98 Accord 2.3L: PCV and Blow by?

[Finz]

With the car running, if I remove the oil filler cap or remove the PCV, a forceful amount of air is blowing out of the valve cover. I've seen some YouTube videos where people are adding an Engine Flush to a running engine with no problem. If I tried this, no question, I'd be wearing whatever I was trying to add.

Looking thru another web site and someone posted a similar issue... they were told that this was Blow-By and not a problem - just a typical issue with a HM vehicle

This 1998 Accord has 187,700 miles. The timing chain was replaced at 175k. The PCV is changed routinely and, when running, a good amount of vacuum can be felt if you place your finger over the tip. I did a dry compression test a few months ago and the numbers were spot on - can't recall exactly now but I'm, thinking in the 190 range...?

A couple questions:

1. What exactly is blow by?
2. Is the amount of air coming out through the valve cover (oil fill and PCV) anything to worry about?

Any feedback would be appreciated

Thank you

 

[tig1]

Blow by can be caused by excessive ring wear as the exhaust gasses "blow by" the rings into the crank case.

However, blow by more often is caused by ring coking. This happens when OCI are abused(mostly by dino) and the oil begines to oxidize and varnish forms. Also oil oxidation can cause ring coking where the piston rings become incased in carbon deposites and the rings lose their ability to compress against the cyl walls, allowing exhaust gasses to "blow by" the piston and rings. With blow by your engine losses power and engine wear can be come a real problem.

 

[Finz]

Thank you Tig1

Would you say, then, that forceful air blowing out through the valve cover IS blow by?

Is there any way for a Driveway mechanic to determine whether or not ring coking exists?

Would a compression test provide any insight? I performed a compression test a few months ago and was pleased with the numbers. Granted I did a dry test only.

A week or 3 ago I also did a Kreen piston soak over a 48 hour +/- duration. Not a lot of smoke after start up... Lasted about 30-45 seconds...

When I say forceful air, I'm talking hair dyer force

 

[Quest]

blow-by is coming from incomplete sealing of piston rings (esp. 2 compression ring gaps)..so even brand new engines will have blow-by (ring gap cannot seal 100% realistically)...as engine wears as it ages, blowby will increase.

I do not view blowby as an evil thing---it's normal to have blowby. While excessive blowby may not be viewed as anything good, truth is, I'd be more concerned about abrasive-related compression ring wear and oil control ring gets stuck causing oil burning then just a bit of blowby...

PCV valve design on a normally aspirated engine is known to draw vacuum under normal cirumstances...so that vacuum will aid the drawing of blowby gas.

That's why it's never a bad idea to service/replace PCV valve on a regular basis.

Q.

 

[FZ1]

Does the oil blacken?

 

[ram_man]

Its an ohc engine there are cams in the head spinning. That could easily be the air your feeling.

 

[Clevy]

Air is constantly moving in and out of the crankcase as the crank turns and the pistons move up and down displacing air on the oil side of the engine.
Cylinder blow by is only a minor contributor of the moving air unless there is a serious ring sealing issue.

 

[Finz]

Yes it does blacken quite fast

 

[Finz]

I don't believe ring sealing is an issue as the compression test performed a couple of months ago reflected good numbers... If bad rings, bad compression... No?

 

[Clevy]

Originally Posted By: Finz
I don't believe ring sealing is an issue as the compression test performed a couple of months ago reflected good numbers... If bad rings, bad compression... No?


Correct so if compression is good then blow-by really isn't an issue to be concerned with.

 

[Finz]

Just so unexpected - the amount of force blowing out.

As mentioned, the vacuum when placing my finger over the PCV is quite strong.. That said, that portion ofhte system is working well, too.

You agree?

In otherwords, no Seafoam and anything like that needed

 

[brages]

Does the engine start easy, run well, and consume oil at a reasonable rate?

If so, just drive it! Why worry about a 15-year-old car with 180,000 miles...?! Just keep up on the basic maintenance.

 

[FZ1]

Try some Mobil super high mileage oil. It's a blend and is,slightly,more dense. Stopped the burn on my Accord. The blackening is blowby and /or a dirty sump. Shorten the oci to clean the engine up.

 

[Finz]

Good deal FZ1... thank you

 

[Finz]

Starts easy... runs very well and oil consumption is a bit of an issue which is why I'm up to my elbows in valve train. Consuming about a qt every 1,000 miles or so. Predominantly short hop/local driving

Frankly, I am worried about a 15 year old car that is showing signs when it should be a car that could/should go another 100k

I'm more than willing to invest a little time and money now to help me get there. I've always felt that if easy fixes are handled early, saves big fixes down the road.

So I'm not so sure basic maintenance is the issue as that's been done. Trying to determine if I'm entering another level of maintenance

 

[gofast182]

I'm sketchy on the details so this could be wrong but my sister's '00 Accord was using about the same amount of oil. We suspected a head gasket but the coolant is clean. Turned out to be a bad PCV and distributor gasket (IIRC....like I said I'm sketcthy on details as this was a while ago).

 

[RobS]

Originally Posted By: Finz
I don't believe ring sealing is an issue as the compression test performed a couple of months ago reflected good numbers... If bad rings, bad compression... No?


Most likely yes, you should do a leakdown test as well to get a complete picture of the engine's health.

 

[Finz]

Thanks GoFast -

PCV should be fine but the Distrib gasket? Interesting - I changed the rotor last week. What a PIA: getting that little screw out. Thank God for directional mirrors

RobS... I'm sorry I didn't do a leak-down at the time. Changing one of the axles tomorrow and, if that doesn't beat me too badly, I may do that test. Regular oil, right? Just a teaspoon or so?

 

[Clevy]

Originally Posted By: Finz
Just so unexpected - the amount of force blowing out.

As mentioned, the vacuum when placing my finger over the PCV is quite strong.. That said, that portion ofhte system is working well, too.

You agree?

In otherwords, no Seafoam and anything like that needed


I would seafoam it anyways. It can't hurt,it's cheap and it strokes a potential contributer off the list.
Come on. Who doesn't like that smokeshow.
I've found that seafoam first then repeat with mmo leaves a light layer of oil on the intake track and the intake valves which may help valve seal when closed.
At the very least it does no harm and has always helped my vehicles with light throttle responsiveness.
What can it hurt?

 

[Finz]

LOL.. Love the smoke - then i don't have to cut my grass as often

So how is it used? I think I read somewhere and saw some Youtubes where Seafoam was poured into the hose leading off the PCV?

Disconnect the hose from the PCV valve and slowly pour into the hose?

It's that easy?