Vanos work, good time for cams?

[Cubieman]

So say you have your Vanos removed along with cam bolts. How much further must one go to completely replace the camshafts?
I know I could watch a YouTube vid or whatever but I'd like to hear how much more work it would be to do the cams at that point because I've got a CSL tune, headers/airbox, seems like cams form the holy trinity on these cars.
I see the kitty cat cams are quite reasonably priced. Please tell me that its really difficult so I can just proceed with Vanos and forget cams and not keep spending.

[ATB88]

My understanding is it's a decent amount more work and needs more precision tools, definitely not a "while you're in there". Also from what I understand, the hidden cost in cams is having to replace your 24 rocker arms as well. They end up costing about as much as the cams themselves, and add considerably to the labor.

Would like not to be wrong about this, I'm running out of time and money to f*** around with lol

[terra]

Front that point, it's essentially a matter of removing the cams, installing the new ones, and then proceeding with your vanos work as you would have. If you're doing things 'properly' and changing the rockers as well, that adds a fair bit of work - you'll need to remove a good portion of the front end to remove those rocker shafts.

This DIY covers it pretty well: https://m3support.net/thread/186/e46-m3-cams-diy

For whatever it's worth, removing those impulse wheels was a lot harder for me than that DIY suggests - perhaps because my engine was not nearly as pristine as Obioban's. I ended up having to break out a torch and use my impact wrench to break them loose. No damage and everything works fine now... but perhaps worth just buying new hardware for that stuff

[heinzboehmer]

Haven't done it myself, so can't comment on how much longer it will make the job.

However, removing cams with all the VANOS stuff off basically requires removing the spring clips and the cam bearing caps. Then you have to swap over a couple parts from the old cams to the new ones and reinstall.

[BMWahba]

yeah, i regret not putting cams in when i did the vanos.

[ATB88]

Front that point, it's essentially a matter of removing the cams, installing the new ones, and then proceeding with your vanos work as you would have. If you're doing things 'properly' and changing the rockers as well, that adds a fair bit of work - you'll need to remove a good portion of the front end to remove those rocker shafts.

This DIY covers it pretty well: https://m3support.net/thread/186/e46-m3-cams-diy

Huh I thought I remembered reading that you need some fancy and expensive BMW cam press tool or something like that do avoid damaging them on install? But this guy doesn't. I guess that's something that can just be avoided if you're being careful? I guess the real question is how necessary is it to replace the rocker arms.

[terra]

Huh I thought I remembered reading that you need some fancy and expensive BMW cam press tool or something like that do avoid damaging them on install? But this guy doesn't. I guess that's something that can just be avoided if you're being careful? I guess the real question is how necessary is it to replace the rocker arms.

Official procedure is using the cam press. And it would make it a bit easier if you have one. But it's totally doable without it if you follow the procedure in that post.

[duracellttu]

Yeah this is a money question. Cams and rockers are pretty pricey. If you want to do them eventually anyways, they it makes sense to save the extra time and do them now. They obviously require a customs tune. Again, if you are already doing this because of the CSL airbox work, then its another saved expense. I say go for it. Cams add a decent amount of power and really transforms the car. I have no regrets with mine.

Huh I thought I remembered reading that you need some fancy and expensive BMW cam press tool or something like that do avoid damaging them on install? But this guy doesn't. I guess that's something that can just be avoided if you're being careful? I guess the real question is how necessary is it to replace the rocker arms.

The cam specialty tool, like most specialty tools, just makes your life easier. If you arent time constrained and have attention to detail / patience, you can get along with out it.

[heinzboehmer]

Also from what I understand, the hidden cost in cams is having to replace your 24 rocker arms as well.

What's the reasoning behind replacing the rocker arms? Never really understood why this was necessary (unless significantly worn of course).

[ATB88]

What's the reasoning behind replacing the rocker arms? Never really understood why this was necessary (unless significantly worn of course).

I'm sure someone knowledgeable will chime in, but, my understanding was something about individual rocker arms wearing specifically to the cam lobes they operate with. If you try and re-use the rocker arm that wore specifically with the old cam lobe with a new one then bad things (accelerated wear, failure) could happen. Or even if you just re-shuffled your worn rocker arms and re-used your same cams it'd also be bad news. But I've read a lot of people who say that you can usually get away without it. I've never taken the time to learn more and understand this better.

[digger]

What's the reasoning behind replacing the rocker arms? Never really understood why this was necessary (unless significantly worn of course).

the cam and follower bed in together which means the surfaces on both surfaces actually get modified on a microscopic level, so there is a slightly higher risk of wear issues with a worn follower and new cam. Its a bit like putting new piston rings without honing the bores it's not just about visible wear its microscopic detail that you need a profilometer to see. I'm sure plenty of people reuse them without issues but there are many things you can do but it doesn't mean you should. It ultimately comes down to it depending if you want to risk accelerated wear and metal going through the engine or play it safe.

[heinzboehmer]

I'm sure someone knowledgeable will chime in, but, my understanding was something about individual rocker arms wearing specifically to the cam lobes they operate with. If you try and re-use the rocker arm that wore specifically with the old cam lobe with a new one then bad things (accelerated wear, failure) could happen. Or even if you just re-shuffled your worn rocker arms and re-used your same cams it'd also be bad news. But I've read a lot of people who say that you can usually get away without it. I've never taken the time to learn more and understand this better.

the cam and follower bed in together which means the surfaces on both surfaces actually get modified on a microscopic level, so there is a slightly higher risk of wear issues with a worn follower and new cam. Its a bit like putting new piston rings without honing the bores it's not just about visible wear its microscopic detail that you need a profilometer to see. I'm sure plenty of people reuse them without issues but there are many things you can do but it doesn't mean you should. It ultimately comes down to it depending if you want to risk accelerated wear and metal going through the engine or play it safe.

That makes sense. Thanks for the info guys. The price for the followers is very unfortunate though.

Edit: Wait how come this isn't also an issue when installing new rocker arms? If the wear is microscopic and the cams bed into the rockers, then wouldn't there be metal circulating through the engine even with new rockers? If you reuse your rocker arms then wouldn't the new cams exhibit accelerated wear until they match the rockers and then from there on out wear would be minimal?

[Obioban]

I didn’t replace the rocker arms. Assuming wear can be measured by oil analysis or valve change shim change needs, I’ve had no increased wear over the last 40,000 miles (miles I’ve had the cams in).

Vanos is a great time to do them if you’re not doing followers. Adds 1-2 hours to the vanos lockdown (and all the vanos bits have to come off to replace cams).

[BMWahba]

I didn’t replace the rocker arms. Assuming wear can be measured by oil analysis or valve change shim change needs, I’ve had no increased wear over the last 40,000 miles (miles I’ve had the cams in).

Vanos is a great time to do them if you’re not doing followers. Adds 1-2 hours to the vanos lockdown (and all the vanos bits have to come off to replace cams).

That's definitely the route I want to go, saving a $1,200 expense on rockers. My OCD however is trying to convince me otherwise....

[ChipperM3]

I didn’t either when I installed 288/280’s. I’m not one to scrimp on the spending sometimes required to do things correctly, so I struggled with this one. Although the arguments against doing are valid, I felt comfortable doing it based on other members results who didn’t.
I just went in to check on things; cam and follower wear looks fine, but more importantly, valve adjustment after about 8000 km is fine. I made some adjustments, but only to get just that little bit closer to perfect.