Robert here with my 49 half ton, 235ci engine. I’m noticing lately a lot of gray smoke coming from blow by tube. Engine operates at normal temp 170 when hot and not overheating. Anti freeze at normal levels. Any thoughts? Much appreciated.
Temperature would be dependent on the thermostat value........160* thermostat and 170* running temp would be normal. Also going to vary on where temp value is measured. Some use 180* thermostat to run warmer.
As for the smoke or vapor..........condensation vapor would be normal. When was the oil changed and how is the truck be used ? On hard acceleration or decel does it smoke from the tail pipe.
What is the history of the engine? Rebuilt ? Compression or cylinder leak down testing would measure the general health. Blow by on well used engine would be expected. Large amount of water vapor from the draft tube on truck that is used casually could also be normal. It takes a long time for the oil to reach temperature.
Robert, as others have indicated you may not have a serious issue at all. A quick question and suggestion. How long does the truck set between drives? And if weeks at a time or it's generally only used to go short distances (3 or 4 miles) a monthly drive of 20 or so miles continuous driving will get everything up to temp, cooking off any moisture in the engine and oil as well as the differential and transmission. Worse thing we can do with our classic vehicles is not drive em.
Added as an afterthought. Change the oil to 15w40 diesel rated oil. It's good for the engine and may help.
Thanks for the info fellow members. I really drive the truck occasionally and not in the winter months. I haven’t touch the motor as far rebuild etc. I put the truck on my lift today and inside the blow by tube walls I was able to remove a light coating of light brown gunk. One other time the blow by spit out this substance. I’ve changed the oil about a year ago and aa I said only driven it a little, and short trips were 5-10 minutes at speeds of 35-40 mph. In answer to some of your questions, I have a 160 thermostat in there. On hard acceleration I don’t notice any unusual smoke coming out of tailpipe. I think a compression check would be wise as well as cylinder leak down testing. I’d like to do this myself and not bring to a garage. Do you need expensive equipment? I’ll change the oil a s you suggested Ron.. Thanks.
You can pickup a compression test kit reasonable at you local parts house. Pretty straight forward test. IMHO I would install a 180 stat, first and foremost.
If you have an O’Reillys or Autozone you can get a loaner compression tester. Disconnect the coil center wire. Block throttle wide open. Take all the plugs out. Get pencil/paper ready and start with #1 doing a dry test first. Record results. Then put a teaspoon of oil in each cylinder starting with #1 again for a wet compression test. Record the results. Report back with the results. ðŸ›
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
If your only "issue" is blow by coming out if the blow by tube, just drive it more often for longer periods. They are supposed to drip. We don't rebuild our carburetors for carbureting, nor our generators for generating. (We do however change out our pistons for [censored], ) Carl
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
I read a "funny" remark on another board about oil viscosity numbers. "The first number is the time in seconds it takes for oil pressure to reach the last rod bearing. 5W: 5 seconds." Not science but the trend is there.
To run a compression test you screw the fitting into the spark plug hole. Time for you to watch a YouTube video or two on how to do it.
Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
If you're in a position where you can see smoke coming from the road draft tube, the main problem is that you're NOT in the driver's seat. Drive that thing like you stole it- - - - - -engines that get lots of exercise keep all the contaminants boiled out of the crankcase and they don't have issues with moisture buildup and steam. That's not "smoke" you're seeing- - - - -it's water. The road draft tube only ventilates the engine properly at speeds of 30 MPH or above. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
