Blue/white smoke right bank


I have a 1978 Chevy K10 that has a lot of work put into it and still requires some on a consistent basis. 4-5 years ago I put a new Mr. Goodwrench motor in it swapping out the distributor, intake, and few other extras all done by myself along with my fathers cherry picker/hoist. Have driven it over these past few years very little and have around 10,000 miles on it at this point. It recently has started puffing out blue/white smoke from the right bank, and after having driven it long enough to foul the plug I have found it to be in the # 7 cylinder. This is a job I believe to be bigger than this CAT scan tech and will take it to a mechanic, but I am wondering what some of the possibilities are so I do not go to mechanic totally ignorant. I have no regular mechanic and am not looking forward to the surrendering of this task. My only thoughts are a bad valve guide, or ring slots in a line. Neither one seem likely on a Goodwrench motor with so few miles. Please educate me on what I should expect. Should I make certain to take it to someone that will do a ?pressure let down/leak test??? Is there such a thing?

Thank you for your time!

Matt Hawkins

Indianapolis, IN 46234


Have you checked the level of the transmission fluid?

The transmission has a vacuum modulator that uses engine vaccum for it’s control. If the diaphram within the vacuum modulator developes a leak, transmission fluid can be drawn into the engine via the vacuum hose. And this can cause a grey/white smoke out the exhaust.

Crawl under the truck, and on the side of the transmission you’ll find a metal canister with a vacuum hose attached. Remove the vacuum hose from the modulator, and if transmission fluid leaks out of this connection, the modulator requires replacement.