Cleaning Individual Throttle Butterflies

[Shock(/\)ave]

Does anyone have any information on the procedure one must undertake to clean our individual throttle butterflies?

The original owner of my car suggested they be cleaned regularly as part of the preventative maintenance schedule and I have no idea how to go about doing so. All of the various manuals available are obviously of no use in this regard, and I'm not about to touch this engine myself without knowing exactly what I'm doing.

This is something everyone with our particular breed of engine needs to know how to do correctly as the butterflies must be kept clean to maintain proper throttle response.

Thanks in advance! :buttrock

[Gizmo330iT]

Remove the ram tubes and plenum chamber and clean with carb cleaner.

[ModenaM3]

You should probably post more about your car, Gizmo318i !

[Gizmo330iT]

You should probably post more about your car, Gizmo318i !Do a search on my name, theres plenty already. :)

[JamesM3M5]

Don't see the need to clean them. The only oil they get is from either an excessively oily filter or the PCV. I prefer paper since they filter much better than any aftermarket (yes, even sticky oiled foam ones) filters.

[GazM3]

if u track the car or drive it hard u can get oil film in there. Aligning the throttle boides together is probably a good idea if u have the trumpets removed also.

[M3 Euro LTW]

Our S50B30 and S50B32 engines are incredible, high performance engines that share many characteristics with all out race engines, and by law also have to comply with many regulations regarding clean air emissions.

There are a multitude of reasons you can get oily film on the intakes in our stock configuration engines.

James mentions one. Surely if you change to an oiled intake filter, you run the risk of bringing that oil onto the throttle bodies.

In my experience, the primary source for oil in the intake plenum/boot is from another source.

The cylinder head in each of our motors vents to a small oil-vapor separator on the LH side of our engine blocks. The cylinder head often has postive pressure driving the oily vapor out past the separator where the "filtered" air is then forced into the intake plenum, and ingested through the throttle bodies.

This takes place behind the air filter, so it is basically "raw" oily air going in. There is a drain in the bottom of the intake plenum to prevent TOO much from collecting in there, but the very fact that the drain is there means that the engineers knew that at prolonged high speed rpm, or possibly even banked driving occasions, that a significant amount of oil and oil vapor may collect in the cylinder head, and make its way past the oil-vapor separator into the intake plenum.

As you can imagine, this is good for the environment, not so good for your plugs or performance. Racers typically vent the cylinder head to a separate oil-vapor separator, and (if they're smart**) drain this to the oilpan so that they don't risk it filling up.

An unlikely secondary source is oil coming up from the drain into the plenum, but I rather doubt this is the source. It would take a lot of frothing and blowby in the engine and oilpan to push that mess up into the plenum.

On the S50B30 there are two locations to place better oil restrictors into the cylinder head to help cut down on this problem, one is externally accessible, and I believe that Korman easily supplies this part on request. The second, like the S50B32 needs to be put into place with the cylinder head off. This modification is really not necessary on a street car. (IMHO)

Dry sump systems can do a lot to decrease vapor and oil in the top (and bottom) of the engine, but that is a rather drastic way to fix this problem.

I will try to post a photo of how I resolved this on my website, ABLOriginalParts.com for people to reference.

Many aftermarket companies have these devices, and its not a particularly hard item to put into place. One would delete the factory separator, route the hose off the head to your own device, and then (IMHO**) route the drain from the device back to where the factory oil vapor separator drained into the oil pan.

In my case, I deleted the oil separators entry point to the plenum and deleted the drain from my plenum. I used the factory drain 'nub in my oilpan to accept the drainage from my separator.

Good luck!

** as a funny aside, my first installation of this system was along with a home-brew drysump. With the small K&N filter off my separator, and a small piece of paper sitting on top of the opening, I was able to demonstrate that at only 100 rpm over idle, I had true vacuum in the cylinderhead, and no more positive pressure! Accordingly, I didn't drain the container, I left the stop-cock on the bottom. But.... I did leave it open by accident.

First time out, at close to 150 mph down the front straight at Road America, that prolonged full throttle acceleration down the front straight put enough oil into the container and down and out onto my front and rear right tires that the ABS went nuts in the brake zone, and I was lucky to keep the car straight into the kitty-litter. It took me a while to figure out where all the oil was from! It has a drain now.

Experience: Another name for the School of Hard Knocks.

Alex Lipowich

[liquidtension]

good info! :thumbsup:

[Shock(/\)ave]

Our S50B30 and S50B32 engines are incredible, high performance engines that share many characteristics with all out race engines, and by law also have to comply with many regulations regarding clean air emissions.

There are a multitude of reasons you can get oily film on the intakes in our stock configuration engines.

James mentions one. Surely if you change to an oiled intake filter, you run the risk of bringing that oil onto the throttle bodies.

In my experience, the primary source for oil in the intake plenum/boot is from another source.

The cylinder head in each of our motors vents to a small oil-vapor separator on the LH side of our engine blocks. The cylinder head often has postive pressure driving the oily vapor out past the separator where the "filtered" air is then forced into the intake plenum, and ingested through the throttle bodies.

This takes place behind the air filter, so it is basically "raw" oily air going in. There is a drain in the bottom of the intake plenum to prevent TOO much from collecting in there, but the very fact that the drain is there means that the engineers knew that at prolonged high speed rpm, or possibly even banked driving occasions, that a significant amount of oil and oil vapor may collect in the cylinder head, and make its way past the oil-vapor separator into the intake plenum.

As you can imagine, this is good for the environment, not so good for your plugs or performance. Racers typically vent the cylinder head to a separate oil-vapor separator, and (if they're smart**) drain this to the oilpan so that they don't risk it filling up.

An unlikely secondary source is oil coming up from the drain into the plenum, but I rather doubt this is the source. It would take a lot of frothing and blowby in the engine and oilpan to push that mess up into the plenum.

On the S50B30 there are two locations to place better oil restrictors into the cylinder head to help cut down on this problem, one is externally accessible, and I believe that Korman easily supplies this part on request. The second, like the S50B32 needs to be put into place with the cylinder head off. This modification is really not necessary on a street car. (IMHO)

Dry sump systems can do a lot to decrease vapor and oil in the top (and bottom) of the engine, but that is a rather drastic way to fix this problem.

I will try to post a photo of how I resolved this on my website, ABLOriginalParts.com for people to reference.

Many aftermarket companies have these devices, and its not a particularly hard item to put into place. One would delete the factory separator, route the hose off the head to your own device, and then (IMHO**) route the drain from the device back to where the factory oil vapor separator drained into the oil pan.

In my case, I deleted the oil separators entry point to the plenum and deleted the drain from my plenum. I used the factory drain 'nub in my oilpan to accept the drainage from my separator.

Good luck!

** as a funny aside, my first installation of this system was along with a home-brew drysump. With the small K&N filter off my separator, and a small piece of paper sitting on top of the opening, I was able to demonstrate that at only 100 rpm over idle, I had true vacuum in the cylinderhead, and no more positive pressure! Accordingly, I didn't drain the container, I left the stop-cock on the bottom. But.... I did leave it open by accident.

First time out, at close to 150 mph down the front straight at Road America, that prolonged full throttle acceleration down the front straight put enough oil into the container and down and out onto my front and rear right tires that the ABS went nuts in the brake zone, and I was lucky to keep the car straight into the kitty-litter. It took me a while to figure out where all the oil was from! It has a drain now.

Experience: Another name for the School of Hard Knocks.

Alex Lipowich

I'd like to give you a much deserved (and belated) thank you for this most excellent post Alex. Your contributions to this forum are greatly appreciated. :buttrock

[tynashracing]

Alex, pics would definitely be appreciated. I've been wondering what to do about this!

[M3 Euro LTW]

Ken,

I finally have my garage more set up for working on the car, and, my fiancee's camera works well to take images, and post them.

I'll try to update the website tonight, and put some photo's of this set up on the website for everyone.

(hint, I get home from work around 830 pm, if you want, give me a buzz around 9:30, and I'll try to post up!)

I would also like to post a photo or two of the new front bumper assembly, and how I handled the brake ducts... I'm proud of how it turned out, and anyone could duplicate it pretty easily.

Thanks by the way for the props on my long post. What is so strange about this whole problem is that I did a ton of reading, asking around, and talking to people about the issue, and it was another racer who finally explained to me what the external venting was all about, and how it worked. The community can help out so much. Got a good head start on this from somone in the S14 crowd actually back when I was struggling to solve the problem.

I've long had a tendancy to want to preserve the general engineering that BMW put into my car. This was a case where the goals of the engineering were NOT performance, but rather environmental. For a race or heavy duty track set up, it is FAR from optimal in factory form. My first attempt at fixing it was to preserve the idea of venting into the plenum (The Germans must know what they're doing!) by putting in a SECOND industrial oil-vapor separator (designed for pneumatic tools) in a series with the factory one. I hid it under the TB assembly, and its drain "T"ed into the drain from the factory one, and then down into the pan. Even with two of these in a series, I was getting oil vapor into the plenum. The factory swirl separator only works when there is vacuum inside the plenum, it is terrible otherwise and with postive pressure in the cylinder head, oil vapor is blown right into the plenum past the factory oil/vapor separator. I would not risk a one way valve in there to avoid it, or you're going to blow gaskets in the top.

Alex.