Greetings all!
I have a problem with an otherwise (mostly) perfect restoration, and reading in this forum, I see that others have experienced this too but may not have found the cause. Here are some of my observations.
As a background, my '72 Midget (1275) has had a top to bottom restoration done on all of it and I've been through the engine thoroughly (vatted, bored, turned, balanced, alloy head, etc.) No expense was spared to do the job right. I did the work myself, except for the machine work, and I am an experienced mechanic. I should mention that I live in the SE USA and this car is operated on 60F days minimum. The smog pump was missing when I got it, but the evap system is still intact.
When starting the vehicle cold, everything is fine. I back the car out or the drive and accelerate down the road. The first time you run it up through the gears (within 2 miles or so) it suddenly blows great clouds of oil smoke out the back. I should mention that it also did this before the major rebuild on the motor. I traced the problem to the oil separator on the timing cover. It fills with oil and apparently burps a significant quantity of oil up the breather tube into the carbs. I have verified this by running the engine at fast idle and observing the inside of the separator. While observing the oil in the separator, removing the oil fill cap had no immediate effect on the oil level in the separator chamber. If I were to bring the car to operating temperature before driving it, this would not happen, but very few folks drive like that. If I disconnect the crank breather and run it, it doesn't blow smoke either.
It is not crankcase pressure as best i can tell, not entirely. Using a pressure gauge mounted to the evap canister input on the valve cover, I determined that the crankcase pressure reaches about 1/4 - 1/2 PSI before the smoke starts and the pressure drops off (and stays off) for the rest of the run. My separator is NOT clogged and neither are the oil return holes from the timing cover to the crankcase. I am running 10W-40 oil. The separator just fills up momentarily and then once it "pops", the system behaves normally.
I used to own a '73 1275 back in the late 70's and it never did this, ever.
I have seen others post here of this exact same problem and they never
gotten a definitive answer. It was always, rings, guides, seals, etc.
Thats not the case here since all that is new and I have a smoking gun.
(pun intended)
Am I just missing something.
Has oil changed that much and the separator is no longer "adequate" for todays oils?
Thoughts?
Michael
-Michael