Lead pudding in older cars. The product of incomplete combustion, water vapor, and oil mist whipped into a primordial goo through the whipping of the crankshaft, and cam and the flailing of the rocker arms. Made worse by short trips, incomplete crankcase ventilation, poor filtration of the oil.
The other day at work a customer came in with one that puzzled us a little. He has a 3 liter (4 cyl) boat and he checked the oil, it was full, and they went boating. It was up on plane and he started hearing the lifters rattling, but still had oil pressure on the gauge. When he pulled the dipstick there was no oil on it at all. He only had one quart of extra oil on the boat so he dumped that in and limped on home. Next day he checked the oil and now it was overfull by about a quart ! Only thing we could come up with was that the oil return holes in the head are plugged up with sludge and the oil pump sucked the pan dry, then when it sat overnight the oil slowly seeped back down. Either that, or something screwed up in the oil filter, but we weren't sure that would affect it that way. We told him to pull the valve cover and check the drain holes, but haven't heard back from him to see what he found. Don
A lot of the sludge you see in older motors was caused by the paraffin content in the oil - Pennzoil was probably the Worst for this. paraffin is essentially a wax and it would just build up inside the top end in particular.
thats the flavor ... clean it out and see how bad the next pot tastes ... as for sludge it was water , carbon , lead , sulpher , metals , dust and dirt , that fell out of suspension in the oils most modern oils use a dispersant in the detergent package to keep the carbon and dirt floating so it can be pumped to the filter and removed
You have water from the atmosphere and the water that is the main byproduct of burning gasoline...then you have it supplemented by all the miscellaneous gases and fumes coming along with the water and dirt, sometimes making the sludge acid enough to corrode metal inside the engine... Biggest cures IMHO are running proper thermostats, as the engine needs to be hot enough to cook off most of these, and a PCV to get the fumes the hell out of the crankcase and back into the furnace. I suspect this stuff might well be more important than filtration...
I believe they did-I've got two or three but I broke the handles trying to split firewood with them. Shoulda stuck to sludge.
I had a long time friend that was an auto machinist. He would ask every customer what oil they ran when they dropped off engines for rebuild. Pennzoil was by far the sludge maker back in the day. Modern Pennzoil with the new oil standards is now pretty good stuff.
I must admit the more I read about oil and all the different types the more confusing it gets trying to figure out which one I should be using for each type of engine. Even the whole sludge thing is hard to figure out sometimes because I have seen engines where the guy changed oil every 2.500 miles religiously and yet when the motor came apart it was full of sludge. I used to add mineral spirits to some of the engines and let them idle for 20 minutes and then drain the oil but once the engine really gets sludge up good sometimes I needed a screw driver and a hammer to get it out of the bottom of the pan. Oils have changed a great deal over the years and certain engines need one type while other engines need sometime completely different. I know a lot of guys like the Brad Penn oils. Jimbo
There are many different reasons an engine will get sludged up. Short trips don't let condensation burn off. Too cold of a thermostat that won't let the engine ever get up to temp. Overheating an engine. Poor PCV set up. Poor oil flow. Clogged oil passages. Using crap oil. Not changing the oil. I could go on and on.
I looked at a site about saving petrol/useing Hgas, they said Hgas helped get rid of the sludge and made the motor run cleaner, they also said filtering the crankcase air like you would for an air compresser ( like a jar with glass marbles, to catch the water, and a gause thing to catch the dirt) also cleaned motors of the sludge. I've not tried it and wouldn't know if it works. I am going to try the filter thing, got the stuff, just haven't put it on. I've also been told changing the oil when hot helps, and yes it feels better in winter.
Thanks for all the replies. Way back when, we used to remove sludge by draining the oil, filling the engine with 1 quart of 10 weight oil and the rest kerosene, and letting the engine idle for an hour. The crankcase contents were always black and usually thick when drained. Sometimes the hardened sludge would clog the oil pickup screen, but the treatment usually worked. Yeah, I know it's dangerous, but the world was different in 1957.
I did the same on a 70's pontiac 400, pulled the valve covers and scraped/ shop vac'd as much junk as possible,ran it with 2 qts of 50 wt and 4 quarts of naptha,kept it at 2000 rpm for an hour. It cleaned a tremendous amount of crap out that engine, not sure if it helped the bearings. I put another 20K hard miles on it.
gramps recipe was 4 quarts kero and a quart of dexron II , that was the only gm product in that household till my cars started showing up as he worked at Ford in management . and when I changed out that mess it was blacker than the aces of spades , that 351 lasted 300K miles in that grand marquis till my cousin was broadsided in it . on the farm the other grandfather would just fill the crankcase with diesel , run it for 10 -15 minuts and then drain and pour a quart of light oil in it to flush the diesel out . and change the filter, that old WD tractor of mine is still running to this day .going to need valve seats soon
Back when I was a teen and just learning about this stuff, I put a cam in my 63 Bonneville. When I removed the intake I found alot of sludge and thought I would scrape it loose. Most of it went down into the pan and even though I changed the oil it still plugged up the pickup screen on the oil pump and starved the engine of oil. It started knocking soon after that and had 3 pounds of oil pressure. I also learned how to rebuild an engine after that. Don
My great uncle had a saying: "Don't disturb the dirt". What he meant was unless you plan on doing a total and proper rebuild, you should leave it alone.
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