Loose oil cap fix?
October 30, 2012 7:07 AM   Subscribe

[Carfilter] The oil cap on my car vibrates itself loose, causing oil to spill out onto the engine and thus wreathe my hood in some lovely smoke. Oil cap has been replaced once already to try and fix this, to no avail. What are my options?

96 Saturn SL2. At this point I'm assuming something has been damaged/warped around the threads or bit where the oil cap rests (think a mechanic may have done this at some point in the last few months, but can't prove anything, alas). I'm hoping someone will have a particularly clever (and cheap!) fix for this I can do myself. Barring that, what if I just caulk the outside of the cap? I still need to put oil into it but I could just run a boxcutter around and free the caulk, put the oil in, then re-caulk it? Maybe?
posted by curious nu to Technology (10 answers total)
Best answer: I don't know exactly how you oil cap looks, but your solution sounds like it might work. When things vibrate loose over time, often just a tiny amount of force will hold it in place.

A bit of steel wire around the oil cap secured to a fixed point nearby might also work.
posted by Harald74 at 7:49 AM on October 30, 2012

Best answer: Loctite? This is a an adhesive that you squirt onto a bolt to keep it from vibrating loose. It works great, and you can still get it loose when you need to, although it is a LOT harder. It's like $2, at any Pep Boys, etc.
posted by dirtdirt at 7:58 AM on October 30, 2012

Best answer: High temperature automotive tape exists; smacking a stripe across the cap should keep it from vibrating open.
posted by davejay at 7:59 AM on October 30, 2012

Best answer: Caulk will be very difficult to do because of the amount of oil present - silicone does not stick to oily surfaces. This is the same for loctite but is even worse because if it does work, you'll struggle to get the cap off again.

How hard does it clamp down? It is possible the seating face for the seal (o-ring or flat seal) is damaged and there isn't enough upwards pressure on the cap to prevent it rattling loose. Depending on the sealing face I'd be tempted to get a fatter o-ring (make sure it is an oil safe material) so that you get more 'squish' when you tighten the cap down (if you see what I mean). If the threads are good enough that you can tighten the cap against a fatter o-ring and so get 3/4 of a turn of compression of the seal as opposed to, say, 1/4 then you may stand a chance of it working a bit longer.

If not, and the cap was definitely replaced with a new one, then it should be relatively cheap to replace the valve cover itself, I'd have thought? Not a major job to do (I don't think) so it may be worth considering.

posted by Brockles at 8:11 AM on October 30, 2012 [1 favorite]

Best answer: Drill a small hole in the edge of the cap and safety wire it onto some convenient part of the engine.
posted by Confess, Fletch at 8:36 AM on October 30, 2012

Response by poster: I'll try the auto-tape first, and if not, then drill and wire-secure.

Brockles: thanks! I didn't realize that whole top part was just a cover, I thought it was the top of the engine itself. So if nothing else I know I can do that.
posted by curious nu at 8:53 AM on October 30, 2012

Safety wire has the advantage that anyone who works on the car will understand what's up when they see it.
posted by ryanrs at 10:32 AM on October 30, 2012

Best answer: Check your PCV valve and the crankcase breather on the side opposite of the PCV valve.

"If left uncorrected, the result is plugged oil rings, oil consumption, rapid ring wear due to sludge buildup, ruptured gaskets and seals due to crankcase pressurization, oil thrown out around the filler cap and consequent rough engine operation."
posted by the Real Dan at 11:12 AM on October 30, 2012

Response by poster: Parts store guys suggested looking at PCV valve also, so once the rain abates a bit I shall take a look at that.
posted by curious nu at 12:57 PM on October 30, 2012

Response by poster: PCV valve seems to have sorted the immediate problem. Thanks!
posted by curious nu at 10:11 AM on November 20, 2012

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