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E21 (1975 - 1983)

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Old 05-23-2011, 06:19 PM
agent4573 agent4573 is offline
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Location: California
Join Date: May 2011
Posts: 1
Mein Auto: '82 320i
Overheating, can you tell me why?

I just bought an 82 320i with 132k miles on it. Changed the oil and radiator fluid when I got it home. Its about 65 outside, and when I go about 65 the temp gauge creeps up close to the red. When I'm around town or idling, it sits right in the middle of the gauge. The manual says the temp may creep up under high load, but I was wondering if this was normal or if there was a way to keep the temp down? I live in the Mojave desert so the car has to deal with 120 degree days this summer with the A/C on. Right now its having a hard time making the 30 minute drive to work and its not even close to hot outside.
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Old 01-25-2012, 07:24 AM
MPG320I MPG320I is offline
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Location: Mexico City
Join Date: Jan 2012
Posts: 3
Mein Auto: BMW 320I 1981

I has the same problem.
First I changed the water pump, then I changed the Thermostate but the problem is the auxiliary fan. You have to check that this fan is working. It is ver easy to start it.

Good look,

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Old 06-24-2012, 07:06 PM
galaxyflier galaxyflier is offline
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Location: Saratoga Springs, NY
Join Date: Apr 2010
Posts: 35
Mein Auto: 1981 320i (E21)
MPG320I is absolutely correct! The auxiliary fan is essential. It not only comes on when the AC is operating, but it's also controlled by a temp sensor in the bottom of the radiator. If the radiator is not cooling the coolant sufficiently, the aux fan will come on and push more air through the radiator, especially at low road speed. I've driven my '81 across the Mojave and AZ during summer and the temp gauge never got above three-quarters of the way to the red with the aux fan running continuously. Some other things to check are the condition of the radiator and the water pump. A previous owner could have used Stop-Leak in the radiator to cure a small leak and clogged up the radiator core. If the water pump has a metallic impeller, it could be corroding away. I had that happen on a Ford F-100 with a 360 V-8. The impeller was corroded to the point where there wasn't enough left of the impeller blades to move the coolant fast enough to maintain proper cooling.

You don't have to overheat the M-10 engine very many times to warp the head and blow the head gasket. So, if I were in your position with a car with an unknown history living in a desert climate, here's what I would do: Remove the radiator, take it to a radiator specialist and have it checked out. Get it re-cored if necessary. Pull the water pump and take a look at the impeller and the bearing seals. If any thing looks questionable, replace the pump. Ditto for the thermostat. If the hoses look old, replace them too. Also, take a look at the plastic shutoff valve for the heater. It's located near the firewall next to and below the brake booster. Replace if evidence of leakage is present.

If the car has the stock AC system, don't get your hopes up about being cool during a Mojave summer. The AC system that was installed in the E21 worked okay as long as it didn't get too hot outside. The one on my '81 was worthless at ambient temperatures above 90F. I finally took it out when it failed for the umpteenth time.

Hope this is helpful.
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Old 09-15-2012, 03:24 PM
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BMWFatherFigure BMWFatherFigure is offline
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Location: Perth, Western Australia
Join Date: Aug 2012
Posts: 4,116
Mein Auto: E23;E32;E34;E38;R50;R55
If a PO used high phosphate coolant it will chemicaly damage an alloy radiator byond repair - new core. Does it have a fan clutch? If so change it. +1 on the other suggestions.
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E21 318i; E23 735i; E30 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i
I've just changed my wiper blades and now my reverse lights don't work. Should I change my fuel pump relay?
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Old 10-03-2012, 07:50 PM
lucienkidd lucienkidd is offline
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Location: Reno, Nevada
Join Date: Oct 2011
Posts: 1
Mein Auto: 1980 BMW 320i
First, clean the electrical terminations on the ribon cables for the main console to get a more consistent reading from the sensor. The heater control valve on my 320i was allowing water to flow through the radiator all the time. I replaced it.
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Old 01-04-2013, 09:56 AM
GeorgeBush234 GeorgeBush234 is offline
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Mein Auto: Passat
You re a funny dude lucienkidd
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