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E34 (1989 - 1995)

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  #1  
Old 03-25-2017, 09:07 AM
David Arabiat David Arabiat is offline
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Location: Jordan
 
Join Date: Nov 2011
Posts: 120
Mein Auto: 1988 BMW E34
M50 operating temperature

Hi guys ,
I have this tricky situation and I need some advice ..
My car is an 1988 e34 with an m20b20 --> m50b25tu swap .. the engine runs great .. but I have a tricky situation with the engine temperature .
When I did the swap , I didn't change my instrument cluster , I still have the analog old school cluster of the m20 .. in order for the temperature gauge to work , I used the brown single pin temperature sensor in the engine block ( out of an m20 into the M50 block ) , so logically I thought the temperature gauge would be higher than 12 o'clock since the operating temperature of m20 is 80 c and the m50 is about 90-92 if I'm not mistaking .. and the temperature gauge did show about 1 o'clock ( doesn't reach the 3/4 mark ) . Today I decided to take the car when warm and check it with an OBD .. the good news that I didn't have any faults .. the not so good news is that the engine temperature showed 96 C .. my question is - is that too high for the m50 ? Should I try to use a lower degree thermostat ? ( currently 88C , but I have a spare 79C )
My fan clutch is working .. no coolant leak .. the engine runs fine .. I just don't want to risk overheating it ..
Can you guys share your experience with the operating temperature readings of your engines with the diagnostic tool ?

Thanks for all in advance
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  #2  
Old 03-25-2017, 06:25 PM
sk_latigre sk_latigre is offline
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Location: Long Beach, CA
 
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Mein Auto: '03 X5 Sport / '91 525i
I use an 80c thermostat in my 91 and it's always dead center. I believe the 88c is for the M60, which can fit an M50. Correct me if I'm wrong
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  #3  
Old Yesterday, 03:34 AM
paul1733 paul1733 is offline
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Mein Auto: 2 x 1988 bmw 525i's
Changing your cluster or thermostat will not help because it is electronic & you have an 1988 model. Your problem may very well be the coding plug since your ECU is still being told that it's still a 2.0L.
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  #4  
Old Yesterday, 07:26 AM
David Arabiat David Arabiat is offline
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Mein Auto: 1988 BMW E34
Quote:
Originally Posted by paul1733 View Post
Changing your cluster or thermostat will not help because it is electronic & you have an 1988 model. Your problem may very well be the coding plug since your ECU is still being told that it's still a 2.0L.
Wouldn't the whole cluster show faulty info if the problem was the Coding plug ?
My main concern was the 96 celcius showed on the diagnostic values , and not the fact that my instrument cluster shows perhaps inaccurate readings
I think the OEM thermostats for the m50 were 88 and 92 .. at least in Europe that is .. Switched to a 79 thermostat yesterday since summer is near ..the temp gauge shows between 1/4 and 1/2 .. closer to 1/4 ..That means the actual coolant temp could be around 70 ( if it's is correct to assume that this instrument cluster shows 1/2 for 80 degrees )
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  #5  
Old Yesterday, 10:55 AM
Mr._Graybeard Mr._Graybeard is offline
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Mein Auto: '95 540i, '95 525it
Did the 95 reading come with the engine off after reaching operating temperature? Sometimes heat soak can cause the engine temp to spike after coolant stops circulating.
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  #6  
Old Yesterday, 01:45 PM
David Arabiat David Arabiat is offline
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Mein Auto: 1988 BMW E34
Quote:
Originally Posted by Mr._Graybeard View Post
Did the 95 reading come with the engine off after reaching operating temperature? Sometimes heat soak can cause the engine temp to spike after coolant stops circulating.
The vehicle reached the maximum temperature while idling , then I drove it like a couple of kilometers and parked it without shutting it off , plugged the device in the diagnostic socket , and we checked the live values , namely the current coolant temperature .. so no , I didn't turn the engine off

If the temperature was 96 I wonder why the auxiliary electric fan didn't kick in ?.. I read different opinions about the auxiliary fan activation temperature .. some say 92 celcius .. others say 99 celcius ..
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