left oil cap off for ??? long...

[JHZR2]

Hi,

The cost of adding LC - I left my oil filler cap off for some unknown duration... Likely from early October through today, when I did my scheduled oil change. Less than 500 miles (all highway), and mostly sitting, but I was mad.

Forunately I planned to do a used oil analysis, so we shall see... The oil looked perfect coming out, the cap was still under the hood, sitting on the battery, and looked quite clean, as did the filler neck.

On all of my other cars, when I open or even crack the filler with the engine on, itll stall, or run extremely rough. My truck (98 S-10 ZR2) must have a different setup, maybe because it is a V6 instead of an inline engine.

Has anyone ever done this before? Anything I should be worried about? The truck ran good as new, so I didnt know any different!

Thanks,

JMH

 

[Tosh]

"Has anyone ever done this before? Anything I should be worried about?"

Doesn't Iffy Lube get away with this (and worse) every day? My car runs fine with either the oil filler cap or fuel filler cap off. I don't think you have anything to worry about (except for distractions).

 

[andyd]

heh heh, I left Banner Elk NC. The last thing I did before taking off for a 200 mile drive was to top off the oil in my 528e. 2hrs later, the low oil light came on. In maybe 100 miles the cam had slung a qt of oil out of the filler. The cap was where I'd left it on top of the intake manifold. That was 30k back. No issues except for mess.

 

[pmwalter]

Don't some cars have a spalsh type guard on them that pevent the oil from splashing out? My 98' Camry has such as guard that makes it really slow to fill with oil. I imagine the same would be true in reverse.

 

[JHZR2]

andy,

I'm suprised that your car ran at all! My E30 318i wont run with the filler cap off!

Thanks for the replies!

JMH

 

[brianl703]

An interesting thing (on OBD-II cars) to do is to hook up a scantool, watch the long term fuel trim, and pull out the dipstick slighty and notice that the fuel trim goes up (adding fuel to compensate for unmetered intake air) with the dipstick out and back down with the dipstick back in.

Neither of my Ford vehicles stall or run rough when the cap is removed.

 

[JHZR2]

depends on how the dipstick is set up...

On my BMW, the dipstick tube is below the oil line: removal of the dipstick does not change a thing.

JMH

 

[andyd]

The 88 528e has a Motronic 1.1 ECU. Its pretty adaptive. It will run w/o the oil filler cap but the idle is real rough.

 

[Gary Allan]

My 78 320i ..nope. Pull the dipstick or lossen the cap ..stalls. They must have run the crankcase under full manifold vacuum. I think mine was the simple, but reliable, J-jetronic injection. The 5 and 6 series, got the L-jetronic, IIRC.

 

[V1]

I did that to my '88 Camry 4-banger. Changed the oil, jumped on the interstate, and drove for 350 miles before I realized what I had done. The dipstick was dry. I thought my engine was toast for sure, but it ran great for the next 60,000 miles before I sold it.

You're engine is probably fine. Some engines will spray every ounce of oil out in a matter of minutes if the oil galleries are aimed right at the filler hole. Doesn't sound like the case for you though, J.

 

[TallPaul]

I am interested in what your UOA looks like. My PCV breather hose fell off its filter for a whole OCI and lead was 476 ppm. I don't think you will get that because the PCV system is designed to draw air. Also I was driving daily through a construction zone which didn't help (sand was in my airbox and so likely in the engine too).

 

[Gary Allan]

My son borrowed my Caravan a couple of summers ago. He drove to NC to visit a friend. After he came back ..whenever I opened the hood ..I'd find a drip of oil falling from it. I kept looking for where it was coming from. After I had mentioned it for the 10th time, he finally fessed up and admitted that he had added a quart of oil and had forgotten to put the cap back on. He only realized it when they stopped and there was smoke coming from under the hood. He said the cap stayed right where he left it on the intake plenumn.

The reason that he waited so long to say anything was to assure that the van had been back in my hands long enough to have sustained no apparent damage.

And they always blame the person that goes postal

 

[JHZR2]

Interesting that he saw smoke to indicate that the cap was off...

Im running GC, but I doubt that it wouldnt smoke just by virtue of the oil type...

I was VERY suprised that there was no evidense of any residues, splatters, smoke, etc. for the whole time... granted 80+% of the time was on the highway, but still, Im just glad there were not apparent ill effects.

Thanks,

JMH

 

[kreigle]

I've left the cap off my car twice now. No smoke, just oil spattered all over the top of the engine and underside of the hood. The only way I suspected each time was I could smell the oil vapors.

The dealer left the cap off my wife's 2001 Civic on the last oil change before we traded it in - she drove it for a week before we figured it out. She saw the cap sitting on the top of the engine when I popped the hood to change a burned out headlight bulb. If the headlight hadn't burned out, she might have never known until the next oil change. Needless to say, she b*tched them out real good and made them take it in and re-check the oil level.

Yes, Hondas run really well without the oil caps. The PCV valve meters the air so well that the engine doesn't know anything is wrong.

 

[ekpolk]

Posted by JHZR2:

quote:

---

depends on how the dipstick is set up...

On my BMW, the dipstick tube is below the oil line: removal of the dipstick does not change a thing.

JMH

---

My G35 does not skip a beat when you open the oil filler with the engine running - no subjectively noticeable effect at all. It would be interesting to hook up a scanner and see if the ECU is responding, though.

There is no dipstick tube in this car, just an opening in the block into which you thread the stick. Though I generally love the VQ35 V-6, this part of the design is brazenly idiotic -- the little hole is very hard to see and reach, and is lined up right below the oil fill port, and apparently, the nearby oil drain passages. So you guessed it, pouring oil in with the dipstick out results in an immediate gusher of fresh oil, that lands of course, on the exhaust! Anyway, the little hole is well above the oil level, obviously.

Back closer to topic, my Mom, a very bright and good hearted person, is nevertheless, a carkiller of the worst kind. Hers get an oil change about every 50k miles or five years, whether they need it or not.

Her previous car, the old mid-size rear-drive LTD (the car that preceded the original Taurus in the 80s) got driven for at least two years with no oil filler cap in place (early version of the 3.0L pushrod V-6 IIRC). This engine was copiously sludged, but for whatever reason, ran on for over 10 years and started, most of the time, in harsh New Hampshire winters. It was a constant short tripper, usually driven 1.5 miles to work, and little else. I've wondered more than once if this impromptu crankcase ventilation might actually have reduced her water-in-oil contamination. Who knows. Go figure.