How long can you drive without oil cap?

[REKCUT]

One of those crazy stories that i can't wrap my mind around. Sort version is I was fixing some rough idle issues and got new plugs and wires. Installed last Saturday evening/ Sunday morning. Took a couple of test drives Sunday and idle was better but still would jump from 400 to 700 what coming to a stop. Sometime that day I also added 1/2 quart of oil. Monday did 50 or so miles in the snow, down through creeks and up and downs some bumpy roads. Tuesday back under hood looking for cracked intake hose. More miles and I pull green EGR modulator and realize its bad and that hose coming out of bottom is split. Order new and pick up Wednesday and install. Drive truck to 40 miles down to cabin by Branson and spend night. Get Thursday and drive 25 miles to Harrison and meet brother-in-law at walmart. Can hear a little bump by foot and realise front shock is a little loose so Im under hood with wrench roll on radiation and tighten both front shocks. Then i proceed to run 150 miles down through Ozark mountains. Multiple creak crossing and bumps.

Thad evening about 10 miles out from the walmart oil level light comes on going up hill and off when leveling out. I know that this means I'm a little low on oil so i check when i get to in-laws truck.

Here is where I can wrap my mind around what happened. Open hood and oil is everywhere and no oil cap. I'm stunned and my Brother in-law point out that the cap is sitting on winch spool.

1. I left beers and coffee on rear bumper and made short drives around town but I am having a hard time believing that the oil cap would ride on top of the winch spool for a week and easily 300 miles with half being on dirts roads and trail.

2. If it went all that way with no cap, why would the oil only start escaping over the top of the engine on the last half of the trip and not the first 4 days and 150 miles. I was under the hood daily working on things and maybe the cap missing wouldn't jump out at me but the oil spray would have.

3. If the cap came off on the last day how did it move forward and fall out of the engine bay and onto the winch.

The bumper is a custom low profile with exposed winch like a slee short bus.

I'm cleaning up today and will watch for further issues but I am stumped on this story.

 

[CJF]

Weird things happen.

I once did 2-3 days of commutes before realizing my cap was sitting on top of my air cleaner.

 

[SmokingRocks]

Not sure how you’d miss the cap not being on if you were under the hood that much.
Two things occur when the cap is off:
1) your idle will be piss poorsince the intake manifold won’t be able to pull vacuum on the crank case. And by piss poor I mean stumbling 350-450rpms and that’s if it doesn’t just stall out all together.

2) you will lose considerable amount of oil out the opening. More so during high load/rpm. And it will be all over the engine causing smoke and smells.

Like I said I have no idea how you’d miss those signs which makes me think the cap wasn’t tightened down and backed itself off. Voodoo magic happen when parts rattle loose causing them to end up in the least logical places, so I wouldn’t spend much time piecing that puzzle together.

As long as there was oil in it you are likely fine. (since your oil light worked I assume everything is peachy)

 

[Heckraiser]

Oil cap off makes a big mess. I'm guessing it backed itself off due to vibes and bounced it's way to it's final resting point. Or a gremlin or tweaker removed it for s***s and giggles.

 

[bajaphile]

Not much to add aside from a similar story.

It was 10 years ago, but I did the same thing on my 3rd gen 4runner. Prepping for 650 mi trip to SW Baja and did my oil. I drove 12 hours pretty much straight just stopping for gas. I get to my camp spot and see oil dripping. Open my hood and the entire engine bay is drenched!! I freaked out because I was about 150-250 miles from the nearest town. Realized it was just my oil cap, found it wedged somewhere in the engine and luckily had 2 quarts of oil with me. Everything was fine aside from the mess.

 

[lumbee1]

I love my ARB and hate my ARB. I've put soo many tools, drinks, cups, and my oil cap on the flat sections of the bumper under the headlights. Most of the time I drive around with them there but I recently lost a long 17mm wrench and bit driver that I left on the bumper after adjusting my steering box.

IMG_8655 by Jonathan Jones, on Flickr

 

[REKCUT]

What started this sequence was a very rough idle so that is what i was watching. The continued rough idle Saturday through wed day when i installed new blue top modulator and tubing. The trip down through the mountains was as silky smooth as the engine has ever run.

 

[Heckraiser]

wheeling with coffee cup on bumper pic is pretty sweet

 

[REKCUT]

Unlike the ARB, my winch spool is out in the open.

 

[REKCUT]

I can't get a consensus on effects of oil cap off on a 80. I have suggestions that it makes a big mess but other say that its not under pressure there and has that small lip.

 

[Proven]

I don't see how this would have harmed you beyond the loss of oil. I am going to guess it had an effect on scavenging and crank case pressure, but I can't think of anything that would have harmed your engine. I wouldn't recommend doing it too often because it does put you at risk for moisture in the oil.

As a peace of mind idea you might change your oil.

 

[SmokingRocks]

I thought my post was pretty straight forward..

Two things occur when the cap is off:

1) your idle will be piss poor since the intake manifold won’t be able to pull vacuum on the crank case. And by piss poor I mean stumbling 350-450rpms and that’s if it doesn’t just stall out all together.

2) you will lose considerable amount of oil out the opening. More so during high load/rpm. And it will be all over the engine causing smoke and smells.


Likely you are fine, the 1fz-fe has a healthily over-sized oil reserve capacity.


I was replacing vacuum lines the other night and forgot to put one back in before trying to dive home from the shop. I pulled it out of the bay and noticed a s***ty idle, one look at my vacuum gauge and I realized that I likely forgot to install a hose... that was it.... Vacuum gauges are great for diagnosing these things.

 

[carbon60]

I love my ARB and hate my ARB. I've put soo many tools, drinks, cups, and my oil cap on the flat sections of the bumper under the headlights. Most of the time I drive around with them there but I recently lost a long 17mm wrench and bit driver that I left on the bumper after adjusting my steering box.

I totally get that! I had to force myself to implement a rule about not leaving anything on the bumper. Lost too many things. Though, just last week, I drove around all day with a jug of coolant in front of a headlight. I was thinking my lights were a tough dim, too…

 

[ZackR]

The engine will be fine as long as the oil pressure never went too low, which it wouldn't as long as there was enough oil still in there. I'm surprised you haven't received a more intense berating from the forum but everyone makes mistakes now and then.

One thing I would recommend when attacking all of these repairs is to slow down a little and think about what was done, how it looks, and do a final scan before closing the hood.

 

[JohnVee]

......do a final scan before closing the hood.

Yep. I left an oil cap off once. Now it always gets a look before the hood closes, no matter the reason for being in there.

 

[gummycarbs]

Schrödinger's oil cap.

 

[2KCruiser]

I once did a test drive without the cap on and it threw a code. I don't remember the code, since it was a few years ago. But what I did was I then cleared the code, drove it again for a day, no check light. Then I pulled the cap off, drove for a few miles and light popped up again. Cleared the code again and put the cap back on, never happened since.

 

[retrofive]

I'm amazed it run at all. With my cap off it borders on dying. Maybe some one popped the hood and pulled a sad prank? As far as harm, doubt it, typically the light comes on when 1qt low, so 1qt maybe was splashed out, but that won't cause anything but a mess.

 

[LS1FJ40]

After losing a 12mm gear wrench down in the fender on my 93 I made a small box that I set on the engine (usually manifold to the fender). 16”x24” 1/2” plywood scrap with 1x ripped down to 2” for the sides. ALL tools/parts/screws etc go in it when I am working under the hood.

FWIW, my 93 stubbles and died the one time I tried to add oil while it was running. Haven’t tried it since.

 

[JeepinPete]

Its funny the varying effect leaving the cap off has. On my '95, there is no change in idle or performance. Done it twice, made a mess both times, but other than the smell of the burning oil on the exhaust manifold, I had no other indication.