Excessive Blowby. Air Fuel Mixture (1 Viewer)

[landtoy80]

If a motor has excessive blowby can that blowby cause problems for the rest of the motor?

Can it cause a lean condition? That is, the MAF tracks the amount of air entering the motor. With excessive blowby, that is adding more air to the motor, just like a vacuum leak after the MAF. Wouldn't that cause a lean condition? Or because it exhaust gas, it will not affect the air fuel mixture?

If there is more pressure in the crankcase, where will the pressure go if the PCV system is overwhelmed?
On the 1fzfe's PCV system there is a intake vent (to let air into crankcase) and the pcv valve (to suck air out of the crankcase). This is how the PCV system works, right? Will any excessive blowby gas pressure be pushed out intake vent and into the throttle body?

I see some oil inside coming from the intake vent so there must be blowby gasses entering both the PCV and intake vent. The PCV valve is working. Would this indicate that I have excessive blowby?

 

[elhombre]

It is not scientific, but I have heard of people saying that you can take the oil fill cap off and turn it upside down over the hole. Rev the engine and there should not be enough air pressure to blow the cap off. Never tried it on a cruiser. More of a diesel thing. Be sure to keep it from being pushed off and dropped down into the spinning fan.

Is the oil you see the only problem? Or do you have a code? Just remember that the EGR system does exactly what you described with the exhaust gas being re-introduced into the intake, and the engine deals with that just fine all day long.

Is your PCV valve working? You should be able to shake it in your hand and hear the ball inside rattling back and forth.

 

[landtoy80]

PCV valve is working.

I hooked up a gauge to the dipstick and checked for pressure and vacuum and so far at cold idle there was no pressure and just a tiny bit of vacuum. I will get some hoses and drive with the gauge on the dip stick to see what I get at hot high rpm's.

With the vent hose off, there is a good amount of blowing from it but I have no idea how much pressure there should be.

 

[landtoy80]

I am going to use the linked thread to try and deal with blowby.
Better Crankcase Venting. Krank Vent?

 

[landtoy80]

Did some reading and found that the PCV valve meters the flow rate. Too much air flowing through the valve will lean the air-fuel mixture.

<<<Problems can also occur if someone installs the wrong PCV valve for the application. As we said earlier, the flow rate of the PCV valve is calibrated for a specific engine application. Two valves that appear to be identical on the outside (same diameter and hose fittings) may have different pintle valves and springs inside, giving them very different flow rates. A PCV valve that flows too much air will lean the air/fuel mixture, while one that flows too little will richen the mixture and increase the risk of sludge buildup in the crankcase. >>>

I would assume the same for the EGR, its metered and the ECU compensates for the flow of exhaust.

 

[landtoy80]

For those that were flowing this thread.
I have been venting the crankcase to atmosphere and the oil vapor was overwhelming.

I changed the oil. Drive 50 mi today with no smell at all. I bought a new PCV valve and hooked it up this after noon and left the vent port open to atmosphere to relieve excess pressure. Drove 50 more miles and no smell.

With the new PCV valve hooked up and a plastic bag on the vent port of the valve cover, I started the motor. The plastic bag filled up instantly at high idle. When motor dropped to normal idle the bag would fill up slowly but when I rev the motor it filled up instantly. This confirms that I have excess pressure in the crankcase.

Now that the excess blowby gasses can escape, hopefully the issues of pressure in the crankcase (diluted oil, stinky oil, seeping seals) will be reduced. With fresh oil, there is no issue of stinky oil vapor. Now I just need to make or buy a catch can to catch oil oil vapor. Thinking of using a small ammo can as a catch can. Prior to venting, my oil pan was the catch can where all the unburnt fuel, blowby gasses and oil vapor just condensated and fell to the pan.

I should of looked into this problem about 100,000 mi ago when I noticed that the PCV hoses and oil fill cap were seeping oil. I just ordered a new filler cap and put hose clamps on the hoses. That is when I noticed that my oil consumption when up and I started to use additives to deal with it.

 

[landtoy80]

To end this thread, I have added this update.
I will no longer be using this thread for updates.
Any more updates will be posted in a new thread.

After about 700 mi of venting to atmosphere along with the PCV valve hooked up, the crankcase no longer has pressure. After about 600 mi, the hose/pipe that I hooked up to the vent port that runs to the rear bumper was accumulating fluid somewhere. So I mocked up a catch can. Its spaghetti sauce glass jar that I installed two ports on the lid and put a scouring pad inside as a baffle. After 96 mi there was just a little clear fluid in the jar, no oil yet. The oil level has not gone down yet. I usually dont have to add my first qt of oil till 1800 mi, its gets progressively wore at the oil get diluted. Will see what happens now that the crankcase can vent away the moisture.