Q&A with Kit Foster: November 20, 2014

Q. This is an answer to the question from Jim Vouk regarding timing gear lubrication on a 1936 Chevrolet (Oct. 26). Stripped timing gears are probably the most common major engine failure in the early Chevrolet engines. This is caused by a lack of oil reaching the gears. The timing gear oil nozzle is fed by gravity from the oil that passes by the front cam bearing. The oil flows down to the nozzle from the cam bearing through a milled slot on the back of the engine front mounting plate. This slot fills with sludge thus blocking off the oil supply. Often the gears are just replaced and the oil flow continues to be blocked, thus more stripped gears. It is necessary to remove the front mounting plate from the block to clean the slot.

A little history of the timing gear lubrication: From 1929 through 1931 the main and cam bearings were fed oil from a pocket above each main bearing. The oil in the pocket, fed from a low-pressure oil line, seeped through the main bearing and followed a passage to the cam bearing (for 1930 and 1931 the center main bearing was pressure-fed). In 1932, oil pipes pressure-fed all three main bearings so the flow to the front cam bearing improved but was still gravity fed. In 1936, the pipes no longer fed the mains but rather the oil gallery was built into the block. The new four-main bearing 216 for 1937 fed the timing gears in the same manner with slight improvements made through 1948. In 1949, the timing gear oil supply was pressure-fed by a passage from the front main bearing but the plugging-up problem of the milled slot continued as the sludge formed in the engine. Frequent oil changes and the use of the best detergent available back then helped to eliminate the problem. Chevrolet changed to full-pressure oiling to the rods with the 1953 Powerglide engine and all 1954 and later engines. The oiling of the timing gears remained the same and the problem persisted, but was not common.

A few months ago, I had an oiling system article in the Vintage Chevrolet Club of America magazine, the Generator and Distributor, where I described the timing gear oiling on the 1929-1936 three-main-bearing engines. In a short time there will be another article in an upcoming G&D covering the 1937-and-up four-main-bearing engines. This photo shows the back side of the front mounting plate with the milled slot.

— Gene Schneider, West Allis, Wis.

A. Thank you. As I’ve said before, the real experts are our readers.

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Q. I have a 1995 Chevy Tahoe that has a split tailgate in the back. The window lifts up independently and the tailgate folds down flat, much like the old station wagons. Does anybody know the last year this type of rear cargo configuration was offered in the Tahoes? Most new ones I’ve seen now have a liftgate. Any info would be greatly appreciated.

— Dave Yohr, Seymour, Wis.

A. I believe the year 2000 redesign of the Tahoe and Suburban introduced the liftgate in place of the old station wagon-style window and tailgate. I remember the style being introduced at the New York International Auto Show and the GM rep saying they kept the cargo door option because of requests from trailering customers, many of whom found the doors more convenient. The doors were dropped in 2005. In any case, 1999 would be the last year of the style you are probably looking for.
Some may wonder why I’m entertaining a question on so new a vehicle. Well, very soon the 1995 Tahoes and Suburbans will be 20 years old, and in any case, many of us use them as tow vehicles for our old cars. Remember, owning a Suburban or Tahoe means never having to buy a minivan.

To submit questions to this column: E-mail angelo.vanbogart@fwmedia.com or mail to: Q&A, c/o Angelo Van Bogart, 700 E. State St., Iola, WI 54990-0001.

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