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Thread: M50 Thermostat Housing Assembly HELP

  1. #1
    Join Date
    Feb 2005
    Location
    Plymouth UK
    Posts
    21

    Default M50 Thermostat Housing Assembly HELP

    Hi Everyone

    Here is my tale......I very recently bought a 520iSE M50, I noticed that the car was running very cool so I started to investigate. I have discovered that the thermostat appears to be inserted the wrong way i.e. the spring was on the outside of the engine block (this did not seem correct to me), I removed the thermostat but only with the aid of punching a very large screwdriver right throught it, it must have been hammered in!!!

    It appears also that the thermostat housing has a hairline crack in it (its plastic) so that will also need to be replaced, oh and the waterpump has the plastic impeller (its the OEM 1992), thank heaven for Visa cards!

    My problem is this, just exactly which order does this all go back together, I ask this because there is no picture in the manual I have and I have yet to see one that has been assembled correctly, see above!

    I understand that the housing should have a gasket in addition to the rubber ring seals, that seems to be missing too!

    Is this correct, from the engine block going outwards:

    thermostat (spring inwards), thermostat rubber ring, flat housing gasket, thermostat housing (with integral square gasket), four bolts.

    Your help is very much appreciated.

    Triv

  2. #2
    Join Date
    Mar 2004
    Posts
    454

    Default

    Quote Originally Posted by Triv
    Hi Everyone

    Here is my tale......I very recently bought a 520iSE M50, I noticed that the car was running very cool so I started to investigate. I have discovered that the thermostat appears to be inserted the wrong way i.e. the spring was on the outside of the engine block (this did not seem correct to me), I removed the thermostat but only with the aid of punching a very large screwdriver right throught it, it must have been hammered in!!!

    It appears also that the thermostat housing has a hairline crack in it (its plastic) so that will also need to be replaced, oh and the waterpump has the plastic impeller (its the OEM 1992), thank heaven for Visa cards!

    My problem is this, just exactly which order does this all go back together, I ask this because there is no picture in the manual I have and I have yet to see one that has been assembled correctly, see above!

    I understand that the housing should have a gasket in addition to the rubber ring seals, that seems to be missing too!

    Is this correct, from the engine block going outwards:

    thermostat (spring inwards), thermostat rubber ring, flat housing gasket, thermostat housing (with integral square gasket), four bolts.

    Your help is very much appreciated.

    Triv
    This may help
    http://www.realoem.com/bmw/showparts...e53270ec4f1127
    Scott
    1995 BMW 525i w/139K miles, EAT Chip - (Gone)
    07 525i 22K, 07 328xi (41K)
    1982 Mazda RX-7 w/147K miles (Back again!)

  3. #3
    Join Date
    Feb 2005
    Location
    Plymouth UK
    Posts
    21

    Default

    Thanks Scott, that was just what I needed. I was right after all, thanks again!

  4. #4
    Join Date
    Feb 2005
    Location
    Plymouth UK
    Posts
    21

    Default More problems

    I called BMW Plymouth to check availability of thermostat housing gaskets and they tell me that I do not need the paper gasket as well as the square rubber insert!?!? (I already have the circular thermostat gasket)

    Surely I need BOTH gaskets? Any ideas? Should I just buy both?

  5. #5
    Join Date
    May 2004
    Location
    Japan
    Posts
    9,248

    Default

    I checked on a German website and they offer the thermostat plus 1 gasket
    http://213.70.196.72/webdata/ImageDa...ld/79/4236.JPG
    part number of the gasket is BMW 11 53 1 265 084

    Apparently from built year 09/1992 the thermostat was changed from opening 88 degree Celsius to 92 degree Celsius.

  6. #6
    Join Date
    Feb 2005
    Location
    Plymouth UK
    Posts
    21

    Default

    well it appears that the paper gasket was used on 'stat housings up to 04/1992 and the rubber insert was used after 05/1992.
    I have decided to fit both the flat paper gasket and the rubber insert seal as an added precaution even though BMW insist I no longer need the rubber insert, even though it leaks water without it!!!!!!

  7. #7
    Join Date
    Jan 2004
    Posts
    4,150

    Default The fit on the oring seal is designed in such a way that when you

    tighten it down you squeeze the oring just the correct amount. By adding a paper gasket as well you are affecting the amount of squeeze on the oring. I would just use the oring and a light coating of hylomar on the 2 surfaces, a very light coating, that will seal anything that the oring doesn't and the hylomar will squeeze out allowing the surfaces to mate all the way





    Quote Originally Posted by Triv
    well it appears that the paper gasket was used on 'stat housings up to 04/1992 and the rubber insert was used after 05/1992.
    I have decided to fit both the flat paper gasket and the rubber insert seal as an added precaution even though BMW insist I no longer need the rubber insert, even though it leaks water without it!!!!!!


  8. #8
    Join Date
    Feb 2005
    Location
    Plymouth UK
    Posts
    21

    Default

    Bill, I have been thinking about that and I believe you are right. I have looked at the rubber seal and it is sort of 'pointed' suggesting that it spreads out to form a seal on compression against the block. An additional gasket may stop this from happening of course. I have managed to get hold of a metal housing (not readily available in the UK) and looking at it, I just find it hard to believe it will seal all over by just relying on the rubber insert and the thermostat rubber ring. I guess I will just have to try it and see!

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