Classic/Antique Car Repair/rings or valves

Advertisement

Expert: - 9/24/2008


Question
Brad, My 55 Chevy, 235ci 6 cyl, powerglide is starting to smoke a little blue smoke. Mostly at a light while at idle coming from the crankcase draft tube, or it's noticeable it in my mirror coming off the freeway coasting down from speed. Car runs great other than that. Would this be caused by piston rings or by valve guides?

Answer
At this point without a compression test my guess is that it is mostly Valve guides and or seals. That is indicated by the smoke under deceleration when intake manifold vacuum is the highest. Some times an examination of the spark plugs will give a clue. If the oil splatter, dark spots on the tip insulator, are on one side then that indicates valve guides. As that surface was closest to the valves and received the full spray of oil. The smoke coming from the breather tube is more of an indication of compression rings slightly leaking blow by into the crankcase. Two different problems.
Brad

Classic/Antique Car Repair

All Answers

Answers by Expert:

Ask Experts

Volunteer

Brad Sears

Expertise

All automotive including antique and collectible. However if the car has been modified I can only answer in general terms and maybe get you pointed in the right direction.

Experience

Automotive tech instructor. Syndicated auto columnist 1970's though the early 1990's. Syndicated auto radio talk show, Ask Brad About cars, CBS Radio 70's through 90's TV Show "Last Chance Garage" 1980's PBS-TV syndicated. Auto instructor for the following companies: Fram Autolyte Holly Carter AMF Ford Motor University Of Conn Blue Hills Technical School Sugar River Technical Center Grew up in a family garage in Needham Mass and turned wrenches from the age of 14.

Publications
Manchester Union Leader, Nashua Telegraph, Motor Service Magazine, Yankee Magazine, Popular Mechanics (Saturday Mechanic early 80's), Los Angeles Times, New York Times, and lots more.

Education/Credentials
More than I care to remember. Basically Franklin Technical Institute in Boston, Northeastern University, Fitchburg State Teachers College, Tufts University, and a lot of factory schools along the way.

Awards and Honors
Moto Award winner. And much more.

©2012 About.com, a part of The New York Times Company. All rights reserved.