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Classic/Antique Car Repair/Chevy 454 dieseling problem

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Expert: - 12/11/2008


Question
We recently purchased an old motor home ('86) and am very happy with operations, except for a continuing dieseling problem.  We've gone the tune-up route but it didn't seem to help with this issue.  I've read about Seafoam and it doesn't seem like a safe bet for us.  What can  you recommend?

Answer
I assume that you are talking about after run when you shut the engine down. The main cause is a throttle opening too much on shut down. I believe that there was an idle solenoid on that engine when new that when you shut the engine off closed the throttle. If the solenoid is there the idle speed is set with it and the closed throttle position is set with the idle stop screw. As far as I am concerned "mechanic in a can" products are a cover up. Just my opinion.
Brad

Classic/Antique Car Repair

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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.

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