can do when they are normal sized tiny little buggers. somthing to do with sizing down on an engine (and an ant) means less stress and wear. can you imagine a big block chevy running at 3600 rpms all day long with no oil pump, no oil filter, and only splash lube? it just wouldnt work. the engine would tear its self apart even it it has dippers installed on the big ends of the rods to splash sump oil around. small engines can do this and they do it very sucessfully because of the fact that they are smaller.
 
Top