Another crazy car question...

[Renken2000Classic]

So I opened the oil fill cap on my Acura the other day after I started it, to add some oil, and it was pressurized... That surprised me. It's a 3.2L VTec. Maybe Japanese cars don't have "PCV"? Probably normal, I just didn't expect that.

Great car, it just drips a lot of oil. I had to take something in the oil system off earlier in the year when I replaced the timing belt tensioner (oh boy), and it had a formed O-ring that I didn't replace. It dripped before, but it seems even worse now. The "normal" thing would've been to do the cam and crank seals (and water pump...) while I was in there, but I just wanted to get it to run again w/o disturbing the timing belt (the belt and WP had been done only 25k ago or so, and should've still been good).

Car is the kind of rare 6-speed and fun to drive ('05 TL). I've had the exhaust messed with too, and it sounds really good.

 

[Scott Danforth]

Shouldn't be pressured

 

[Lou C]

Blow by?

 

[stresspoint]

normal , all those things spinning in the motor make pressure.
lift the cap off another motor same vintage and compare the result.

as Lou suggested you may also have some blow by.

 

[jimmbo]

Blow By would create pressure, the spinning and reciprocating parts wouldn't create Pressure, Turbulence perhaps, but not Pressure, as half the pistons are going one direction, and the other half are going another, the air inside the Crankcase is still in balance. However, an engine with an odd number of Cylinders might be a different story

 

[tpenfield]

Temperature rise creates pressure, . . . But I would think there should be pressure relief (somewhere) . . .

 

[Scott Danforth]

lets put it this way:

the PVC system should put a slight vacuum on the crank case when running. this does 2 things:
#1, controlling aerosols from oil splashing and blow-by. This is why the PVC valve was introduced in the 50's
#2, a slight vacuum on the crank case also improves windiage and helps make the engine run slightly more efficient.

there should be no pressure

pressure in the crank case will make the motor run less efficient and push oil out of all the seals.

 

[Alumarine]

Are you sure it wasn't vacuum?

 

[dingbat]

So I opened the oil fill cap on my Acura the other day after I started it, to add some oil, and it was pressurized... That surprised me. It's a 3.2L VTec. Maybe Japanese cars don't have "PCV"? Probably normal, I just didn't expect that.

Yes, Japanese cars have PVC valves
Yes, the crank case will pressurize if the PCV is stuck shut.

 

[jimmbo]

lets put it this way:

the PVC system should put a slight vacuum on the crank case when running. this does 2 things:
#1, controlling aerosols from oil splashing and blow-by. This is why the PVC valve was introduced in the 50's
#2, a slight vacuum on the crank case also improves windiage and helps make the engine run slightly more efficient.

there should be no pressure

pressure in the crank case will make the motor run less efficient and push oil out of all the seals.

The PCV was introduced in the mid 60s, prior to that, engines had a Draft Tube that extended below the bottom of the car, and crankcase blowby was evacuated this way. It didn't help purge the crankcase very well at low speeds or when parked. The early PCV systems were still open to the Atmosphere, usually via the Oil Breather Cap, and under WOT, would vent through the Cap as there was little if any Manifold Vacuum. Running a hose from the Cap/Valve Cover to the Air Cleaner solved that Emission Issue.

 

[Renken2000Classic]

Are you sure it wasn't vacuum?

Ok, somebody slap me... It does seem to be vacuum. I wondered about that. It sounded just like the air escaping from my Caprice gas tank when it's nearly empty, just not as loud. That's prob vacuum too, lol.

 

[Scott Danforth]

Ok, somebody slap me... It does seem to be vacuum. I wondered about that. It sounded just like the air escaping from my Caprice gas tank when it's nearly empty, just not as loud. That's prob vacuum too, lol.

I would verify pressure vs vacuum. I would also make sure your PVC system is operating properly

 

[Renken2000Classic]

There is just the slightest pull on the cap when it's unscrewed and I'm lifting it off. Tried to see if a bit of smoke would pull into the dipstick hole or blow away, but there wasn't enough to tell.
I had just started it when I first noticed it the other day, and it seemed like a lot of air (movement) to me; maybe it's a little different when it's warmed up. Didn't seem like quite as much just now (it's warm). Guessing...

 

[Grub54891]

Just a silly question. Did you remove the cap to add oil when it was running?

 

[Alumarine]

Ok, somebody slap me... It does seem to be vacuum. I wondered about that. It sounded just like the air escaping from my Caprice gas tank when it's nearly empty, just not as loud. That's prob vacuum too, lol.

I know on my Toyota trucks if I pull the dipstick when it's idling the idle changes. I can't remember if it goes up or down.
I also can't remember why I did that in the first place. It wasn't to check the level!

 

[Renken2000Classic]

Just a silly question. Did you remove the cap to add oil when it was running?

Yes. Multitasking - warm it up, add a little oil at the same time. Not my usual practice though.

Funny thing about the dipstick - it's got a crosshatched area that holds oil. IOW, you can't check it cold w/o wiping the dipstick (like I usually do on my others). When I finally found that out, it was 1+ qts low. I'm thinking HOW is the oil still full and it's been dripping for months? Lol. Well, it wasn't.

I went about 10,000 miles after the first oil change I did on it, because it just wasn't getting dirty in appearance. Prob no or not much blow by in that case. Typical well-made Japanese stuff. Well other than the seals, lol.

 

[Grub54891]

Well there you have it. If you pull the cap when running it'll do that. stop motor. Let sit for a bit. Remove stick, wipe and check. Problem solved.