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Discussion Starter #1 (Edited)
2002 (7/02) 325i - 160k miles. I got her @ ~108k miles. I do not know if O2 sensors have ever been replaced.

I recently pulled the P0491/P0492 (secondary air injection system insufficient flow) codes.

I plan to replace the pre-cat O2 sensors, and then pull the intake to replace vacuum line, check valve and control valve.

While I am in there, I plan to replace the CCV, and thought I might as well replace the oil filter housing gasket as well. Intake gasket will get replaced at same time.

Anything else to do while I am under there?

I thought I remembered reading about a vacuum line mod to decrease oil consumption. She is consuming oil some way/where.

Thanks all!
 

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Starter is (more) accessible with the intake manifold off if you are into preventative maintenance.

Coolant hard pipes are good to do while there, they crumble at the ends and will start a slow leak, many replace them when under there even if you aren't actively leaking coolant.

Also change the vacuum caps on the back of the manifold... actually just replace every vacuum line you touch, they probably all need it.

Replace the dipstick tube O-ring, the one at the bottom that seals it to the oil pan. While you have the dipstick removed make sure to blow it out with air or brake clean, it can clog.

Speaking of vacuum caps, the vacuum line mod is called the "O2 Pilot Mod" and you can search for a thread here. Essentially you run a vacuum line from one of the unused capped vacuum ports on the back of the manifold to the port on the CCV diaphragm. I did this when I dove under the intake and believe it helped.
 

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Discussion Starter #3
Starter is (more) accessible with the intake manifold off if you are into preventative maintenance.

Coolant hard pipes are good to do while there, they crumble at the ends and will start a slow leak, many replace them when under there even if you aren't actively leaking coolant.

Also change the vacuum caps on the back of the manifold... actually just replace every vacuum line you touch, they probably all need it.

Replace the dipstick tube O-ring, the one at the bottom that seals it to the oil pan. While you have the dipstick removed make sure to blow it out with air or brake clean, it can clog.

Speaking of vacuum caps, the vacuum line mod is called the "O2 Pilot Mod" and you can search for a thread here. Essentially you run a vacuum line from one of the unused capped vacuum ports on the back of the manifold to the port on the CCV diaphragm. I did this when I dove under the intake and believe it helped.
Thank you!
Found the O2 Pilot Mod: https://forum.e46fanatics.com/showthread.php?t=1115223
 

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You're welcome.

For this job I highly recommend heading to Youtube and searching for the user 50sKid, he has a lot of fantastic E46 content and if you want his 2 part CCV replacement videos you will be able to follow him as he removes the intake manifold and touches a lot of the pieces you will need to interact with.
 

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Discussion Starter #5 (Edited)
You're welcome.

For this job I highly recommend heading to Youtube and searching for the user 50sKid, he has a lot of fantastic E46 content and if you want his 2 part CCV replacement videos you will be able to follow him as he removes the intake manifold and touches a lot of the pieces you will need to interact with.
I did find the 50sKid videos on YouTube when I did the CCV a year or so ago - you are right, they are nice and detailed. I cleaned the dipstick tube (double-walled) when I had it out.

Are the coolant rubes difficult to replace? I am guessing I lose a lot of coolant in the process...
 

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Are the coolant rubes difficult to replace? I am guessing I lose a lot of coolant in the process...
If you replace the coolant hard pipes you should drain coolant from the radiator and block beforehand. The trouble with replacing them is they may be crumbling at the ends and you will need to make sure you clean any debris out. It is also not always easy to tell if the pipe is properly seated, from what I recall they don't click in as the radiator hoses do.

Check out realoem.com for the part numbers, should be easy to find if you've looked for part numbers there previously.
 

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2002 (7/02) 325i - 160k miles. I got her @ ~108k miles. I do not know if O2 sensors have ever been replaced.

I recently pulled the P0491/P0492 (secondary air injection system insufficient flow) codes.

I plan to replace the pre-cat O2 sensors, and then pull the intake to replace vacuum line, check valve and control valve.

While I am in there, I plan to replace the CCV, and thought I might as well replace the oil filter housing gasket as well. Intake gasket will get replaced at same time.

Anything else to do while I am under there?

I thought I remembered reading about a vacuum line mod to decrease oil consumption. She is consuming oil some way/where.

Thanks all!
Crankshaft sensor. Dip stick o ring. Engine coolant temperature sensor. Heater hoses.
 

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Thank you all. Where is the crankshaft sensor located?
It's under the starter motor. It's really awkward to get to when everthing is attached to the side of the engine. So when you have all that out of there you should replace it. It's a good preventative maintenence item.
 

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Discussion Starter #11
It's under the starter motor. It's really awkward to get to when everthing is attached to the side of the engine. So when you have all that out of there you should replace it. It's a good preventative maintenence item.
Thank you - I added the sensor to my cart.
 

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Take a look at your Vanos oil line (or buy it and the crush washers and return if not needed).
Probably only need the o ring for crankshaft sensor but definitely do OFHG
Disa o ring, throttle body gasket, and air distributor o rings. So cheap there is no reason not to.
Replace all vacuum hoses
 

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Thank you - I added the sensor to my cart.
By the way, you will have your dipstick out if you do this. The dipstick hole will be open. If you do change the crankshaft sensor make sure you block the dipstick hole with a rag or something before you remove the screw from the sensor. Just in case you drop it. You don't want it going down that hole.
 

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Discussion Starter #14
By the way, you will have your dipstick out if you do this. The dipstick hole will be open. If you do change the crankshaft sensor make sure you block the dipstick hole with a rag or something before you remove the screw from the sensor. Just in case you drop it. You don't want it going down that hole.
This is gold - thank you! :thumbup:

I hope it is not one of those "ask me how I know" stories... :ben:
 

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Discussion Starter #15
Take a look at your Vanos oil line (or buy it and the crush washers and return if not needed).
Probably only need the o ring for crankshaft sensor but definitely do OFHG
Disa o ring, throttle body gasket, and air distributor o rings. So cheap there is no reason not to.
Replace all vacuum hoses
You all have been a huge help, thank you!

I am going to pass on the starter motor, my cart got spendy enough...
 

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Discussion Starter #16
Starter is (more) accessible with the intake manifold off if you are into preventative maintenance.

Coolant hard pipes are good to do while there, they crumble at the ends and will start a slow leak, many replace them when under there even if you aren't actively leaking coolant.

Also change the vacuum caps on the back of the manifold... actually just replace every vacuum line you touch, they probably all need it.

Replace the dipstick tube O-ring, the one at the bottom that seals it to the oil pan. While you have the dipstick removed make sure to blow it out with air or brake clean, it can clog.

Speaking of vacuum caps, the vacuum line mod is called the "O2 Pilot Mod" and you can search for a thread here. Essentially you run a vacuum line from one of the unused capped vacuum ports on the back of the manifold to the port on the CCV diaphragm. I did this when I dove under the intake and believe it helped.
It looks like there are 2 different starter motors for my application, one is 140mm long, the other option is 180mm.

I am guessing one is more preferable to the other?
 

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It looks like there are 2 different starter motors for my application, one is 140mm long, the other option is 180mm.

I am guessing one is more preferable to the other?
The one that is preferable is the one that is made for your particular car ;)

One has threaded flanges and the other does not. RealOem should tell you what you have.
 

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This is gold - thank you! :thumbup:

I hope it is not one of those "ask me how I know" stories... :ben:
No. You should get into the habit of stuffing rags or paper towels into any hole that leads to the sump whenever you expose it. Before you pick up another tool. It's a good habit to get into.
 

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By the way, you will have your dipstick out if you do this. The dipstick hole will be open. If you do change the crankshaft sensor make sure you block the dipstick hole with a rag or something before you remove the screw from the sensor. Just in case you drop it. You don't want it going down that hole.
This is gold - thank you! :thumbup:

I hope it is not one of those "ask me how I know" stories... :ben:
No. You should get into the habit of stuffing rags or paper towels into any hole that leads to the sump whenever you expose it. Before you pick up another tool. It's a good habit to get into.
OP, the same advice is good for the cylinder intake ports once you remove the intake manifold. Plug them with blue shop paper towels to keep dirt & debris out of the cylinders.

Its also good habit to clean the area really well before removing the dipstick tube & intake manifold to keep dirt and grime from falling in as you remove them. Blowing things out with compressed air is ideal, especially for the intake manifold area. Use the computer keyboard air cans if you don't have compressed air.
 

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