Other than the oil pan, where are some common places where FDs leak oil?
I can't seem to find any particular source, other than maybe the oil lines.
Maybe a dipstick with a sloppy gasket?
Does anyone know a good way to pinpoint the location of oil leaks? UV dye?

 

The 2 o rings on the oil filter pedestal along with the rear main are the 2 big ones we see outside of the oil pan.

 

Probably a thorough degrease of the engine would be a good first step to locate a leak, something like truck wash maybe.

Based on the dipstick, if it's LHS of the engine....might be simply an oil fill, oops moment by your mechanic. Could look at the p/s reservoir, always a film there on anything that sees G.

You had a mid 90s car from memory with the PCV takeoff? I'm assuming that, and the old outlet leading to the twins might be running to a catch can, if you're using a standard neck, hoses there cooked hard? Mention of o rings on the filter pedestal reminds me the neck has an o ring as well as a gasket at the base.

 

Also, the o-ring on the plastic oil filler neck.

UV dye does a great job of helping to pinpoint the leak ime.

 

Ironically, the one place I am pretty sure it's not leaking oil.

Best I can do is throw bottles of brake cleaner at it. I am considering getting an engine washing head for my air compressor so I can spray it with bulk degreaser.
I might also use some disposable cotton work gloves to clean the engine. Using my hands is probably the only way to deal with all the little crevices.

Indeed, I previously had a massive blowby/oil contamination problem caused by overfilling. It still produces a bit of blowby because it's a track car, of course. I previously vented the catch can into the engine bay, but I've newly attached a hose to vent it below the car, just to make sure.

It's a 96, so I don't think it has a PCV (I don't fully understand the evaporative emission control system, but there is a tiny little factory catch can under the throttle body elbow).
It's possible some of the factory hoses have got hard. I replaced a few of them with silicone years ago, but not all of them.

I will see about checking the filler neck.

I wrapped some electrical tape around the dipstick gasket. I had done this years ago, but I took it off for one reason or another. A single layer gave a surprisingly snug fit.

Indeed, my PS reservoir is especially greasy, and one of my PS feed hoses (not pressure hoses) looks like it needs to be replaced. I can't tell whether the contamination is engine oil or PS fluid, though.

Which o-rings are prone to failure? The one on the filler cap, or the one that connects the neck to the block?
I want to use UV dye, but I'm not sure where I can actually get it here. It would at least let me know if it's engine oil or P/S fluid.

 

One quick word of advice. If it's an aftermarket oil filler neck, mine required two O-rings (doubled up) instead of one on the block of my new engine in order not to leak.
Mike

 

It's stock.

I wonder if my catch can really needs a breather filter, rather than venting it to atmosphere. Or maybe I need a better, bigger catch can with well-designed baffles.

 

The best catch can breather is an exhaust spike.


If you have had a pissy foam/mesh thing on a catch can that isn't drawing through to turbo inlet I'd expect your engine bay to be bathed in a fine oil slick.

 

....I just left one of the nipples open to atmosphere because that's how the car came...

"bathed in a fine oil slick" is pretty much the perfect description.

My Greddy air filters turn black really quickly...

 

I was referring to the one that connects the neck to the block. The o-ring on my car didn't fail but it was not the correct thickness so it leaked.

Can't help you on sourcing. I got my "kit" from Amazon.
Dye: Kit part to make it more visible:

 

If you haven't changed it out in a while, the hose for the PCV that goes from the oil fill neck over to the pipe to the turbo inlet can get pretty crusty and weep. That's where I caught my oil stains coming from.

Jason

 

Should be safe on the PCV, unless an engine build and swap of both the neck and UIM(?) has happened at some stage. The tank under the elbow is fuel vapor controlled by the purge solenoid.

I'd probably try and get one of the replacement aftermarket necks, preferably baffled, with a decent size outlet nipple for the track. Lots of the Japanese catch cans would be undersize here to legally use on a circuit. A baffle plate in there is good also, to try and slow air movement, the breather, if you're trying to limit oil mist in the engine bay, larger is better, I think we had a 3/4" entry k&n initially due to space and it would blow crud out over the can.....I think it's 1 1/4~ 1 1/2" now.

​​​​​​​I'm not sure if that hose between the reservoir and the steel pipe is ever oil tight even when new! The cap gasket is worth a check as well.

 

You are right, it's not a very big catch can. I could probably fit a larger one.

One of the two nipples from the filler neck is indeed piped back into intake right before the turbo, so I think maybe I should cap that one off and pipe the catch can into the intake (or feed both to the catch can somehow).

Maybe I should put some absorbent material around the PS cap, return (feed?) hose, and other potential leak areas just to see if those are sources of leaks, or just victims.

 

Can't hurt to test. I did that in my race car when troubleshooting once. Cut up a used sock and held it in place using either a rubber band or zip tie.

 

So far, my '94 had (or has) oil leaks from the following sources, in chronological order:

Rear turbo compressor shaft seal
Oil pan gasket
Oil filter pedestal O rings
Oil filler neck O ring
Oil level sensor O ring
Oil Metering Pump O rings

I used fluorescent dye and a UV light to track some of them down; others were obvious to the naked eye.

 

It was the power steering return line soft hose, as I sort of expected.
I was told this needs to be replaced once in a while.