13 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHOil residue engine bay
Reported or suspected cause
3.4l motor
Suggestion or failed attempt
No successful repair reported for this finding.
0
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1
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0
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Leading evidence: '3.4l motor' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is '3.4l motor' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check crankcase pressure' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
Everyone, please, go out to your car/garage...open the engine lid, shine a flashlight in there, look around, hell, even pull the dipstick and manually check your oil level.
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Anyone know what this oil spray/residue
could be from? It's mostly covering the plenum, plenum boots, plastic portion of the intake manifolds. There isn't any on the too of the block where the starter is. I can't seem any cracked hoses or connections. The inside of the plenum is spotless.
Is the oil fill tube secured to the engine or broken? Mine was a little loose, although I just had a little oil on top of the block, it's right there. Yours could be really loose or broken.
Only other source of oil there I can think of, could be the AOS vent to intake if your AOS had failed, but then the oil would be inside the intake.
There's an oil cooler towards the back, but if the area near the starter is clean, that's probably not it.
What year car do you have? Out of curiosity, where does the vacuum line on the right of the throttle body go? The check valve on the left is to the main vacuum system. Porsche Sport Exhaust uses another check valve, on mine (2004) it is off of the rear intake resonator tube. Seeing that vacuum line go directly to the intake without a check valve is strange to me.
Its probably the 3.4l motor. The vac line in the right is for the fuel pressue regulator and is correct with no check valve.
My guess would also be a cracked oil fill tube.
I'm with everyone else so far - the oil fill tube is probably cracked or broken. It is not a difficult job to replace it AFTER you get the alternator out.
Sorry, it's a 2001 C2 3.4.
Yes, the right vac line goes to the fpr.
The AOS lines appear to be fine. I'm not 100% sure if the AOS is failed or failing, I have no symptoms, but plan on changing it over winter.
I'll check the oil filler tube for cracks. The top of the block, oil cooler, starter are all clean. My RMS or ims seal are leaking so my only guess was oil be doing around - also replacing those over winter.
I second the oil filler tube. If its original it will crack if you look at it wrong. I forgot to unclip mine from the airbox once and it was toast when I pulled the airbox up. Good thing it was on the roller with a failed engine at the time.
All the plastic hoses at 20 years old are due for a change...
That oily dirt looks like it�s caused by the AOS return line going to throttle body. Most likely a worn out �o� ring at connector. Or AOS line not connected properly.
The more I look at it, you might be right.
The best way to find out is clean it all up and keep an eye on it. Hard to believe people let things like this go unattended for so long.
Got the the oil filler neck, it doesn't look to be cracked at all. AOS connector o-ring looks ok and soft too. I'll replace both anyway and see if it stays clean in the spring.
If the oil filler tube was cracked you'd have oil all over the top of the engine no? It looks like you've got a fine spray or weep going on that's just picking up all the dust that flies around in the engine bay. I'm going with the O ring connection on the AOS line that feeds the throttle body/intake...
Yes, I'm with you on this one. I know I'm a bit picky about my engine bays, but this is almost unbelievable. For something to be amiss, coated with oil, and unattended or unnoticed for so long is not right...not right at all. Everyone, please, go out to your car/garage...open the engine lid, shine a flashlight in there, look around, hell, even pull the dipstick and manually check your oil level. Wow, now don't you feel better now?!?!
OP - I also suspect the AOS to intake. Known leak point. Clean up the area, check oil level somewhere at half level and warm up engine. Use a manometer to check crankcase pressure. Have someone on the throttle while you observe area around throttle body for pressure readings on manometer and moisture traces forming, especially after high rpm lifts.
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