Engine oil leak

[Zorro_X]

Hi,
I'm having an engine oïl leak making oïl fall down among the sparking plugs cover down to the exhaust where it burns and makes a lot of smoke.
I read it could be caused by distributor "O" ring broken. Does someone have a picture or a diagram showing where is that "o" ring ?
I've a Toyota Previa 4WD from 1993
Thankyou in advance for your help,
Z

[pdgizwiz]

This is a very common issue with the Previa. The leak could be from either the valve cover gasket or the distributor O-ring. Both are made of rubber, and rubber becomes old and brittle with time. If you don't know when either of the two were replaced last, you should plan to replace them both.
The distributor is attached to the rear of the cylinder head, which is underneath the passenger seat on the right side of the van. To replace the valve cover gasket it is necessary to remove the passenger seat and peel up the carpet to reveal the hatch over the engine. While this sounds like a lot of trouble, it is really quite simple with common tools. It's a relatively simple job (https://www.toyotanation.com/forum/85-previa-forum/365347-valve-cover-gasket-spark-plugs-replacement-pictures.html), and one that every Previa owner should know how to do, because it's more a matter of when it's needed than if. I've had a half dozen Previas and this is generally the first service that I find that they need.
It's important that the sealing surfaces are well cleaned when re-assembling it. Toyota's FIPG works well as an adhesive, but be careful not to use too much between the gasket and the cover - the excess won't squeeze out of the groove and the cover won't seat right. Don't over-torque the bolts or they will break. I use a bit of blue Loctite on the threads and torque them to 8-10 Nt-m. They are special shoulder bolts and the shoulders should seat against the head surface.
Here's a thread on it. (https://www.toyotavantech.com/forum/showthread.php?744-Previa-valve-cover) I'm sure there are others.

The distributor has to be removed to replace the O-ring around it. Note the slot where it bolts onto the head. Since your distributor's position is adjustable for ignition timing, I suggest marking it's position before you remove it to save yourself the hassle of setting the timing. Pry the old O-ring out - it will probably be brittle enough to come out in two or three pieces. Clean the groove out and stretch on the new one - reassemble with a bit of oil and you should be good for another decade.

[Zorro_X]

Thankyou very much for your answer. Actually It's leaking around 1Litter / 500Km it is too much so I'm not using it anymore until its repaired.
I'll go for both gasket and O-ring then replace them.
Thankyou again ! :)

[Zorro_X]

Hi,
It took some time, but i've just buy new parts to repair those leaks !