Compression test results

[ty222]

I have been restoring my 2 lately and I'm nearing the end but I burn oil and sometimes hear an odd engine noise so I thought I'd try a compression test.

All of my results were between 200 and 204 psi I've not seen readings this high before what are people's thoughts? I was using a new pressure tester, accelerator fully pressed

Could this be so good it's bad?

[Alex Knight]

Pistons have compression rings AND oil control rings.

They do different jobs.

[ty222]

Nice one Alex, so 200 psi I could have fantastic compression rings but the oils are naff.

It burns a ridiculous amount, Mot next so hope it gets through emissions.

[Carolyn]

The factory compression is 185psi.  Higher than that would indicate wet rings (excess oil) and carbon build-up on the cylinder-head and piston crowns.  That tallies with the oil consumption.

The oil control rings will be gummed up and stuck in the pistons.  There is no amount of additives that will deal with this, I'm afraid. 

Engine out and a mild rebuild will be needed.  Clean up pistons, new rings, hone bores, Replace valve seals while you're in there. 

A small modification to the oil control holes in the pistons is also good to do.  Enlarge the ones that are there (there are four of them, and add two more, or get a set of eight-hole MAG pistons.

Or you could go for a known good used engine.  Once you've done the work of taking it all out, betting on a used engine may not be the best way to go.

It will probably pass emissions.

[ty222]

Thanks Carolyn, thats perfect advise, i think if thats my only option ill try and get it through MOT this year and have summer and then look towards a 2zz upgrade.

[furbern]

You 'could' try an ester cleaner something like AutoRx or similar to free off the rings. I have read it is effective if you rigorously follow the instructions, but I admit I have never had to try it

[Beachbum957]

Many years ago, there were a couple products listed as "top engine cleaners" that would free gummed and carboned rings. A couple really did work. But they contained some rather nasty chemicals and there was some question if they would damage catalytic converters.  The newer formulations are safer, but don't work nearly as well.  In the US, the ACDelco GM Original Equipment 10-3007 Top Engine Cleaner seems closest to the older formulations and does work somewhat, although it isn't a miracle product.  Other car manufacturers also sell similar products. Some people try Seafoam, but most report it doesn't do much.

Trying a cleaner like the ACDelco probably won't hurt anything, but none of the current cleaners will fix badly stuck rings, and ultimately a tear down will be needed.