Hi everyone, I am going to visit my family down south texas and I have my 1962 cadillac it has a 390 engine on it When I lived in california we did a dry compression and noticed all cylinders had somewhat of an ok compression any where between 130-165, except for one of the cylinders it was at 30. One old schooler told me that perhaps the lifter or valve is stuck and he would fix it for me but that never happened. My question is i moved to Texas this past year i don't have money now to rebuild the engine. My brother has poured transmission oil thru the carb to loosen up the valves it's running pretty good it still has blow by according to my dad there's no signs of blue or black smoke. Wondering if I pour some Mystery Motor Oil if it will make the car run better? If so where do I pour it? I've seen some people pour it on the gas tank and other people top it as a 5th quart of oil top it and leave over night and then drive it. Thought I'd ask you guys to see what your experience was and well does it work? Engine runs smooth on freewaay, it idles fine but well i do get some blow i already changed the PCV Valve. I wanna drive it back to San Antonio, for about 2 hrs. so wondering if i can make it?
You need to paek it before you do more damage. Cures in a can generally only lead to more expensive repairs. Marvel Mystery oil,added to the oil will potenialy free a lifter stuck to sludge. in the gas it can loosen carbon in the combustion chamber and rings. Good luck; bandaids are usually an expensive way to go.
Sounds like you have a hole with stuck rings nothing to loose at this point. If it was mine I would put a pint of Marvel in the oil and run the engine for 30 minutes. Find the cylinder with 30 PSI....pour a few tablespooons down the spark plug hole on that cylinder and let it sit a week or so.Turn the engine over with the spark plug out to get any extra oil out of that cylinder and put the spark plug back in and run the engine... Re test. If the engine doesn't get better, it's time for a tear down and repair.
If the plugs aren't fouling and you got good oil pressure, I say drive it. Once the oil pressure goes, you will have major wear and fouling plugs means the compression is gone. One bad cylinder that still fires is not going to hurt anything but the gas mileage.
I had a problem with a 350 engine that would run fine and every once in a while it would start to shake just like when you pull off a plug wire. Thinking that my problem was electrical I changed the following parts, plug wires, spark plugs, all vacuum lines, and finally the distributor thinking maybe the shaft was shorting out once in a while and yet I still had the problem every so often. A friend thought I had a lifter the was hung up from time to time and suggested Marvel Mystery Oil so I had one quart to the oil and I have never had the problem again. I learned an interesting listen and that is sometimes when you swear the problem is electrical it's not but it feels that way. It worked for me and it just might work for you. Jimbo
I also had a 62 Cadillac with LOTS of blow by and with regular motor oil it sounded like it was going to explode (loose main bearings) so I would run up to 40 or 50% Lucas Oil stabilizer and I still drove the crap out of it here in Arizona... 150 miles at a time on the highways and I got decent gas mileage for big road barge like that. the blow by was so bad I had to direct the blow by into the air cleaner .
Go to an auto parts store or wally world & get a can of restore for an 8 cylinder. It is good for around 800 to 1000 miles depending on how bad your engine is. If that don't help drive the sucker it is not going to get any better. Prepare your wallet for a rebuild. Small short trips will kill an engine in short order. Ya gotta get them warmed up nuff to burn off the condensation. Probably too late for your 390.
I had a '79 Chevy wagon that was supposed to have a dead cylinder and it had an anti-fouler on the #8 plug. It sat in my driveway (I was going to use it for parts) and I put a fresh plug in it.. ran great. The car was used by the PO for short drives. I registered it and drove the hell out of it for 6 years. It used some oil, but ran strong. Once in a while it fouled the #8 plug again.
When I was just a kid an old timer showed me how to free up stuck valves and get rid of carbon buildup. Remove the air cleaner and run the engine at a fast idle. Take a small can of either Bardahl or Marvel Mystery oil and punch about six ice pick holes in the bottom and hold it over the carb. Dribble the oil into the carb and keep the idle up. All kinds of smoke and chunks will blow out the exhaust but after running a few cans through it the engine will smooth out and run noticeably better. And it will kill any Mosquitos in the area. If you still have a problem just drive it until it dies, it's already broke.
Mopar Combustion Chamber Cleaner is a good product for removing carbon. if the blowby is caused by carbon sticking the compression rings it should help.
Marvel's does what it is supposed to, it is a light machine/penetrating oil. It is just the stuff for old motors. Run it in both fuel and the oil if you want to try it for unsticking things. Generally it works right away but give it a couple hundred miles if necessary. Replaces 1 quart of oil, and iirc, 4 oz. per 10 gallons of fuel.
Here a picture when I ran Marvel oil through my carb with the 56 buick station wagon .No bugs around for miles .lol.Bruce.
I'd drive to the beach and back.. 20 mile round trip... 3 quarts of oil. I used to save the waste oil from work and carry it around in 3 gallon cans.
Years ago I drove an old Buick. I was having a diesleing issue. I hit up the Chevy parts counter for a can of "GM top engine cleaner" you would get the engine good and toasty, pull the air cleaner and pour it down at high idle, till is bogged way down, then shut it off and let it soak in. This stuff was nasty looking. Anyhow. I did it in the parking lot at work. You can imagine the smoke rolling out of it. Thought the bank next door was gonna evacuate. Next day, a guy from the EPA comes by. Seems the little outhouse looking thing at the end of the parking lot was an air quality monitoring station. "We got some unusualy high readings, might have been a glitch, you guys see any smoke in the area?" NOPE!! Not me!!!
thank u so much for your suggestions. i will do that this thursday when i see my parents for thankgiving. hehehe i will come and post up the results. thank you everyone i appreciate it.
Try MMO in the crankcase and fuel (per directions) before going the mosquito fogger route. I had the 292 in my pickup rebuilt by a garage and something wasn't quite right. The oil was turning black right away, carbon black. I had always heard don't bother with snake oils but thought I'd give MMO a try. That was 20 years ago. Whatever the problem was, it sure cleared it up.
if you have stuck rings really soaking the bad cyl might help. I use a mixture of auto trans fluid and diesel and pour the cyl full and let it soak. if its worn heat up some 90 weight gear oil and STP really hot almostto the point it catches fire. And using a funnel pour that mixture into the cyl. and let it cool and then spin the engine over with that spark plug removed to blow out the excess. the congealed mixture will seal the compression for a time. Enough to get it through the car aucton anyway
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