What’s causing my car to overheat?

[Unregistered]

I just flushed the coolant/antifreeze and now my car is overheating. First, I drained the coolant. Second, I added radiator cleaner with water. Run the engine for 30 minutes and now my engine started to overheat. What’s causing my car to overheat? It was running great before the flush… Could there be a blockage or air in the system? If air in the system, what’s the best method to get the air out?

[JR'Z 525]

Please tell us more. We need to know the year, model etc....
JR

[darron525]

I just flushed the coolant/antifreeze and now my car is overheating. First, I drained the coolant. Second, I added radiator cleaner with water. Run the engine for 30 minutes and now my engine started to overheat. What’s causing my car to overheat? It was running great before the flush… Could there be a blockage or air in the system? If air in the system, what’s the best method to get the air out?
did you bleed your system?? I don't know what year and model ,but on my 93/525i m50 engine there is a bleed screw to left of the radiator cap with a phillips head on it. You have to unscrew it and pour water or fluid in the radiator until it circulates thruogh the engine and comes out of that hole.When you get water commimg out of that hole then you have pushed all of the air out of the block.

check this site for a better reference bmw e34.net (http://www.bmwe34.net/e34main/maintenance/engine/Coolant%20replacement.htm)

Darron

[632 Regal]

here ya go...

http://www.bmwe34.net/e34main/maintenance/engine/Coolant%20replacement.htm

[Unregistered]

Thanks for the info... I tried to bleed the air from coolant but I'm still overheating. I noticed that the down radiator hose is not really hot. Does this mean my thermostat is not opening? Could it be a coincidence that my thermostat decided to go bad as I did my radiator flush? Or if the air still in the system could cause the coolant flow to stop??? Like I said, the down hose to the radiator isn’t hot like the upper hose. Could a radiator cleaner contribute to thermostat failure since I use it before my system started to overheat.

[stevebuk]

Thanks for the info... I tried to bleed the air from coolant but I'm still overheating. I noticed that the down radiator hose is not really hot. Does this mean my thermostat is not opening? Could it be a coincidence that my thermostat decided to go bad as I did my radiator flush? Or if the air still in the system could cause the coolant flow to stop??? Like I said, the down hose to the radiator isn’t hot like the upper hose. Could a radiator cleaner contribute to thermostat failure since I use it before my system started to overheat.

It still could be air in the system. On one of my 525i 12v cars the only effective way to bleed the system was to pour the coolant in through one of the heater hoses. All other methods of bleeding the system on this car failed to get the air out.

[Deke NorCal]

If it is a 535i - Check the small hose that runs from the above the top radiator hose to the coolant recovery bottle at the back of the engine compartment.. that line going in there has to be free of blockage-

Thanks to bmwe34.net for the info, saved me from cooking one for sure

[Jimmy535i]

Check the thermostat and waterpump. I had similar experience with 1994 525i.
If waterpump has plastic impeller it may have broken up and is not pushing water
properly through the system. Or your thermostat is not openning.

[JD525]

I just had mine changed. I had a radiator hose and thermostat replaced, so I was supprised when the car got hot at lights. You can tell if it is bad by running the engine and then turning it off, with the hood open. If the fan spins for a few seconds, then the clutch needs to be changed. If the fan stops when the engine stops, it is good. Check it out.

[Unregistered]

I've had a thermostat stick closed, the engine will get hot but the hoses will then stay cool. If the waterpump is working you should be able to detect flow at medium revs (with the engine cold) by removing the radiator cap and looking down through the radiator filler (depends on which type of rad you have as to whether you can see it though - it's very clear on the rads with the expansion tank on the side, there's a small opening below the filler kneck where there will be a stream of pumped water).