Over-pressurizing Cooling System. Head/Headgasket?

As Mango said, I flushed both radiator and cylinder block as well. I wanted to flush out the entire radiator from inlet to outlet, so I did not remove the drain plug.
Here's the outcome of garden hose frenzy. Engine was ice cold, flow of water was same even when the engine was running.
1) ET-> Upper hose
2*) Radiator inlet-> Block drain plug, temp sensor port when it's taken out.
3**) Radiator inlet-> Backflow when temp sensor is installed. Goes no where. why????????
4) Radiator outlet-> Radiator inlet. No kidding.
5) Upper hose-> Block drain plug.
After this, I let the air out til the needle reaches 12o clock. At this point, radiator did not get hot no matter what.
Then followed dmax's alternative bleeding method. After several attempts, entire radiator and lower hose got hot, hot air blew strongly as well.

Nevertheless, coolant overflows and overheats after few minutes of test drive. It was perfectly fine at idle as I stated above(I let it idle for 15 minutes), temperature wouldn't even go over 210F. When it does, fan kicks on and cools down. Temp is around 190-200F @ 3-4k. Upon acceleration, temp goes up to 210, but cools down immediately (180F) as vehicle reaches 30-40mph. Goes up to 200F again at stop, and so on. It overflowed while driving, which never happened at idle!!

When it overheated, radiator and lower hose weren't even hot. They WERE hot at idle before the test drive. 2 minutes of test drive made that difference. Wtf?
Belt was soaked, but it shouldn't affect the cooling capability at all. Tensioner is making weird noise and tension is bit weak (I can push the belt with moderate force, using a flat-head screw driver), but it seems good enough. Tensioner pulley is new, idler pulley is new as well. Belt is new as well.

I can't stop thinking of possibility of a cracked head. But seriously, if it really IS cracked, RPM shouldn't be stable, lots of steam should come out of tail pipe as the engine currently has water only. (Ambient temp is around 70F today)


New WP, T-stat, radiator, upper&lower hoses, aux fan switch, ET, trans T-stat. ALL OEM. Old factory tensioner, that's it.
Flushed completely(no soapy foam anymore), bled real good(good heat in cabin, fully warmed radiator), no more going-nuts pusher fan at idle.
STILL OVERFLOWS AND OVERHEATS.
What am I still missing?

Dude would you please explain what you mean by "overflowing". How the hell is your system overflowing. Put the damn cap on. Speaking of caps, you didn't buy a new ET cap did you? Get one. Also, you temps aren't bad. It is NOT supposed to go over 100C.

Wish I knew why, but water overflows through the ET cap right before it overheats. (As stated above, rad/lower hose cold when that happens.) It's the only consistent symptom from the beginning.
It does not overflow at idle when everything seems to be in perfect working order (warm radiator and lower hose, hot air in cabin, etc).

ET cap is new, 2 months old, OE. And yes, I did put the cap on, tight.

Originally Posted by mack89

Wish I knew why, but water overflows through the ET cap right before it overheats. (As stated above, rad/lower hose cold when that happens.) It's the only consistent symptom from the beginning.
It does not overflow at idle when everything seems to be in perfect working order (warm radiator and lower hose, hot air in cabin, etc).

ET cap is new, 2 months old, OE. And yes, I did put the cap on, tight.

Water is getting too hot. period. it's getting too hot because your cooling system isn't working as designed. you have air pockets which is probably caused by a leak. stop the leak, bleed the system, and make sure air is flowing over the radiator at idle.

Consider this a professional mango top tip

Wait, are you saying that air gets sucked in through the leak point and create air pockets? I'd believe that if I had any experience that could verify your theory..I had had coolant leak for a long time before this, but this kind of symptom was never exhibited. And unless the system has negative pressure, I don't believe that air could get infiltrated. Besides, using pressure tester(applied 19psi) confirmed that there was no leak at all.

Just crossed my mind. I never used radiator cap funnel when the cooling system has good circulation at idle. Maybe I should do 4k rpm bleeding method and force the air pockets to evacuate while the funnel's in place instead of the ET cap. At least that will scratch the improperly bled system from culprit list. What do you think?

Originally Posted by mack89

3**) Radiator inlet-> Backflow when temp sensor is installed. Goes no where. why????????


When it overheated, radiator and lower hose weren't even hot. They WERE hot at idle before the test drive.
What am I still missing?

I think I'd try to find out what is going on here. Installing sensor should not block hose.
Maybe lower hose is getting blocked above idle

@dknightd
Oh yeah, that..I wasn't thinking enough. Temperature was cold, thermostat was closed, hence the no-flow. I guess I can scratch it from anomalies list.

So...list of culprit is getting narrowed. Air pockets, or tension(less likely). I'll keep it posted.

dont know what to tell you buddy-

When you bleed the system, do you do it with the engine cold?

I recently did the "Mango" overhaul. Bled the system with the engine cold, key in the ignition in the run position, heater temperature on highest setting, fan on lowest setting (but still on). This opens the thermostat, you can hear the relay. I never had a problem. Checked the coolant level every morning for 3 days, and had to add maybe 4 ounces of distilled water to get the level correct.

Contrary to intuition, BMW engines must be bled with the engine cold.

Don't really need to read through the whole thread i think... have you checked the radiator for the ventilator, if that's clogged it can cause all sorts of trouble...

Let me throw in a couple more possibilities.

1. The little rod inside the thermostat is a heating element. On the M54 the thermostat actually opens at a higher than normal temperature. The heating element is designed to put additional heat into the thermostat to regulate its opening point. If memory serves me correctly, the system runs a little hot at part throttle cruise, and the engine management system turns on the heating element when it needs to lower the thermostat opening temperature.if anything is wrong with the heating element, wiring connections, or ECU control system, your thermostat will open at a higher temperature. I believe, without the assistance of the heating element, the thermostat opens above the boiling point of water. That would explain why testing your thermostats in boiling water would not cause them to open.
   
2. You also mentioned that just before it over heats you are getting steam coming out of the expansion tank cap. The stock cap is designed to vent at 2.0 bar or 25 psi. If you have a bad expansion tank it may not allow pressure to build in the system, which would significantly reduce the boiling point.

Since it seems like you've already tried everything else you might take a look at those two items.

Good luck.

@wildirish317. Indeed I bled the system with engine cold, multiple times..Didn't make any difference at all.
Btw, that clicking noise might be the water valve closing and opening, not the relay.

@Angelic0-. I'm not sure what you mean by ventilator. Fan? Fins?

@MotorMan. Thanks for suggesting additional possibilities. Indeed the heating element could be the culprit since every other candidates dropped out, but I'm not even sure how to run diagnostics on that heating element. I've applied 12v on one of the spare thermostats, probe didn't get hot at all. Maybe I did something incorrectly while performing test. Or maybe there's a possibility of rusted/damaged X60003(connector of #3 module of DME)? #45 of X60003 is for the thermostat. And OBD2 scanner shows the P0101, MAF malfunction code even though it has functioning MAF. Might be related...

By the way, you said 'If you have a bad expansion tank it may not allow pressure to build in the system, which would significantly reduce the boiling point.', did you mean expansion tank cap? ET cap is only few months old, I don't think it's not malfunctioning.

By ventilator, i mean the climate control... your heating instrument for the passengers...

the language barrier is killing me here, i know what the name for this is but it just got sucked out of my head... both when i wrote the inital post and also now when i am explaining this :')

You may still have a bad ET even if its new. Is it OEM/eBay? Sorry if you mentioned this before. Maybe try a new cap at least?

OP, it isn't too late to fly me in for a personal mangofication of your car. $1,695 (parts, coolant, airfare, lodging and beer not included)

Please list the part numbers from my cooling thread which you have NOT replaced yet. Lets start there??

@Angelic0-. Well at least Icelanders speak English as good as their first language, don't they? :p. It's my second language and still not perfectly fluent. Imagine yourself facing the language barrier when you're about to explain this mess . Anyway, climate control system is working great. Water(heater) valve operates fine, too. Since the heater blows hot air and every component in heater system is in working order, I scratched heater system from possible culprit.

@scarede46er. I may need to clarify this. You and MotorMan both said 'expansion tank', not the 'expansion tank cap'. You meant to say ET cap, right? Correct me if I'm wrong.
So, the expansion tank was replaced with OE part delivered from WorldPac, cap is OE one as well. A friend of mine at shop has 03 330i, can't hurt to try a fully functioning part on my car. I'll try and let you know.

@.
So the deal is to let you fix my car with that money, and I sleep in my car without groceries and gas, yes?
THEN YOU SIR HAVE A DEAL!! LOL Lets do this.

Here's the list of parts that I have not replaced yet.

• Water pump pulley Part# 11511436590 (It seems to be a metallic, makes funny noise when tapped)
• Coolant drain crush washer at engine-block Part# 07119963200 (I did put a most thin washer I found at tool box, it doesn't seem to leak anyway)
• Water pump pulley bolts x4 $0.25 ea. Part# 07119904524 (uh...........)
• Expansion tank mounting plate (optional) Part# 17111436251 (Possibly have a tiny leak, but it does not leak when 17-19 psi of pressure is applied.)

Oh yeah, engine temperature sensor hasn't been replaced yet. But it seems to be functional because OBD scanner showed correct coolant temperature even when the lower hose was cold.

Originally Posted by E46Mango

Water is getting too hot. period. it's getting too hot because your cooling system isn't working as designed. you have air pockets which is probably caused by a leak. stop the leak, bleed the system, and make sure air is flowing over the radiator at idle.

Consider this a professional mango top tip

Sorry to bump Mango but as my friend exited my E46 today he said my exhaust fumes smelled like anti freeze

Stupid app didn't submit the rest of my reply.

Anyway my radiator light indicated fluids were low so I topped off on that. There has not been any signs of leaking in the area I park on base.

Sorry didnt mean to break down the post into 3 but my app is acting up.

Anyway here a pic of the exhaust and what's coming out and it went away after I drove it to the gym and back.

@juliopinto03
How cold was it when you took that picture? Your town seems warm enough compare to Dallas(below 33F in past two days, wtf), and besides that, water vapor disappears pretty quickly. As far as I know, burning coolant cloud should look like smoke grenade. @1:20,