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hydrolock
It's not about the water, it's about the oil!
Risk of Hydrolock
While hydrostatic lock is normally associated with damage from water or radiator fluid, liquid oil can be just as damaging to the combustion chamber. The M96 and M97 engines are vulnerable to hydrolock from oil even under normal driving conditions. Porsche engine experts who work one these cars on a daily basis will tell you that damage to engines due to symptoms related to hydrolock is as ubiquitous if not more so than the intermediate shaft bearing problem. They tell us that this issue may have been overshadowed by all the internet chatter, press and class-action lawsuit given to Intermediate Shaft Bearing. However, hydrolock should not be ignored as a serious risk for the 996, 986 (Boxsters and Caymans), and early 997s. One of the problems is that unlike the IMSB failure that can be traced to the source of the problem from metal fragments, hydrolock does not provide easily discernible evidence that allows the technician to trace the damage back to its origins, especially since oil is expected to be seen in its natural environment. Many times the correct diagnosis is missed.
The combustion chamber is intended to work in an environment of air and gas along with minuscule particles of oil from the PCV system blow-by. During the compression stroke at the point where intake and exhaust valves are closed that air/fuel mixture compresses in preparation for ignition. The next stage is called the power stroke where the spark plug ignites the mixture in the combustion chamber and literally explodes, and the effect is to push the piston down. That forces causes the crankshaft to rotate and all is good. However, like water, unintended large volumes of oil will not compress or ignite in the manner the chamber was designed to do. The oil then acts as a force against the piston and thanks to the laws of "ideal gas" and thermodynamics, the piston stops, rod bends, cylinder sleeve cracks, and the crankshaft is bent. The effect is almost instantaneous and the crankcase can be ruined in the process, the crankshaft bearings destroyed and the shock can even cause cracks in the engine block. The effect of hydrolock can be catastrophic.
Why is the M96.M97 motor any more vulnerable to hydrolock than any other vehicle? It is because PCV oil can accumulate over time at the top of the manifold in a reservoir-like cavity that allows it pool. The arrow in the picture below shows where the oil accumulates. Normally occurring PCV blow-by oil are tiny particles that build up over time in the cavity of the intake manifold, that oil will pool to
to become a source of liquid oil that could then be absorbed by the engine as a gulp.
Should a small amount of oil make its way down to the cylinder head, damage is not likely but the evidence can be seen in the form of a random (or chronic in more serious cases) puff of white smoke from the exhaust. However, should a large enough quantity pour into a cylinder as a gulp, the results are not limited to environmental damage. A hydro lock event will cause major damage to the engine.
Unlike an IMSB event that can occur without warning, hydrolock fortunately provides a warning in the form of smoke coming out of the exhaust. If you see smoke exiting your exhaust pipes, one of the reasons can be due to small amounts of oil making their way into the combustion chamber. Of course smoking exhaust can also be caused by other problems, but if it is due to oil accumulation in the manifold reservoir the engine needs immediate attention.
The first picture below shows the air/oil separator on the left and one intake manifold on the right. The air/oil separator connects to the intermediate piece which sits between the two manifolds and is attached to the throttle body. The vent line between the air oil separator and intermediate piece is longer but was cut to fit picture. You can see where that vent enters the intermediate piece. The two graduated measuring cylinders shows the amount of liquid oil that fits in each of the manifolds when the cars sits on a level plane.
The second picture below indicates the location of where the oil accumulates in the manifold. There are two manifolds per engine and each has the same design where oil can accumulate. The next picture below shows where the liquid goes when the manifold is tilted to show the liquid seep down the runners. The same effect could happen after a sharp turn or sudden stop. The next picture shows two normal M96 rods next to two similar rods that have been damaged due hydrolock from seeping oil that originated in the manifold. The two bent rods were not able to complete their compression stroke because the combustion chamber was filled with liquid oil. The next picture below shows the effect of hydrolock on a cylinder wall. The third picture shows the damaged cylinder next to a normal cylinder.Below is a video from one of our members showing how to identify when the control arm bushings are deteriorated and in need of replacement. The bottom picture shows another example of hydrolock damaging cylinders 1 and 3 with what are called D-Chunk damage. According to the technician who submitted this picture, the manifold was inspected and discovered a large amount of oil in the reservoir. This motor had 25,000 miles on it and the owner specified engine failure occurred while making a sharp turn in the San Gabriel mountains.
Header photo courtesy of AutoEvolution.com
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ULTIMATE AOS - USPTO Patent # 11,326,489
DESIGN THEORY
The Ultimate Air Oil Separator (UAOS) works by taking a systematic approach to the problems associated with the design of the Porshe Air Oil Separator (PAOS) and corrects them through engineering improvements.
The UAOS application has been expanded to fit not only the 996, but the 997.1 and 986 and 987.1 engines.
Porsche AOS Design Problems and UAOS Design Solutions
1. Diaphragm Failure
Problem - The PAOS is well known for failure of the flow control diaphragm which can lead to a number of problems including: (1) rough idling and fuel trim faults, (2) increased oil consumption, (3) excessive smoking at start-up and during spirited street and track driving, (4) catalytic converter and O2 sensor failure, as well as (5) catastrophic hydrolock.
Solution – As a design improvement, the UAOS mitigates the risk of diaphragm failure by doubling the thickness of the diaphragm from 0.020 inches in the PAOS to 0.040 inches in the UAOS.
2. Catastrophic Hydrolock
Problem - When the PAOS diaphragm fails, it’s unable to control the flow of air from within the crankcase to the intake. This results in an increased vacuum within the crankcase which then draws oil from the sump into the intake manifold of which the oil then passes the intake valves and accumulates in the cylinder. Hydrolock typically occurs when the amount of oil accumulates above 60cc creating an intense pressure in the cylinders that results in catastrophic engine failure from cracked cylinders and bent rods.
Solution - As a design improvement, the UAOS mitigates the risk of hydrolock by incorporating a specially designed Accumulator between the Vortex and the Flow Control Diaphragm regulator that works as a secondary oil separator to ensure no oil makes it to the intake manifold, plus copper mesh filters for extra efficiency. In addition, the UAOS also has a microprocessor controlled infra-red warning sensor in the Accumulator which is set to activate an in-dash warning if oil accumulation reaches a dangerous level. This indicates a fault in the Crankcase Vent System, allowing for operator intervention before the threat of hydrolock can occur.
3. Oil Flow Limitations
Problem –
· The M96/97 engines with the Porsche “Integrated Dry Sump” system has a very large oil pump that pumps a high volume of oil through the xxxx
· 40% of this oil ends up in the top end of the engine in the heads, IMS and chain area.
· There are two return oil pumps (scavenge oil pumps), one in each head on Bank 1 and Bank 2.
· When driving aggressively in high-G Force turns, all the oil in the top end goes to one side in one head, so only one return oil pump can return oil to the sump.
· With the UAOS System, overfilling the oil level will provide more oil to be returned to the sump with the scavenge pumps. This cannot be done with the Factory AOS.
· The UAOS system also has dual drains to drain back the oil faster to the sump so that it will not be overwhelmed by the overfilling of the oil level.
Solution - With the UAOS Street & Track, the Extreme Track Duty Drain Back can drain oil twice as fast as the Motorsport AOS back to the sump. The Motorsport AOS still uses the Factory drain to get the oil back down to the sump, The UAOS also uses the factory drain but includes a Second Drain to make the drain back twice as fast.
4. Oil Capacity Limitations
Problem –
· Overfilling the oil level has shown through comprehensive data to be the best thing you can do to help stabilize oil pressure. But this cannot be done on the Factory AOS, it will overwhelm it….
· The Porsche Motorsports AOS has a larger body that holds more oil, but this lowers the oil level in the sump and contributes to oil pressure instability.
· With the emission legal UAOS Street only version the oil level can be run at the “full mark” in contrast to run to the “half way mark” which was recommended by Porsche in (bulletin #).
· In addition, the emission legal UAOS Street and Track version can be run at .5 to .75qts “overfull” to help stabilize oil pressure when on the Track.
· Further, the non-emission legal UAOS Track Only version can be run at .75 to 1.25 qts “overfull” to further help stabilize oil pressure for Track Events.
· Where the Factory AOS and Porsche Motorsport AOS only use 1 element ( a Vortex) to control/keep out oil from the engine, the Emission legal UAOS Street version uses 4 elements to keep oil out of the engine making it many times more efficient.
· The Emission Legal Street and Track version adds another element making it 5 elements to keep the oil out of the engine,
· The non-emission legal UAOS Track Only version adds yet another element making the total of 6 elements.
· So you can see why the UAOS system is so efficient, it has had a lot of R & D gone into the development of it in just a few years.
Solution - Increases Oil Capacity - The UAOS is so efficient ,the engine can be ran "over-filled" with oil to help mitigate oil pressure instability on the Track. ( with Drain Back option or Track Only non-emission legal vesion).
5. Intermix
Problem - PAOS failure is also known to cause intermix issues on the 996/997.1 engines due to its design of running both oil and coolant through the PAOS. Plastic housing cracks appear internally due to the heat cycling resulting in coolant flowing into the oil thru the chamber at the back of the diaphragm.
Solution – As a design improvement, the UAOS eliminates the need to run coolant thru the UAOS by relocating the diaphragm to a much warmer spot near the throttle. This design not only eliminates the risk of intermix, but it also eliminates the unnecessary line, connections and clamps that could cause additional external leaks.
6. Replacement Costs
Problem - When the factory PAOS fails, the procedure is to drop the engine and replace the PAOS. Not only is the cost of the new PAOS expensive but the service procedure to replace it is extremely expensive in time and high labor costs.
Solution - The UAOS eliminates the need to continually replace the PAOS, which is a costly and time-consuming job for most shops. Instead, the UAOS is designed to only replace the inexpensive flow control diaphragm regulator which is moved to an easy access location near the throttle body and can be replaced in a matter of minutes versus hours for the PAOS. The "Vortex" part of the air-oil-separator is left in its factory designed location and drains the separated oil back to the oil sump with the UAOS Street & Track, and into the Accumulator for draining with the UAOS Street. This makes any service easy and labor effective, saving substantial money in replacement parts and labor hours year over year.
Section 2 –
UAOS Variations
· UAOS-Street
· UAOS-Street Elite
· UAOS-Street & Track
· UAOS-Street & Track Elite
· UAOS-Track Only
· UAOS-Track Only Elite
UAOS
The UAOS complete kit for the Porsche 996/997.1 models includes the following: (1) black anodized aluminum Accumulator, (2) infra-red sensor, (3) plug-n-play harness, (4) aluminum relocation bracket for change-over valve, (4) custom hoses, (5) flow regulator, (6) mounting hardware, and (7) a pre-sealed AOS with a lifetime warranty, (8) as well as a 2-year unlimited mileage warranty on all other components*. Please note our UAOS-AL 99MY kit also includes the optional 15mm rubber elbow and clamps needed for early models with the vin split 99xs6 26672 and 99xs6 55501 for the early two piece brake booster design. $710
UAOS Kits
§ UAOS-AL 99MY fits cable throttle body Coupes and Cabs (C2's).*
§ UAOS-AL 996.1 fits 99C4's (E-gas) Coupes and Cabs, 2000, and 2001 3.4 models.
§ UAOS-AL 996.2 fits 2002, 2003, 2004, and 2005 3.6 models.
§ UAOS-AL 997.1A fits 997.1 3.6 models (2005 up to eng# 695 08696).
§ UAOS-AL 997.1B fits 997.1 3.6 models (2005 eng# 695 08696997 and up).
§ UAOS-AL 997.1C fits 997.1 3.8S models.
§ UAOS-AL 986.1A fits Boxster 2.5 engines
§ UAOS-AL 986.1B fits 1999-2002 2.7& 3.2 engines
§ UAOS-AL 986.2 fits 2003-2004 2.7 & 3.2 engines
§ UAOS-AL 987.1 A fits 2005-2006 Boxster & 2006 Cayman
§ UAOS-AL 987.1B fits 2007-2008 Boxster & Cayman
*Warranty - The UAOS has a 2 year unlimited mileage warranty on all components except the pre-sealed AOS which carries a "Lifetime Warranty". The 2-year unlimited mileage warranty is for material and craftsmanship only and does not cover labor or anything outside of parts replacement. Warranty is provided by ultimateaos.com.
UAOS-E (Elite)
The UAOS-E (Elite) features a Billet Black Anodized Aluminum Accumulator, Customized Optical Microprocessor Controlled Infra-red Sensor, OEM components, Custom hoses, aluminum change-over relocation bracket, Plug-N- Play wire harness/relay, mounting hardware, connectors, "Lifetime OEM AOS" complete kit price $1,050.00
UAOS High Mileage/Extreme Track Duty Auto-Drain (UAOS-HMETD)
An optional upgrade to the UAOS is the High Mileage/Extreme Track Duty Auto-Drain, which is recommended for older engines or if you plan on tracking your 996/997. The UAOS-HMETD will stop the need to drain the Accumulator and frequent warnings of the Infra-red sensor. The kit includes all fittings, hose, seals, connectors, clamps, and a new Genuine Porsche oil fill tube pre-fitted with connector and seal for $175.00 ($10.00 shipping)
UAOS high mileage/Extreme Track Duty Auto Drain fittings
These high quality banjo bolt fittings and pressure seal (145psi) for UAOS Aluminum Accumulators ONLY. Includes everything needed except the oil fill tube, you will need to drill 1/2 inch (.500) hole and insert the seal/fitting, (instructions included). $75.00 ($0.00 shipping)
UAOS coolant by-pass kit
UAOS coolant by-pass kit uses high temp silicone rubber caps rated at 450F and 145psi and positive seal clamps and brass connector to replace factory plastic connector..... free shipping .........Note : to use with UAOS ONLY:::::will be included in all UAOS kits for 996 after 4/11/2021. $25.00
Black Aluminum Anodized Accumulator
Black Anodized Aluminum Accumulator is rugged and beautiful at the same time with "Cotes de Geneve" machining pattern showing through the anodizing. The Accumulator collects any unwanted oil/water vapors, and is incorporated with an Infra-red sensor that warns of dangerous accumulation and ENDS HYDROLOCKING!
rear cover/bracket integral design that’s Tough enough you can run over it with a truck
installed view on engine
Diaphragm Comparison – UAOS vs. Porsche AOS and Motorsports AOS
The factory Porsche AOS and the Porsche Motorsport AOS uses the same diaphragm made by Mann+ Hummell.
In contrast, the UAOS uses a diaphragm that is much larger and twice as thick as the factory Porsche AOS and Porsche Motorsports AOS.
As an example, the Porsche diaphragm is approximately 16mm thick.
While the UAOS diaphragm is over 40mm in thickness.
AOS Failure
If the AOS fails, excess oil will be drawn into the engine causing extreme smoke, lower octane that can cause "pinging" (metalic sound like marbles), and can even lock the engine known as Hydrolock, resulting in bent or broken rods and cracked cylinders.
This is the amount of oil it takes to cause this damage.
Here is where the oil often accumulates until you go up a hill or turn a curve.
When you go up a hill or turn a curve, the oil that has accumulated in the intake flows into the cylinders.
Add picture or diagram showing oil build-up in cylinders that results in hydrolock.
Here is an example of bent rods from Hydrolock.
Here is the classic D-chunk caused by Hydrolock
Here is another example of multiple cylinders cracking as a result of Hydrolock.
OIL FLOW
The Motorsport AOS has a chamber twice the size of the standard AOS, while this helps keep oil from the intake it also means less is in the Sump and contributes to oil starvation...Another example of an engineer not seeing the whole picture...
