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FAQ / REFERENCE => M42 Reference => Topic started by: RIPDOTCOM on November 24, 2007, 07:29:56 AM

Title: M42 Vacuum Diagram
Post by: RIPDOTCOM on November 24, 2007, 07:29:56 AM
Picked up a 91 318 2 days ago. Had a bad fuel pump but the previous owner pulled apart the IAC system and any hoses that go to the intake boot as well as the pcv hose. I can tell you where everything goes on an M20 with my eyes closed but this is my first M42. Does anyone have a basic diagram showing how the system is plummed up? If you have a pic send it to ripdotcom@comcast.net or post a link here. Also , if there is anything not required to be hooked up please note it.
Title: M42 Vacuum Diagram
Post by: Wise Old Dog on November 24, 2007, 07:53:25 AM
Do a search. It has been covered many times. I think D Clay posted a good drawing recently.
Title: M42 Vacuum Diagram
Post by: strad on November 24, 2007, 10:56:33 PM
Grossly simplistic, but. . . valve cover breather connects to throttle body, and icv connects to intake air boot -- and there's a whole mess of other things in between!  :)
Title: M42 Vacuum Diagram
Post by: RED IS 91 on November 25, 2007, 07:25:54 AM
From the stolen file...................Hope it helps
good  luck

(http://i141.photobucket.com/albums/r73/bogeyman700/318is-hose-nightmare.jpg)
Title: M42 Vacuum Diagram
Post by: tjts1 on November 27, 2007, 06:28:30 PM
Quote from: RED IS 91;38307

(http://i141.photobucket.com/albums/r73/bogeyman700/318is-hose-nightmare.jpg)

I would love to have 5 minutes of one on one time with an aluminum bat and the person that designed that crap.
Title: M42 Vacuum Diagram
Post by: RED IS 91 on November 27, 2007, 07:29:25 PM
Quote from: tjts1;38453
I would love to have 5 minutes of one on one time with an aluminum bat and the person that designed that crap.


Some people say it's simplistic .:eek:
" I dunno about that"

Once again , gl
Title: M42 Vacuum Diagram
Post by: D. Clay on November 27, 2007, 09:23:42 PM
It's been so long that I forgot where I found that image.
Title: M42 Vacuum Diagram
Post by: strad on November 27, 2007, 11:58:32 PM
Quote from: RED IS 91;38460
Some people say it's simplistic .:eek:
" I dunno about that"

Once again , gl


I didn't mean the system was simple lol.  Just my explanation of it.  

It is actually really simple -- BMW just used about 10 too many parts to put it together lol.
Title: M42 Vacuum Diagram
Post by: tjts1 on November 28, 2007, 10:04:32 AM
Why does the crankcase ventilation or the idle air need to be preheated with coolant? Who the hell thought that was a good idea? I'm surprised they didn't preheat the preheat. On a volvo for example that whole preheat mess is contained in 1 component. In the intake to the airbox there is a trap door that rotates between cold air from the grill (on th left) and hot air from near the exhaust manifold (right). It tries to maintain a minimum 70f intake temp.
(http://farm3.static.flickr.com/2250/2045568968_598dc6f8d5.jpg)
Mind you its not perfect either. After 10 years or so the thermostat always fails on the hot air side so most of the old non turbo volvos you see driving around are actually sucking down 180f intake air through a straw. And people wonder why volvos are slow. But at least it can be fixed with some pliers and ball of aluminum foil.
(http://farm3.static.flickr.com/2274/2044777539_8d9dd44d7d.jpg?v=0)
Title: M42 Vacuum Diagram
Post by: RIPDOTCOM on December 04, 2007, 07:49:33 AM
I did a search after I posted (a little overzealous) anyway, capped the 2 ports and re routed the pcv and IAC. Runs rough but its getting there.
Title: Why the hell does it need to be so complicated! Damn you BMW!
Post by: mkodama on May 11, 2008, 03:56:28 AM
Well, I like to improve/simplify things so here are the thoughts going through my head:

Things that need to connect to the vacuum port behind the throttle:
1. Fuel pressure regulator, to compensate for intake vacuum
2. Idle air control valve, for a faster idle during warm-up
3. Crankcase vent, to create a vacuum in crankcase/burn vapors

So why not do this?  Any thoughts or opinions?
(http://i187.photobucket.com/albums/x115/mkodama/proposedsetupsm.jpg)

as opposed to this mess
(http://i141.photobucket.com/albums/r73/bogeyman700/318is-hose-nightmare.jpg)
Title: M42 Vacuum Diagram
Post by: ClodKing on May 13, 2008, 06:16:03 PM
Yeah my engine is in pieces right now. An answer to this would be great before I put it all back together again...
Title: M42 Vacuum Diagram
Post by: mkodama on May 14, 2008, 02:34:51 AM
Quote from: ClodKing;49253
Yeah my engine is in pieces right now. An answer to this would be great before I put it all back together again...


I wish I had my 318is right now, but unfortunately I won't have easy access to it for the next few months so I can't experiment and give you a straight answer right now.:(

 The concept of everything is pretty simple as shown in my diagram that needed only 3 lines.  BMW just made things more complex by adding additional tubing to preheat various things with the coolant and so on.  In general, the factory setup and routing of vacuum lines is the safest route to follow at this time.

Hopefully in the future I could test the other options and have a clear response.
Title: M42 Vacuum Diagram
Post by: haledj on May 14, 2008, 03:23:11 AM
The idle control valve needs to connect before the throttle, the other two need vacuum.

That's what the barb on the intake tube is for.
Title: M42 Vacuum Diagram
Post by: mkodama on May 15, 2008, 03:16:19 AM
Quote from: haledj;49288
The idle control valve needs to connect before the throttle, the other two need vacuum.

That's what the barb on the intake tube is for.

Ahh, I was initially kinda confused by that statement but understand it now.  The confusion/problem is just from the not so good drawings, so I've decided to redo them.  I appreciate the input, thanks.

RED: Intake Boot to Idle Air Control Input
GREEN: Idle Air Control Output to Throttle Body Vacuum Port
BLUE: Engine Vent to Throttle Body Vacuum Port
YELLOW: Fuel Pressure Regulator to Throttle Body Vacuum Port
(http://i187.photobucket.com/albums/x115/mkodama/proposedsetuprevision1b.jpg)

Any problems or confusions with this setup?

And, which ports specifically on the throttle body have vacuum and which don't(if any)?
Title: M42 Vacuum Diagram
Post by: Cobra Jet on May 16, 2008, 10:01:18 AM
NEW PROPOSED ROUTING BY mkodama:
(http://i187.photobucket.com/albums/x115/mkodama/proposedsetuprevision1b.jpg)

ORIGINAL BMW ROUTING:
(http://i141.photobucket.com/albums/r73/bogeyman700/318is-hose-nightmare.jpg)

Hmmm...  very interesting!  I'm also wondering if this could be another possible "delete" mod and how it would work?

What someone should do too (especially those of you creative w/ CAD or Photoshop) - use the one of the above diagrams and do the common M42 "hose delete" under the intake THEN add in the proposed new vacuum routing, so we can see what it would really look like.  I think some of the hoses and related parts in the original BMW diagram above are already deleted when the M42 hose delete mod is accomplished....


mkodama - just curious, have you attempted it?
Title: M42 Vacuum Diagram
Post by: mkodama on May 16, 2008, 10:09:34 PM
Quote from: Cobra Jet;49501
NEW PROPOSED ROUTING BY mkodama:
http://i187.photobucket.com/albums/x115/mkodama/proposedsetuprevision1b.jpg

ORIGINAL BMW ROUTING:
http://i141.photobucket.com/albums/r73/bogeyman700/318is-hose-nightmare.jpg

Hmmm...  very interesting!  I'm also wondering if this could be another possible "delete" mod and how it would work?

What someone should do too (especially those of you creative w/ CAD or Photoshop) - use the one of the above diagrams and do the common M42 "hose delete" under the intake THEN add in the proposed new vacuum routing, so we can see what it would really look like.  I think some of the hoses and related parts in the original BMW diagram above are already deleted when the M42 hose delete mod is accomplished....


mkodama - just curious, have you attempted it?


I'm confused about what specifically you are suggesting by "adding" the new vacuum routing to the hose delete.  

The picture that I made doesn't utilize the cooling system like the stock setup.  In my version, I erased a few things like that throttle body heater and some of the tubing that would normally attach to the idle control valve.

And just in case you want to see, here is the coolant hose delete that goes along with the vacuum line delete.  It removes the crankcase vent post-heating, and throttle body heater.

stock:
(http://i187.photobucket.com/albums/x115/mkodama/stocksetup.jpg)

my version:
(http://i187.photobucket.com/albums/x115/mkodama/proposesedsetup.jpg)
Title: M42 Vacuum Diagram
Post by: Wise Old Dog on May 17, 2008, 08:12:40 AM
Are you going to cap off the nipples from the head and the plastic outlet pipe? Or run a bypass hose?
Can the vacuum hoses that are still needed, be supported by only one source outlet?
Would the fluctuation caused by the ICV movement cause problems with the FPR vacuum needs. Maybe there is a reason the ICV hose hooks up further upstream than the other 2 hoses.
I don't see what is gained by re-locating the source for these 3 hoses.
Title: M42 Vacuum Diagram
Post by: mkodama on May 17, 2008, 08:30:30 PM
Quote from: Wise Old Dog;49571
Are you going to cap off the nipples from the head and the plastic outlet pipe? Or run a bypass hose?
Can the vacuum hoses that are still needed, be supported by only one source outlet?
Would the fluctuation caused by the ICV movement cause problems with the FPR vacuum needs. Maybe there is a reason the ICV hose hooks up further upstream than the other 2 hoses.
I don't see what is gained by re-locating the source for these 3 hoses.


All very good questions and points.

-The nipples on the head and the plastic pipe can be done either way.  It has been shown that it is not necessary for coolant to flow out of the nipple on the side of the cylinder head so it can simply be capped off.  Alternatively, bypassing from the output on the head to the plastic pipe also works.

-Concerning vacuum fluctuations and which vacuum ports each line should connect to, I simply just don't know how many vacuum connections there are on the throttle body and which are used for each purpose.  If I had my car in hand(or even a good picture), I would be able to draw a much more precise routing.  The fuel pressure regulator should probably be connected to a different source than the other two.

-I was never trying to change the source of the vacuum lines, just the complicated mess between the source and whatever device that needed vacuum.
Title: M42 Vacuum Diagram
Post by: vonkamp on May 18, 2008, 07:48:33 AM
Quote
-The nipples on the head and the plastic pipe can be done either way. It has been shown that it is not necessary for coolant to flow out of the nipple on the side of the cylinder head so it can simply be capped off. Alternatively, bypassing from the output on the head to the plastic pipe also works.


I just did this and was going for the bypass option but changed my mind.
The water outlet at the head (#12 on the drawing) is 3/8 hose (or metric equiv.) and the inlet at the plastic pipe (#20 on drawing) is 5/8 hose. I could not find a quality 3/8 to 5/8 hose barb so I went with the capoff option. been driving every day with no problems.
Title: M42 Vacuum Diagram
Post by: ClodKing on May 19, 2008, 01:34:38 PM
Quote
I just did this and was going for the bypass option but changed my mind.
The water outlet at the head (#12 on the drawing) is 3/8 hose (or metric equiv.) and the inlet at the plastic pipe (#20 on drawing) is 5/8 hose. I could not find a quality 3/8 to 5/8 hose barb so I went with the capoff option. been driving every day with no problems.


This is the point I am at right now in the coolant hose delete mod. I am still trying to figure out which route would best.

Typically our summers aren't too hot. But on occasion we will get a week or two of 40+ degree humid as hell weather...

But just like you said I couldn't find a good fitting to make the splice with. I even went to a hydraulic hose shop and their idea for an adapter would measure out to atleast 4-5" long...

I may just end up capping off the hose barbs.
Title: M42 Vacuum Diagram
Post by: mkodama on May 20, 2008, 01:51:00 AM
Quote from: ClodKing;49693
This is the point I am at right now in the coolant hose delete mod. I am still trying to figure out which route would best.

Typically our summers aren't too hot. But on occasion we will get a week or two of 40+ degree humid as hell weather...

But just like you said I couldn't find a good fitting to make the splice with. I even went to a hydraulic hose shop and their idea for an adapter would measure out to atleast 4-5" long...

I may just end up capping off the hose barbs.


Yeah, if you want, I could find the posts of other people that have capped this nipple off and had no problems and even gave an update a few months later.  

If that is not enough proof for you, a member of bimmerforums.com did a stroker kit on his M42 so he had about 2.1 liters of displacement and 11.6:1 compression ratio.  He also had performance software and I think a higher redline and he never had a single problem either.  I think he just put a bolt in the nipple and welded it or something simple like that.
Title: M42 Vacuum Diagram
Post by: Asserti on May 20, 2008, 08:50:37 AM
I've noticed a while ago... I have no throttle body heater! :|

I'm going to install my cleaned injectors in a few weeks and will check then how it looks under the inlet, will take some pics also, I'm keen to know how it looks, my other M42 does have the throttle body heater.
Title: M42 Vacuum Diagram
Post by: mkodama on May 20, 2008, 04:53:43 PM
Quote from: Asserti;49751
I've noticed a while ago... I have no throttle body heater! :|

I'm going to install my cleaned injectors in a few weeks and will check then how it looks under the inlet, will take some pics also, I'm keen to know how it looks, my other M42 does have the throttle body heater.


Yeah, it was an emissions requirement thing to my knowledge, and also prevented ice forming which could freeze the idle control valve open causing the idle to stay really high.

Just out of curiosity, what year and model is the car without the throttle body heater?
Title: M42 Vacuum Diagram
Post by: Asserti on May 22, 2008, 06:12:09 PM
it's a European (Belgian) 318is from september 1990.

The other Is'es I've seen over here are with throttle body heather. I'm really curious about the routing of the cooling tubes. First I want to know if the car came this way from the factory or it happened on a certain point in it's life
Title: M42 Vacuum Diagram
Post by: mkodama on May 22, 2008, 06:40:50 PM
Yeah, if you look in the BMW ETK, it shows an option for both a non heated and heated throttle body.  I wonder what determines whether the car gets a throttle heather or not.

(http://i187.photobucket.com/albums/x115/mkodama/Picture2-5.png)
Title: M42 Vacuum Diagram
Post by: ClodKing on May 23, 2008, 08:15:54 AM
Yeah I ran a bypass, but I wish I didn't...

It didn't turn out as nice as I planned it to be. The adapter I had to use was too long, and the bends that hoses had to do made them kink. So I am going to cap them off after I get the car safetied, and E-tested. Not because I think a mechanic will freak out if those nipples are capped off, but because I don't want to tear the intake apart again.... hahaha.


Does anyone know of a good place to order pipe caps from??
Title: M42 Vacuum Diagram
Post by: BlackBMWs on July 21, 2009, 10:08:10 AM
Quote from: mkodama;49773
Yeah, it was an emissions requirement thing to my knowledge, and also prevented ice forming which could freeze the idle control valve open causing the idle to stay really high.

Just out of curiosity, what year and model is the car without the throttle body heater?


It appears my 91 M42 does not have the throttle body heater plate, but the cooling hoses still route through the bottom of my throttle body itself.  :cool:
Title: M42 Vacuum Diagram
Post by: blalor on March 04, 2011, 11:41:27 AM
Quote from: RED IS 91;38307
From the stolen file...................Hope it helps
good  luck

(http://i141.photobucket.com/albums/r73/bogeyman700/318is-hose-nightmare.jpg)


Since this image has disappeared (grrrr), here it is from my Flickr account:
(http://farm6.static.flickr.com/5294/5496902419_5315d39e72_o.jpg) (http://www.flickr.com/photos/blalor/5496902419/)
Title: M42 Vacuum Diagram
Post by: benton318i on July 21, 2012, 08:28:27 PM
Quote from: mkodama;49558
I'm confused about what specifically you are suggesting by "adding" the new vacuum routing to the hose delete.  

The picture that I made doesn't utilize the cooling system like the stock setup.  In my version, I erased a few things like that throttle body heater and some of the tubing that would normally attach to the idle control valve.

And just in case you want to see, here is the coolant hose delete that goes along with the vacuum line delete.  It removes the crankcase vent post-heating, and throttle body heater.

stock:
(http://i187.photobucket.com/albums/x115/mkodama/stocksetup.jpg)

my version:
(http://i187.photobucket.com/albums/x115/mkodama/proposesedsetup.jpg)






Can anybody identify #17 in the stock diagram? I have no idea where to get that hose from!
Title: M42 Vacuum Diagram
Post by: Nelson_40 on July 21, 2012, 09:59:52 PM
#17 is 11 15 1 739 266. You can get it at various places online, in many places it will be a URO part. But if you need to replace it I really suggest reading the mess under the intake  thread and deleting a bunch of that junk under the intake.
Title: M42 Vacuum Diagram
Post by: benton318i on July 21, 2012, 10:23:23 PM
:) thanks so much! you just made my day