Left oil cap off after change

Mandingo · 04-04-2012, 12:16 PM

Well I did a smart thing.

I changed my oil last night and forgot to put the oil filler cap back on.

During my commute this morning, I noticed that when I would clutch-in to upshift the engine emitted a loud whining sound (only in high rpm above 5500 or so). I could also feel a vibration in the pedals. Clutch-out and power on -> no noise or vibration at all.

When I arrived, I popped the hood and (amazingly) found the oil cap right where I left it on my brake/clutch fluid reservoir cover. Also, there wasn't a single drop of oil in the engine bay. I'm amazed that none shot out of there during my 2 high rpm trials. Oil level is the same -- a few mm below H mark.

After lunch, I tested it again (with the cap on this time

) and no more noises or vibration as expected.

So! Questions for you car gurus:
What caused the loud whining noise and vibration with the clutch out? Some kind of oil pressure imbalance when engine was allowed to spin down from high rpm? Could that have starved the engine of oil at all?

Thanks for any helpful opinions!

DEpointfive0 · 06-17-2012, 06:25 PM

Not really sure what caused your problem, yeah, oil pressure being non esistant is a problem, but as long as there was oil circulating, you should be ok

MattP725 · 06-17-2012, 07:53 PM

You could make a case that the oil cap muffles some engine noise but the chances of any damage is little.

Your oil travels far down the block after filling. My main concern would be contaminants from driving without the cap but if you noticed it after one ride I'd think it was ok.

modme · 06-17-2012, 08:21 PM

Positive crank case pressure.

fuct · 06-18-2012, 09:19 AM

Quote:

Originally Posted by modme

Positive crank case pressure.

sounds like a cool name for a band!

MaDMaXX · 06-18-2012, 12:16 PM

Quote:

Originally Posted by modme

Positive crank case pressure.

It's a sealed system, until this happens, lots more air getting into the system unmonitored,

Mandingo · 06-18-2012, 06:23 PM

Thanks for the feedback everyone.

I feel pretty certain that my Z is just fine. I'm just glad I caught it early. I had googled my issue a while back and found a guy that left his oil-cap off for an entire week-long road trip

04-04-2012, 12:16 PM	#1 (permalink)
Mandingo Track Member Join Date: Nov 2010 Location: Dallas Posts: 624 Drives: '10 370z 6spd Rep Power: 3370	Left oil cap off after change Well I did a smart thing. I changed my oil last night and forgot to put the oil filler cap back on. During my commute this morning, I noticed that when I would clutch-in to upshift the engine emitted a loud whining sound (only in high rpm above 5500 or so). I could also feel a vibration in the pedals. Clutch-out and power on -> no noise or vibration at all. When I arrived, I popped the hood and (amazingly) found the oil cap right where I left it on my brake/clutch fluid reservoir cover. Also, there wasn't a single drop of oil in the engine bay. I'm amazed that none shot out of there during my 2 high rpm trials. Oil level is the same -- a few mm below H mark. After lunch, I tested it again (with the cap on this time ) and no more noises or vibration as expected. So! Questions for you car gurus: What caused the loud whining noise and vibration with the clutch out? Some kind of oil pressure imbalance when engine was allowed to spin down from high rpm? Could that have starved the engine of oil at all? Thanks for any helpful opinions! __________________ some mods

06-17-2012, 08:21 PM	#4 (permalink)
modme Enthusiast Member Join Date: Mar 2009 Location: NY Posts: 345 Drives: G37 Rep Power: 16	Positive crank case pressure. __________________ GTM Twin Turbo Stage 2\|GTR Turbo/Engine Gauges\|KW V3 Coilovers\|HKS Exhaust\|Oil Cooler\| Vossen CV1

06-18-2012, 06:23 PM	#7 (permalink)
Mandingo Track Member Join Date: Nov 2010 Location: Dallas Posts: 624 Drives: '10 370z 6spd Rep Power: 3370	Thanks for the feedback everyone. I feel pretty certain that my Z is just fine. I'm just glad I caught it early. I had googled my issue a while back and found a guy that left his oil-cap off for an entire week-long road trip __________________ some mods

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06-17-2012, 06:25 PM	#2 (permalink)
DEpointfive0 Premium Member Bitches Join Date: Jan 2012 Location: SoCal Posts: 14,824 Drives: a lot Rep Power: 17151	Not really sure what caused your problem, yeah, oil pressure being non esistant is a problem, but as long as there was oil circulating, you should be ok

06-17-2012, 07:53 PM	#3 (permalink)
MattP725 A True Z Fanatic Join Date: May 2011 Location: Toms River, NJ Posts: 1,904 Drives: 2010 40th Rep Power: 16	You could make a case that the oil cap muffles some engine noise but the chances of any damage is little. Your oil travels far down the block after filling. My main concern would be contaminants from driving without the cap but if you noticed it after one ride I'd think it was ok.