The test for bedded rings in a newish engine

Post by **niftyrodman** » Sun Jul 14, 2019 10:17 am

There must be a rule of thumb for the difference in compression between oiled and dry to confirm or deny that the rings have bedded in properly.

Post by **oliver90owner** » Sun Jul 14, 2019 10:38 am

They will be oiled if the engine is hot? Oiled compression tests are best for valve leakage.

I think an air leakage test tells you more about an engine.

Is this on a rebored or re-rung engine? Engines that are just fitted with new rings can have other underlying faults if the correct decision process, on suitability for re-ringing, is not checked out properly.

Post by **niftyrodman** » Sun Jul 14, 2019 2:51 pm

No problem there, rings were checked in bore for gap and installed perfectly. Oiling has nothing to do with valves as they face down. Oiling is all about rings sealing, and my theory is that if rings have run fitted well, there will not be a huge difference in compression,? providing of course that the oil is only no more than 3 squirts with an oil can. Just an interesting thought thats all.....no alarm. Ive never checked on previous engines. All new valves here. The "oiled" comp test is to split off the rings from the valves to artificially disguise broken rings etc, so if you oil it up and the comp is still low its a leaking valve

Post by **BobHood** » Thu Jul 18, 2019 1:10 pm

Niftyrodman,

I agree about the oiling up bit, it does make a difference, but you won't get a true reading of the compression till the engine is up on running temperature. Then you stop the engine, take out all the plugs, and do the compression test on each cylinder in turn with the throttle wide open. If you don't open the throttle you'll get a lower reading, as I've found from experience myself.

Post by **niftyrodman** » Mon Jul 22, 2019 11:58 am

Thanks Bob, done all that. Now here's the thing. When I first set the engine up I had the wrong needle in the SU Too rich, and it overfueled to the point I think that it may have contaminated the oil in the sump with unbunt fuel. An that smoked on acceleration and when under power. now its not doing that, and nothing else has changed except an oil change and also now is 20/50 instead of 15/40

Morris Minor Owners Club

The test for bedded rings in a newish engine

The test for bedded rings in a newish engine

Re: The test for bedded rings in a newish engine

Re: The test for bedded rings in a newish engine

Re: The test for bedded rings in a newish engine

Re: The test for bedded rings in a newish engine