Oil Leaks

[jporter]

I’m in the process of fixing some oil leaks on a 98 Boxster with a 2.5L engine (84K miles) and thought the following pictures would be of interest to others with leaky engines.

The first picture is the classic “nose drip” under the car.

The second picture shows the major sources of the leaks. The intermediate shaft area seems to be the most significant in the clutch housing and the RMS looks much better than I expected. The major cause of the oil leaks is the AOS as can be seen on the right side of the picture.

The third picture shows a close-up of the intermediate shaft area.

The forth picture shows a close-up of the bellows of the AOS and you can see a LARGE hole on the left side of the bellows. I also noticed in the picture what looks like tape that was used to cover the hole. I'll get a closer look what looks like tape when I remove the AOS this weekend.

The last picture shows some seepage from the oil filler hose.

[rsfeller]

Boy the main seal is clean on this! Very helpful photos too.

I have two questions...

1. What is the AOS

2. Is this engine benched or did you just drop the trany and have the engine suspended with the special tool?

Thanks.

Shawn

Edited August 30, 2007 by rsfeller

[jporter]

The AOS is the Air Oil Separator and the car is up on jack stands. The engine is supported from the top with a backup underneath.

Edited August 30, 2007 by jporter

[rsfeller]

Thanks, didn't have my Bentley with me and read of the AOL failures before...but couldn't recall if that was what you were referencing. So dropping the trany was very do-able just with the car on jack stands?

[jporter]

The work was easier than I thought, but not easy. There are some tough-to-reach bolts. I could have used an incredibly strong 6" tall gnome to remove the top bolt on the transmission. I found it easier to remove this bolt from the top. The use of a motorcycle jack helps when removing the muffler and transmission.

I will post some comments and pictures of the whole process when I'm finished. For example the Bentley manual suggests removing the muffler at the joint next to the muffler and I found it easy to remove it at the joint next to the cats.

[rsfeller]

Great info, we'd all love a good write up for when our RMS goes!

I'm always curious how much work can be done with the engine in the car or if benching it is the easiest way.

Any idea what may have caused the hole in the bellows? Old age, tear, ect...

[jporter]

Any idea what may have caused the hole in the bellows? Old age, tear, ect...

No ideas at this point. I'll take a close look when I get it out and maybe I will see something.

[Tool Pants]

If the cam covers and/or spark plug tubes also leaked then you would have all bases covered....

[jporter]

If the cam covers and/or spark plug tubes also leaked then you would have all bases covered....

I changed the plugs earlier this year and didn't see any problems there - maybe next year. I'm considering leaving the original seal in since it looked ok and plan to only change the bolts.

I just finished changing the AOS and filler tube. Having the transmission out of the way made these changes easier. The back side of the bellows on the AOS was almost completely gone. I'll post some pictures tomorrow.

[jporter]

The following images are of the original AOS I replaced. The backside of the bellows (toward the front of the car) was gone. This could have been worsened when removing the AOS.

This is a close-up of the bellows and you can see the significant deterioration of the rubber on the inside of the bellows. My guess on the cause would be a combination of chemical reaction at elevated temperatures.

[WilliamsF1]

The following images are of the original AOS I replaced. The backside of the bellows (toward the front of the car) was gone. This could have been worsened when removing the AOS.

This is a close-up of the bellows and you can see the significant deterioration of the rubber on the inside of the bellows. My guess on the cause would be a combination of chemical reaction at elevated temperatures.

I recently had this damage aswell - and the mechanic only changed the plastic tube part.

Should I have replaced the whole AOS ?

[jporter]

Should I have replaced the whole AOS ?

I had the same thought when I looked at the damage. I already had the new AOS so I just replaced the whole unit. There have been updates to the AOS since 98 and the new AOS looks significantly different than my original. The two most obvious changes are the geometry at the top of the unit (don't know the significance of this change) and what looks like a significantly improved seal for the other connection to the crankcase. Maybe someone else can elaborate on the significance of changes on the new AOS.

Edited August 31, 2007 by jporter

[djomlas]

how long did it take you to change out the AOS?

[jporter]

how long did it take you to change out the AOS?

The actual change out probably took less than an hour. This was easier for me since I had the transmission out of the way – I suspect this would be much more difficult with the transmission in the way. I also replaced the oil filler tube between removing the old AOS and installing the new unit – this time was not included in the hour estimate above.

Cleaning up the mess left from the leaking oil and accumulated dirt represented about half the time. Getting the new AOS seated was the next most time consuming part as the new seal on the tube that attaches to the side of the crankcase has a significant amount of interference. It takes sometime figuring out how to remove the hoses that have “clip” fitting. You have to squeeze these and pull them off at the same time which was a little difficult due to the available space, having the car on jack stands, and the way I was supporting the engine from the top. The last issue is removing the spring clip that holds the bellows to the crankcase. This was easier for me as I had bought a spring clip remover with an extension for replacing a leaky coolant reservoir earlier in the summer.

I didn’t include the time researching the AOS and there is some great information in this site and a very good description of the replacement by Mike Focke at the following link.

http://mike.focke.googlepages.com/airoilseparatorreplacement

If I had seen the damage before ordering parts I would have considered changing just the bellows as mentioned in WilliamsF1 post above. This would have been very easy for me. You would still have the spring clips to deal with, I don't know how difficult it would be without transmission removed, and I don't know if you can just order the bellows.

Edited September 1, 2007 by jporter

[John V]

Cleaning up the mess left from the leaking oil and accumulated dirt represented about half the time. Getting the new AOS seated was the next most time consuming part as the new seal on the tube that attaches to the side of the crankcase has a significant amount of interference.

I have a question for you about this part of the AOS installation. I know exactly what you mean about getting the AOS seated - that lower-most connection to the crankcase was a major PITA for me. In fact, I'm not sure I even got it fully seated. I'm seeing a little bit of oil seepage from up there and I suspect I didn't get it seated enough. My bellows is sealed and not leaking.

How much of that lower seal is visible with your new AOS installed? I'll try to take a pic of mine tonight to get your opinions. Thanks.

John

[jporter]

How much of that lower seal is visible with your new AOS installed?

I did mine by feel and I think I covered the seal - just barely - I hope. There were 2 small shoulders on the top and the bottom of that portion of the AOS and I could not get these to be flush with the surface. I just put everything back together last night so it will be hard to get a good look at the seal, but I'll try and let you know if I can see the seal or leaks - nothing on the floor yet.

[John V]

How much of that lower seal is visible with your new AOS installed?

I did mine by feel and I think I covered the seal - just barely - I hope. There were 2 small shoulders on the top and the bottom of that portion of the AOS and I could not get these to be flush with the surface. I just put everything back together last night so it will be hard to get a good look at the seal, but I'll try and let you know if I can see the seal or leaks - nothing on the floor yet.

Thanks for the input. I guess I did get my AOS installed all the way, but it's tough to tell and I was second guessing myself when I saw oil leaking.

As it turns out my leak was caused by the oil filler pipe. It appears to be cracked at the interface just before it goes into the engine. It's causing a small oil leak (but even small ones make an unholy mess on the engine) down the passenger's side of the motor. Ordered a new tube today so hopefully once that's in it will be over.

[jporter]

Ordered a new tube today so hopefully once that's in it will be over.

Good luck with the filler tube. The connection at the trunk side is hard to reach. I did the trunk side from underneath as I had the big parts out of the way, but still have the wounds on my wrist from rubbing against all the hoses in the way.

I recall someone mentioning that you could get to this connection by working from the coolant reservoir in the trunk. I replaced a leaky coolant reservoir earlier this summer and the oil filler section of the reservoir is a separate part that can be removed, but it will take some effort to do this as you will have to unbolt and disconnect some parts to get enough play to disengage the oil filler section of the reservoir. I believe the oil filler section of the reservoir is the part that the oil filler tube attaches to with a spring clip in the engine compartment.

Although I hope I don’t have to replace the filler tube for another 9 years, I would think others will appreciate any insight you gain on how to make what should be a simple procedure easier.

[1schoir]

Ordered a new tube today so hopefully once that's in it will be over.

Good luck with the filler tube. The connection at the trunk side is hard to reach. I did the trunk side from underneath as I had the big parts out of the way, but still have the wounds on my wrist from rubbing against all the hoses in the way.

I recall someone mentioning that you could get to this connection by working from the coolant reservoir in the trunk. I replaced a leaky coolant reservoir earlier this summer and the oil filler section of the reservoir is a separate part that can be removed, but it will take some effort to do this as you will have to unbolt and disconnect some parts to get enough play to disengage the oil filler section of the reservoir. I believe the oil filler section of the reservoir is the part that the oil filler tube attaches to with a spring clip in the engine compartment.

Although I hope I don’t have to replace the filler tube for another 9 years, I would think others will appreciate any insight you gain on how to make what should be a simple procedure easier.

You can gain some additional access (and viewing) through the large round opening in the trunk firewall that has a large rubber plug going through it. It's located just to the left of the coolant tank. There is a bundle of wires routed there to the computer which is mounted on the driver's side top of the firewall. If you pull that plug (including the wires) rearwards, you can see and you can reach in there if your hands are small enough. It's an additional access that helped me when removed/replaced my coolant tank.

Regards, Maurice.

Edited September 7, 2007 by 1schoir

[John V]

Thanks very much for the tips, guys. This should be next weekend's project - once the parts come in from Sunset.

I'll post some pictures and procedure if I discover anything beyond what you all have already mentioned. Thanks again!

[jporter]

The following are some thoughts on this project. There is much information in this and other sites as well as the Bentley manual and these are only some additional thoughts on the procedures. These apply to my 98 Boxster.

I did the work myself and put the car on jack stands. I used a motorcycle/ATV jack to remove the muffler and transmission – this made the effort much easier. If I tried to remove the transmission without the jack, I would probably still be under the car with the transmission on top of me while my wife was trying to figure out how to get the mess cleaned up. Following is a picture of this jack. I will make a shorter handle next time I use it as the long handle would hit the bumper and moving the jack further under the car caused the lift to rise.

I used a 2x4 on blocks to support the engine as shown in the following picture and I don’t think I would recommend this approach. I hope someone has a better solution. The hardware results in the load pivot point being under the 2x4 so it would not flip over and a chain wrapped over a 2x4 would give me serious concern of this happening. The hardware also bent from the load as you can see in the picture and even though I adjusted it once, the engine was about ¼ to ½ inch lower when I reinstalled the transmission (based on transmission mounts). I also spent a significant amount of time thinking about what would happen if the 2x4 broke when I was under the car.

I used a slightly different approach then shown in the Bentley manual to remove the muffler. The muffler was supported by the jack shown above. I removed the muffler by sliding the connectors (after loosening the bolts) out of the way at the cats as shown in the following picture. I then unbolted the muffler at the transmission mount. These bolts are easier to get at than the muffler support frame on top of the muffler. These bolts will slide back, but will be stopped by the muffler. The small support frame at the end of the transmission will come down (probably fall at some point) with the muffler. You have to pivot the muffler to get it down as the U shaped section attached to the end make the whole unit too wide to drop straight down. Reinstalling the muffler at these connections was also easy.

There are 6 bolts mounting the transmission to the engine. One of the bolts (bottom left corner) was a triplesquare internal nut. I got several strange looks when I asked people at different auto and hardware stores for the proper tool to remove a triplesquare internal nut bolt, but finally found someone at Autozone who recalled that he had a strange set of tools that might work. They were triplesquare, but were too long so I had to cut the one that was the proper size to a shorter length. This can be seen in the following picture.

The bolt at the top of the transmission is hidden behind something called a muffler that is attached to the air box. This can be loosened to get to the bolt and is shown in the following picture.

For the life of me I could not get this top bolt off from underneath the car. I tried flexible and wobble extensions. I eventually rounded two of the corners and looked for another approach. I found that I could get to the bolt from above as shown in the following picture. I had to use a straight ended closed-end wrench to remove this bolt. I tried an open ended wrench and thought I was going to round more corners and eventually used a GearWrench with an extension to get the bolt off.

I would get a couple of extra long M12 bolts to help align the transmission and clutch as this took several tries.

I was told by the Porsche parts dealer that Porsche does not indicate that you will have to replace the "J" tube when installing a new AOS on a 98 Boxster – only on the 97. He checked and confirmed that the 97 and 98 originally used the same "J" tube so I ordered the replacement tube. This is needed as the old tube is too short (probably could be forced) for the new AOS as shown in the following pictures.

I also didn’t replace the RMS as this seemed to be in good condition. I suspect it’s the original because of the location and I figured why mess with something that appears to be working. The design of the new seal is somewhat funky with an extended coated lip with some small ridges on the inner surface that contact the shaft. I may be old school, but the new design didn’t give me any confidence that it would work better than the one already on the car. Someday I may regret not installing the new seal. I plan to look at the seal in about a year – unless I have to look at it earlier as a result of seeing some leaks coming from the clutch housing.

[jporter]

How much of that lower seal is visible with your new AOS installed?

I did mine by feel and I think I covered the seal - just barely - I hope. There were 2 small shoulders on the top and the bottom of that portion of the AOS and I could not get these to be flush with the surface. I just put everything back together last night so it will be hard to get a good look at the seal, but I'll try and let you know if I can see the seal or leaks - nothing on the floor yet.

I got a chance to look at the AOS connection this morning. I found that I could see it from the back right corner of the car and following is a picture I took of the AOS connection at the side of the crankcase.

[Baconaire]

I'm getting ready to replace my clutch on my 98 this weekend. I have an RMS in case. To what do you attribute all the gunk around the intermediate shaft? I would have assumed that was a drip from the RMS.

Thanks for the great pics and suggestions.

[jporter]

I thought it was due to leaking from the bolts for the intermediate shaft cover. These bolts appear to go through the case and the new bolts have sealant applied to them.

I noticed this past weekend that the drip is back so I plan to take a look at the RMS and intermediate shaft cover in a couple weeks to try and locate the leak. It should be easier to locate the source since I cleaned everything up last time. I just need to order new flywheel bolts.

[kbrandsma]

I'm replacing my oil filler tube and was wondering about connection in the trunk? Or is the connection that leads to the trunk at the engine side of the firewall?

Thanks!

K. Brandsma

98 Boxster

Edited January 21, 2008 by kbrandsma