Car smokes - sometimes

[pasadena_commut]

The P5 my daughter now drives smokes like crazy - sometimes. This is the formula for a
smokey start:

1. start the car when it is cold.
2. drive it, but not long enough for it to warm up. Even 30 seconds is enough, like backing it out
of the driveway and parking it on the street.
3. let it sit several hours
4. restart

Change any of that and it won't smoke. The key thing seems to be that it will smoke hours
later if it is parked when it isn't fully warmed up. The usual tricks for making a car smoke because
of bad rings don't do anything. Once the initial few seconds of smoke at start up are over, one can cruise down
from 50mph then stomp the gas, and there is no smoke. Similarly, if after steps 1 and 2 the car is turned off,
and restarted 5 minutes later, there is no smoke.

The car has always smoked on starting if it has been a very cold night, near or below freezing, no matter what happened earlier. The sequence described above is new though.

Sometimes it burns oil. Sometimes it doesn't. There are no leaks and the coolant is clean.

Valve stem seals???

 

[wolfy53]

Yes, valve stem seals and or the valve guides.

I replaced just the valve stem seals on mine and I wish I would have taken it in to have the valve guides done as well. Mine still smoked on start up.

 

[pcb]

Being as either oil rings or valve guides/seals are both big expensive jobs, it would be good to know for sure which one it is.

I would suggest pulling your plugs Before starting the car at step number 4.

If there is oil on top of any your pistons then it almost certainly ran down past the valve guides/seals.





Perhaps the valve guides/seals need to be warmed up to start sealing better, much like the oil rings.

If your car is fully warmed up, then the guides/seals are sealing so the oil drains out of the head and not into your cylinders ???

(in case you haven't seen this thread,..)

http://www.mazdas247.com/forum/showt...=1#post5504992


Another good thread,...

http://www.mazdas247.com/forum/showthread.php?123792748-Smoke!

 

[pasadena_commut]

It was in the shop today for unrelated reasons and the mechanic stuck some sort of probe up the tailpipe which he said indicated that it was not burning a detectable amount of oil. It had been fully warmed up when parked last night and did not smoke when it was started this morning and driven to the mechanic (only a 2 minute drive). It did not sit for more than 4 hours before he got to it, and it didn't smoke when it started, even though it had been parked cold. (It has been very warm the last few days, which might have also cut down on how "cold" cold was.)

His opinion was that we should just watch the oil level carefully and wait. If the motor blows up or it starts burning a lot of oil or shows other major problems, then replace the motor. I'm not up to rebuilding a motor myself, and the cost of having it rebuilt by a shop is more in parts and labor than swapping in a "new" one.