Xoutpost.com - View Single Post - SOLVED - Engine Failsafe after Valve Cover Seal Replacement for Blue Smoke

McDonaldD · #21 07-25-2013, 07:13 PM

A B Able Truck - I'm glad you were able to resolve the flagrant symptoms you observed using a fashioned filter and a scotchbrite pad. I also could not agree more with you on "I believe you should diagnose each vehicle on an individual basis - Regardless of BMW guide/valve stem history." However, the underlying cause of our/your symptoms is not be resolved by your solution - your solution is very risky hack to the PRV system that only solves a few symptoms by stemming the flow of oil into the intake.

But, WHY is oil making its way into the intake? The logical answer is that the PRVs are not functioning as they should. Okay, but WHY did the PRVs tear, plug, or fail to close? Explained below, again, the non-functioning PRVs (torn, plugged, etc.) are still only be a symptom of the larger and underlying problem - The crankcase is leaking and can no longer hold a vacuum (prevent the atmospheric pressure from pushing molecules of "air" past the gaskets and seals, and into the crankcase).

How do I know its a vacuum issue? Again, unless old age or some unforeseen anomaly destroyed your Pressure Regulating Valves (PRVs), the blue clouds of smoke, the rapid oil consumption, and/or the failed PRVs all point to a lack of vacuum in the crankcase - there is a study spring that holds open the PRVs. In order for the PRV to close, the pressure from the external atmosphere must be greater than the the sum of pressures exerted by internal (crankcase) atmosphere + the force required to compress the spring. At equilibrium, exterior and interior pressures are equal - so the force of the spring is what is holding the PRV in the open position. As the vacuum generated by the running engine evacuates the pressure of the interior (crankcase), it leaves only the force of the spring to hold the exterior atmosphere at bay. The force of the spring is designed to be less than the pressure exerted by the exterior atmosphere; leading to the compression of the spring in the absence of an interior pressure (vacuum). So, if the designed/intended levels of vacuum (at all RPM) were present, the PRV would function as designed and would stay sealed; only opening to let blow-by gas through when necessary (force generated by blow-by gas pressure + the spring's ever present force is equal to or greater than (=>) the pressure of the exterior atmosphere.

In addition to only being forced open by blow-by gas pressure - the PRVs and Valve Covers have several safe-guards to prevent oil from making its way into your intake - shields, traps, gravity, etc. However, if a crankcase leak is preventing the PRVs from normal operation, these safeguards become overwhelmed. Only when these safeguards are overwhelmed do we get oil into our intake.

Like you suggested, placing a series of filters would certainly stem the flow of some/most/if not all OIL into the intake - which is good. However, those filters would not stem the flow of unmetered air, from the vacuum leaks, into the crankcase. Your filters are merely preventing oil from passing. Your filters are not returning your vehicle's crankcase ventilation system to its normal working state. Your filters do nothing to stem the unabated, and unmetered flow of atmosphere and blow-by gas into your intake. Those filters certainly do not return your crankcase to a state of vacuum; which is the reason the PRVs are not operating to begin with.

If we were just hacking together a way to prevent the smoke cloud problem, we could just put in the aforementioned filters, plug the holes on the intake, and remove the connecting pipes - effectively venting the crankcase into the atmosphere. Not only is this against the U.S. and CA law, it would also increase the flow water-vapor laden atmosphere into your crankcase. That water vapor in the atmosphere is the cause of the "cheese" people see accumulate in/on their PRVs. Sure, applying your filters might allow you to temporarily pass smog and they would make your car run temporarily closer to "normal"...but those filters would also exacerbate the already unnecessary wear and tear the vehicle was experiencing from the initial problem. Water and oil do not mix. While the original crankcase leaks allow water vapor into your crankcase, the addition of said filters would just compound that issue. The filters would stem the flow of water-vapor just as they stem the flow oil. The filter and the oil that the filter collected would increase the likelihood of fast-moving water vapor colliding with, and trapped inside a droplet of oil (stuck to the filter). When enough oil and water collects, the drop gets heavy enough, drips off the filter and flows back into your motor - where it can cause rust, corrosion, electrolysis, and decomposition of your oil. Best case, the drop "dries" on your filter and you can change the filter. Worst case? Your crankcase acts like a greenhouse and has a large quantity of condensation and water-ladened oil. Unfortunately for the filter solution, the original issue the filters set out to solve would not pose as much of a threat as the filtered solution does. The un-filtered solution provides fewer opportunities for oil and water to collide. So, we already know the unfiltered solution has issues with water vapor - why would we want to compound that issue by collecting it on a "condensation screen" - which the filters would ultimately act as. The symptoms of the problem would not be immediate but it would be a larger problem than had you not placed those filters.

I'm not trying to be mean, I'm trying to explain why your filter solution is, ultimately, not a solution at all. I am trying to make it overtly obvious to the readers of this thread that your filters will ultimately cost them more than fixing the underlying issue - vacuum leaks a la oil leaks.

In a later post, I'll give more in-depth information on where to look, what you're looking for, what you should replace, what overlapping maintenance can be performed, and a list of parts - both required and recommended. Since we're working on cars, a human metaphor seems appropriate: The filter solution suggested by A B Able Truck is like icing a broken leg because you think the swelling is the sole reason your leg can no longer support your weight. The swelling is not the reason you are unable to walk, its the shattered bone. Using your filter method merely suppresses the smoke cloud, oiled intake, and oil consumption. It encourages you to drive around - all the while causing more harm than would otherwise be possible. In reality, immediately fixing the vacuum leaks is your best chance at ever running again. Simply installing a series of makeshift filters is like walking on your broken leg after you have used ice to suppress the swelling - you'll be lucky if you can ever walk again; let alone, run. Driving with a filter solution, such as yours, could lead to internal rusting of your camshafts, crankshafts, etc.; degraded oil performance (read: unnecessary wear and tear on the entire engine; and the filters could be dislodged and pushed into the motor by the humanly-incomprehensible power these motors generate. An overhaul of the valve covers and upper timing covers will be an order of magnitude cheaper than replacing a corroded engine block, rusted crank- and cam- -shafts and so much, much, more. Trying to patch or ignore this problem will likely make your problem infinitely worse.

Just as Valve stem seals are certainly not the problem you are trying to solve, filters before/after your PRVs are definitely not the solution. The parts necessary to overhaul the sealing surfaces of the upper engine are relatively inexpensive - its the labor cost that will get you. The job is not that difficult - its just a lot of parts and tools, space, and time necessary to perform the job over two or three days.

Like I said, my next post(s) will include the parts list, job outline, tricks and tips, and N62 maintenance jobs with overlapping-labor.

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