mx5cartalk.com

Hi Folks,

I've got an oil leak that seems to be coming from somewhere around the back of the motor The oil seems to be blowing back up towards the front of the engine and leaves a deposit of oil around the leads/spark plugs The MX doesn't drop large amounts of oil and the oil level hasn't dropped a lot since I've owned it. My MX has done over 400,000 k's and as I'm new to the MX scene any help/advice would be greatly appreciated.

Flows back up over the engine......sounds like a violation of the law of gravity?

I'd suggest that the cam cover (aka Valve cover) casket is leaking. It is a rubber casket that seals around the edge of the cam cover, and also the spark plug holes. So in reality you may be seeing two leaks that look like on?

Have you tried cleaning the oil off and then seeing if it returns. If so then you can loosen and correctly retighten the cam cover bolts and see if it this seals it properly, or replace the casket..ensuring it is bolted down correctly.

Here is some more info on the casket

http://www.miata.net/garage/valvecover/index.html

J.

Something else to consider, if the oil leak at the back of the engine is also on the drivers side it could be the Crank Angle Sensor (CAS) O ring seal. It is important to replace the seal if leaking as the oil will drip onto a rubber blanking plug under the CAS. The plug will perish and fail. If it fails it can cause coolant fluid to leak.....

http://www.miata.net/garage/cas_seal.html

J.

Thanks for the info J. I did clean all the oil I could find in the engine bay to check for possible leaks. The oil ontop of the cam cover is the only one I could spot that has reappeared, I think I will have to get those two gaskets replaced when I get the MX serviced next week.