MX5 Racing News - (no longer maintained)

Engine near death - oil analysis tells the tale

Oil pressure on the engine has been low since purchase. Despite some trips to Oregon and a full season of autocrossing the pressure has not seemed to drop much until very recently.

After an oil change and new filter it's above where it was when the car was purchased last year. One of the steps in any oil change I perform is sending a sample of the oil out for analysis. This is helpful for identifying potentional problems such as poorly performing air filters, excessive engine wear etc.

The analysis just came back on the Miata's 178,000 mile old engine and the news is not very good at all.

DAVID: Does this engine still have oil pressure? Unless you are using some sort of additive, the copper and lead are from bearings, and they show very poor wear. Universal averages show typical wear from this type of engine after a 3,685 mile oil use run. Copper and lead are clearly abnormal. The upper cylinder metals were at above average levels, but not too awfully high considering the maturity of the engine. Silicon was high so we suggest checking the air filtration. Running this engine at full throttle may cause a catastrophic failure.

I'm thinking I need to source a low mileage 1.6L engine for a swap. My co-driver is excited about performing an engine swap (neither of us have done one in decades) plus without any event commitments we can take our sweet time and do it all up just right.

For ref, there are the totals for copper and lead. It's beyond excessive, amazing to me that a connecting rod has not exited the block yet.

Copper Average: 4 Measured: 1287
Lead Average: 1 Measured: 913

I'm also running one of those ricer cone intakes so it looks like it's totally worthless too. That's a nice data point *shrug*. I guess I could find a K&N and slap it on there for a little improvement with another engine.

Once I am able to re-charge the racing budget I'll be purchasing another engine. Likely a good low-milage donor engine since decent 1.6L engines appear to be easier to source (and a lot cheaper) than trying to rebuild even a very good core.

More news as this develops, based on this brrreeeport.

posted by Foto Veloce @ Thursday, October 13, 2005