[redlineclipse]

First of all, hi everyone. I am new to the forum. I have been a bimmer owner for a while, but I finally got my hands on a 335i. I have been looking for 2 years and been patient and found my car. I love it. That being said, I have only had it for a month and I'm about to get to know it... consummate the ownership I do all my own work and have been since being a teenager. So I am not new to mechanical concepts. I have read the forum and I don't really see an exact match for my symptoms. I hope this post is in the right area, if not, feel free to move. So...

Out of nowhere, the car gave me the engine temp message last night in a driver through. Because I know how bad overheating can be, I didn't even complete the order. I drove straight to the space immediately in front of me and the car had already changed to the red (on CCC) engine overheating message. The car was in limp mode but I only had to roll 15 ft. I shut the car off immediate and took a look under the hood.

First, there was a little coolant on the edge of the coolant reservoir. I didn't see any steam coming out though and I don't have a clue where it came from. My reservoir went on my old e46 and it actually popped (loud noise). This was nothing like that and again if it was cracked I would think that I would see the steam pouring out of the crack.

Second, I let it cool and checked the level. The coolant level was good.

Third, I hooked up my bluetooth obdII adapter and monitored the temp for the ride home. The needle shot up immediately. 220F then climbed to 248F. I got the yellow message (on the CCC) "Drive moderately...." I pulled over again. IMMEDIATELY! because overheating scares me. It took a while to cool. I started up and again, turned the heat to full blast (wasn't hot, lead me to think the coolant was low) and the climb happened again. This time I made it to walgreens and bought some distilled water. I opened the bleeder screw and filled the reservoir. It took about a cup of water. Got back on the road....temp started creeping again (240F). This time, before the yellow light (on the CCC), I gave it some gas. The heater blew hot air and the temp dropped immediately to 218F. it stayed that way for about a mile and started to climb again, thankfully, I was on my road and turned into my driveway.

So my thought process is ....

If the reservoir cracked, coolant was obviously lost and thus made the heater blow cold. I am more concerned with how the pressure or heat got high enough to crack the reservoir. Does the cap have any pressure release of any kind. BMWs don't have a typical overflow tank, so how does excessive pressure leave the system? Is it possible that the cap released steam and the coolant on the reservoir was residual from the steam?

As far as the quick overheating and the drastic drop on the final stretch... I almost feel like the thermostat was stuck in the closed position. From what I have researched, the system is set to fail to the open position in order to prevent overheating in the case that the thermostat goes. It almost seems like the thermostat finally responded and opened, leading to the drastic drop in temp on the final stretch. Would you think that's a fair assessment?

I am concerned because there are no codes. I would think that a system that is so advanced would at least throw a thermostat code or a water pump failure of some kind.

I think that's everything. I tried to be as thorough as possible. I am trying to determine where to start. I am thinking thermostat which is usually replaced with a pump at the same time (sucky job and expensive ) but I don't want to just throw parts at it, if that is not the problem.

I have seen a test where you purge the waterpump with the gas pedal reset and then watch to see if the pump line sprays into the reservoir on start. (to determine pump operation).

Is there anything that I can do to test the thermostat before I tear the whole front end off of my car?

Any help at all would be greatly appreciated. I'm eagerly awaiting your response. This is all I can think about today. This is also my daily driver so I'm struggling to have it parked. The e46 has a completely locked caliper (I'm going home to replace that right after work today so I at least have a vehicle to drive to work.)

THANKS GUYS!!!!

[srey]

If you're not losing coolant, but the car is overheating it makes me wonder if the coolant is cycling at all. Perhaps your water pump is shot. Maybe a clog in the system. Is your fan operating?

[redlineclipse]

Originally Posted by srey

If you're not losing coolant, but the car is overheating it makes me wonder if the coolant is cycling at all. Perhaps your water pump is shot. Maybe a clog in the system. Is your fan operating?

The fan is working. Here is a pic of the coolant on the reservoir.




https://drive.google.com/file/d/1l8v...w?usp=drivesdk

[srey]

Originally Posted by redlineclipse

The fan is working. Here is a pic of the coolant on the reservoir.




https://drive.google.com/file/d/1l8v...w?usp=drivesdk

Hmm. After seeing the pic I've identified the issue. Someone colored all over your vin# in red. j/k

So the cooling system isn't really leaking, and there is enough fluid. Maybe you have some air in the system and need to burp it. Maybe the coolant isn't flowing at all due to blockage, stuck thermostat, or broken water pump. IDK.

[redlineclipse]

Originally Posted by srey

Hmm. After seeing the pic I've identified the issue. Someone colored all over your vin# in red. j/k

So the cooling system isn't really leaking, and there is enough fluid. Maybe you have some air in the system and need to burp it. Maybe the coolant isn't flowing at all due to blockage, stuck thermostat, or broken water pump. IDK.

Will the cap on that reservoir relieve pressure? Is that possibly where the little bit of coolant came from?

Is blockage common? I hate to flush and refill the whole system just to have to drain it to replace the pump... to drain it and refill again. I'm not whining...just thinking out loud.

Is there a way to test the thermostat or show something with a K+Dcan Cable in INPA? I don't have my setup working yet, but I should be able to get it going if it would help me see something specific to the water pump or the thermostat.

[TemjinX2]

you didn't tell us how many miles you have on the car and what maintence items have been replaced.

But just to take a wild guess....the oem water pump is known to fail between 60-70k. So if your in that mileage range and it hasn't been replace, then its probably the water pump.

Are you you using a bmw app to read the codes like Carly or INPA? some times bmw codes will not show up on obdii app readers

Second guess would be...some times the radiator is develop micro fractures where the radiator only leaks when the cars at operating temp due to the temps and pressure. you might be losing pressure that way, therefore causing the coolant to boil. but usually you will see coolant in the undertray.

I'm leaning toward new water pump. BMW used a POS electric plastic water pump for the N54.

there threads on common things that need to be replaced on the N54. I would check that out as well.

[redlineclipse]

Originally Posted by TemjinX2

you didn't tell us how many miles you have on the car and what maintence items have been replaced.

But just to take a wild guess....the oem water pump is known to fail between 60-70k. So if your in that mileage range and it hasn't been replace, then its probably the water pump.

Are you you using a bmw app to read the codes like Carly or INPA? some times bmw codes will not show up on obdii app readers

Second guess would be...some times the radiator is develop micro fractures where the radiator only leaks when the cars at operating temp due to the temps and pressure. you might be losing pressure that way, therefore causing the coolant to boil. but usually you will see coolant in the undertray.

I'm leaning toward new water pump. BMW used a POS electric plastic water pump for the N54.

there threads on common things that need to be replaced on the N54. I would check that out as well.

Thanks for the replies!!!

I am at 87,000. So it sounds like the pump is par for the course. I can't speak too much of the history because I bought it used about a month ago. I have a K-DCAN cable and INPA... I just have to get it setup. Would that show me something specific to the waterpump? If I have to replace it, I just have to do it, but I would like some peace of mind knowing that everything points to that.

[TemjinX2]

Originally Posted by redlineclipse

Thanks for the replies!!!

I am at 87,000. So it sounds like the pump is par for the course. I can't speak too much of the history because I bought it used about a month ago. I have a K-DCAN cable and INPA... I just have to get it setup. Would that show me something specific to the waterpump? If I have to replace it, I just have to do it, but I would like some peace of mind knowing that everything points to that.

i believe it should. You can also read DME codes using MHD as well.

i had warranty on my car, so i did not specifically replace it, but i doubt they would replace it unless it had a code.

If you have a nice SA at your local BMW dealership, they can print out the service history of the car. Usually they just black out the names.

[Jklad]

Sounds like a failed water pump, right around the same mileage mine failed. Replace both the pump and the tstat at the same time. Also inspect your radiator or expansion tank for leaks or seepage, might want to just proactively replace the tank since it's not an expensive part. FWIW inteplaced my wp and tstat At 89k die to failure, and my expansion tank and radiator were replaced last month at 145k due to seepage and a small crack. On a 2007.

[dpaul]

There's something you can do to assess the pump action without any software or tools. This procedure starts a built-in air purge function for the cooling system which runs the pump:

1. Remove the cap from the reservoir
2. Switch on ignition.
3. Set heater to maximum temperature and turn fan down to
lowest speed.
4. Press accelerator pedal for 10 seconds to floor. Engine
must not be started.
5. The purging procedure will start and lasts for ~12 minutes. You should hear the pump and water moving around - excessive, grinding noise indicates a dying pump. You should see a stream of coolant shooting into the reservoir from a small opening near the top.

I've replaced the pump twice in 50Kmiles - not a great design. There are many, many posts about this. Be happy you don't have an xdrive - twice as hard to get to the damn thing for replacement.

[torrque]

My bet is on the water pump also; but change the thermostat also once you get in there as they are a bitch to get to...

[BM3Rrrr]

I had the same thing happen to me last week, it was the water pump. Replaced the tstat as well.

[redlineclipse]

Parts are on the way. I'll update after the job is done

[Paanzerfaust]

Originally Posted by redlineclipse

Parts are on the way. I'll update after the job is done

Most of the bases have been covered in this thread, and from the sound of it the pump should fix your problem but there's also a possibility that the previous owner didn't do the bleed procedure properly - as a previous poster said the e90 has a self bleeding system which is obviously different than most cars and previous BMW'S.

It doesn't sound like this part is the issue but be aware that there is a coolant line that runs on top of the radiator that is often brittle and prone to cracking and leaking on the 335, especially older models that have gone through their fair share of heat cycles.

[cn555ic]

I had something similar. What turned out to be my issue was the battery. The battery was weak and didn’t provide the proper voltage to the water pump and other accessories. Changed out the battery and everything was fine again. Car used to overheat a lot. Check your battery too.

[JordanG9009]

2007 335i - 140K (cannot verify until later whether water pump or tstat has ever been replaced)

Hi guys just wondered if you could help.....completely stock 335i that since the beginning of the week...have been hitting intermittent overheating issues.

A number of weeks ago, general water, oil checks, and noticed the coolant was slightly lower than usual so did top up at the time. Coolant since then has not dropped so suspected there may be air in the system.

Went through the steps highlighted to perform self bleed and there did appear to be small pockets of air in the system. Have repeated these steps over the course of the week just in case there is a leak coming from somewhere but there doesn't appear to be.

Cannot see any coolant leaks from where the car is parked overnight.

Oil temp never rises above 100c and having monitored the issues over the course of the week. The following occurs.

From cold - ranging from 15 -20 mins of all types of driving (town to motorway/highway) once the temperature gets to 120c, i get the yellow overheating warning which within a minute of this appearing I receive the red warning (switch off - for 30 secs). Once I have started the car again, all is well and no overheating will occur.

I am yet to plug in OBDI reader to see if any fault codes are present however im looking for the best way of managing the issue without having to replace the water pump if it isnt necessary.

Having done the "Bleed" routine (which other forums and videos state is also a way of testing whether your water pump is in working condition) it appears that the water pump is operational, which leads me to thinking my issue has to definitely be with the Tstat.

Any advice would be much appreciated.

[Seahawksnation2]

Originally Posted by JordanG9009

2007 335i - 140K (cannot verify until later whether water pump or tstat has ever been replaced)

Hi guys just wondered if you could help.....completely stock 335i that since the beginning of the week...have been hitting intermittent overheating issues.

A number of weeks ago, general water, oil checks, and noticed the coolant was slightly lower than usual so did top up at the time. Coolant since then has not dropped so suspected there may be air in the system.

Went through the steps highlighted to perform self bleed and there did appear to be small pockets of air in the system. Have repeated these steps over the course of the week just in case there is a leak coming from somewhere but there doesn't appear to be.

Cannot see any coolant leaks from where the car is parked overnight.

Oil temp never rises above 100c and having monitored the issues over the course of the week. The following occurs.

From cold - ranging from 15 -20 mins of all types of driving (town to motorway/highway) once the temperature gets to 120c, i get the yellow overheating warning which within a minute of this appearing I receive the red warning (switch off - for 30 secs). Once I have started the car again, all is well and no overheating will occur.

I am yet to plug in OBDI reader to see if any fault codes are present however im looking for the best way of managing the issue without having to replace the water pump if it isnt necessary.

Having done the "Bleed" routine (which other forums and videos state is also a way of testing whether your water pump is in working condition) it appears that the water pump is operational, which leads me to thinking my issue has to definitely be with the Tstat.

Any advice would be much appreciated.

So did you resolve this because I'm having the same problem basically

[vt]

OP, did you get to the end of it?

My 335is did something similar yesterday. Unfortunately, I wasn't the one driving it, so below is the hearsay followed by my own observations:

- Driving in stop and go city traffic up to 50mph;
- suddenly, heater started blowing hot air full speed;
- "overheating, slow down" message popped up on the instrument cluster;
- within seconds, the car started losing power, and very shortly thereafter "overheating, stop immediately" message popped up.

The driver had no other chance than to stop in the middle of the street (there was no chance to get out, it all happened that fast), and was able to get out of the street, wait it out, and crawl home slowly in about half an hour. As the car was pulling into the garage, I heard the fan howling to max RPM every five seconds or so.

Coolant level was low, but not *that* low, and what are the chances of a coolant level sensor failure? No visible leaks (though indeed there were traces of coolant on top of the tank), no OBD codes thrown, either.

[Frank.gallegos23]

Okay I need help if anyone knows what this issue is. I have a 335i 2007, every time the oil temp reaches 210 it would tell me the car is over heating and go into limp mode, I have to restart the car then it’s okay to drive it again for about another 30 min until it tells me again. I changed the thermostat, the coolant temperature sensor, water pump is good. Radiator is good. Plugged it in to an OBD and coolant temperature is where is suppose to be as well as oil temperature. The car IS NOT overheating but it tells me it is, if anyone knows why pleaseeee help me out.

[Monsieur Jacques]

2011 335i 130k, recently changed my tstat, wtr pump, and fan and still get over heating warning orange then goes red....dont know what else to do. suggestions....

[jsune]

Originally Posted by Frank.gallegos23

Okay I need help if anyone knows what this issue is. I have a 335i 2007, every time the oil temp reaches 210 it would tell me the car is over heating and go into limp mode, I have to restart the car then it’s okay to drive it again for about another 30 min until it tells me again. I changed the thermostat, the coolant temperature sensor, water pump is good. Radiator is good. Plugged it in to an OBD and coolant temperature is where is suppose to be as well as oil temperature. The car IS NOT overheating but it tells me it is, if anyone knows why pleaseeee help me out.

Take off the under tray and see if there's coolant leaking. You could have a micro crack on one of the coolant hoses or possibly the radiator outlet on the drivers side.

[jsune]

OP, your thermostat is likely sticking and should be replaced. Also, the reservoir can leak from the seam above the vacuum lines. If you see coolant there, around and down the side of the reservoir, then replace it as well.