L-Jet TPS is all oily, the bottom of the Throttle Body etc.... Options

[malcolm2]

Taking the TB off to be rebuilt and could not help but notice that the under side is covered with oily dirt. 20,000 miles since I put it all together, but this area has, by far, the worst build up.

The boot seems pretty stiff but no obvious cracks of holes.

1. I assume the oil is coming from the oil tower filler neck. But why would it blow out with air sucking in? 1st thought the stiff boot did not make a good seal and this is my vacuum leak. But again shouldn't it suck in? But the btm clamp screw on the boot was very tight.

2. is this normal?

3. are the "S" boots available new?

[Rob-O]

Are you missing any of the oil seals in the cap? That would allow a steady flow of oil misted air right back into the intake. There are two baskets on the cap. A lower, then a spring that circles the cap and then an upper seal. These are ON the cap. If the lower seal is missing or hardened, it would allow oil pass to the tube that runs to the intake. The upper seal just seals the cap, so oil doesn't get out of the top of the filler.

There are two other gaskets on the oil filler itself. The cork gasket that fits between the engine block and the oil filler housing. There is also a small o-ring that fits between the two pieces of the filler assembly (the oil filler neck and the oil filler housing).

[malcolm2]

Are you missing any of the oil seals in the cap? That would allow a steady flow of oil misted air right back into the intake. There are two baskets on the cap. A lower, then a spring that circles the cap and then an upper seal. These are ON the cap. If the lower seal is missing or hardened, it would allow oil pass to the tube that runs to the intake. The upper seal just seals the cap, so oil doesn't get out of the top of the filler.

There are two other gaskets on the oil filler itself. The cork gasket that fits between the engine block and the oil filler housing. There is also a small o-ring that fits between the two pieces of the filler assembly (the oil filler neck and the oil filler housing).

I didn't think about that, but this issue could also be that TOO MUCH oil is escaping.... I will look at it closer.

Turns out the cap does have 2 seals. Maybe 3. I can't remember if one sits at the very top of the funnel. Mine does not have the spring you mentioned.

Anyway one is and O-Ring, one is flat. I recently tried to get a new flat one. I thought 914Rubber had one, but it turned out to be for the gas cap.

my guess is that the oring seals the upper, larger diameter of the funnel and the flat one rests on the edge of the step from large dia to small.

I did not replace the flat seal at that time. But I did flip it over, you can see an indention were it has been sealing since 1975. They were both pliable, the only damage looked to be the indention and that did not seem to be a failure. The cap is very tuff to turn and once loosened the seal makes it tuff to even pull the rest of the way out.

Now that I think about it. Why have the hose returning to the intake if you are gonna seal the cap so well?