How To: Increase Compression Chamber Pressure

[Chisel86]

Ive often thought about doing this, but what are the effects to the oxygen sensors with all that carbon blowing through the system? Would it be a good idea to remove them (not disconnect the wires) just for the cleaning and then replace them afterwards?

[razor02097]

I would be more worried about clogging the catalytic converter before ruining an O2 sensor.

[TheIVJackal]

Would people advise to pour in water at a level just before stalling the vehicle?

[bestclimb]

I have tried this on a very tired engine. It may have helped but I duno. To get carbon off the valves I have hit the rockers on the valve side to knock them around a bit with a heavy rubber mallet. Made a noticeable increase in compression when doing leak-down type tests.

[Cobb]

Oh, I thought you wanted to increase the compression ratio. To restore some lost compression from bad rings what we did back in the day was pour a qt of motor oil down the carb, much like the guy poured the can of water. It made a hell of a lot of smoke, but the resulting bath helped the rings as well as valves.

The compression test wet vs dry will tell you right away if its valves or rings thats the cause.

Originally Posted by Daox

If you have low compression and free up any carbon build up, you're only going to make your low compression worse. Chances are that carbon is helping keep compression up.

[arcosine]

Take the engine apart and rebuild it.

[razor02097]

Please do not pour motor oil in the air intake of your vehicle. I guarantee you will regret it.

[gone-ot]

...do some research on the Continental AVCR-1360 "Variable-Compression-Ratio" diesel engine that GM used in their XM1 Tank prototype, the experimental tank that lost out to the Chrysler/General Dynamics "Turbine" XM1-B during the Jimmy Carter presidential years.

...brief SAE info on the AVCR-1360: http://papers.sae.org/760051/

[MTXA]

Be very wary about pouring liquids into a running engine as it can cause a hydrostatic lock and then it is game over.

I don't believe in most engine rebuild in a can snake oils because they simply cannot replace worn metal and tolerances and only serve as a short term band-aid. Sticky rings can usually be freed up with a couple short interval oil changes.

I do recommend Sea Foam added to a full tank of gasoline for safe carbon removal. When I first tried Sea Foam, I experimented with it on an air cooled Duetz diesel that had severe carbon build up and when I tore the engine down, the combustion chamber and valve stems were amazingly clean. I have had consistently good results with it in the commercial fleet that I maintain.

[3-Wheeler]

Originally Posted by Cobb

.... what we did back in the day was pour a qt of motor oil down the carb, much like the guy poured the can of water.....

Yes, the excess *may* loosen things up for about two seconds, just before that *new* amount of excess oil begins to carbonize back up around the rings, and stick them better than they were before!

Jim.