E34 overheating

[jwe34]

So it's been a while since I actually drove my E34 (work has kept me traveling and busy). Still trying to source out a manual conversion for my car. However, I ran into this while driving the last time I drove it:

1) I drove it for about a week and thennoticed the car starting to over heat... so i pulled over noticed that it was low on coolant. So i got it filled back up. I smelled coolant, but there were no visible leaks anywhere and it seemed to be concentrated around the expansion tank area the most... so I figured pressurization issue, replaced the expansion tank cap and noticed the new cap had a moving valve of sort, the old cap was pretty much as hard as rock in that regards. Moving forward I noticed that the guage looks like this when the car sits at a light: IMG_0086.JPG. Now I am wondering if I have another issue or if this looks normal.I ordered a new radiator thinking the current one maybe plugged up. EVERYTHING else has been replaced in the coolant system sans heatercore, thermostat, hoses, water pump. I have never heard the auxiliary fan kick on either, however will the aux fan cause it to tick over a hair tot he middle mark like this ?

[zubbie]

It's common for the aux fan resistor to fail and prevent the fan from running. I would also check the following before you spend too much money.

1. The small tube between the coolant tank and the rad. Blow air through it to ensure its not clogged.
2. A leak inside the car from the heater core. Sometimes wet carpet.
3. Your car is bled properly.

normally the guage should read just left of straight up, although mine just crosses the line to the right because my temp sensor is off slightly.

[wmrcs]

It's common for the aux fan resistor to fail and prevent the fan from running. I would also check the following before you spend too much money.

1. The small tube between the coolant tank and the rad. Blow air through it to ensure its not clogged.
2. A leak inside the car from the heater core. Sometimes wet carpet.
3. Your car is bled properly.

normally the guage should read just left of straight up, although mine just crosses the line to the right because my temp sensor is off slightly.

Definitely check these, but also try adding some Water Wetter to your system. It might bring it down a few degrees meanwhile so you can track down the real issue.

[FullMonty4x4]

Hello
What is the function of the AUXILIARY THERMOSTAT (#1730682) located in the airbox with 2 coolant hoses connected to it?
I read somewhere that its suppose to regulate coolant flow going to the throttle body to avoid freezing during winter.
Is this the only function of this part?
I ask because i live in a tropical country & i notice that my coolant hose from the cylinder head going to the Auxiliary Thermostat is "bulging".
I'm forced to assume that the Auxiliary thermostat is "closed" most of the time & not allows coolant flow & stresses this hose even more.
With this, (1) should i just bypass (my means of installing a U-shaped Aluminum pipe) the auxiliary thermostat & allow continuous flow of coolant to my throttle body?
(2) Or, by-pass the Aux Thermostat & the Throttle Body so that coolant from/to the cylinder head flows directly to the cooling system (the hose connected to the rear coolant pipe of the throttle body)?

Thank you in advance.

[shogun]

The thermostat valve is for throttle body heating. Depending on the outside air temperature warm/hot coolant is fed thru, to heat up the throttle body valve. http://www.instructables.com/id/Repl...at-in-BMW-E34/
Maybe by-pass with a u-tube is easiest as you do not need it in the Philippines. Whatever is easier to fix.
Here some pics + ideas of elimination on E30 M20 https://www.r3vlimited.com/board/sho...d.php?t=152509

[FullMonty4x4]

Hello again Shogun!
Always good to get good tips from you (since my SLS issue on my non-SLS car), thank you.
Cheers & more power!

[FullMonty4x4]

Definitely check these, but also try adding some Water Wetter to your system. It might bring it down a few degrees meanwhile so you can track down the real issue.

Had a similar issue before with my old radiator & thermostat.
After installing a new Behr radiator, with 2 bottles of BMW coolant (plus distilled water) & an 80 degree thermostat (formerly 88 degrees), temp gauge reads before the half mark.