[MiRhodes]

Hello all,

2008 bmw 335i N54

Background to where we are today. About three weeks ago I was on the highway for about 30 mins and got off an exit. At the exit I got a overheating warning, quickly followed by the red overheating warning. I instantly pulled over and shut the car off. I ran my Libra obd II reader and the car temp was at 250. I let it sit for about five minutes and just tried to start it to see where the temp was at. It was still at 250 but instantly went to 200 with no more warning lights. The car ran perfect after that to get it home after closely monitoring the temp the whole way. I got a rental and had my water pump and thermostat replaced. I got the car back and the same night got the same exact warning. Frustration.... I am still randomly getting these warnings after riding on the highway and the temp spikes to the 240’s until I restart the car. Does anyone know what could be causing this and how it corrects itself after a restart. Also no heat comes out of the vents when it’s overheating but as soon as you restart it the heat comes back. I bought a coolant sensor today to replace just to cross that off the list of things to check.

Thank you

[OP3NAIR]

Did you bleed the system after you replaced the pump? No heat sounds like the system is air locked.

[arkie6]

Was the air purged from the cooling system after the pump was replaced? If not, the system could be air bound causing localized hot spots and/or loss of flow due to air pockets.

[MiRhodes]

Originally Posted by arkie6

Was the air purged from the cooling system after the pump was replaced? If not, the system could be air bound causing localized hot spots and/or loss of flow due to air pockets.

Yes, I ran through the purging process multiple times. It is acting identical to before the replacement and definitely no air in the system.

[IcedBlitz]

Originally Posted by MiRhodes

Yes, I ran through the purging process multiple times. It is acting identical to before the replacement and definitely no air in the system.

Was the coolant topped off after the system was primed? Since the system purges air bubbles out, you will need to add a bit more coolant after priming the system and driving it for a while (about 20 miles).

I would also check to make sure the float inside the reservoir is not stuck on something. Just tap it a few times and you should be good.

[robthewrench]

It sounds like you only checked for codes with a standard OBDII reader. You should check for codes with a BMW specific reader and cable. The OBDII reader won't show you water pump related codes since they are not emission control related.

It also sounds like you have a waterpump electrical fault that is intermittant. This would explain the no heat that is then reset when you restart the car. It is possible the new pump is faulty or you have a power issue at the pump's connector.

[MiRhodes]

Originally Posted by robthewrench

It sounds like you only checked for codes with a standard OBDII reader. You should check for codes with a BMW specific reader and cable. The OBDII reader won't show you water pump related codes since they are not emission control related.

It also sounds like you have a waterpump electrical fault that is intermittant. This would explain the no heat that is then reset when you restart the car. It is possible the new pump is faulty or you have a power issue at the pump's connector.

Thank you for the input. I believe we are going to try to install a new water pump and I will be sure to check the connectors.

While I'm at it, I will replace the coolant temp sensor and oil sensor. I will keep you all posted on if this resolves the issue

[BashShah]

Originally Posted by MiRhodes

Thank you for the input. I believe we are going to try to install a new water pump and I will be sure to check the connectors.

While I'm at it, I will replace the coolant temp sensor and oil sensor. I will keep you all posted on if this resolves the issue

You know if you ran a air purge multiple times, then you would have heard the Water Pump working.
so replacing the water pump may not do anything.
BUT your TSTAT does not have a electrcial connection, and that might be the fault even if it is new.

I had an issue where my Brand new Tstat was stuck in closed state.
also when you sat 240 and 250 temp..... I am asuming you have a USA car, and it is measured in F and not C temps.
and is this Oil Temp.

if it is Oil temp then 240 and 250 for N54 is very normal.

[MiRhodes]

Originally Posted by BashShah

You know if you ran a air purge multiple times, then you would have heard the Water Pump working.
so replacing the water pump may not do anything.
BUT your TSTAT does not have a electrcial connection, and that might be the fault even if it is new.

I had an issue where my Brand new Tstat was stuck in closed state.
also when you sat 240 and 250 temp..... I am asuming you have a USA car, and it is measured in F and not C temps.
and is this Oil Temp.

if it is Oil temp then 240 and 250 for N54 is very normal.

Thank you for the guidance. I actually have a dash command app and run the jb4 with coolant on the oil temp. Just so I can keep an eye on it. When it is acting up the coolant usually tops out at 250 until I shut it off and back on. Then right back to 190-200 it goes.

[mojobmw_e90]

If u think u have a big air pocket in your system even after bleeding it a few times, blow inside the coolant tank, this will force coolant into the system and you will hear it move

[BashShah]

Originally Posted by MiRhodes

Thank you for the guidance. I actually have a dash command app and run the jb4 with coolant on the oil temp. Just so I can keep an eye on it. When it is acting up the coolant usually tops out at 250 until I shut it off and back on. Then right back to 190-200 it goes.

Now that is cool to have.
i still say, try a new Tstat, make sure it is a different brand than the one you currently have.
you didn't say whether you heard the WP work during a purge?

Option 2, You might just have a serious block in 1 of the coolant lines.

what are the chances that Oil and Coolant are mixing? like OFHG might do it.

[mweisdorfer]

You know if you ran a air purge multiple times, then you would have heard the Water Pump working.
so replacing the water pump may not do anything.
BUT your TSTAT does not have a electrcial connection, and that might be the fault even if it is new. - Bash

Nice point. One should almost always replace the thermostat and U shaped hose that connects both when the water pump goes.

The water pump could have been faulty upon delivery, but it's not likely.

Topping off the coolant reservoir, after a purge or two and then re-purging it one last time after topping it off is always a smart move.

[kaw900r]

Just replaced water pump and new thermostat but when I try to purge I never see any water being pushed back into the reservoir. Do I need to have the front end a little higher or any little tricks to get it to flow? Unless I purchased a faulty pump...

Went out and still nothing started it up and turned heat on and never got warm or anything on highest temp and blower setting...

[mojobmw_e90]

Originally Posted by kaw900r

Just replaced water pump and new thermostat but when I try to purge I never see any water being pushed back into the reservoir. Do I need to have the front end a little higher or any little tricks to get it to flow? Unless I purchased a faulty pump...

Went out and still nothing started it up and turned heat on and never got warm or anything on highest temp and blower setting...

U need to bleed the system. Bmw is a self bled system. Fan on low speed, temp set to high, floor gas pedal and hold for 10sec, should hear the pump kick on. Runs for 12mins. Make sure you do not close the drivers door during this process as it will stop the bleeding procedure

[david in germany]

Originally Posted by mojobmw_e90

U need to bleed the system. Bmw is a self bled system. Fan on low speed, temp set to high, floor gas pedal and hold for 10sec, should hear the pump kick on. Runs for 12mins. Make sure you do not close the drivers door during this process as it will stop the bleeding procedure

And don't start the car! All the above but key on and engine off.

[kaw900r]

OK I will try again because I'm pretty sure I closed the door. No where have I heard or read about that but definitely will try it. If not heading to store for new lifetime warranty. T/u both

[kaw900r]

Held pedal to the floor for 20sec just to be safe and still nothing is happening but giving it a few minutes to at least try to shoot some water

[kaw900r]

Must be a bad pump, also changed the fuse under hood passenger side to be safe still not purging. Lesson learned on deals going to O'reilly's lifetime warranty $326...

[rsyed07]

FCP's lifetime warranty for water pump and T-stat if you plan on keeping the car long. No hassle lifetime warranty on OEM parts.

[kaw900r]

Got it for 310 + tax and went with a new t-stat also even though I had purchased them online earlier this year but price to good to be true I guess. It's all back together getting ready for the adding of fluid and purge. Didn't take long at all the 2nd time around...

[kaw900r]

Originally Posted by kaw900r

Got it for 310 + tax and went with a new t-stat also even though I had purchased them online earlier this year but price to good to be true I guess. It's all back together getting ready for the adding of fluid and purge. Didn't take long at all the 2nd time around...

It's fixed...

[kaw900r]

Well no it wasn't finally went 4 a drive and it over heated. Backed it in so front would be a little higher and let it run. Ran for a while temp went yellow and off. Turned car off and it sounded like the water pump ran for a few minutes since I never heard it before. I do have heat now and will check/dtive when I get back home...