Results 1 to 11 of 11

Thread: Z3 Radiator Installation - Expansion Tank Questions

  1. #1
    Join Date
    Oct 2017
    Location
    Colorado
    Posts
    91
    My Cars
    1995 BMW 318TI I6 Swap

    Z3 Radiator Installation - Expansion Tank Questions

    Hello All,

    Feeling pretty silly here. I have a 318ti that has an M50 swap, and I have been running the OEM 4cyl radiator with the M50. The OEM 4cyl radiator recently started leaking and after a bit of reading around, I decided to purchase the Z3 radiator as most see that as an upgrade.

    Since the 4cyl has an expansion tank integrated into the radiator, I know I need to purchase an expansion tank to use with the Z3 radiator. The problem I'm having is trying to grasp why so many people have such a hard time bleeding their E36 expansion tanks. The Z3 radiator has the two main openings for inlet and outlet, and one small one for what I assume is the expansion tank. Is it not as simple as connecting any expansion tank to that line with an appropriately rated (2 bar?) cap, and placing the opening above the port on the radiator?

    What am I missing?

  2. #2
    Join Date
    Jun 2010
    Location
    NY
    Posts
    9,079
    My Cars
    1997 328i
    A lot of us have lowered cars and the expansion tank in the front is often a few inches below the heater core back end of the car so an air pocket can form.

    Most of us don't use Z3 radiators, there are upgraded all aluminum radiators that a lot of us use, some have bumped out sides for a bit more capacity. Plumbing it should be straight forward.
    Attn. NEWBIES: Use the search feature, 98% has already been discussed.
    Click the search button, select "search single content type", select the "e36 sub forum" specifically, try the "search titles" then try the "search entire posts".

  3. #3
    Join Date
    Oct 2017
    Location
    Colorado
    Posts
    91
    My Cars
    1995 BMW 318TI I6 Swap
    Thanks for the input, seems simple enough.

  4. #4
    Join Date
    Jun 2005
    Location
    New England
    Posts
    25,402
    My Cars
    F90 M5; E36 M3 Turbo
    Even a stock radiator in a 6 cylinder E36 is hard to bleed due to the mounting of the expansion tank on the radiator. It’s not the high point in the cooling system. This does not change with the Z3 S54 radiator, which is a very good radiator at a good price in recent years.

    A few of us have changed to the Euro M3 high mount self bleeding expansion tank. It’s basically an E30 tank with a new hard pipe, and mounts in the passenger rear corner of the engine bay.
    Last edited by pbonsalb; 12-16-2018 at 06:29 AM.

  5. #5
    Join Date
    Oct 2017
    Location
    Colorado
    Posts
    91
    My Cars
    1995 BMW 318TI I6 Swap
    What makes it self bleeding, just the fact that it's higher than the heater core? I'm headed to the junkyard tomorrow to see what kind of expansion tanks are available. My '95 TI does not have SAI, but it does have a battery in that location, so I'll have to find somewhere else to mount it.

  6. #6
    Join Date
    Jun 2005
    Location
    New England
    Posts
    25,402
    My Cars
    F90 M5; E36 M3 Turbo
    Yes, highest point in cooling system means the air goes there and can get out. You could try the front side of a shock tower for mounting a tank . There is a Euro M3 washer reservoir that goes in the bumper cover if you need to move your reservoir to make space for the tank. The place where your battery is located might be the highest spot under the hood that could fit an expansion tank. 6 cylinder E36 have the battery in passenger rear wheel well but that space might not exist in a ti so maybe you can’t move the battery.
    Last edited by pbonsalb; 12-17-2018 at 07:41 AM.

  7. #7
    Join Date
    Mar 2013
    Location
    THE DIRTY THIRD
    Posts
    263
    My Cars
    '95 M3
    Just get one of these, it’s pretty foolproof.

    https://www.summitracing.com/parts/otc-75260
    Last edited by SyCK; 12-16-2018 at 10:40 PM.
    Turbo E36 M3 with all the things..

  8. #8
    Join Date
    Oct 2017
    Location
    Colorado
    Posts
    91
    My Cars
    1995 BMW 318TI I6 Swap
    I apologize for my stubbornness on this, but I'm still not getting it.

    Every OEM coolant tank has 2 openings on the bottom (one for the sensor and one for the hose), but the realoem diagrams do not show the hose connection on the bottom. Where is it supposed to go? I was at the junkyard yesterday and the e36 there had the expansion tank with the two openings on the bottom, but there is only the one overflow nipple on the radiator, and nothing was connected to the bottom opening of the expansion tank. RealOEM also shows the expansion tank on the driver's side of the car for the US version, which I don't think is correct.

    e36:


    For the Z3 you can see that the expansion tank appears to have the same large diameter opening on the bottom, but nothing is connected to it. Is the z3 rad really just filled by the nipple with the 1/8" opening on that nipple?:
    Last edited by nnamssorxela; 12-17-2018 at 10:27 AM.

  9. #9
    Join Date
    Jun 2005
    Location
    New England
    Posts
    25,402
    My Cars
    F90 M5; E36 M3 Turbo
    Bottom of tank medium size hose goes to cooling system hard pipe that runs along the intake side of the block. Small hose on top of tank goes to vent on top of inlet side of radiator. This is true of Z3 and E36 6 cylinder cars. I have run stock and Z3 S54 radiators and stock and Euro M3 tanks.

  10. #10
    Join Date
    Oct 2017
    Location
    Colorado
    Posts
    91
    My Cars
    1995 BMW 318TI I6 Swap
    Thanks, I just found the diagram that shows that, and it all makes sense now. I guess I'm blind because I do not see anything coming off of the 4cyl radiator that is currently installed, but I'll poke around when I get home. Is there any reason why the small line goes to the top and not the bottom of the expansion tank? I'm planning on having my tank with both openings on the bottom, and I can't imagine it makes a difference.

  11. #11
    Join Date
    Jun 2005
    Location
    New England
    Posts
    25,402
    My Cars
    F90 M5; E36 M3 Turbo
    I don’t know the answer but assume the vent line is on top to avoid putting air into the coolant since air bubbles reduce cooling system efficiency and can create hot pockets that could lead to detonation.

Similar Threads

  1. radiator expansion tank question
    By pment in forum 1991 - 1999 (E36)
    Replies: 19
    Last Post: 12-20-2014, 08:31 PM
  2. LSx swapped e46 radiator/expansion tank questions
    By greenmonster138 in forum Engine Conversions
    Replies: 5
    Last Post: 08-30-2011, 11:20 PM
  3. M3 Radiator/expansion tank question
    By Chuck6902 in forum 1992 - 1999 M3 (E36)
    Replies: 5
    Last Post: 07-11-2008, 03:04 PM
  4. Coolent expansion tank question Please Help!
    By stuttgart in forum 1992 - 1999 M3 (E36)
    Replies: 6
    Last Post: 06-24-2004, 03:03 AM
  5. radiator and expansion tank replacement
    By sealbeach740 in forum 1995 - 2001 (E38)
    Replies: 4
    Last Post: 04-22-2003, 08:27 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •