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| AOS III - The Replacement BoxsterBob - San Carlos - 9 years ago |
A recent trip to the beach resulted in the Boxster recreating a James Bond Smoke Screen Scene from Goldfinger. I knew right away the AOS I replaced at 75k, was now DOA at 135k. Fortunately there was a turn-out and I had cell service and my trusty AAA card.
I had it towed to my driveway and sat tight until the new AOS I ordered from Pelican parts arrived. The good news is, my car is still running great after 16 years and 135k miles. The bad news is, I’m now on my second round of replacing the Boxster’s “Achilles heels”; AOS, water pump, coolant tank...
The failed AOS looked like this.
Because the AOS completely failed with a major smoke episode, versus the proactive replacement I did at 75k, I decided to pull the throttle body and clean it (never done before) and swab out the cross tube and plenums. There was a good amount of oil in there!
Here is the throttle body after 135k …
After a few minutes with electronics cleaner, paper towel and an old toothbrush…
Even after removing as much oil as possible from the parts down stream of the AOS, it still required a 30 minute drive (I waited for dark to avoid the stares and finger pointing) to get rid of the residual smoke. I contemplated replacing the plugs, but they are almost new, and my commute this morning was fine. Good power and a much improved idle.
I’m good for another 75k of AOS Bliss!
I had it towed to my driveway and sat tight until the new AOS I ordered from Pelican parts arrived. The good news is, my car is still running great after 16 years and 135k miles. The bad news is, I’m now on my second round of replacing the Boxster’s “Achilles heels”; AOS, water pump, coolant tank...
The failed AOS looked like this.
Because the AOS completely failed with a major smoke episode, versus the proactive replacement I did at 75k, I decided to pull the throttle body and clean it (never done before) and swab out the cross tube and plenums. There was a good amount of oil in there!
Here is the throttle body after 135k …
After a few minutes with electronics cleaner, paper towel and an old toothbrush…
Even after removing as much oil as possible from the parts down stream of the AOS, it still required a 30 minute drive (I waited for dark to avoid the stares and finger pointing) to get rid of the residual smoke. I contemplated replacing the plugs, but they are almost new, and my commute this morning was fine. Good power and a much improved idle.
I’m good for another 75k of AOS Bliss!
| Ha. Just 2 AOS's? I'm on my 3rd replacement AOS. I get 80K to 100K miles from the thing.... MarcW - 9 years ago |
Last one failed pretty much like you describe. I happened to glance in the rear view mirror as I was pulling way from a stop light and spotted the huge cloud of smoke.Hadn't spotted any smoke earlier. The amount of smoke was enough to hide a battleship. As I drove down the street the smoking stopped and I tried to nurse the car to a dealer about 10 miles away. Got caught at a long stop light and the smoke just billowed out and the engine started running rough so I picked a nice easy to get to with a flat bed tow truck parking space in a local grocery store parking lot and got my money's worth from my premium auto club membership. Had the car taken the dealer.
Didn't bother to clean anything. Just picked up the car after the AOS was replaced and drove it. After the 3rd AOS the whole thing gets kind of routine. What doesn't get routine is the feeling one has driving the car as it is smoking like crazy. I wanted to crawl into a hole.
Didn't bother to clean anything. Just picked up the car after the AOS was replaced and drove it. After the 3rd AOS the whole thing gets kind of routine. What doesn't get routine is the feeling one has driving the car as it is smoking like crazy. I wanted to crawl into a hole.
Boxsterra - 9 years ago |
| Re: All's well that ends well BoxsterBob - San Carlos - 9 years ago |
Boxsterra - 9 years ago |
Surprising that they haven't fixed it even after 4 revisions.
FWIW, the newest part is under $100 at Sunset Porsche
FWIW, the newest part is under $100 at Sunset Porsche
| Re: Yup, that's the latest one BoxsterBob - San Carlos - 9 years ago |
I paid $116.47 with free shipping, so it guess it wasn’t too bad.
I didn’t take the failed AOS apart, but I assume the failure occurs at the diaphragm in the round part on top. I’m not sure if there are any other “moving parts” in the rest of the device. If that’s the case, separating the round diaphragm from the rest of the part, via a screw fitting or clamp could make the point of failure (diapragm) a maintenance item, swapped out like spark plugs or oil filters without the need to replace the PIA piece, mounted to the engine block. Simply disconnect the J-Tube and R&R the diaphragm from the top engine service access. Easy-peezy.
Pedro’s TechnoAOS has a nice ring to it!
I didn’t take the failed AOS apart, but I assume the failure occurs at the diaphragm in the round part on top. I’m not sure if there are any other “moving parts” in the rest of the device. If that’s the case, separating the round diaphragm from the rest of the part, via a screw fitting or clamp could make the point of failure (diapragm) a maintenance item, swapped out like spark plugs or oil filters without the need to replace the PIA piece, mounted to the engine block. Simply disconnect the J-Tube and R&R the diaphragm from the top engine service access. Easy-peezy.
Pedro’s TechnoAOS has a nice ring to it!
| Do you remember the good old days Bob, when we sat around and said things such as: SMILIN - 9 years ago |
OMG, did my engine blow? CRAZY amount of white smoke!
...and...
OMG I almost got killed by a gangsta because my horn inadvertently honked when I hit the brakes!
...and...
OMG my car is dead...I can't even turn the ignition switch!
...and...
OMG my trunk is full of coolant!
But now, it's just, go to Pedro's Garage and look at the write up to remind you of the repair you did a few years ago
...and...
OMG I almost got killed by a gangsta because my horn inadvertently honked when I hit the brakes!
...and...
OMG my car is dead...I can't even turn the ignition switch!
...and...
OMG my trunk is full of coolant!
But now, it's just, go to Pedro's Garage and look at the write up to remind you of the repair you did a few years ago
| Re: Do you remember the good old days Bob, when we sat around and said things such as: BoxsterBob - San Carlos - 9 years ago |
Hey Doug, Throw in the following and I'm 6 for 6 (better than I'm doing in my MM Pool) 
OMG...My car just pee'd in the parking lot and the water pump pulley shaft needs a Depends!
...and...
OMG... It rained last night and now my alarm won't set, the windows won't go down and the car won't start!
Pedro's Garage provided the R & R and drying of the CLU and so far, not only is it functioning again, but my 16 year old key remote started working again!
OMG...My car just pee'd in the parking lot and the water pump pulley shaft needs a Depends!
...and...
OMG... It rained last night and now my alarm won't set, the windows won't go down and the car won't start!
Pedro's Garage provided the R & R and drying of the CLU and so far, not only is it functioning again, but my 16 year old key remote started working again!
| You didn't mention ... Pedro (Odessa, FL) - 9 years ago |
... the posts where Chuck had to change the offending phrase for the icon of a dro of oil.
Happy Reminiscing
Pedro
Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)
Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
Happy Reminiscing
Pedro
Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)
Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
| Re: Should the AOS be changed at a certain mileage? My 2000S only has 45k but its 15 years old. Pedro (Odessa, FL) - 9 years ago |
Many people change it as preventive maintenance at 75,000 - 100,000 miles.
I believe in "if it ain't broke, dont fix it".
There are several levels of failure for the AOS.
It can fail where it produces a ginormous cloud of smoke or it can fail where it just has a rough idle.
The cloud of smoke is actually oil getting into the combustion chamber. A couple of drops are not a big deal, but high oil quantity into the cylinders can cause engine hydrolock (not good).
You can test for a failed AOS by opening the oil fill cap. If it shows excess vacuum hold on the cap most likely the AOS is done.
Also, when the AOS starts to fail you'll notice lower MPGs.
Replacing the AOS in the earlier Boxsters is a royal PITA. It's a piece of cake in the 987/Caymans. In the 996/997 it's practically impossible without dropping the engine.
Happy Boxstering,
Pedro
Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)
Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
I believe in "if it ain't broke, dont fix it".
There are several levels of failure for the AOS.
It can fail where it produces a ginormous cloud of smoke or it can fail where it just has a rough idle.
The cloud of smoke is actually oil getting into the combustion chamber. A couple of drops are not a big deal, but high oil quantity into the cylinders can cause engine hydrolock (not good).
You can test for a failed AOS by opening the oil fill cap. If it shows excess vacuum hold on the cap most likely the AOS is done.
Also, when the AOS starts to fail you'll notice lower MPGs.
Replacing the AOS in the earlier Boxsters is a royal PITA. It's a piece of cake in the 987/Caymans. In the 996/997 it's practically impossible without dropping the engine.
Happy Boxstering,
Pedro
Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)
Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
| good to know, thanks Pedro. *NM* Naples986 - 9 years ago |
| Re: Should the AOS be changed at a certain mileage? My 2000S only has 45k but its 15 years old. BoxsterBob - San Carlos - 9 years ago |
At ~75k, I noticed the start up puff was growing and lingering. I knew that waiting for it to fail completely would leave the car crippled, so I changed it proactively. I have been working in Chicago nearly every week since November, so the car went from a daily driver to a driveway queen for 3 months and I didn't notice any change on the few occasions I drove it. Mine chose the ginormous cloud route over the rough idle the second time around. 
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