another blow by question (1 Viewer)

stevebradford

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I ran my blowby tube to a Venturi at the end of my exhaust. No more smell in the cab at stop signs, better ring seal from crankcase Vacuum A nice bennifit too is many of my small engine leaks stopped.
This is the better way to do it.

Yours will work just fine, your hose might rub there. As long as you don’t mind a couple drips of oil where you park your all good! If you can find a spot to tuck it into the frame channel as I do. You won’t get the drips on the drive way and your frame will be real nice and dirty, but no rust on that one side.
 
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@franklin40 , do you have an update on your blow-by issue since you removed your catch can and vented it directly to the open air? I'm wondering because I am still having a fair amount of blow-by with my Provent 200 installed.
 
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i have so little oil on my valve cover it’s become a non issue. it’s night and day. i’m no longer having to top up my oil between oil changes. only troubles is on a hot day i can smell some oil vapour when sitting in traffic. driving it disappears. i can live with that for now
 
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May I ask about how much oil you were having to top up between oil changes prior to venting to the air? I'm going through about 2 liters of additional oil every 5,000 km. It seems high to me, but the exhaust (smell) does not indicate it is burning oil. I'm hoping there is a simple solution here...

Thanks @franklin40 !
 

Nz Nath

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I routed my breather to a chassis rail after first reading this thread, however I get a small amount of light smoke coming from holes in the chassis when idling stationary. The breather actually goes through a catch can first, however after noticing the smoke I tested it without the catch can and I get smoke out of the breather. I think only when warm but I'm not certain.

The oil level doesn't drop much/at all on the dipstick over 5000kms, the catch can collects a tiny amount of oil over that time, maximum 50mls.

I read somewhere that this could be due to a failing vacuum pump or a vacuum leak, but I couldn't find any more references on the internet.


I had my turbo rebuilt, then modified again soon afterwards, and was advised by the turbo guy that oil was leaking past the brand new seals, and to check my breather. If my piston rings were shot and causing excessive blowby wouldn't I also be burning oil out the exhaust? My brake booster is at least partially operative as if I start the truck with my foot on the pedal it moves a bit. But my brakes are piss poor so it wouldn't surprise me if the booster/servo was leaking vacuum.
 
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@Lumpskie and @franklin40, has venting to atmosphere cured, or at least significantly decreased, any oil consumption you all were experiencing? I have a Provent 200 installed and it is capturing oil (it is not capturing the amount of oil that I am consuming however!), but I'm still using some oil and wondering if, for whatever reason, it is a pressure/constriction issue. Both my turbo and intake manifold (near the gaskets) have oil soak/weeping. Not enough to drip, but definitely noticeable. Wondering if venting to the atmosphere helps any in this case. Thanks!!!
 
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The Provent has a mixed reputation on many forums. Some claim it's cured every problem known to man, others say it caused them all!

If I recall correctly, Dougal tried a Provent and it did not work, so he modified it. Again, I think he reversed the flow of the Provent and it work better, but not as good as expected. Maybe Dougal will respond?

On my Isuzu 4BD2 diesel, the stock engine breather has a oil vapor separator built into the valve cover, with a secondary external seperator on the side of engine with a drain line that allows any oil to reenter the sump. The final outlet vented to the intake preturbo stock, which is not good IMHO, so it's now vents to the atmosphere. This system works well on my engine.

I have considered extending the vent hose into the frame rail, as I do have a small amount of oil collect below the vent hose...But never have.

A good test of excessive crankcase pressure is to remove the valve cover oil cap, if you have one, and place the loose cap on the opening. If the loose cap is blown off, there is too much pressure and it needs to be addressed.

You could do the similar step by step test with any existing venting in the valve cover, separator, blocked hose, etc., to find any problems.

Good luck.
 
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@Lumpskie and @franklin40, has venting to atmosphere cured, or at least significantly decreased, any oil consumption you all were experiencing? I have a Provent 200 installed and it is capturing oil (it is not capturing the amount of oil that I am consuming however!), but I'm still using some oil and wondering if, for whatever reason, it is a pressure/constriction issue. Both my turbo and intake manifold (near the gaskets) have oil soak/weeping. Not enough to drip, but definitely noticeable. Wondering if venting to the atmosphere helps any in this case. Thanks!!!

I haven't had any issues with running the vent down to the frame. I change my oil every 5000 miles or so. I haven't checked exactly what my oil consumption is. But, I know it's low enough that I don't pay attention to it. I have no oil drops, spots or leaks either. And, since I'm (we're) in the U.S., I haven't gotten any grief for this setup during inspection either. I'll to check my oil on the dipstick during lunch today. I think I changed the oil in October...
 
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I also have the provent. It works but not in the way I would expect. IMO the filter element is only good until it saturates, which in my case was only a few thousand kms. Then it will vent to atmo no matter what through the pressure relief valves. I also agree that the can should have been reversed. As is, liquid oil enters through the top of the filter, runs down the element, and quickly saturates it. If it had entered through the bottom then it would bypass the element and likely give it a lot more life.

There might be enough flow through the filter at idle to work correctly, but I'm guessing most of that blowby is working its way through the provent's relief valves at any amount of throttle. I think it helps with the smell when at stoplights but thats probably about it.

I tried a smaller coalescing filter at one point. It saturated and most of my oil left the engine via the dipstick. Blockage is baaaad.
 
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my oil consumption has really nearly gone away. i have a few drips now that i changed my oil pan but i only have to wipe the side of my valve cover once every couple oil changes and it’s otherwise clean. i haven’t run a hose to my frame yet. just vent straight out the valve cover.
 
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Thanks for the updates y'all, I appreciate it. Sounds like I need to give the direct to air venting a try. I'm guessing my Provent 200's filter is saturated like @dan1554 mentioned, as it has been installed for over 60k kms, and that this may be why it is experiencing blow-by oil weepage on the turbo and intake manifold gaskets. There is a small amount of oil near the pressure release on the Provent 200 itself, so this would corroborate what @dan1554 is talking above.

The "excessive blow-by" test using the loosened valve cover oil cap resting on the opening has been done and there is no rattling or bouncing of the oil cap, which is a good sign.

Also, I change the oil (Chevron Delo 400 15w40) every 5,000 kms so I keep a pretty close eye on my oil level. And I always check it when the engine is cold, as well as the truck being level.
 

IanB

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Thanks for the updates y'all, I appreciate it. Sounds like I need to give the direct to air venting a try. I'm guessing my Provent 200's filter is saturated like @dan1554 mentioned, as it has been installed for over 60k kms, and that this may be why it is experiencing blow-by oil weepage on the turbo and intake manifold gaskets.

The weepage at the intake manifold gaskets could be a sign that the gaskets have shrunk and the bolts have loosened. I replaced mine a few years ago, many of the bolts could be loosened by hand!
 
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FWIW, Im hanging on to the provent, but I won't be shelling out money for new filters. Pretty sure it still works on idle, and performs catch can duties.
 
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Quick update...I vented to atmosphere for several hundred miles and the area where I had the vent hose exit became an oily mess. My oil consumption did not really change at all, so it is as if venting to atmosphere did nothing for me. Instead of making a mess on the underside of our HDJ81, I rerouted the PCV vent tube to go back to the factory setup (post air filter, pre-turbo). I originally had a Provent in there, but I was still getting oil consumption. Any thoughts on where to go from here? It drives great, gets decent fuel mileage, and the exhaust does not indicate any sort of massive oil burning or anything. Our 1-HDT maybe consumes a liter of oil for every 1500 kms, sometimes more if we we're driving at extended highway speeds, sometimes less if not.
 

IanB

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Quick update...I vented to atmosphere for several hundred miles and the area where I had the vent hose exit became an oily mess. My oil consumption did not really change at all, so it is as if venting to atmosphere did nothing for me. Instead of making a mess on the underside of our HDJ81, I rerouted the PCV vent tube to go back to the factory setup (post air filter, pre-turbo). I originally had a Provent in there, but I was still getting oil consumption. Any thoughts on where to go from here? It drives great, gets decent fuel mileage, and the exhaust does not indicate any sort of massive oil burning or anything. Our 1-HDT maybe consumes a liter of oil for every 1500 kms, sometimes more if we we're driving at extended highway speeds, sometimes less if not.

What oil are you using? You can pull the valve cover and bend the tabs so the openings for the oil to get out is smaller, just don't go so tight as it could chance restricting air flow. If you run the engine with the oil fill cap loose sitting on the opening, is it dancing wildly?

Edit: I see you answered that last one above already.
 
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I know routing the hose into the intake pre-turbo is stock on many engines, but IMHO, it's a bad idea.

When the crankcase vapors are routed to the hot turbo, the body and blades tend to get coated with carbon from the burnt oil residue. I think that is hard on the turbo.

Manufacturers know the turbo will last past the warranty period, so don't care. But as the engine wears, blow-by is going to increase, causing more oil to be burned onto the turbos components.

If the oil cap test is good - not knocking the cap off the valve cover, then your problem could be a restrictive vent in the valve cover. Has the engine been apart at some point? If not, damage is unlikely.

Are there any external oil leeks at seals or gaskest? Many times, excessive crankcase pressure will cause these type of leaks.

My engine was/is direct vented stock. It does have a oil separator with oil pan drain stock. No smell or problems.

Here is a picture of my set up - Best picture I have. Valve cover hose goes to the top, small hose on bottom right drains oil into sump, larger hose on left vents to atmosphere.
1925583
 
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Thanks @IanB , @Greg_B and @doug720 ... I will look into the metal tab thing. My guess is that the metal tabs are at the stock location, without having looked. I hope it is something as easy as adjusting those tabs :)

I am using either Chevron Delo 15w40 or Shell Rotella 15w40, depending on which is available/cheaper. Both motor oils are standard, conventional oil (i.e. not synthetic). I haven't really noticed a difference in oil consumption between the two brands either. I figure they are both decent quality oils.
 

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