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When taking off refill oil cap

I was checking my oil and my car was running I took the oil cap off before shutting off the car and there was a lot of air pressuring out is this something to be concerned about?

No need to worry. Unless you are a mechanic you should not be reaching anywhere under the hood with it running. You can look if you think there is a problem but don’t touch.

Why do u think asking I just never noticed it I wasn’t looking to be talked to like I don’t know anything, I was just trying to figure it out and make sure its nothing to worry about thanks

Check oil with running motor? Do u check trans fluid level with motor running or not running. Quiz time. I watch all girls garage. Chicks know some things. Mostly what director tells them.

You check it with it running

I’m only asking about the oil cause I’m trying to figure out what’s wrong with my car I figured someone on this site would be kind enough to help since I don’t know and my brother isn’t here to help me my car hasn’t been wanting to start battery is good when I jusmp it starts rite up and when its worm it starts every time so I’m just looking for answers

Now I feel like an idiot. I have been checking my oil all these decades after the vehicle has sat overnight. I have also been using the dipstick with engine off.

We’d love to help. But to do so we need some information
the year, make and model,
the mileage on the odometer,
a description of the problem,
a brief history of the vehicle; maintenance, repairs, that sort of stuff.

If the only problem is concern about the pressure you mentioned, know that pressure coming out of the oil fill hole on an operating engine is normal. A bit of oil may even splash out the hole when the cap is removed with the engine operating. That too would not be abnormal.

Post back and we’ll try to help.

Its a 2005 ford focus I have just recently got my motor mounts replaced and it just seen like something is wrong. And its not wanting to start all the time had my battery checked its fine when u jump it starts right up mayed the started? Not sure tho. I keep up on maintance regularly. The only reason I discovered the air coming out was I was checking things out after I got it started

How many miles does the car have on it?
Did they also test the charging system?
How old is the battery? Is it the original battery?
What’s the temperature been where you live?
When was the last time you had the spark plugs changed?
Exactly what does it do when it doesn’t start?
Do you drive only short local drives, or does the engine get a good chance to recharge the battery after each start?

The air is normal.
The starting difficulty sounds like it may be just an old battery. Perhaps a charging system problem. It can test okay when warm out, but fail when cold. And lately it’s been freezing in most of the U.S. A typical battery is considered getting old at about 5 to 6 years.

Beyond that, a life of all short local trips doesn’t give the engine a chance to properly recharge the battery each time and the battery can slowly become weak.

Post back.

I’m not out at my car for the miles lol its way cold been 28 when I leave for work in the morning my battery is 2 years old. When trying to turn over it just stops it hardly trys to start I can’t explain it rite. Maybe its to cold but I never ran into this before and I have had my car sense 2008 my spark plugs and everything were done a few months back and I do only drive to work and back majority of the time

Well, you don’t. That’s fine. Nothing wrong with that. Don’t be defensive when you don’t know stuff. That’s for 12 year olds. And don’t swear here. The regulars don’t like it.

@VOLVO_V70 was giving you advice that will keep you from getting your hand torn off. There was no need to give him attitude.

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I forgot what kind of car it was I found this out on but some oil filler caps when not in place with engine running will cause oil to spray all over. I believe I was changing the oil and started it with the cap not in place. Had a little clean up on aisle 2.

“Do u check trans fluid level with motor running or not running.”

Nice try

It depends on what vehicle we’re talking about

I score . . . !


You said you just had the engine mounts replaced. You might try asking the shop that did the work to recheck and be sure the engine ground cable is well mounted at both ends. It may have been disturbed recently and a poor ground can cause all sorts of strange headaches.

How far is the drive to work? If it’s not far enough to warm, the engine fully, it isn’t far enough to recharge the battery of the energy taken from it to start the engine. The problem could simply be that the battery is slowly getting drained. The solution may be to simply take the car for a drive a few times a week or so on the way home.

Motor mounts changed and doesn’t start all the time.Sometimes they jack up the engine high enough to cause damage to wiring, but that’s hard to do. If you turn the key and the engine doesn’t turn You might look for the ground connection between engine and body, sometimes located on the fender or on the firewall area. On my GMC truck it was near the master cylinder. If it’s broken it has to be fixed before worse problems happen to electrical parts.

There are vents on the engine to allownormal pressure in the carnkcase to escape into the air filter housing. Apparently your vents are plugged or the engine is badly worn allowing too much blowby for the vents to handle. Look at your air filter housing and find the ~1" diameter rubber hose that leads to the engine and disconnect it from the filter housing. Start the engine and see if there is pressure under the oil fill cap and if there is replace the cap and check for pressure escaping the hose. If no pressure is escaping that hose something is plugged.

If you are talking about the cap where you add oil and air is being released through the cap opening with the cap off, yes that is a problem. It should suck air into the engine with the cap off. Test this with a piece of paper. With the engine running, cap off, lay the paper across the opening. If the paper is sucked down, OK. If it is blown away, problem.

If there is a problem, it could be a plugged PCV valve. The PCV valve goes between the intake manifold and either the crankcase or valve cover to draw air and oil fumes back into the engine to be burned. There is usually a fresh air port in your air filter to provide make up air if needed.

Pressure builds up when you have blowby of your piston rings. This is expanding gasses that are pushing the piston down to create power, but the rings are not sealing well enough so that some of these gasses get past the rings and into your crankcase. When the blowby is greater than the PCV valves ability to remove them from the engine, then you have pressure in the engine.

None of this has anything to do with your starter issue though. If using jumper cables stops working, then your starter is bad. Most likely you have a defective battery.

Probably not.

When I take the oil fill cap off my Insight with the engine running, it feels like a wind blowing out. BUT, it’s actually pulsing in and out and I don’t feel the “in” pulses. When I set the cap on the opening loosely (lightly held with my fingers), it just jiggles with no apparent net air flow out.

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