[Big Chaze]

I have 2000 528i. Cooling system was overhauled two months ago and bled properly. All of a sudden, temp needle shot up all the way to the right, but the red light did not illuminate. There was no smoke at all after driving the car for about five minutes and loss most of the coolant through the cap on the expansion tank. There was a total loss of power and lots of rattle/click type noises. Ses came on and Dis and Inpa both revealed oil temp sensor/coolant temp sensor faults/shorts negative ground. Now even when I depressed the clutch there are wierd sounds coming from the clutch area.
Is it possible for both sensors to go bad at the same time? Its sounds unlikely.

 

[e39540iv8]

So how fast would you say the temperature shot up. If I was you I would have stopped immediately but again, how fast did it go up.

 

[doru]

Maybe the double temp switch bit the dust p/n 13621703993 in this diagram?

P.S.: just noticed that you had a almost TOTAL loss of coolant in the expansion tank - you kept the old cap, you didn't change it out with a new one? Something went wrong there. If lucky, you have only toast sensors (temp sensors) which you have to check, including the ones at the OFH - oil pressure sensor & temp sensor

 

[cn90]

Did you have an overheat event prior to the cooling overhaul?
If so, the damage might have been done.
Do compression tests!

 

[Big Chaze]

It turns out my bosch pump that was less than two months old went bad. Plastic impeller was shattered inside the housing. I shouldve went with a metal impeller.
Car wasnt over heating before overhaul....just figured Id do preventive maintenance.

 

[doru]

Thanks for posting back on your finding. Plastic impeller or not, I don't think it's normal to break after only 2 months.
There might be some other issues beside the material the impeller is made of, unless it's made who knows where and it's a fake Bosch unit.

 

[Big Chaze]

I hear you. I cant believe that thing just went. I got the pump from fcp groton... Second time something goes wrong with their parts. Never again.

 

[doru]

I went with the more expensive Stewart high performance one. Skeptikal at the beginning due to the price. I'm a believer now. Keeps the flow running very nicely. We had some 30°C and in stop-and-go traffic, I can see the 96°C flickering when idling for minutes. Usually the temp stays between 92°C-94°C. Was at 98°C steady under the same circumstances with the OEM pump.

 

[bluebee]

cant believe that thing just went./quote]

Is your engine ok?

 

[Big Chaze]

cant believe that thing just went./quote]

Is your engine ok?

I believe the engine is fine, but to be sure im doing a compression test this week. I will post back the results.

What stumps me is that the needle was past the red and there was no smoke coming from the motor whatsoever.

 

[shaftdrive]

the needle was past the red and there was no smoke

It's not an area I know much about but I always figured the "smoke" was steam.

And that the steam was from a leak of liquid coolant vaporizing on the hot engine.

Is there usually steam when there is no leak?

If for example the fan wasn't working, wouldn't the temperature shoot up without steam occurring?

Or if the thermostat were blocked shut, wouldn't that cause the engine to heat up enough to make the needle move to the red zone without generating steam?