Lapping piston rings

[Ed Wright]

Originally Posted by Bob Mulry

Hi,

I worked at a Cadillac Dealership and had to work on the HT4100 engines. The tune up guys would send the cars to heavy duty to have the trans diagnosed for no full throttle upshift. We would run a can of TEC through the engine to remove the varnish from the valve stems to prevent them from sticking. Re-road test and the trans was fixed.

The varnish caused the engine RPM to flatten out and not reach the RPM needed by the governor to do a full throttle upshift.

We pulled out a lot hair on that one.

Bob

Interesting!

[Rich Biebel]

I can definitely identify with the difficult diagnosis issues from my days as a dealer mechanic.......Mid 1970's Pontiac-Jeep-Subaru line mechanic....flat rater

GM was producing some really poor stuff and the Jeeps and Subarus new to this country had more than their share of problems....

[Bob Mulry]

You got it right...............

440-T-4, 700-R-4, 200-4-R, 200C some them so bad that the factory said when you get it figured out call us and we will put out TSB's....

They built them and early in the production runs we had to figure out how to fix all of the drivability problems......

As time went on the factory got a handle on them and had updates for the problems...

I worked at several dealerships Chevy, Pontiac, Olds, GMC & Cadillac but no Buick dealerships and we raced one of those also............

Bob

[Rich Biebel]

The Bon Ami deal was only something I heard about but did not remember how it was actually used. My apology for giving bad info there. 50 years ago is hard to remember. Makes more sense in the top of the engine and not in the oil. The stuff is abrasive and Pontiacs don't need any help with spinning bearings ....lol Total Seal sells a powder to use on your cylinder walls to help seat rings. I have used it. Maybe they heard about Bon Ami....!

[older racer]

we use to dribble bon ami, down carb on radial aircraft engines to help rings seat . it was bit smokey, lol. it was used as a last resort before engine was torn down. it would deglaze the bores?

[Rob Petrie E395]

For the guys who used top engine cleaner. Have you ever tried Ice Water? Basically do everything the same as top engine cleaner. Except use ice water.

[Pvt Parts]

Originally Posted by Rob Petrie E395

For the guys who used top engine cleaner. Have you ever tried Ice Water? Basically do everything the same as top engine cleaner. Except use ice water.

I idon't know about ice water but I have seen guys crack the throttle open and shoot a garden hose down the carb. A little pre-teardown steam cleaning I guess.