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Is it normal for air to blow out of oil cap?

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Old 09-03-2011, 06:47 AM
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BM08
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Default Is it normal for air to blow out of oil cap?

As title just discovered mine does when the engine is running, just wondered is it normal?
Old 09-03-2011, 07:04 AM
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rubinsbin
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do you think its normal?
isnt it followed by oil being blown all over the engine when the bonnets down!
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Old 09-03-2011, 07:11 AM
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Would you say there is a lot of pressure there with the cap off.
Old 09-03-2011, 07:11 AM
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tommytwotanks
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im no expert, but i'd say it''s not normal, probably worn valve stems, do you get any smoke coming up ?, my brother had this many years a go on a fiesta mk1 1100

tommy
Old 09-03-2011, 07:29 AM
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vwturbo
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if the engine noise increases when u remove the oil cap, and it makes this chugging sound.. somethings up, bottom end pressure or something, one of my cars used to do it, then it threw a rod 2 weeks later.
Old 09-03-2011, 07:47 AM
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Dicko&Vacant
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Its normal when the engines fooked lol
Old 09-03-2011, 08:05 AM
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MAD Ade
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A generally worn engine most likely.
Old 09-03-2011, 08:11 AM
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tabetha
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It depends on your definition of air, a faint breeze is normal, anything more points to pressure in the crankcase, no engine in the world will seal 100% so there always will be some, but a faint breeze.
tabetha
Old 09-03-2011, 08:53 AM
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Nothing to worry about, it's just VTec kicking in
Old 09-03-2011, 09:13 AM
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BM08
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It's proper blowing but no smoke at all, car seems to run fine and go well....

I've checked google, some say it's bad others say it's normal.....
Old 09-03-2011, 09:17 AM
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On my escort it was due to a nice hole in a piston...... Man that made me laugh ......... Put the cap back on and turned it over it blew the cap god knows where lol
Old 09-03-2011, 01:43 PM
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BM08
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Anyone else? Whats the best way to test if it's ok or terminal?
Old 09-03-2011, 01:51 PM
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Firstly, check the crank case breather is connected and also not blocked up !!

Disconnecting the breather will increase the air flow out the cap as a check

If all else fails, get a compression test done for all cylinders to check you havent got excessive bore wear or holed piston !
Old 09-03-2011, 01:53 PM
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As said above it's normal on a worn engine. On a good engine there should be a slight vacuum.
It tends to be blowby from the piston rings pressurising the crank case.
Compression/leak test your engine. You could run like it for years if its only worn rings, but fix it if you can afford to.
When it gets really bad it can start blowing oil through the breather system into the intake and give clouds of smoke out the exhaust. This will most likely happen after you top the oil level up or slightly overfill it.
Old 09-03-2011, 04:45 PM
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BM08
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Thanks for the replys chaps


Just popped it round to Honda earlier and a techie came out and had a look, he unscrewed the cap abit and said thats fine mate.
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