AOS modification.
04-19-2019, 09:36 AM
#64
Drifting
04-19-2019, 12:35 PM
#66
Rennlist Member
04-20-2019, 12:21 AM
#68
Can someone summarize this for the masses? Does this replace the AOS, mitigate a failed AOS, or provide a safeguard against a future AOS failure?
04-20-2019, 01:00 AM
#69
Drifting
The challenge seems to be to find a catch can that fits the confined space, has a dipstick and an accessible drain valve and has 3/4" ports. It also needs to look stock so it passes the visual test for Smog.
To satisfy most of the criteria on a different engine I used a stock can from a 2000 M62 4.4i BMW X5 .It is unusually small in diameter and very long. It is black plastic and cost about #20 on Flebay Maybe others can find a better alternative:
The BMW part # is : 11151705237.
To satisfy most of the criteria on a different engine I used a stock can from a 2000 M62 4.4i BMW X5 .It is unusually small in diameter and very long. It is black plastic and cost about #20 on Flebay Maybe others can find a better alternative:
The BMW part # is : 11151705237.
04-20-2019, 07:06 AM
#70
Advanced
When the AOS fails during operation as it did to 808Bill, it can dump a large amount of oil into the intake. When this happens your first instinct is to pull over and kill the engine. This can leave a large amount of oil in - usually cylinder 4. The next time the car is started that oil can have the cylinder hydrolocked. As Jake pointed out in Bill's blown motor thread, just cranking with the starter can bend the rod on cylinder 4. Jake also mentioned he has seen a bent rod then cause the piston to perforate the cylinder wall.
The mods discussed here will send the output of the AOS to either a catch can, and/or into the air box on the other side of the air filter, far upstream from the intake. I am understanding that this prevents the amount of oil being dumped into a single cylinder that would be required to hydrolock it. Therefore, you would possibly get a soaked air filter and/or relatively harmless smoke.
Can someone verify that I understand this correctly or please correct me? Thanks.
04-20-2019, 08:41 AM
#71
Rennlist Member
Dana, that sums it up really well from what I understood.
Fix/replace your AOS and ad a safeguard to the system!
Fix/replace your AOS and ad a safeguard to the system!
04-20-2019, 08:52 AM
#72
Rennlist Member
The challenge seems to be to find a catch can that fits the confined space, has a dipstick and an accessible drain valve and has 3/4" ports. It also needs to look stock so it passes the visual test for Smog.
To satisfy most of the criteria on a different engine I used a stock can from a 2000 M62 4.4i BMW X5 .It is unusually small in diameter and very long. It is black plastic and cost about #20 on Flebay Maybe others can find a better alternative:
The BMW part # is : 11151705237.
To satisfy most of the criteria on a different engine I used a stock can from a 2000 M62 4.4i BMW X5 .It is unusually small in diameter and very long. It is black plastic and cost about #20 on Flebay Maybe others can find a better alternative:
The BMW part # is : 11151705237.
Can you post a pic of your install and describe how you plumbed it?
04-20-2019, 11:40 AM
#73
I am trying to piece this together myself but as I understand it, it mitigates the effects of a failed AOS and is insurance against a catastrophic failure.
When the AOS fails during operation as it did to 808Bill, it can dump a large amount of oil into the intake. When this happens your first instinct is to pull over and kill the engine. This can leave a large amount of oil in - usually cylinder 4. The next time the car is started that oil can have the cylinder hydrolocked. As Jake pointed out in Bill's blown motor thread, just cranking with the starter can bend the rod on cylinder 4. Jake also mentioned he has seen a bent rod then cause the piston to perforate the cylinder wall.
The mods discussed here will send the output of the AOS to either a catch can, and/or into the air box on the other side of the air filter, far upstream from the intake. I am understanding that this prevents the amount of oil being dumped into a single cylinder that would be required to hydrolock it. Therefore, you would possibly get a soaked air filter and/or relatively harmless smoke.
Can someone verify that I understand this correctly or please correct me? Thanks.
When the AOS fails during operation as it did to 808Bill, it can dump a large amount of oil into the intake. When this happens your first instinct is to pull over and kill the engine. This can leave a large amount of oil in - usually cylinder 4. The next time the car is started that oil can have the cylinder hydrolocked. As Jake pointed out in Bill's blown motor thread, just cranking with the starter can bend the rod on cylinder 4. Jake also mentioned he has seen a bent rod then cause the piston to perforate the cylinder wall.
The mods discussed here will send the output of the AOS to either a catch can, and/or into the air box on the other side of the air filter, far upstream from the intake. I am understanding that this prevents the amount of oil being dumped into a single cylinder that would be required to hydrolock it. Therefore, you would possibly get a soaked air filter and/or relatively harmless smoke.
Can someone verify that I understand this correctly or please correct me? Thanks.
04-20-2019, 12:12 PM
#74
Rennlist Member
Thanks. AOS replacement is an engine-out procedure for my car, so it's not something I care to have done very often. This sounds like a good bit of insurance between replacements. It would great if someone could put together a DIY with photos and parts description/numbers.
Very simple, you have to move the AOS vent line out of the high vacuum trajectory from after the throttle body to before.
I did not do it myself as I had it installed as a package with IMS replacement and a cooling modification (relocated Low temp thermostat, GT3 waterpump and reprogrammed high fan settings with an extra temp sensor on the cooling water leaving the rads)
But the DIY is as simple as this:
1. Disconnect the AOS vent line from the intake.
2. Cap off the open intake connection.
3. Reroute the AOS vent line accross the engine bay to the right side
4. on the right side of the air filter box max a hole so the rerouted AOS vent line fits tighly through and sticks in the airbox under the air filter
5. make a hole in the oil filler cap, or use a 997 oil filler cap (more sturdy). secure an elbow fitting in it and connect a vent line which ends up the same way in the airbox under the air filter.
Step 5 is not necessary. It is an extra safeguard against overpressure in the crankcase for whatever reason. If you check the later 997 DFI setup you will see such a vent connection on the oil filler tube
Additionaly you can mount a catch tank in the right side of the engine bay and pass the two lines through it. It gives some additional filtering if dirty oily air gets past the AOS.
When using a catch tank and rerouting the vent line the only thing to take into account to not choose a too small diameter, the engine needs to be able to get the blow by out without any bottle necks. All the above is kind of straight forward. choosing the right diamter pipes is the inventive part. I have no idea where the sweet spot is.
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fourblades (10-11-2019)
04-20-2019, 12:51 PM
#75
Rennlist Member
I am trying to piece this together myself but as I understand it, it mitigates the effects of a failed AOS and is insurance against a catastrophic failure.
When the AOS fails during operation as it did to 808Bill, it can dump a large amount of oil into the intake. When this happens your first instinct is to pull over and kill the engine. This can leave a large amount of oil in - usually cylinder 4. The next time the car is started that oil can have the cylinder hydrolocked. As Jake pointed out in Bill's blown motor thread, just cranking with the starter can bend the rod on cylinder 4. Jake also mentioned he has seen a bent rod then cause the piston to perforate the cylinder wall.
The mods discussed here will send the output of the AOS to either a catch can, and/or into the air box on the other side of the air filter, far upstream from the intake. I am understanding that this prevents the amount of oil being dumped into a single cylinder that would be required to hydrolock it. Therefore, you would possibly get a soaked air filter and/or relatively harmless smoke.
Can someone verify that I understand this correctly or please correct me? Thanks.
When the AOS fails during operation as it did to 808Bill, it can dump a large amount of oil into the intake. When this happens your first instinct is to pull over and kill the engine. This can leave a large amount of oil in - usually cylinder 4. The next time the car is started that oil can have the cylinder hydrolocked. As Jake pointed out in Bill's blown motor thread, just cranking with the starter can bend the rod on cylinder 4. Jake also mentioned he has seen a bent rod then cause the piston to perforate the cylinder wall.
The mods discussed here will send the output of the AOS to either a catch can, and/or into the air box on the other side of the air filter, far upstream from the intake. I am understanding that this prevents the amount of oil being dumped into a single cylinder that would be required to hydrolock it. Therefore, you would possibly get a soaked air filter and/or relatively harmless smoke.
Can someone verify that I understand this correctly or please correct me? Thanks.
This is a great summary, I can never articulate as clearly. I either am too technical , or too general , or jump back and forth from too technical to too general and end up sounding like gibberish. Good job !!
