98 528i overheating, thermostat?

Last week I was sitting with the engine running and the A/C on. All of a sudden, POP!!! and I saw all this smoke shooting out from under the hood. Holy SSSSS... What happened was the car was overheating and I hadn't noticed the needle was in the RED and the bottleneck connector on the top rear of the Radiator had cracked in half and the hose was shooting all the coolant all over the place. I had the waterpump replaced last summer after having the same symptoms. I can't rule out the waterpump yet, but I'm not gettin any leaks and the fans are both working fine. Starts running very hot when I'm at a stop, or driving down side streets, but when I'm moving fast it's fine. Assuming it's not the WP, could it be the thermostat telling or not telling the engine to circulate the coolant? The thermostat seems like a pretty simple thing to replace.
Also, is there anything I can do to check if it is the WP, or if there might be a clog in the radiator? Does the Thermostat tell the Aux fan to kick in?

Thanks.

Last week I was sitting with the engine running and the A/C on. All of a sudden, POP!!! and I saw all this smoke shooting out from under the hood. Holy SSSSS... What happened was the car was overheating and I hadn't noticed the needle was in the RED and the bottleneck connector on the top rear of the Radiator had cracked in half and the hose was shooting all the coolant all over the place. I had the waterpump replaced last summer after having the same symptoms. I can't rule out the waterpump yet, but I'm not gettin any leaks and the fans are both working fine. Starts running very hot when I'm at a stop, or driving down side streets, but when I'm moving fast it's fine. Assuming it's not the WP, could it be the thermostat telling or not telling the engine to circulate the coolant? The thermostat seems like a pretty simple thing to replace.
Also, is there anything I can do to check if it is the WP, or if there might be a clog in the radiator? Does the Thermostat tell the Aux fan to kick in?

Thanks. I don't know if you read my blog check it out and see if you need any more info. I'm also lost for words. I live in Palmdale California.

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I also live in Palmdale on the west side near 60th and ave N. We should get together and see if we can figure out what's going on. This week I'm replacing all the hoses and temp sensor and flusing the rad. out.

You said smoke came from under the hood? The same exect thing happened to me a wile back. Its was the a/c unit and the smoke came from the belt when it went. The reason its overheated is because of the exrta stress thats put on the engine from the a/c being almost siezed? Thats where my money is. Let me know. Good luck!!!

You said smoke came from under the hood? The same exect thing happened to me a wile back. Its was the a/c unit and the smoke came from the belt when it went. The reason its overheated is because of the exrta stress thats put on the engine from the a/c being almost siezed? Thats where my money is. Let me know. Good luck!!!


Nah, A/C unit is fine. I think it's either the head gasket, or a blockage somewhere. When the car starts to overheat, I can open the bleed screw next to the thermostat housing and then the engine starts to cool down. So something is blocking circulation, or letting air into it. I'm gonna have the coolant tested for traces of oil and go from there.

wile is sitting at idle can you touch the fan and get it to stop. it maybe the fan clutch? also a easy fix. good luck.

wile is sitting at idle can you touch the fan and get it to stop. it maybe the fan clutch? also a easy fix. good luck.

I appreciate the suggestion, but it's common knowledge that you Should be able to stop the clutch fan easily unless the clutch is engaged, which won't happen until the temp starts to climb above operating temp. And being it's 20 degrees outside, that won't help me.

One thing I just noticed today, I was massaging the hose at the top right of the Radiator, and noticed air bubbles coming from the Thermostat Housing cover. Could this be the cause? I'm sure it doesn't help.

sounds like you need a new thermostat! let it overheat and tuch the upper and lower rad hoses, if one feels hotter then the other the thermostat is stuck and need to be replaced

sounds like you need a new thermostat! let it overheat and tuch the upper and lower rad hoses, if one feels hotter then the other the thermostat is stuck and need to be replaced

Would that still mean it's stuck? or could it just be that fluid isn't passing over it due to air blockage?