My Honda Accord...major blowby..or..? (vid inside)

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This is my 2000 Honda Accord 'beater' car. The compression, and more importantly, leakdown numbers are excellent-leakdown was less than 10% on all cylinders. However, it blows a massive amount of air from the oil fill. If you can't tell what I am doing in the video, it's holding a paper towel against the bottom of the hood! LOL! (some swearing in the vid, originally made it to show a good friend). I have no idea what is causing this. PCV system is working properly. Take a guess, if it's something I can look at without tearing it apart too much, I will.

Honda
 
Really make sure the PCV is up to snuff and the air filter is clean. I suspect you used a junk leak down tester. There are a bunch of junk tools on the market. You need to attach high pressure supplied air to the cylinder through the spark plug hole and than take the oil cap off. Make sure the cylinder your testing is on the the compression stroke. While your at it, listen through the exhaust, open the radiator cap and if you hear air or see bubbles.... .
The engine could run good for another 100K miles+ that, who knows.
 
Originally Posted By: skyactiv
Really make sure the PCV is up to snuff and the air filter is clean. I suspect you used a junk leak down tester. There are a bunch of junk tools on the market. You need to attach high pressure supplied air to the cylinder through the spark plug hole and than take the oil cap off. Make sure the cylinder your testing is on the the compression stroke. While your at it, listen through the exhaust, open the radiator cap and if you hear air or see bubbles.... .
The engine could run good for another 100K miles+ that, who knows.


I know how to do a leakdown test and have the proper tools to perform them. In fact, I have tools for performing a leakdown test that most do not (screw in whistle for indicating compression stroke, spring loaded screw in TDC indicator, etc). With that said, I may change out the actual pressure gauges (or swap them around at least) on my tester just to ensure the equipment is in good operating condition.
 
Originally Posted By: skyactiv
I would just keep driving it and not worry about it if it drives good and doesn't belch out smoke.



I agree on all counts! Not worried at all, it's just fun to try to figure it out (without tearing anything apart besides normal service procedures).
 
Most inline 4 cylinders will pulse an alarming amount of air out of the fill cap when running. This is usually normal and nothing to be worried about if it's not displaying any other indications of engine issues.

I'll bet if everyone on this forum pulls the oil cap off their inline 4 cylinder engine while its running will find there is a lot of pulsating air escaping. Stop worrying.
 
How's the oil burning? If it's not spewing blue clouds all over the place, I wouldn't worry about it too much. If it was really bad, it would be puffing out clouds of smoke out of the oil fill like a steam engine!
 
Coupla times I have forgotten to put the filler cap back on. It takes only a 100 miles to trip the low oil level light. A qt low. OHCs thrash oil compared to rocker arms
 
Originally Posted By: Tman220
Most inline 4 cylinders will pulse an alarming amount of air out of the fill cap when running. This is usually normal and nothing to be worried about if it's not displaying any other indications of engine issues.

I'll bet if everyone on this forum pulls the oil cap off their inline 4 cylinder engine while its running will find there is a lot of pulsating air escaping. Stop worrying.



Sorry for my post....you beat me too it.
 
Curious: If you are confident of the leakdown test, what is the mechanism you propose which explains the "massive amount of air" expelled through the filler cap?
 
All, all the 4 cylinders i've had blow quite a bit air from the fill hole with the engine running, including my recently acquired Escort, don't know why, my other V6 engined Ford doesn't blow any at all.

I made this video last week, engine running hot, you can see the oil mist and air escaping through the fill hole in the video, excuse the valvetrain noise, Ford CVH engines tend to have worn cams and lifters and this is not an exception, runs great though
smile.gif


https://www.youtube.com/watch?v=PjL2VCbH5rU
 
First, keep in mind the back side of a piston moves as much air around as the front.
Second, an air pulse coming out of a hole can move like a projectile.
That's how an "air cannon" can blow a candle out from 50 feet.
OTOH a pulse of air sucking into a hole does not reach out.
That's why the pressure pulses can hold the sheet of paper against the hood.
 
Originally Posted By: TurboTravis
PCV system is working properly. Take a guess, if it's something I can look at without tearing it apart too much, I will.


Let me guess it still has the original pcv valve in there but has been deemed ok because it still rattles. Usually the internal spring on these break around the 60k mark but will still rattle. Replace with an oem one for around $12 or so. The F23 will start consuming oil when the pcv valve goes bad.
 
Originally Posted By: circuitsmith
First, keep in mind the back side of a piston moves as much air around as the front. ...
True, and the volume of air (or blowby gases) moved outward by the two descending pistons is not exactly balanced by the volume sucked inward by the two ascending pistons on a 4-cylinder at all crank angles. Thus, the pulses you feel, even if there's minimal blowby. (That's much the same reason that 4-cylinders vibrate, unless equipped with balancing shafts to counteract their inherent secondary imbalance.)
 
Originally Posted By: KrisZ
Is there any type of rocker cover vent tube on this engine or just the PCV?

This might indicate a couple of tight valves. They probably seal ok exactly at TDC, but start to open/close prematurely.


I recently performed the valve adjustment procedure.
 
Originally Posted By: SatinSilver
Originally Posted By: TurboTravis
PCV system is working properly. Take a guess, if it's something I can look at without tearing it apart too much, I will.


Let me guess it still has the original pcv valve in there but has been deemed ok because it still rattles. Usually the internal spring on these break around the 60k mark but will still rattle. Replace with an oem one for around $12 or so. The F23 will start consuming oil when the pcv valve goes bad.



You guessed wrong.
 
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