Preventing dirty engine oil and PCV elimination

PCV Valve elimination and other factors to clean up engine oil and improve engine performance.

This is well ahead of my needing to know this, but I have been reading about what seem to be symptoms of engine piston rings not sealing correctly, poor combustion (related to ring failure) and generally low power of the motor.

This is a big surprise to me after many years running dedicated Propane vehicles. Apart from reduced power dry fuelled engines should enjoy very clean oil and much smoother running. So I have a couple of questions about what is normal?, which maybe are also suggestions. I have read an article on this site about natural gas thickening oil, but I have never heard of that before, but have never had a natural gas vehicle, nor know anyone who has. There are many thoughts on using correct oil with propane, but I have done it all and never had “oil Problems”, nor heard of any with propane.

  • PCV total elimination. I stole this from the Gadgetman groove forum. The PCV valve draws a portion of crankcase gas into the intake using engine vacuum, this caused filtered air from the air cleaner to enter the crankcase to displace combustion/flammable gasses; Hence- the Positive crankcase flow. Note: this only occurs during no-load. During high load there is excessive blowby and insufficient vacuum. If woodgas reduces power by 30% the PCV would often be nearly fully defunked!! Additionally the PCV reduces vacuum and makes combustion of any liquids much harder. I proved this taking up the Gadgetman challenge with unleaded fuel. If you disconnect the PCV I DID GET 10% better economy and it ran better!!! Any and ALL liquid doesn’t burn until it has been changed to a vapour, heat can be stolen from combustion to do this, but vacuum is the preferred method! Any lost vacuum has consequences! It’s a no-brainer to me and I now happily disconnect PCV’s. Being Environmentally friendly (and allowing blowby gasses to continue to leave the motor) I always vent the PCV port the same way as the breather port I.E - connected to the aircleaner.
  • Spark plug heat range? This is a real crazy thing. Using Propane “they” always recommend 1 grade colder spark plugs. This is demonstrated by manufacturers in their factory dedicated propane vehicles as well! I used to follow this recommendation until I experimented with 1 grade hotter…A very noticeable difference. Of course, Spark plug selection is explained well from spark plug manufacturers. Every motor may be different. The procedure is to increase heat range until the tip becomes baked and shiny. Then go to the previous cooler plug. A plug tip must run at 600 degrees C to stay clean and work properly. Getting a clean crisp combustion is required to load up the piston rings and prevent contamination of engine oil.

Does anyone know or have suggestions why the oil gets dirty so quickly with Woodgas? It is something that I will be spending more time on…

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I guess another way to say what I mean is that I believe rings sealing and keeping oil clean is not caused by rings in good condition etc; as much as it is caused by good combustion on top of the piston. To reverse the order might give further clarity. I believe that if the combustion was to be truly messed up, by changing valve clearances on one cylinder as an example; then that cylinder would immediately increase blowby into the sump PLUS starting pumping oil upward past the rings at the same time! I say I have seen this when a cylinder has damaged a valve. There is a company in Queensland Australia called CEM Cost Effective Maintenance. They developed the prodecure called the Honey oil treatment. Following their regime they have Diesels almost going between services and keeping the oil “honey” clean. basically they add a fuel catalyst to clean up the burn, a very strong oil flush and good friction modifiers. They are easy to find on the internet…although they don’t have a fuel additive for woodgas …lol.

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I thought the PCV expelled gasses to the intake so it can be burned away, and the Breather is what allows fresh clean air to enter the block?

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Hey Cody, Thats basically exactly right, the point is if it should be done before or after the throttle?. As made it wastes vacuum, which is a really negative thing! It also can only do what you describe when there is lots of manifold vacuum PLUS it stops doing it as the motor comes under load and blowby gasses increase. Under high load most motors have blowby gasses exiting the block from both the breather port AND pcv. But, at both high and low engine load the PCV is always wasting vacuum, which in my experience has a negative impact on how well the motor runs. And more negative impact on starting as it doesn’t introduce fuel. Its hard to compensate for at starter motor cranking speed. Sorry to get technical on a small point but just trying to help. Basically all crankcase gasses should be burned away rather then vented like older engines were, but just do this before the throttle plate! Doing it after the throttle plate is supposed to sweep the inside of the block with clean filtered air (only does it at idle). And it costs fuel economy. My focus here, is that it reduces the rings sealing and contributes to dirtier engine oil (along with a few other things). A “crisp” or clean combustion keeps oil clean. Im a bit of a fanatic with engines, not sure if this topic will interest woodgas people if it is seen as irrelevant when the fuel is free?? But clean oil is important to!

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The one thing I’ve noticed in common with a few sludge incidents is they all had their PCV deleted or never had one. Just an observation.

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You are correct on all you say Niel Wiese.
But you left off that the actual “PVC” valve in an engineered system does variable flow regulate.
Also American/Canadian engine PVC system used to be high flow sweeping systems. It was the non-American system that were usually just a crankcase pressure blow-off system. US emission installed regulations compliant, yes. But the engine oils on these did get crankcase contaminates dirtier much quicker. And it was the better keep oils from getting contaminated systems that “they thought” would allow for the extended oil intervals changing. Fine, sorta’ OK unit the engine begins to have increasing blow-by caused by their rings carboning up no longer being cleaned from that extended service oil. Not then allowing rings to have freedom of movements. And the valve seals harden no longer sealing from acids building up in that extended interval oil use.

This is my, I thinks . . . diesels from too rich of combustion do carbons soot blacken their oils much quicker. Remember they are the most carbons dense of liquid fuels. Then gasoline.
With propane a relatively low carbons engine fuel. Methane CH4 many fewer carbons than even propane.
Non-finite combustion controlled engines on DIY woodgas and chargas are going to have high crankcase carbons loading from normal rings blow-by.
Our gasifer systems are engine vacuum sucked for CO safety reasons. And a reasonably easy way for the engine itself to regulate for proportional gas made production.
So, yes we must stop PVC intake sucking to not screw up with our vacuum for gas production.
Sure. Sure. This could all very be finitely controlled with bi-directional active digital logic. Then sensors. Duty cycling actuators and such. Ha! These all goober up in usages with internal contaminates coatings; and combustion acids eating up tubes and control valves. Have to be added to time-in-service and miles-in-use maintenances to screens&filters change and clean. The newest electronic PCV European car system as the latest example of overengineering creating a new maintenance/repair $$$ needs.

Ha! Look at virtually all modern single cylinder engines and how they crankcase "ventilate? Into the air box after the filter before the throttle plate just exactly as you propose.
Your idea is sound. But then back to woogas systems causing the air box to be under near constant suction, negative pressure. You will be negative pressurizing the crankcase. So what.
For personal use engine, just more frequently changing out engine oils is also a very DIY, easy, costs effective solution too.

Regards
Steve Unruh

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Thankyou Steve, lots of knowledge again! Yes, I did leave out that PCV should maintain a constant flow, with high manifold vacuum is closes to reduce flow and at wider throttle openings with less vacuum it opens up attempting to give the same flow. I dont wish to get tangled in PCV operation tho. You said that Woodgas will provide high crankcase carbons past normal ring blowby. I still dont see why that is the case. And regardless of why it is the case I would do all I can to clean it up. The CEM Honey oil treatment I mentioned above is something I do for diesels…its something to see when a diesel oil is still clean after 100 hours of use!!! The clean oil means so little…but proves so many other things about the motor. My spark ignition motors also get special treatments, if the treatments work, then it is proven in how clean the oil stays. Hot spark plugs, generous plug gap, PCV delete, fuel additive, oil flush to clean rings at oil changes, etc are things I do as normal practice.

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Good points everybody.
And remember: a engine running on woodgas has higly poisonous crankcase gasses, 30%co, and positive pressure, should NEVER ventilate “free” not even during a short test-run, best is to feed it back to the engine.
This was well known during the woodgas-era, always open crankcase ventilation at that time, poisonous gas sucked up through rusted floor, or around gearstick.
They actually tested cars by driving around with a bird in cage in the passenger seat (compare to coal miners) even cats was used as they are highly sensitive against carbon monoxide.

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I agree all good points on PCV- Now i wounder if or how much too much vacuem in the crank-case might cause oil too rise away from the pick up tube.OR put BUBBLES in the oil-OR NOT?

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Hi Kevin, Now you have me thinking! And I don’t even know how the setup works! I presume you mean if the crankcase vapors are connected to the suction line from the gasifier? I did read that it takes 9 inches of vacuum to draw through the gasifier. I did a quick search and water boils at 156F or 69C with a vacuum of 9 inches of mercury (water boils at room temperature with enough vacuum applied to it). Oil boiling point is much higher (luckily!!), but oil would be much hotter! Yikes!!
I think you might have just hit on something that could be an issue! Makes me think of lots of things but I think I will give this some thought. Perhaps disposing of crankcase gasses should not be done into the intake line pulling from the gasifier?? Also engine oil seals and gaskets would not be designed to have this type of vacuum. The vacuum would be slightly higher if the breather pipe was exposed to 9 inches of vacuum and the PCV line was exposed to 15 inches of vacuum (with restricted flow of course).

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Well just for some ideas here, the old motor in my toyota ran at idle between 14 and 16" of vacuum before it ever got wood fuel. the oil pressure ran at 60-80psi cold, and under normal operating conditions the pickup tube is about 5" below the oil level in the oil pan. I have many many times with that motor abused the gasifier at over 60" of water in the hay filter reading and never was able to suck oil out of the engine into the intake manifold where the pcv line hooks in

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Hi Neil,
I posted a link to that article just because some of out members here seem to have had the same experience with oil thickening, gelling, polymerizing when using woodgas. I was hoping that the type of oil used in NG vehicles might help us woodgassers.
Rindert

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I just remembered as i read your post I once talked to a mechanic who worked on a commercial NG motor, he told me that NG uses double the volume that propane does. He said the venturis that draw the gas (NG) are exactly double the size of propane. Some fuels use a very low ratio to air for complete burn. Propane is between 2 to 10 percent and I think 7:1 is the correct ratio. Very high ratios of fuel to air would be another similarity between NG and Woodgas! But as for me I am still Stuck at why oil must get dirty with a dry gas fuel!! I hope to find a way to improve combustion, that will improve the piston rings sealing…and then the oil will stay cleaner and last longer.

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I have no idea of how the air and woodgas will be mixed to the correct ratio in my future setup. I guess if I am to work out where the engine crankcase breather will go - then i need to know how it is done. I really want to avoid the electronic control device I have already seen. I know the engine intake is used to draw through the gasifier. I also read 9 inches is required to do the pulling. does all the air going into the motor come through the gasifier? Is there another aircleaner intake where the crankcase breather can vent to without seeing the 9 inches of vacuum? - and still be 100% vented into the intake of the motor to eradicate the dangerous gasses and prevent discharge to the environment? Could someone please post their favourite non-electronic “carby” setup for woodgas?

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Woodgas is never 100% dry, it’s very difficult to dry the gas in an expedient way that is also serviceable and inexpensive without adding too much bulk.

I think that can contribute a lot to the sludging. But engine temps should be enough to keep it evaporated.

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I think one way to prevent engine sludging could be a bypass filter. Especially if you use a ZDDP heavy oil, soot will ruin Zinc dependent engine oil. Soot will always get into the engine, it also gets into diesel engines. The soot could be causing engine oil to congeal, maybe via reaction with other additive packages or just from the particles thickening like corn starch in soup.

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Woodgas is homemade stuff and kinda rough. It contains some water vapor, soot, probably some ash, certainly some hydrogen sulfate, and I’m sure other undesirable things. Hydrogen sulfate combines with water to form sulfuric acid which corrodes zinc throttle bodies and brass throttle plates. We have seen these problems on this forum. ‘Sour gas’ is a very old and well known problem in the oil & gas industry, and there are industrial engines out there that are designed to use it. However, getting access to the type of data that went into building those engines has proven difficult.
It would seem to make sense to me that if one were able to reduce the amount of ‘blow by’ it might reduce the amount of contaminants in the oil.
Rindert

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Hi Neil,
I noticed on post 8 you mentioned that you were concerned about pulling 9 inches of mercury vacuum. Reminder that wood gassers are pulling water inches which are considerably less.

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Hi Darrell, Thanks heaps for correcting that! Who knows how long before I would have noticed I was wrong! 9 inches of water is a lot less trouble in the engine sump area compared to 9 inches of mercury.

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You are most welcome Neil. I am sure someone else would have pointed it out. It is a common mistake with us newer to the trade.

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