I bought a rebuilt 292 Y block that,s been sitting for two years but finally the hot Rod is up and running, it doesn’t start to smoke until the motor is at operating temperature . I’ve pulled the plugs, a couple are burning nice and clean a couple more are carbon coated black and at least two of them are oil coded. The crank case is not overfilled, I pulled the plugs again and looked and different ones are running clean and different ones are oil soaked??? The engine rebuilder thought maybe the PCV valve is not working correctly and it has oil soaked the intake manifold. I’ve blocked off the PCV valve and it doesn’t seem to make any difference however, I’ve only ran it maybe 20 miles. More time needed ? Does anyone have any other thoughts? Thank you,RAY
How many miles total have you driven this engine? Did you follow any break-in procedures? Quite often it would take at least 150 to 200 miles for the rings to seat properly, depending on what type of rings were used in the rebuild(chrome rings do take a while).
New engine?.....I ***ume so. Run it. Maybe the rings need to seat. New exhausts? Sometimes old pipes are contaminated. No luck after running it.... Look at valve seals and rings being broken or installed incorrectly.
Its possible during the Two years of setting moisture has condensed in the cyls and the rings have stuck to the piston lands. I hear stuff like break in ect. But properly crosshatched cyl walls the rings should seat in about 30 minutes. With a new flat tappet cam you need to run the engine for 30 minutes at 3000 RPM to break in the cam. Unless you have chrome rings the rings should be seated during the initial run in at first start up. My dad bought a B john Deere farm tractor in 1958 that was supposed to have a new ring job. always burned oil. fouled plugs ect. The reason was claimed to be the rings never seated. We tore that engine down in 1964. And to my suprize the s****er rings where installed backwards. instaed of s****ing oil to the crankcase it forced oil into the cyls. We Turned the rings around and put it back together and the oil burning stopped. If I was betting I would think you will have to tear the Y block down to fix it.
What the others said plus: Which transmission are you running? If it is a vacuum controlled auto it ay have a ruptured modulator diaphragm. I once had a 283 with Powerglide that was smoking and it showed that it was ****ing ATF through the vacuum port.
Agree, compression test or maybe better, mechanic's vacuum gauge connected to manifold. A whole bunch of engine derangements can be discovered right away. I am awful leery of buying a "rebuilt" engine unless I know for a fact the person is of good character. Blocking off the PCV is not the answer, the engine has to vent those gases. The draft tube system works as far as that goes.
I think you will have to do a compression test and maybe you will find out something, but I bet you will find ring problems in those cylinders with the oil soaked plugs. Broken rings, stuck rings or even like "old wolf" said rings installed wrong. Some of this may show up with a compression test, dry test then retest with some oil in cylinder. Buying "rebuilt" motors is always a gamble. What kind of "hot rod" ? I have a 292 in my Model A.
Dump a pint of Marvel Mystery Oil into the oil and drive it locally for a week. That should loosen up stuck or sticky rings.
I had a 292 in a 62 ford back in 67. It smoked terribly. The oil return holes in the heads were plugged,the valve covers would fill up and force oil past the valve stems. Very smoky. Cleaned out the holes...no more smoke.
Run a compression and leak down test on all cylinders and compare the numbers. Within 25 PSI compression and 5% leak down would be OK, then I would look at the heads. 2X^ If they did not use new rocker arms they could be worn and dumping oil that is going down the valve guides. Use a breather on the fill tube and the crankcase vent pipe. PCV?? PCV: you spend thousands of dollars to have your engine rebuilt with all new parts then **** the crankcase vapors back into the intake manifold to contaminate the fuel mixture and reduce your volumetric efficiency.
Engine was broken when I bought it it didn’t smoke at all I’ve probably got 50 miles on it now it seems to be getting better thank you for your response
I bought the engine from a retired auto shop teacher, i’ve talked to a couple of other people have bought rebuilt motors from him and he is in excellent standing with everyone , I certainly hope it doesn’t have to be torn down to fix it. Thank you for your thoughts.
I bought the rebuilt engine from a retired auto shop teacher he’s built several motors and several people have nothing but good to say about him, i’ve blocked off the vacuum to the PCV valve the draft tube is still in operation , still digging in for answers thank you for your thoughts.
I’ve kept good track of which plugs were all oiley which plugs were clean and some that were Black with carbon are now clean , some that are clean our now Black with carbon. If it was the valve seats or the rings I don’t think they be switching back-and-forth ? I’ve got a 1930 model a coupe three speed overdrive transmission , with three deuces on it.
Sounds like a cool car and I think you are right with the problem not changing from cylinder to cylinder, good luck with anything you find.
Fill up the gas tank , grab the old lady and pack a suitcase and throw an extra set of plugs in the glove box and a case of oil in the trunk and take a 500 mile overnight trip. Take back roads so you can vary your speeds. By the time you get home the motor will be broke in and your old lady will have a smile on her face if you do it right. Problem solved. I bought a 53 Ranch Wagon that had sat for 10 years. It used a qt. of oil every 50 miles for the first 200 miles and slowly started smoking less and by the time I had driven about 2000 miles it was down to 800 miles per qt. Which was very acceptable for an non rebuilt original engine.
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