This is my second adventure with bank 2 O2 sensors and pre-cats. The first was with my car (05 BCGT) and yesterday with a friend's 06 FS. The objective was to avoid doing an "engine-out" (as prescribed by the IETIS manual). We had determined the pre-cat was bad in a previous diagnostic session. We removed the center section of the exhaust and the pre-cat puked out catalytic debris. We bolted everything back together and sourced replacement parts. (at this point we had spent about 2.5 hours.)

Let me begin by saying: this is not your typical DIY project! The FS owner is an ex race mechanic with a lot of years of experience. I served as the "sorcerer's apprentice". Here are the highlights:

1. You need a FULL shop including hoist, transmission jack and every tool ever invented.

2. You will need two people and at least seven hours to fix this.

3. Unlike my car, which has the pre-cat and the downpipe as separate units, the replacement pre-cat for the FS came as a single unit with the cat and the downpipe merged. (see pic)

4. The major problem is space. Just fishing the connector ends of the O2 sensors through the firewall takes considerable patience and a lot of removal of engine compartment parts (i.e. filter assemblies,etc.) There are four bolts at the top of the pre-cat (where it connects to the turbo) and three at the bottom. In order to access these, we had to release the sub-frame, remove the rear transmission mount and disconnect the stabilizer cross-bar. All of this effort only gave us about 3/4 inch more room.

5. If the pre-cat and downpipe are separate, it is easier both to remove and to replace. In our situation, we removed the two-piece and installed the single piece. Let me say it was easier to remove than to replace. "easier" is relative. It still took us about 3.5 hours to remove the old units.

6. Several times we despaired. The further we got into the project the more impossible it seemed. However, we persevered and eventually got everything (except one nut at the turbo end {the top nut}). Since we had to vacate the shop, we have elected to revisit this last nut later. We road-tested the car and everything seems much better. No CEL, better performance and better fuel-economy. Total time for the R/R= 7.25 hours.

7. One other thing we wanted to explore (while we had the patient open) was the vacuum line at the rear of the engine at the top. Leaks here have necessitated "engine out". In spite of our lowering of the transmission and the removal of the pre-cat, we are convinced you can't gain access to this ill-conceived vacuum junction. Not what we were hoping for.

8. Please understand: I am not saying that our approach was the correct one. We welcome comments and suggestions from other forum members. While we wait for your responses, we will attempt to grow back the skin on our forearms and knuckles.

 

Wow! Just wow! Bravo and great job!!! I know what you mean about needing every tool, plus sometimes you need to create a tool to get a certain job done. Removing the Ferrari's oil dip stick holder is one of those crazy examples (unless your arm can bend in three places).

As for the ill-conceived vacuum line... Bentley seems to refuse to admit this known problem and help owners when they go bad after a mere 30k miles. Shall I scan the receipt of what they charge for this manufacturer defect?

 

Well done you guys. I saw what was involved when my GT had the vac' pipes fixed. Definitely not a simple one man job.

Please don't scan the receipt Steven. I don't need reminding of what I paid last year for this problem to be put right.
On a positive note, I did get the O2 sensors changed whilst the engine was out.
Actually, I remember anyway, over £5,300 UK including a small service. Ouch!

Les.

 

Thats a shame about the vac lines Peter, it would have been great to have a fix.
Is there any possibility to re run the offending line, perhaps cutting it and bridging out the leaking part??
Frank.

 

PMS, I'm truly impressed!
as you said, this doesn't look like the typical DIY job....

regarding the infamous vacuum line, I have been told that up to the 2005 MY.
you can replace it by removing ''only'' the drive line.
from 2006MY its ''engine out''!
congratulation BENTLEY that's a very ''efficient'' improvement!

 

Not possible Ulstrup.
Mine is a 2004 and it was definitely an engine out job as confirmed by my Indie.
Sad state of affairs never the less.

Les.

 

Does anyone know what improvements they made to the infamous vacuum line assembly so once the stock section is replaced this situation is solved?

 

I will ask my Indie. My GT is going in within the next few days. He will know for sure.

Les.

 

Les,

you better check what your guy is telling you.

I just spoke with Bentley Monaco and they confirmed me that for the 2003/2005 MY they can change the vacuum pipes by removing the drive line. as from 2006 it's, for some reason, engine out.

they also told me that the ''drive line out'' job is 8/10 hours and much more complicated to do than an ''engine out'' but it still make sense for the owner since it's about half the cost!

 

What exactly is a "drive line out"? Does it mean transmission, drive shaft, etc.?

 

It was a main dealer that did mine and not my Indie.
I will indeed be having a word with him soon.

Here's the proof;


Les.

 

Is the offending vac line visible on your photo...if so any chance putting a wee arrow next to it?
Thanks Frank

 

I understood it is the drive shaft.

 

Here you go;
It's just below the black arrow.

 

I don't think you are correct as the vacuum line is above the transmission. Removing the drive shaft only, won't give you access to the top of the transmission.