Help big engine Problem!

[lebsth]

Hey guys this may sound crazy but it is true .
I own a 1992 535I automatic and im having overheating problems .
I took my car to a shop were they shaved my cylinderhead and installed a new gasket kit
I changed so far ,
Radiator
Fan shroud
Fan clutch
Thermostat
Water pump
The Auxiliar fan is working fine and still yet whenever im in a traffic jam my temperature guage reach's 3/4 or even above as soon as the traffic ease off and i start to drive the temp go's back down to slightly above 1/2.
I really have no clue what to do anymore any suggestions are appretiated thx in advanced .

[bmwpower]

You're overlooking 2 big things in the cooling system:

(1) the coolant bypass/return line to the overflow tank - gets clogged and will cause the car to overheat
(2) the heater core - leaky core and/or allow air in the system

Ask me how I know..:)

Got bit by both at one time...

[dennyg]

There are two speeds on the aux fan. Turn on your air cond. and if aux fan does not turn on then your low speed is not working. Could be the resistor. I had some rubber trim form the bumper stop my fan and ruin the resistor. After replacing it everything is fine again.

[Ken35i]

(1) the coolant bypass/return line to the overflow tank - gets clogged and will cause the car to overheat
(2) the heater core - leaky core and/or allow air in the system

This one killed my car :(
The ID of the hose and the ID of the little pipe that the hose fits onto is way too small.
I managed to ream the little hole bigger...bit of a butchers job, but it's about twice as big now.

[Jehu]

Just to make this Interesting. Once upon a time I broke that vent pipe as they call it while trying to do something near it. Of course you can't drive the car like that and while of course I could have rented a car i merely took two bolts i had laying around and plugged each of the two short lead hoses between which that thin plastic pipe is fitted and drove the car for a couple of days in that fashion and had no overheating problem. Got a new part from Euro Depot and put it in. Since there is an overflow hose from the expansion tank i figured pressure builid up wouldn't caue harm though if the volume within the radiator has nowhere to escape and its volume increases when the thermostat is closed perhaps that would be where a problem might arise,no? So Not advisable but it allowed me to drive to get the replacement part. Maybe i just got lucky but it didn't overheat at all.

[Paul in NZ]

yes as i forgot to mention the Aux Is working good in both speeds and anyhow i replaced the resistor for a new 1 .
About the return hose to the tank when we replaced the radiator all that was checked as i emptyed the tank completly and refilled it with new coolant .
so what?....f you filled the radiator seperately it could still be blocked.Are you losing coolant?To check you should wait till the car is cold and check the coolant tank AND the radiator.If the coolant tank is full but the radiator is not you are losing coolant via the cap,or there is another leakie hose or heater core/circuit.(and the overfow tube is blocked)

[Mitch90535im]

Take that small return hose loose from the radiator and blow into it. Should result in bubbles into the return tank. If not, it's clogged. You might blow the clog out. I discovered that was the cause of my overheating after replacing termostant, fan clutch, and was just getting ready to replace water pump. (A $0 fix)

[JD525IA]

Hey guys this may sound crazy but it is true .
I own a 1992 535I automatic and im having overheating problems .
I took my car to a shop were they shaved my cylinderhead and installed a new gasket kit
I changed so far ,
Radiator
Fan shroud
Fan clutch
Thermostat
Water pump
The Auxiliar fan is working fine and still yet whenever im in a traffic jam my temperature guage reach's 3/4 or even above as soon as the traffic ease off and i start to drive the temp go's back down to slightly above 1/2.
I really have no clue what to do anymore any suggestions are appretiated thx in advanced .


It wouldn't be the first time that one crapped out bad or was bad from the beginning. I had the exact same thing happen to me during a hot time of year. At every stop light, the temp would go up near the red mark. It turned out to be the fan clutch.

You can test the viscous clutch by letting the engine warm up, watch it as it spins, shut off the engine and see if it spins freely or locks up immediately (as it should when hot). They can also fail in the locked state, but you will always be putting extra load on the engine from the added air resistance and it should be fairly apparent.

Check it out.

JD

[bad_manners_god]

Get a 740IL fan clutch, thats what I did, runs even better than our stock.

[lebsth]

yes as i forgot to mention the Aux Is working good in both speeds and anyhow i replaced the resistor for a new 1 .
About the return hose to the tank when we replaced the radiator all that was checked as i emptyed the tank completly and refilled it with new coolant .