Issues Reinstalling the Air Oil Separator

[jluetjen]

I am having a heck of a time getting the bottom connection of the AOS pushed into the block of my 2002 Boxster Base (2.7). I know everyone has problems with the vent hoses, but the connection that I'm having an issue with is shown in the image below.



It's this rigid connection that inserts into the crankcase. (The protrusion associated with the O-ring with the call-out of 2.)

1. I've oiled up the outside of the pictured tube
2. I've swabbed some oil around the hole in the crankcase
3. I've tried reaching down from the top and massaging the AOS in by working back and forth and side-to-side
4. I've tried starting the insert and than using the screws (call-out 3) to pull it in.
5. I've tried pressing it in from underneath the car. I've even tried using a big screwdriver as a lever to push the AOS in

Nothing seems to work. Any ideas?

[husker boxster]

Let's start simple:

Did the o-ring from the old AOS stay on the old AOS or did it slip off and stay in the hole?

[CarGuyNeil]

Originally Posted by husker boxster

Let's start simple:



Did the o-ring from the old AOS stay on the old AOS or did it slip off and stay in the hole?

Yes, this. I'd start there...

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[JFP in PA]

I'll add a second one: Is the new AOS a factory unit, or after market? The AM stuff is actually poorly made crap.

[jluetjen]

Did the o-ring from the old AOS stay on the old AOS or did it slip off and stay in the hole?

I'm not aware of there being an o-ring in the hole.

The AOS was a Hamburg-Technic unit (996-107-023-04-HBT) purchased from our hosts.

I took a measurement of the lower drain tube where it goes into the block. Both units have the triple-groove/o-ring set-up. On the old AOS, the tube and rings have a diameter of 17 mm. The same measurement on the new AOS is 18 mm. It looks like the difference is due to the o-rings being thicker on the new unit, but this may be a result of them not having been installed in the port in the block for the last couple of decades.

In the meantime, the hose that goes across the top of the engine broke off, so I'm waiting for the new hose to arrive before I go further.

[JFP in PA]

Originally Posted by jluetjen

I'm not aware of there being an o-ring in the hole.

The AOS was a Hamburg-Technic unit (996-107-023-04-HBT) purchased from our hosts.

I took a measurement of the lower drain tube where it goes into the block. Both units have the triple-groove/o-ring set-up. On the old AOS, the tube and rings have a diameter of 17 mm. The same measurement on the new AOS is 18 mm. It looks like the difference is due to the o-rings being thicker on the new unit, but this may be a result of them not having been installed in the port in the block for the last couple of decades.

In the meantime, the hose that goes across the top of the engine broke off, so I'm waiting for the new hose to arrive before I go further.

The real problem is that it is aftermarket junk. Send it back and get the real thing; we have had nothing but problems with anything other than factory (lousy fitment, poor life expectancy, etc.), and why we buy nothing from your "hosts".

[Starter986]

Originally Posted by JFP in PA

The real problem is that it is aftermarket junk. Send it back and get the real thing; we have had nothing but problems with anything other than factory (lousy fitment, poor life expectancy, etc.), and why we buy nothing from your "hosts".

You will want to follow JFPs advice.

[husker boxster]

Originally Posted by jluetjen

I'm not aware of there being an o-ring in the hole.

If you're not aware, that means you don't know if it is or isn't remaining in the hole. To verify and know for sure, check your old AOS to see if the o-ring is there OR stick your finger in the hole to verify it's open. It will take less than 5 min to verify.

If the o-ring came off the old AOS and lodged in the hole, your new AOS will not go in far enough to lock in. The exact issue you're having.

JFP taught me to start at and eliminate the simple things first. Can save you a lot of chasing your tail moments.

[CarGuyNeil]

What he said^^^

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[jluetjen]

Originally Posted by husker boxster

If you're not aware, that means you don't know if it is or isn't remaining in the hole. To verify and know for sure, check your old AOS to see if the o-ring is there OR stick your finger in the hole to verify it's open. It will take less than 5 min to verify.

If the o-ring came off the old AOS and lodged in the hole, your new AOS will not go in far enough to lock in. The exact issue you're having.

JFP taught me to start at and eliminate the simple things first. Can save you a lot of chasing your tail moments.

I got my pinky all the way into the gallery -- no o-ring. There was none on the old AOS either.

On my next try to install it, I'll have my wife work the top side of the car to keep the AOS aligned square with the mounting surface, and I'll work from underneath to try to lever some pressure on the AOS to get it into the hole.

I'll let everyone know how it works out.

[jluetjen]

For future reference, here are some pictures of the tube's routing. I'm pretty sure that you'll need to take off both of the plenum cross-over pipes (as in the pictures) and the rigid oil refill tube (already broken off in these pictures :-/ ). Even with them off you'll need to use all of the flexibility of the new tube to install it. I recommend starting by guiding the left side of the tube in from the top of the engine, and then work the right side into place. Even then it will need to be worked through some tight places and the flexible end bent back on itself.

The plenum tubes come off in just a few minutes, so don't be afraid to just take them off.

This first picture is looking from behind the driver's seat back through the fire-wall. The pointer can guide you to the connection.


This view is looking down into the engine bay next to the left rear fender. The tube is routed between the front and the middle intakes. (between the intakes for cylinders 4 and 5). You can only see about 1/4" of the tube below the component with the wires attached to it.


Looking from the right rear of the engine bay towards the left front.


Looking from the left side of the engine bay to the right. I found that I needed to gently tap the tube over the aluminum cylinder-shaped item in the center of the picture. I then bent the flexible part of the tube back onto itself to fit it over the black dome shaped item to it's immediate right in the picture. There are a couple of protrusions from the plenum above them, but the tube will fit around/over/under them.


Finally with the tube in place.


Now I have to figure out how to get enough of a pull on the ends to get them to click on to their connections.

BTW - I also replaced the squealing starter while I was in there. I found that it's easier if the starter is loose while doing this project.

Now about that o-ring...

[jluetjen]

I have spending the last 10 days puzzling about how to reconnect the long tube which I purchased back on to the fitting at the left front corner of the engine. I made sure to lube both ends with some white grease. Sure it's tight for someone with big hands, but even using mechanical advantage to grab and pull the hose onto the fitting - it wouldn't click on. By my estimate I was easily applying at least 40 pounds of tension on the tube end trying to pull it on the fitting. Thankfully the nipple on the engine didn't break off!

So finally I pulled the tube off of the engine again and started to take some measurement and compare them to the tube that came off the engine. Everything measured the same until I got to the o-rings. Long story short, the orange o-ring on the new tube was significantly thicker than the old o-ring, or the separate o-rings that I bought with the tube. Here are some pictures.

Old o-ring:


The orange o-ring that came ore-installed on the tube:




And here is the separate o-ring that I bought, and a second picture of it next to an orange o-ring. The difference in thickness is visible.




Now I have to admit that I was able to fit the other end of the tube (with an orange o-ring) onto the AOS, but in that case I had room to twist the AOS when installing the tube, but there was no way to do this on the other end. The only option is to pull it straight on.

Thankfully I bought some separate black o-rings. I'll try to install the tube using one of them and post the results.

[jluetjen]

That was the problem! Now I can move on to reassembling everything!

[jluetjen]

Originally Posted by JFP in PA

The real problem is that it is aftermarket junk. Send it back and get the real thing; we have had nothing but problems with anything other than factory ....

You were right JFP in PA. I'm just returning the 996-107-023-04-HBT AOS and ordered a genuine Porsche unit (996-107-023-04-M100). For the record, you can see the difference below. The unit that I took off of the car is on the right, the -HBT that I received is on the left.

[JFP in PA]

I have replaced more AOS units than you can probably even imagine; we have tested several aftermarket units and none of them were any good. Fitment issues, like you are suffering, and the life expectancy of a May fly are the most common issues. Considering what a pain in the butt replacing one is for the average DIY without even a lift, the few extra $ for the real thing just plainly makes sense.

[raticosa]

Originally Posted by JFP in PA

I have replaced more AOS units than you can probably even imagine; we have tested several aftermarket units and none of them were any good. Fitment issues, like you are suffering, and the life expectancy of a May fly are the most common issues. Considering what a pain in the butt replacing one is for the average DIY without even a lift, the few extra $ for the real thing just plainly makes sense.

Good to know! I'm at that point but at least my engine is out of the car and I was tempted by the lower aftermarket AOS prices. After other research and this thread, I will go with the Porsche unit now. I'm getting most parts from ******* which has a lifetime replacement policy on all parts so with something like the AOS, it makes perfect sense to go that route.
No affiliation but I only recently learned about fcp's policy and wish I had known sooner. It makes many Boxster purchases not so bad. Well, still bad, but bad only one time!

I also need to replace that long breather hose as one of the connector ends on mine is broken. I've seen a much cheaper brand named JL that sells for around $50 vs around $175 for the Porsche. JFP, do you have any experience with this brand?

[JFP in PA]

Yes, it sucks.

People trying to cheap out on parts for these cars are what keep people like me in business. After multiple failures, it ends up in my shop, where it gets fixed in the manner it should have gotten in the first place. Yes, you can save a few bucks on aftermarket AOS, water pumps, etc.; and then you get to replace it with what you should have used in the first place. Some savings.......

[JFP in PA]

And lifetime replacement guarantees are worthless unless hours of your or a shop's time is free..............

[jluetjen]

Just some closure -- I got the Genuine Porsche AOS, and it fitted perfectly. I than carefully reinstalled everything (especially the vacuum lines) and the car started right up with no smoke, and runs perfectly. There have been no error codes tripped either.

Thanks everyone!