[mr.melanson]

First off I have a charge pipe, catless downpipe, and jb4 running 91 on map 5. Here is what's going on.
While driving on the highway I got the yellow overheating light so I pulled over, let it cool for 10 minutes, then drove 10 minutes to a shop with no problem. The guy there said I've got coolant, so it should be fine unless it happens again. Well it happened again so I took it to a shop an hour away. It seems every 20 minutes I get the yellow overheat warning, I pull over and shut it off. Wait a couple minutes, then I'm fine for another 20. Sometimes while pulling over the light does turn red right as I'm turning it off. So this new shop checks it out, says the fan isn't working properly but they had issues communicating with the car because of the jb4. They also say the water pump seems fine. So they replace the fan and fan assembly ($1600). Left the shop and same problem. Take it back and they do more testing. They said they tried hooking up a sensor they know works and its reading higher than normal temps. Apparently they were getting readings of very high temperatures but it was only slightly warm to the touch... So they tell me they think it's an issue with the DME.
I try driving it and my boost gauge reads like 6psi instead of 13ish when stepping on it and then a yellow engine light half filled in comes on but goes away shortly after as I'm cruising on the highway. So I take it home and remove the jb4, still have the overheating problem. Take it to BMW and they tell me the water pump codes are popping up, and they clear the code and it comes back. So they tell me the water pump needs replacing for sure.
My understanding is if the water pump goes, you can't drive it more than a couple minutes before you overheat. So I am worried doing the water pump and thermostat won't fix my problem. Also the fact the second shop tells me the car doesn't seem to be actually overheating, it's just sensing temps higher than they are...
Does anyone have any ideas? Thanks everyone.

[mrjcover]

Originally Posted by mr.melanson

First off I have a charge pipe, catless downpipe, and jb4 running 91 on map 5. Here is what's going on.
While driving on the highway I got the yellow overheating light so I pulled over, let it cool for 10 minutes, then drove 10 minutes to a shop with no problem. The guy there said I've got coolant, so it should be fine unless it happens again. Well it happened again so I took it to a shop an hour away. It seems every 20 minutes I get the yellow overheat warning, I pull over and shut it off. Wait a couple minutes, then I'm fine for another 20. Sometimes while pulling over the light does turn red right as I'm turning it off. So this new shop checks it out, says the fan isn't working properly but they had issues communicating with the car because of the jb4. They also say the water pump seems fine. So they replace the fan and fan assembly ($1600). Left the shop and same problem. Take it back and they do more testing. They said they tried hooking up a sensor they know works and its reading higher than normal temps. Apparently they were getting readings of very high temperatures but it was only slightly warm to the touch... So they tell me they think it's an issue with the DME.
I try driving it and my boost gauge reads like 6psi instead of 13ish when stepping on it and then a yellow engine light half filled in comes on but goes away shortly after as I'm cruising on the highway. So I take it home and remove the jb4, still have the overheating problem. Take it to BMW and they tell me the water pump codes are popping up, and they clear the code and it comes back. So they tell me the water pump needs replacing for sure.
My understanding is if the water pump goes, you can't drive it more than a couple minutes before you overheat. So I am worried doing the water pump and thermostat won't fix my problem. Also the fact the second shop tells me the car doesn't seem to be actually overheating, it's just sensing temps higher than they are...
Does anyone have any ideas? Thanks everyone.

I myself have experienced that issue last night, Car is currently at the shop now... I'll let you know how it goes and what's the verdict... For some strange reason it's like everybody is starting to have that issue now... All at the same time which is weird...

[NRigs]

Originally Posted by mr.melanson

First off I have a charge pipe, catless downpipe, and jb4 running 91 on map 5. Here is what's going on.
While driving on the highway I got the yellow overheating light so I pulled over, let it cool for 10 minutes, then drove 10 minutes to a shop with no problem. The guy there said I've got coolant, so it should be fine unless it happens again. Well it happened again so I took it to a shop an hour away. It seems every 20 minutes I get the yellow overheat warning, I pull over and shut it off. Wait a couple minutes, then I'm fine for another 20. Sometimes while pulling over the light does turn red right as I'm turning it off. So this new shop checks it out, says the fan isn't working properly but they had issues communicating with the car because of the jb4. They also say the water pump seems fine. So they replace the fan and fan assembly ($1600). Left the shop and same problem. Take it back and they do more testing. They said they tried hooking up a sensor they know works and its reading higher than normal temps. Apparently they were getting readings of very high temperatures but it was only slightly warm to the touch... So they tell me they think it's an issue with the DME.
I try driving it and my boost gauge reads like 6psi instead of 13ish when stepping on it and then a yellow engine light half filled in comes on but goes away shortly after as I'm cruising on the highway. So I take it home and remove the jb4, still have the overheating problem. Take it to BMW and they tell me the water pump codes are popping up, and they clear the code and it comes back. So they tell me the water pump needs replacing for sure.
My understanding is if the water pump goes, you can't drive it more than a couple minutes before you overheat. So I am worried doing the water pump and thermostat won't fix my problem. Also the fact the second shop tells me the car doesn't seem to be actually overheating, it's just sensing temps higher than they are...
Does anyone have any ideas? Thanks everyone.

Replacing the water pump and thermostat should fix the problem.
I just had mine replaced two weeks ago. Had same issue with the yellow and red light. Have not had an issue since I have replaced them.

[mrjcover]

Just got the car back, in my case they replaced Water Pump and Expansion Tank

[mr.melanson]

Thanks everyone. Makes me feel a bit more secure that this will solve it.

[weehe126]

The water pumps fail two ways. By cracking and leaking or having electrical problems that makes it work intermittently causing random overheating. Like said above, replace the pump and thermostat.

[mr.melanson]

I got bad news from the shop. After doing water pump and thermostat, still have the same problem... any ideas??? I'm desperate here.

[juld0zer]

Pull the coolant temp sensor and graph its output, check against the datasheet.

The sensor is actually quite cheap.

Otherwise buy or borrow an OBD2 reader that can read live data and watch your coolant temp. Compare that with your engine oil temp on your dash. They should be close to each other after a 15min drive.

You can also perform a water pump test by actuating the electric coolant bleed function (ignition on, floor the gas for 10s then remove expansion tank cap and observe the spray. It should start off gentle then cycle on and off at high output. I assume with a new pump you should have good output. Obviously only do this on a cold engine.

Water pump can also fail with stiff impellor movement, usually logs a fault for target speed not reached.

Coolant temp sensor is near the oil filter housing. Very easy to get to and swap yourself with a known good one from a friend.

[azrial03]

I have 06 BMW 325i with 110k miles on it. Just replaced the thermostat and sensor. The car will drive exactly 10min to the dot then will show its overheating with coolant temperature of 240 degrees F. If I turn it off and turn it immediately back on (like only off for a second) it will say its normal temperature at 180 degrees F. Then 10min to the dot repeat. Also there are no trouble codes on the OB2 and I already tried to bleed the coolant system. Any ideas?

[ItsaGoose]

Originally Posted by mr.melanson

I got bad news from the shop. After doing water pump and thermostat, still have the same problem... any ideas??? I'm desperate here.

Update?