How to fix excessive crankcase pressure

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Crankcase pressure has been a problem inherent to engines ever since the first were built more than a century ago, but it took the intervention of the EPA to finally deal with it. While the crankcase ventilation systems introduced in the s were originally designed specifically to reduce emissions, they had the side benefit of solving an age-old internal-combustion issue. All engines naturally experience a certain amount of pressure, owing to a number of factors.

Cylinder pressures in a typical engine can easily top to psi during the power stroke; the piston rings keep most of this pressure in the cylinder, but their seal against the cylinder wall isn't airtight. Even if the seal were This pressure encourages oil leaks through the gaskets and contributes to air pollution by sending a constant stream of untreated oil vapor steaming out of the engine's breather cap.

Generally speaking, a street engine will lose about 1. So, a horsepower engine would see about 5 cfm of blow-by through the oil breather, and a horsepower engine will get about The same 1. If your cylinder pressure tops out at psi, you should see about 1 psi of pressure in the crankcase.

Worn-out piston rings are half of blow-by equation, since they'll only seal as well as the cylinders themselves. It's common knowledge -- at least among anyone who's ever seen an Engine Restore commercial -- that tiny scratches in the cylinder will allow excess pressure to leak past the rings. But excess cylinder wear does something else too. When the cylinder bore gets larger, the rings extend slightly, losing a bit of their tension and ability to seal the cylinder.

This extension also causes the ring gaps to grow slightly, which further encourages cylinder leakage. All new cars come equipped with a positive crankcase ventilation system, which is essentially just a vacuum tube running from the valve cover to the engine's intake.

Quick Tech : Benefits of Lowering Crankcase Pressure | Part 1

The slight vacuum in the intake tract offsets pressure in the engine, either neutralizing it or creating a slight vacuum. The PCV system uses a valve mounted in the valve cover to keep engine oil from getting sucked through and into the motor; if this valve malfunctions or gets clogged, the PCV system will fail and you're back to a sealed system.

In really extreme cases, pressure in the crankcase can actually push the PCV valve out of the valve cover with a pop like a champagne cork. Because of the movement of the pistons and the regularity of the combustion events, pressure will typically come out of the engine in regular puffs of pressure instead of a smooth breeze.

Too Much Crank Case Pressure???

These puffs can tell you something about the engine's condition. Ideally, these puffs of pressure should be barely noticeable when you hold your hand over the oil filler cap, manifesting as a slight tremble in pressure. The more powerful the individual puffs, the more pressure is spiking with each event and the more cylinder leakage you have.

If the puffs are powerful enough to move your hand, it's about time for a rebuild. The puffs in pressure should be very regular, with no puff more powerful than another. If you feel a few light puffs followed by a single very strong one, then you know you've got excessive blow-by in one cylinder.

how to fix excessive crankcase pressure

A grizzled, old mechanic with the mental reaction time of a ninja and a horse-whisperer-like, intuitive feel for engines can actually give a pretty good prognosis on engine condition just by feeling for the frequency and power of those individual pressure pulses.

But for those of us who aren't Yoda with a wrench: regular puffs good, irregular puffs bad. A few things can cause excessive blow-by apart from worn cylinders or rings. Powerful spikes in crankcase pressure are a classic sign of a blown head gasket, or a cracked engine block. This is especially true if the gases coming out of the breather hole carry with them a strong stench of raw gasoline. If you smell raw gas, it's time to hang it up and plan for a rebuild. Leaking exhaust valve seals will also contribute to spikes in crankcase pressure, which are particularly noticeable because the valves are just below the oil filler cap.

These puffs will smell more like the exhaust coming out of your tailpipe, with perhaps a slight undertone of additional fuel smell. This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us. Cylinder Wear Worn-out piston rings are half of blow-by equation, since they'll only seal as well as the cylinders themselves.

The PCV System All new cars come equipped with a positive crankcase ventilation system, which is essentially just a vacuum tube running from the valve cover to the engine's intake. Puffing Pressure Because of the movement of the pistons and the regularity of the combustion events, pressure will typically come out of the engine in regular puffs of pressure instead of a smooth breeze. Single Cylinder Blow-By The puffs in pressure should be very regular, with no puff more powerful than another.Home MustangWorks.

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For successful registration, you must use an email address assigned to you by your internet service provider. Too much crank case pressure? I am some what sure that I have too much crank case pressure. I got on it today and after the run my dip stick was popped out about an inch.

Oil pressure cold is 60psi and around 50psi when warm. When getting on it the pressure will move up to around psi.

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Engine has about miles on it. New block, I beam rods, new stock crank, new bearings, new melling standard volume oil pump, main girdle, canton 7qt pan, B-cam, Edelbrock performer heads, new lifters, push rods, 1.

Signs & Symptoms of a Defective Crankcase Breather on a Lawnmower Engine

I havent noticed any smoke comming from the exhaust. If I do have too much crank case pressure what are my options to fix this problem. Sorry so long just trying to give you all as much info as possible. Re: Too much crank case pressure?

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Oil leak is probably caused by the high crankcase pressure. No doubt, you're getting a substantial amount of blow-by the rings. You could do a leak-down test to verify. Put a crankcase evacuation system on it. It'll solve your problems plus build you some extra HP. Find More Posts by Jeff Chambers. I will do the leak down test over the weekend and let you now what I get.Venting a typical V-8 engine isn't a complex affair.

A breather atop each valve cover is usually all that's needed. Of course, replacing one with a PCV valve to introduce a bit of vacuum into the system and to redistribute the unburned hydrocarbons back into the engine via the carburetor or throttle body yields a cleaner and much more environmentally friendly solution.

Supercharged applications, however, can be a bit more finicky. Increased pressure in the crankcase can cause blow-by when using a traditional push-in style breather, covering that trick engine compartment with a fine mist of fuel-oil.

Adding a PCV valve is a good idea, until a boost situation kicks in, at which time the internal check valve is forced shut, rendering the valve moot. At this point, instead of drawing fresh air into the breather and vanquishing the crankcase pressure through the PCV valve, the internal pressure is vented out the breather, possibly resulting in another oily blow-by situation.

This usually happens when the engine is under load or at high rpm, which is when pressure builds up quickly and needs to be relieved the most. The extreme solution to prevent all of this is to install a vacuum pump that continuously draws the pressure out of the crankcase.

For most modest horsepower street engines, however, a vacuum pump is overkill, though it probably wouldn't hurt since drawing out the vapors and relieving any internal pressure is a good thing. What isn't a good thing is drawing too much out of the crankcase, which can be a problem in an engine that builds up significant crankcase pressure and is equipped with a vacuum pump. In this situation, the system can draw out more than just leftover hydrocarbons and vapor, but engine oil as well, requiring some sort of catch can to retrieve the gathered fluid.

It was with this in mind when it came time to design the crankcase ventilation system for our supercharged LS engine. I knew it was going to be important to let the engine breathe, but I also wanted to design a system that wouldn't fill the engine compartment with hydrocarboneous byproduct.

And since proper ventilation is key to improved ring seal, oil scavenging, and windage, I wanted to be sure our supercharged LS had plenty of opportunity to breathe freely.

You'll recall a few months back when we dressed up our engine that we're using PML finned valve covers from Speedway Motors. These feature a 1-inch hole on the top of each designed to accept a push-in breather or PCV valve. Originally, my plan was to use a pair of PCV valves with the internal valve removed, one in each valve cover, plumbed to a Summit Racing breather tank on the firewall.

With the valves removed, the PCV valves simply act as degree elbows.

Venting to Cure Crankshaft Pressure

This setup would be the "inlet" side of the crankcase venting system, while a traditional PCV valve mounted in the valley cover and connected to the intake would act as the "outlet" or recirculation side of the system.

Fresh air would be drawn through the breather tank and down through each valve cover then out the valley of the engine, via the vacuum signal on the intake side of the PCV valve. My initial idea of using a PCV, sans valve, would have worked perfectly. I just didn't like the possibility of blow-by occurring, especially since the valve covers and intake are as-cast pieces, which are especially hard to keep clean given their porous nature.

After whittling a small adapter out of aluminum and a little machine work, I came up with this nifty deal. A similarly sized and branded stainless braided line runs from each valve cover. This tank allows the engine to breathe freely while containing any oil that may be drawn up through the system. The second part of the crankcase ventilation system is related to the valley cover. Later-model LS engines come equipped with a PCV valve grommet location, but our LS crate engine did not, so it was necessary to drill and tap one.

Once again, AN lines and fittings were used to connect the valley cover breather line. An overall shot of the system gives you a good idea how it all works.

The plan, though simple in its form, gave me a moment for pause since a push-in style breather or PCV valve still allows for a little blow-by at the grommet. Since I didn't want to deal with an oily mess as much as I could help it I decided to shift gears. The other problem is the aforementioned fact that when the engine makes boost, the PCV valve in the valley cover would be forced shut, thereby decapitating our crankcase ventilation system.Crank up the boost pressure, get more power.

Cummins ISX ISX15 high crankcase blow by pressure solution bypass

While many understand the merits of increasing the pressure of the air going into the cylinders, fewer understand the virtues of decreasing the pressure within the crankcase. While many high-end classes of racing from Formula One to Pro Stock rely upon dry sump oiling systems that run the crankcase at negative pressure vacuumfew entry-level racecars and even fewer street cars benefit from the negative crankcase pressures of a dry sump oiling system.

The cost and complexity of a dry sump oiling system puts it out of reach of many. Fortunately, the benefits of reduced crankcase pressure can also be accomplished by simpler and more cost-effective means.

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Optimized crankcase ventilation systems and the addition of a vacuum pump can swing positive crankcase pressures to zero atmospheric or even negative values vacuum. Even on the high-end, this may only represent less than 25 percent of the cost of a dry-sump oiling solution. For those that can afford the expense, there is no substitute for a well-designed, high-quality dry-sump system and all of the benefits that can be delivered.

For the rest of us, the benefits of the lower-cost alternatives are well worth the cost. Instead, the reduced crankcase pressure is simply freeing up or realizing new horsepower from increased engine efficiency and reduced power losses. The factory crankcase ventilation system is a positive crankcase ventilated design. At idle and under high vacuum, the PCV valve uses engine vacuum to reduce the crankcase pressure to zero.

However, when intake manifold vacuum is zero or under boostthere is no intake manifold vacuum to reduce crankcase pressure, so the pressure gets directed to the compressor inlets. In most cases, this will create positive crankcase pressure on the order of 3 to 6 psi, robbing performance. An aftermarket solution, like the Buschur Racing Pro Plus R35GT-R Catch Can eliminates positive crankcase pressure by venting the crankcase pressure to the atmosphere by way of the vented catch can.

Lower crankcase pressures 0-to-1 psi result in better ring seal and increased performance usually on the order of a 2-to-3 percent increase in power. The system also eliminated the issue of introducing oil from the crankcase into the compressor inlets, charge piping and intercooler. A dry-sump oil system or a pulley-driven vacuum pump can evacuate crankcase pressure so effectively that it can create a vacuum.

The vacuum is typically regulated to run at -5 to inHg on most applications. The negative crankcase pressures a. Performance usually increases on the order of 3 to 6 percent. Understanding how crankcase pressure is formed is key to understanding how it can be reduced.Featured Products from our Supporting Vendors. Activity Feed DSMtuners. Join the Community! Chat with others, create a build thread, post questions and answers. Get involved! Logging in will also remove many of the advertisements, along with this notice.

Too Much Crank Case Pressure??? Dec 3, 1. Hello all!!! I need help. I am a new proud owner of a 96 GS-T. I recently got the car with the engine nearly dissasembled. I rebuilt the head and reassembled the engine. But now I am having a problem.

Under high boost levels factory I am noticing the dipstick lifts from the tube and allows engine oil to "spit" from the tube and of course it starts to smoke. My question is, what could be causing this?

I have checked the PCV valve and it functions correctly. I performed a leak down test and it passes. After speaking to the previous owner, this was not an issue before.

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So, what did I install incorrectly? What else shoud I check? Any takers? Buy at FealSuspensionStore. Dec 3, 2. Yeah, its known to happen. What I did was used a piece of sloid copper electrical wiring,a nd bent it in a U shape.Featured Products from our Supporting Vendors. Activity Feed DSMtuners. Join the Community! Chat with others, create a build thread, post questions and answers. Get involved! Logging in will also remove many of the advertisements, along with this notice.

Too Much Crank Case Pressure??? Dec 3, 1. Hello all!!! I need help. I am a new proud owner of a 96 GS-T.

how to fix excessive crankcase pressure

I recently got the car with the engine nearly dissasembled. I rebuilt the head and reassembled the engine. But now I am having a problem. Under high boost levels factory I am noticing the dipstick lifts from the tube and allows engine oil to "spit" from the tube and of course it starts to smoke.

how to fix excessive crankcase pressure

My question is, what could be causing this? I have checked the PCV valve and it functions correctly.

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I performed a leak down test and it passes. After speaking to the previous owner, this was not an issue before. So, what did I install incorrectly? What else shoud I check? Any takers? Dec 3, 2. Yeah, its known to happen. What I did was used a piece of sloid copper electrical wiring,a nd bent it in a U shape. Then used a small hose clamp to clamp it so its snug. No problems like this. Dec 4, 3. I will try somthing like that to keep it down but does anyone know what the cause is?

I understand that it is crank case pressure but should there be that much pressure? Dec 4, 4. If it happens even once, figure out the cause and fix it. Dec 4, 5. A new OEM dip stick is about 10 to 12 dollars with an O ring seal that fits tight.

Google for MD I replaced mine yesterday after it popped out under boost. The finger ring was already JB welded back on so the dip stick didn't know whether to drop down or pop out. Last edited by a moderator: Jun 5, Dec 4, 6.Some Encore and Cruze models equipped with the 1. Positive or negative crankcase pressures outside the normal operating range, due to a restriction in any of the induction system components, may cause the oil seal leak.

Connect the tester with the engine off, and then start the engine or record the pressure reading. Normal crankcase pressure readings for the 1. If the crankcase pressure is in the proper range, follow the diagnostics in the appropriate Service Information. Look for any nesting materials, water intrusion, a kinked PCV tube or modifications to the air induction system. Also inspect the air cleaner outlet duct for a blocked PCV fresh air port. If the port is blocked, replace the camshaft cover assembly and retest for proper crankcase pressure.

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