It is apparently "normal" for some oil to come in to the throttle assembly. It looks like it comes from the PCV (Positive Crank Ventilation). From the KZ-TE manual, "Some oil mist blowby from PCV is normal. Do not mistake it for oil leak from turbocharger." Not to say that we definitely don't have a turbo oil leak, but that's what I'd like to believe for now
(I really have no idea how much "some oil mist" is...).There are two throttle butterflies in the throttle assembly, each controlled by it's own shaft. These shafts run all the way through the assembly, and so they need oil seals at either end to keep the turbo pressure (and "oil mist"?) in.
After removing the intake pipe, I could not get the throttle assembly off, as the bolts have become unmoveable (even the "hammer and pin" method, which has never failed me before, would not budge them). I managed to replace the faulty seal without getting the throttle assembly off in the end.
Tips:
- There are a lot of small parts. Be careful not to drop them into the engine bay, or worse, the intake manifold, or otherwise lose them. They are not necessarily replaceable (see below).
- Toyota do not seem to sell the oil seals (or other parts), they only want to sell you the whole throttle assembly. The oil seal which needed replacing in our case was on the sub-throttle (smaller one), which is much easier to remove as the screws aren't stamped in. The oil seal which came out was NOK AG0123E. Replaced with a (seemingly better quality) nitrile rubber oil seal from Sealco / Bearing Man in Isando - part # SM8144; ID=8 OD=14 Depth=4.
- There is a risk of the throttle butterfly screws coming loose and falling into the engine after re-assembly, so pay attention to this (clean, loctite, etc). I was also wary of tightening them too much as then they'll be difficult to get out again without stripping the heads. This is something that is going to worry me, and I'll probably open the whole thing up again to check on them in a bit.
- The throttle butterfly can move around. Tighten it loosely, then close it to check how it fits / allow it to adjust before tightening it fully. If you can get the throttle assembly off then this will be much easier.
(sorry) .