So a friend of mine, She has this Junky old 84 or 85 Dodge Colt with a mitsubishi 4cyl in it. Car runs fine, burns a bit of oil. In the past month the oil cap keeps blowing off every 200 miles or so. The car doesn't lose any oil with the cap off or anything, the cap just blows off never to be seen again. We've tried a bunch of different oil caps but still the same thing. Even replaced the valve cover and still the same thing happens. We're not too concerned about it really, She could care less she just wants it to finally give up the ghost so she can get a new car(she's had it for 6 years). But i want to know what would cause this just out of curiosity sake.

Thanks

PCV valve/system plugged up?

Sounds like the crankcase pressure is alittle high. Most likely from worn piston rings causing excessive blow by or a plugged PVC system. It's kinda wierd that the oil cap keeps popping off. Usually it's the dipstick that keeps popping up.

------------------
1991 GMC Syclone #449 - Stock
1988 Pontiac Fiero GT - 3.4L HT GM Crate Engine
2002 Yamaha V-Max - It makes me poop
1986 Honda Aero 50 - Chicks dig it

[This message has been edited by Zewerr (edited 01-22-2008).]

Assuming that replacement caps fit tightly and not just falling out, its simply too much back pressure inside the engine. Is the crankcase vent working or carboned up.

Sounds like the oil rings are gone and the other vents are plugged. Try replacing PVC valve.

They used to make a cap that had a vent in it, large cap with what looked like steel wool in the top, not sure if they still do.

------------------
Technology is great when it works,
and one big pain in the ass when it doesn't.
Detroit iron rules all the rest are just toys.

quote Originally posted by Patrick: PCV valve/system plugged up?