I just worked on this same problem. Heavy smoke on start-up. Using about 1 reservoir a week of fluid, but very little of it was on the ground. The ACV valve on the pump was leaking fluid into the vacuum lines.. and into the intake manifold. I found some old threads on this problem, but didn't like the fix...sticking a bolt in place of the ACV valve and capping off the vacuum ports on the intake. The part I didn't like was "Go find a similar bolt at the hardware store and screw it in place of the ACV valve". So, I took out the ACV valve.. broke off the plastic defective parts with a hammer and you are left with just the steel threaded fitting...the CORRECT THREADS and flare. Then, I silver soldered the port on the fitting shut. This just caps the well. Screw the fitting back in using a little bit of thread sealant to be safe and VOILA! No smoke, and no leaky. Take out the two vac lines and chuck them into the trash. Go to auto zone and buy the vacuum port cap variety pack for $1.99 and plug the ports in the intake.
The salesman who sold me my 92 sc400 said it would go 250k miles. I'm at 183k... 6 more years!
