Guest AlanD Posted October 16, 2013 Share Posted October 16, 2013 Was there ever a coating or graphite paint used on the inside of a crankcase?Looking inside the crankcase on a 1925 REO 4 cylinder engine, everything has a nice grey color (no surface rust) and it appears to be painted. But when I wipe my finger across any surface inside there, the end of my finger comes back grey and it looks like graphite. My thoughts are either its some sort of graphite paint or coating, or babbitt - which I hope it's not.Thanks for the suggestions on this.Alan Link to comment Share on other sites More sharing options...
Rusty_OToole Posted October 16, 2013 Share Posted October 16, 2013 I have seen a gray sludge coating on the inside of some old engines. I put it down to lead from the leaded gas, or additives in the oil.Have also seen the inside of an aluminum Harley Davidson crankcase that was painted with red paint to seal the casting. Sand cast aluminum can be porous and a coat of paint insures against leaks. Link to comment Share on other sites More sharing options...
trimacar Posted October 16, 2013 Share Posted October 16, 2013 The red paint you mention is probably Gasoila hard-set red varnish....this should be used inside crankcases and transmission housings, particularly when they're made of aluminum, which is quite porous as you mention.There used to be a process called vacuum degreasing that could get the old oil out of the aluminum, but I've searched and can't find anyone who does it. I have an aluminum crankcase now that needs cleaning... Link to comment Share on other sites More sharing options...
Beltfed Posted October 16, 2013 Share Posted October 16, 2013 I believe what you are looking for is called "Glyptal". It is an engine case sealant. Have never see it other than red in color. The gray stuff, in my case, has always been Babbitt or bearing material. Link to comment Share on other sites More sharing options...
trimacar Posted October 16, 2013 Share Posted October 16, 2013 Yep, Glyptal works too....it's amazing how porous cast aluminum can be, I watched someone try to weld on an old crankcase, and the oil just kept bubbling up as heat was applied.... Link to comment Share on other sites More sharing options...
Owen_Dyneto Posted October 16, 2013 Share Posted October 16, 2013 For sure, the preferred coating is Glyptal. As to the gray metal film, I had some analyzed many years ago by atomic absorption spectrophotometry. It was primarily tin, lead and antimony from bearing metal (Babbitt) with smaller amounts of iron, nickel and chromium from other wear surfaces, probably mostly cylinder walls and piston rings. It's just the normal result of an engine slowly wearing. Link to comment Share on other sites More sharing options...
DonMicheletti Posted October 17, 2013 Share Posted October 17, 2013 I love the serious (not conjecture) analysis of the grey film - I have seen it too and wondered. Now I know.Many years ago a friend had a racing Ferrari that had put a rod through the crankcase. Ferrari said that the case was a "special" alloy. I took a chunk of the crankcase and had it analysed to find the way to have it welded properly. The analysis showed the metal to be "Al". Just pure aluminum, no alloy at all . A real surprise Link to comment Share on other sites More sharing options...
nickelroadster Posted October 17, 2013 Share Posted October 17, 2013 You would also want to make sure that the grey stuff was not a result of water in the oil. Water in oil will turn some of the oil into a light grey coating. What ever it is, it should disappear when you change the oil and then I would monitor it to see if it returns. Link to comment Share on other sites More sharing options...
Rusty_OToole Posted October 18, 2013 Share Posted October 18, 2013 Reminds me of a story I heard about a guy who had a metalurgist friend analyse a Karmann Ghia door hinge. The report came back with all kinds of different things in it.The guy said "wow that's the most complicated alloy I ever saw"His friend laughed and said "that's what you get when you throw all the scrap you can find into the pot, along with some floor sweepings and a few old turnips".Another one. Some years back a 1937 Auto Union racing car turned up in the former Soviet Union. It ended up in England, being restored. They had to make a new head for it. They had the aluminum analysed by Reynolds. The metallurgist told them "that's the kind of stuff we make lamp posts and lawn furniture out of". Auto Union was using the most advanced German technology of the time. Guess there has been some progress in aluminum alloys since 1937. Link to comment Share on other sites More sharing options...
Guest RonB Posted October 21, 2013 Share Posted October 21, 2013 The red paint you mention is probably Gasoila hard-set red varnish....this should be used inside crankcases and transmission housings, particularly when they're made of aluminum, which is quite porous as you mention.There used to be a process called vacuum degreasing that could get the old oil out of the aluminum, but I've searched and can't find anyone who does it. I have an aluminum crankcase now that needs cleaning...I have a Machine ,made in the UK, called a vacQuablast. it uses water under high volume,with air-pressure at high volume and 2 bar pressure to propell fine glass beads at the surface. It was developed by Rolls Royce in the 1940's to clean aircraft engine parts without damaging them ,as bead blasting or boiling does. The finsihed surface can be burnished by the machine at a lower pressure and the surface can be handled with bare fingers ,and not leave marks. I am sure these machines or copies of the process can be found in the USA. http://youtu.be/T7O6v25fX50It gets the alloy parts surgically clean. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now