E46 Fanatics Forum banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Ride of the Month Challenge!
1 - 16 of 16 Posts

·
Registered
Joined
·
77 Posts
Discussion Starter · #1 · (Edited)
Hey guys, I'm new to the world of E46's. I just bought mine about two weeks ago. I have already replaced both front wheel bearings, and the valve cover gasket. The one problem is a coolant leak. The car runs fine, but the low coolant light worries me that my BMW could be in danger of overheating. I checked the coolant earlier today and the expansion tank was full. So today in my garage, i pulled the car in. The instrument panel said a headlight was out, so i went to go check that, but left the car in idle. The garage door was open, and it was a hot day. Suddenly the steady hum of the engine started to slow, as if the engine was dying(it was almost overheating). So I ran over to shut off the car, and saw the temperature meter hit the third white line. It wasn't in the red, but near it.

After this scary experience I searched for anything out of place. What i found was that a vacuum hose that ran along the valve cover had snapped. I learned from other threads that this was the Secondary Air Pump Vacuum Hose, and it commonly snaps because it is brittle. This sounds like the cause of the sudden temperature spike, but I want to be sure. Do you guys think this is the problem? For now i duct taped it back together, and put some metal stints to keep the line straight around the break. This is the best i could do for now until i can get another hose.

*Update* This all happened last night. This morning i took a look at the expansion tank and it was bone dry. So i filled it up with coolant and started the car. Seemed to run fine. Pulled out and took a little drive. I drove for about 25 minutes and no complaints. Car ran perfectly, and the fan was running strong.
 

Attachments

·
Registered
Joined
·
457 Posts
Hey guys, I'm new to the world of E46's. I just bought mine about two weeks ago. I have already replaced both front wheel bearings, and the valve cover gasket. The one problem is a coolant leak. The car runs fine, but the low coolant light worries me that my BMW could be in danger of overheating. I checked the coolant earlier today and the expansion tank was full. So today in my garage, i pulled the car in. The instrument panel said a headlight was out, so i went to go check that, but left the car in idle. The garage door was open, and it was a hot day. Suddenly the steady hum of the engine started to slow, as if the engine was dying(it was almost overheating). So I ran over to shut off the car, and saw the temperature meter hit the third white line. It wasn't in the red, but near it.

After this scary experience I searched for anything out of place. What i found was that a vacuum hose that ran along the valve cover had snapped. I learned from other threads that this was the Secondary Air Pump Vacuum Hose, and it commonly snaps because it is brittle. This sounds like the cause of the sudden temperature spike, but I want to be sure. Do you guys think this is the problem? For now i duct taped it back together, and put some metal stints to keep the line straight around the break. This is the best i could do for now until i can get another hose.
That line has nothing to do with the cooling of the engine. You had the car parked not moving which means no air flow into the radiator if your fan isn't kicking on. I had that issue with my car was almost overheating in stop and go traffic and then I figured out my fan stopped working. Replaced it and the problem went away. Since it looks like you don't have the electric fan could be your fan clutch.
 

·
Registered
Joined
·
1,493 Posts
You have a cooling system issue. Vacuum leaks won't cause overheating, but it is still very important to find and fix all air leaks. Take the air box and maf off and take some high res photos of everything and I'll try to give you some advice on what needs replacing.
 

·
Registered
Joined
·
5,461 Posts
The previous owner forgot to tell you about the overheating issue, didn't he?
+1 on checking the fan.
 

·
Registered
Joined
·
2,431 Posts
Check for faulty coolant level sensor. Check for faulty viscous fan coupling. Read codes. That vacuum hose has nothing to do with overheating. Replace it. Read up on your car in this forum. You should verify that the engine has not been damaged as a result of this overheating which appears to have been an ongoing issue. Check coolant for oil contamination, check oil for coolant contamination.
 

·
Registered
Joined
·
42 Posts
You probably need to flush your coolant/bleed the lines it happens, coolant gets old and quits cooling properly. it's like running only water in these cars..


Sent from BimmerApp mobile app
 

·
Premium Member
Joined
·
28,953 Posts
Hey guys, I'm new to the world of E46's. I just bought mine about two weeks ago. The one problem is a coolant leak. The car runs fine, but the low coolant light worries me that my BMW could be in danger of overheating. I checked the coolant earlier today and the expansion tank was full.
You either have an air pocket in your cooling system and/or if you may have issues with airflow due to compromised fans.

Also another thing that happens is the water pump impeller will spin on the shaft and not pump enough water.

Start with the coolant leak. Replace the O-ring on the temperature switch in the lower radiator hose, these leak all the time, they last about 6 years before they start to seep. Any moisture in this area means this O-ring is shot, they usually leak when the engine is cold. See the part number in my signature.

Also since you are new to the E46 and to this car, keep in mind, the car is 13+ years old. If there is a rubber part under the hood, it likely needs to be replaced, along with the fuel filter and fuel pump. Read the links in my signature.

You probably need to flush your coolant/bleed the lines it happens, coolant gets old and quits cooling properly. it's like running only water in these cars..
Man, I thought I have heard everything, then this comes up!! Yes, coolant can be degraded due to corrosion, additives breaking down and the use of tap water with minerals, but this will not likely cause the engine to overheat when idling. Yes, coolant should be changed every few years as well, but getting old and it quits cooling properly??? Not sure whose chemistry and physics class you attended?

I cannot wait until someone put this quote in their signature!!
 

·
Registered
Joined
·
1,430 Posts
Man, I thought I have heard everything, then this comes up!! Yes, coolant can be degraded due to corrosion, additives breaking down and the use of tap water with minerals, but this will not likely cause the engine to overheat when idling. Yes, coolant should be changed every few years as well, but getting old and it quits cooling properly??? Not sure whose chemistry and physics class you attended?
:lol:
 

·
Registered
Joined
·
42 Posts
Actually you must not know these cars, because when coolant gets old it becomes useless, I also said he probably had an air pocket by "bleed" the lines. Bad coolant will make your car over heat, also if you mix it with water to potent.. Thats in any car. I've built 2 of these cars, and I've learned a lot. It could be anything coolant wise and if he's having coolant problems he probably needs to flush the system anyway to get all the crap out if it. ImageUploadedByBimmerApp1402156540.613738.jpg


-Adam
 

·
Registered
Joined
·
42 Posts
Also your broken line shouldn't really hurt anything you'll loose power but, the piece that it goes into your car can actually go with out, as long as you don't have to pass evap.


-Adam
 

·
Registered
2016 340i xD 6-spd
Joined
·
26,980 Posts
You should fix the sap hose anyway, though. You'll get a CEL if you don't and it could result in starting problems and running problems both. Either or both are very easy to fix. Remove cabin air filter housing to get to the back where the small vac hose is attached.

Anyway, read up on all the cooling threads until you feel a chill and start shaking...then you'll be ready to diagnose and fix your system. It could be just the fan or it could be a sensor not triggering the fan, or it could be the beginnings of wp, therm issue...we don't know. I'd say that at the point you're throwing parts at it to 'try' to figure it out, you just go all in and replace the entire system? $300 for a manual...another $150 for a radiator, which, if you're above 100K miles, or so, not a bad idea to put in too (mine lasted 180K miles before leaking...but my car is special!)

Read Mango's sticky above and a few others with 'cooling' in the thread title. Have fun! Don't drive too far until you figure out what's going on, and scan your temp gauge often! Safest is, of course, not driving...I don't know what you know but you could be perfectly fine as long as you're moving, but it might also be a really bad idea.
 

·
Registered
Joined
·
10,549 Posts
If the car overheats when not moving, and cools again when you get to 30-ish MPH or more, then this means the fan clutch is on the fritz. Nothing else matters.

You do not want old coolant, but it will not give the symptoms set you report. You also do not want air in the system, but again the symptom set will be different.

Get the engine up to temp by driving around the neighborhood, then come home and open the hood and use a rag folded up several times to CAREFULLY stop the fan from spinning while the engine is running. Then spin the fan backwards. It should turn around and spin the right way almost immediately, but if the clutch has failed then the fan will coast the wrong way for several seconds.
 

·
Registered
Joined
·
77 Posts
Discussion Starter · #14 ·
Thanks for all the help guys, I'm learning a lot. Could an engine really overheat in 2-3 minutes (after ignition) with no fan?

Oh and one more thing... dmax and tim330i both commented on my thread! Thanks guys!
 

·
Registered
Joined
·
59 Posts
Have you found the root of the problem? My car suddenly over heated yesterday night while idling. Luckily I caught it in time and turned off the car. I let it sit for a few minute and started the car back up to drive it home. As I started driving slowing the temperature dropped to the 12 o'clock position.
 

·
Registered
Joined
·
77 Posts
Discussion Starter · #16 ·
Have you found the root of the problem? My car suddenly over heated yesterday night while idling. Luckily I caught it in time and turned off the car. I let it sit for a few minute and started the car back up to drive it home. As I started driving slowing the temperature dropped to the 12 o'clock position.

That was my first post, since then I've learned so much. This car generally overheats because a part fails in the coolant system. You can also have issues if the coolant isn't bled right, leading to air bubbles.

First, more information. Did you have any work done recently, or did you touch the coolant system?

Second, never let the temperature needle go past 12 o'clock. Did it start overheating at idle, but was fine as you drove?

Third, most likely your water pump or thermostat has failed. Is your check engine light on?

Never let the car overheat. Even once badly can hurt or kill your car. It happened to me.
 
1 - 16 of 16 Posts
Top