Lapping piston rings

[Rich Biebel]

Onan made a product to carbon clean engines. 4C cleaner, and you sprayed it in the carb of a running engine. Similar smell as the GM cleaner and some other products you could buy. Bluish white smoke poured out the engine. It did help but definitely not as effective as removing the heads and carbon cleaning the engine.

An Older Onan flathead engine can literally stop turning over from the carbon buidup. Took a machine out of a support vehicle at the World Trade Center site after 9/11 that did.
We put in a new generator but the old one was just locked up from carbon on top of the pistons.....No time to waste there....

The stuff was easily the best carb cleaner as it dissolved pretty much anything in carb passages.

None of these products are still available and I tried to hunt down a case of 4C a while ago.....None available and no longer made.

Tried a lot of other chemicals....Mopar made a carbon cleaner too but I don't think they sell it anymore either....

SeaFoam works but nowhere near as well.....

[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

[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?