LPT: How to get home on a dying water pump

[Matticus91]

Had several people ask me about this so figured I'd list out what I did.

Please understand that this will only work if you have a FAILING, and not totally dead, water pump. If it's not moving coolant at all, you're SOL and it's time to call for a tow.

NOTE: This is for worst case scenarios only - if you have any other option, you should avoid driving the car. Use of this method is entirely your own decision and I take no responsibility for any damages that may be caused as a result.

If the pump is moving coolant but at a slower or intermittent rate, here's how you can get back home. You'll need a JB4 or other device that can monitor temps for this. If your car ever gives you the RED warning light, stop driving and call a tow. Same goes if you see steam from the engine at any point.

• Step 1: Ensure the pump is working at least a little bit. Run the heat on full blast and see if it's hot, if not and the car is warm, your pump is totally dead.
• Step 2: Set up your JB4 or other diag tool to measure water temp. Oil temp is not a good indicator for engine temp in this situation since coolant temps change much more than oil. I set my JB4 to have the water temp on my fuel gauge. Normal water temps for an N54/N55 are between 200-215. If your tuner/diag tool has the option, set your radiator fans to max as well, you can do this with the MAXCOOL mode on a JB4.
• Step 3: Let the car cool as much as possible before starting it again. Take your time, in this case your options are either to have patience or call a tow truck. Don't risk your engine!
• Step 4: Turn the heat on full blast (highest temp and fan speed). Point it somewhere that you can feel it 100% of the time. You'll use this as a temp gauge as well. If the air starts to get cool, coast to the shoulder and turn off the car immediately since this is an indication that coolant has stopped flowing.
• Step 5: Get moving and drive as moderately as possible. If you're in stop & go, try to keep it steady or turn the car off while sitting.
• Step 6: Watch your temp gauge, feel the air, and look for signs of the temp increasing (movement in gauge) or the pump stopping (hot air gets cool). Keep at it and pull over if needed.

I was able to go about 120 miles doing this and never hit the red for engine temp. I would stop and let the car cool any time it seemed to get above 215F, or if the air became cool. For some reason, restarting the car seemed to get the pump going again. BMW techs said everything was fine and no damage was done on the drive, my t-stat was even in fine working condition.

[Dackelone]

I think I would just have the car towed. Its very easy to over heat a BMW engine when the water pump's flow is reduced or worse nil. I do understand why you made this thread. I think its rather foolish to not pay a tow bill vs paying for a new engine or cylinder head. These new engines run very hot WITH a functioning water pump. I just would not take the chance on damaging the engine.

Dack

[Matticus91]

Originally Posted by Dackelone

I think I would just have the car towed. Its very easy to over heat a BMW engine when the water pump's flow is reduced or worse nil. I do understand why you made this thread. I think its rather foolish to not pay a tow bill vs paying for a new engine or cylinder head. These new engines run very hot WITH a functioning water pump. I just would not take the chance on damaging the engine.

Dack

Completely agree Dack but when it's Christmas, I have family + Dog in the car, and all my tow options (AAA, AT&T Roadside, Warranty Roadside) estimate 4hrs for a truck, I'll do what I need to!

[Esteban]

Thanks for taking the effort to make this thread Matt. If something like this happens to me, which probably will somewhere down the road, I think I'd just have it towed. Don't have a JB4 and don't have your patience. Glad it worked out for you, though.

[sometorque]

Probably wouldn't risk it myself, but I did want to add one thing to this:

The "hidden menu" feature on these cars allows for monitoring coolant temps. If you access the hidden menu option to monitor the coolant temp (i believe this is option 07.00 when scrolling through the hidden menu) while the car is in the "accessory on" position and then start up the car, the center cluster display will stay monitoring this metric until the next time you shut the car off. I used this feature a few times to check coolant and electrical voltage a while back and it was pretty helpful. TL:.DR - you can watch coolant temps without the JB4 using the hidden menu

Here's a bit more on the hidden menu feature - http://e90.wikifoundry.com/page/BC+hidden+menus

[Matticus91]

Originally Posted by Esteban

Thanks for taking the effort to make this thread Matt. If something like this happens to me, which probably will somewhere down the road, I think I'd just have it towed. Don't have a JB4 and don't have your patience. Glad it worked out for you, though.

Highly recommend just towing if possible!

Originally Posted by sometorque

Probably wouldn't risk it myself, but I did want to add one thing to this:

The "hidden menu" feature on these cars allows for monitoring coolant temps. If you access the hidden menu option to monitor the coolant temp (i believe this is option 07.00 when scrolling through the hidden menu) while the car is in the "accessory on" position and then start up the car, the center cluster display will stay monitoring this metric until the next time you shut the car off. I used this feature a few times to check coolant and electrical voltage a while back and it was pretty helpful. TL:.DR - you can watch coolant temps without the JB4 using the hidden menu

Here's a bit more on the hidden menu feature - http://e90.wikifoundry.com/page/BC+hidden+menus

Awesome trick, I'll have to mess with that some more

[KNS]

Not too different to when cars actually had water temp gauges that were somewhat accurate and believable.

Back in the early '90s I had a similar experience with an old Honda. I was over heating (bad thermostat) in Tucson and had to get back to Phoenix. In that car the temp gauge was more than just an idiot light and would actually fluctuate up and down to some degree.

I turned on the heater to max blast and roasted on my way home but the car did fine. Drove it for another five years.

[Matticus91]

Originally Posted by KNS

Not too different to when cars actually had water temp gauges that were somewhat accurate and believable.

Back in the early '90s I had a similar experience with an old Honda. I was over heating (bad thermostat) in Tucson and had to get back to Phoenix. In that car the temp gauge was more than just an idiot light and would actually fluctuate up and down to some degree.

I turned on the heater to max blast and roasted on my way home but the car did fine. Drove it for another five years.

The light itself fluctuated?? That's bizarre. I wonder how they managed that, mechanically, thermal switch maybe?

[KNS]

^^ Ah - what I meant to say was that the water temp gauge was more than just a simple idiot light like you have today or cars that have a gauge and the needle never moves at all.

In that old Honda the water temp needle would actually move up or down a bit beyond just dead center in the middle. You could tell far in advance your engine was getting warm.

[XAMI]

I limp moded' home from a mile or two away on small streets....

[Matticus91]

Originally Posted by KNS

^^ Ah - what I meant to say was that the water temp gauge was more than just a simple idiot light like you have today or cars that have a gauge and the needle never moves at all.

In that old Honda the water temp needle would actually move up or down a bit beyond just dead center in the middle. You could tell far in advance your engine was getting warm.

Got it haha. Yeah that's why the JB4 was so useful here, otherwise I'd have nothing unless I had known about the hidden dash menus!

Originally Posted by IAMX

I limp moded' home from a mile or two away on small streets....

I kind of wish I could force limp mode for valeting lol