Overheating 01 325i, Expansion tank changed.. NEED HELP

Expansion resevior tank cracked while I was driving. Had to stop 5x because car was overheating, but I was adding water to in the radiator cooling it down at every gas station. So I replaced the tank and lower AT t-stat and now everythings IN and no coolant leaks.... But the the damn thing over heats and the electric fan(radiator cooling fan) doesnt come on SO I disconected the electrical cap from the temp switch on the lower radiator hose and the fan does come on, only if its not connected to the switch. So I am wondering What can the problem be?? Is it the Lower Radiator hose Temp Switch? Water pump? T-stat ?? I Had the Regular t-stat on top replaced about 2 months ago.... Hmmm really pissed that it overheats.
Any advice or help please post asap, Thanks again

Did you properly bleed the system when you refilled it after the repair? If not, it could be an air bubble trapped int he system.

Why would you continue to drive it after the tank split? The cost of a tow home would be well worth it compared to a warped head.

wow, sounds crazy, if you done almost all of the changes then your water pump is probably going out. you might as well change everything to be on the safe side

I didn't bleed the system, the heater doesn't work, I'm guessing the blower is out.. is there another way to do it? You don't think the temp switch is bad? when it was running it I unplugged the cap on it the electric fan kicked in but it wasn't cooling down... The temp gauge didn't was getting hotter. The coolant level light came on and the tank was empty so I put more coolant in and still over heating.

you need to bleed the system once you replace the tank

how do I properly bleed the coolant w/ the heater not working. Possibility the blower might be out

Originally Posted by r510c

how do I properly bleed the coolant w/ the heater not working. Possibility the blower might be out

Take your expansion tank cap off and unscrew the bleeder screw about 1 to 2 turns, then start the car. Turn the heater on full blast (91 degrees, three red dots on center dial) and then make sure you direct the air toward your windshield. Add coolant to the expansion tank (slowly, it will keep taking it even when it looks full) and just keep adding till coolant comes out the bleeder screw hole. Once it does, tighten the bleeder screw down and you are all set. Just make sure you do it long enough for the engine to warm up so the thermostat opens.

Originally Posted by smolck

Take your expansion tank cap off and unscrew the bleeder screw about 1 to 2 turns, then start the car. Turn the heater on full blast (91 degrees, three red dots on center dial) and then make sure you direct the air toward your windshield. Add coolant to the expansion tank (slowly, it will keep taking it even when it looks full) and just keep adding till coolant comes out the bleeder screw hole. Once it does, tighten the bleeder screw down and you are all set. Just make sure you do it long enough for the engine to warm up so the thermostat opens.

I usually do mine without the engine running, and the heater fan on low.

All else is as per Dr. Smolck.

okay thanks I'll try it and post the out come, thanks again

Bleeding the system is essential to avoiding pump cavitation. I had the same problem except the top hose sheared off the hose clamp (all OEM parts) and sprayed coolant everywhere...
I was able to find a hose clamp and reattach the hose, but much like yourself I was unaware how to bleed the system. The radiator only took one - 2 gallons of coolant (when I assure you more had leaked out).

To my surprise my engine kept overheating, I got it towed finally only to find out I needed to bleed the radiator. I ended up cracking my tank and just replacing the entire radiator and the lower HOT hose while I was under the hood.

A friend of mine kept driving on a cavitated system and he ended up needing his coolant pump replaced (which is attached to the engine on an E46) and ended up costing him a pretty penny...

Be careful and before you take extreme risks, please consider asking first!
Good luck, hope it worked out for you!

Originally Posted by Llando88

I usually do mine without the engine running, and the heater fan on low.

All else is as per Dr. Smolck.

I don't follow how this would work. You need to have the engine running in order to circulate the coolant and any air pockets in the system. Maybe it's just hot enough in Florida that the fluid self-circulates?

Originally Posted by marlin1881

I don't follow how this would work. You need to have the engine running in order to circulate the coolant and any air pockets in the system. Maybe it's just hot enough in Florida that the fluid self-circulates?

This is how I do it normally, and it works great -

Engine off - uncap the radiator - unscrew the vent screw completely. Next, I keep pouring water not coolant into the radiator and wait for coolant to start pouring out and all the bubbles disappear. Recap radiator and screw in vent screw. Then I turn on my car for 5 minutes letting everything circulate for a little bit and repeat the process once more with the car off.

From what I have seen with the engine on is good too but it is also pretty unsafe IMO...

Originally Posted by theruined

This is how I do it normally, and it works great -

Engine off - uncap the radiator - unscrew the vent screw completely. Next, I keep pouring water not coolant into the radiator and wait for coolant to start pouring out and all the bubbles disappear. Recap radiator and screw in vent screw. Then I turn on my car for 5 minutes letting everything circulate for a little bit and repeat the process once more with the car off.

From what I have seen with the engine on is good too but it is also pretty unsafe IMO...

How do you get your 50/50 mix then? Had you pre-filled with 1 gallon coolant, after drain, and then fill with distilled water until all the bubbles are out?

I didn't realize you could get all the air pockets out, without forcefully circulating the water.

Originally Posted by marlin1881

How do you get your 50/50 mix then? Had you pre-filled with 1 gallon coolant, after drain, and then fill with distilled water until all the bubbles are out?

I didn't realize you could get all the air pockets out, without forcefully circulating the water.

You can it just takes patience...and I get no bubbles in the end, maybe might take an extra iteration or two but it's worth being a bit safer...

I use prediluted so I offset the amount of water I fill with the same amount of prediluted 50/50 coolant. Theoretically its at 50/50 - not always the case, but you can never really tell and with the cooling capacity of ethylene glycol, you can have a 30/70 ratio and still achieve the maximum cooling capacity of the coolant (although sometimes I just fill a bit more coolant than I water I used just in case )

This is not my video but it took seconds to find. The production quality is not great but it shows how to bleed the system. The only point that I would debate is to leave the retainer screw in but loose so you can lightly tighten when the coolant bubbles.

Originally Posted by marlin1881

I don't follow how this would work. You need to have the engine running in order to circulate the coolant and any air pockets in the system. Maybe it's just hot enough in Florida that the fluid self-circulates?

Ah - I should have added the key is in position "2" i.e. there must be something running as there are a lot of fan noises in the engine compartment whilst I am filling up.

I must have done this like 4 times in the last two years, with the coolant overhaul, couple of top hose replacements (leaks) and lately a busted expantion tank.

Thanks for posting that video...good example of how to correctly bleed the system. My mechanic is old school and wont do it this way though. He adds coolant with the engine running and tells me to trust him. Makes me nuts.

Well like smolck said to the very first post to this thread that was the problem, did exactly as he stated in his detailed post and that's all it was ( w/ the engine on ) It guzzled up almost 3/4 gallon of coolant more! It must of taken close to 2 gallons of coolant to completely fill and bleed the system, damn what a hog!! So so far had the car running for 30 mins no leaks and no overheating!! The electric fan kicks in and everything seems to be doing it's job, Very good sign so far.i didn't know such a simple procedure can effect everything running so sound! Thanks again for everyones help and effort!

Originally Posted by theruined

Be careful and before you take extreme risks, please consider asking first!
Good luck, hope it worked out for you!

unfortunately, when 99% of the people ask questions, they get flamed and get told to search.. the problem is, they cant search properly and many times searching leads to inconclusive answers lol.

i like what we did here.... just help the OP out and give him the details rather than just say:

"SEARCH YOU NOOB :facepalm: "

It can be done engine off (this is the method outlined in the Bentley manual). Turning the HVAC system on to full hot merely opens the heater core to allow air bubbles to bleed out with the bleed screw as the highest point of the system. However, when doing it this method, you need to bring the coolant up to temp by driving the car, shut the car off, allow the coolant to cool and recheck coolant level before you can call the job complete.

Doing it Smolck's way eliminates the time required to drive/cool/recheck but runs a slightly higher risk in that you can't monitor coolant temp from the guage, easily check for leaks prior to starting and risk scalding from hot coolant with an open expansion tank.

REgardless of which method, its a good idea to recheck coolant level periodically after working on the cooling system until it reaches a stable level.

Originally Posted by theruined

A friend of mine kept driving on a cavitated system and he ended up needing his coolant pump replaced (which is attached to the engine on an E46) and ended up costing him a pretty penny...

The water pumps in 325s and 330s are stupid easy to get to. Even a first timer should be able to open the hood and R&R the water pump in under 1 hour, including bleeding the cooling system. OEM water pumps are under $100. If your friend had it done at a dealer, they probably charge book rates and MSRP on parts so probably $500. However, running with air in the cooling system will cause bigger problems than a busted water pump - overheating can easily mean new head = $2000+

Originally Posted by gesoffen

The water pumps in 325s and 330s are stupid easy to get to. Even a first timer should be able to open the hood and R&R the water pump in under 1 hour, including bleeding the cooling system. OEM water pumps are under $100. If your friend had it done at a dealer, they probably charge book rates and MSRP on parts so probably $500. However, running with air in the cooling system will cause bigger problems than a busted water pump - overheating can easily mean new head = $2000+

Indeed, hindsight on DIY is always present once you've completed the job and were forced to pay for it since lack of preparation and such would deter someone from initially considering the DIY route. If I had enough balls to do a radiator swap myself I would've done it when mine burst and saved myself a few hundred (something like 5-- on labor )...labor is expensive...

Now I do everything myself...as for my friend I don't recall how much he paid but it was over 500...$147/hr at the dealer for labor, and I know it was more than one...

Originally Posted by r510c

Well like smolck said to the very first post to this thread that was the problem, did exactly as he stated in his detailed post and that's all it was ( w/ the engine on ) It guzzled up almost 3/4 gallon of coolant more! It must of taken close to 2 gallons of coolant to completely fill and bleed the system, damn what a hog!! So so far had the car running for 30 mins no leaks and no overheating!! The electric fan kicks in and everything seems to be doing it's job, Very good sign so far.i didn't know such a simple procedure can effect everything running so sound! Thanks again for everyones help and effort!

Glad to hear everything worked out for you! Sounds like you did everything correctly if it guzzled up a whole lot more coolant than before. Consider it a welcome to the forum kinda vibe (look who's talking ) - and remember - only you can prevent forest fires

Originally Posted by Llando88

I usually do mine without the engine running, and the heater fan on low.

All else is as per Dr. Smolck.

According to the book, you do it without the engine running. Having the car parked on an incline with the front end higher is helpful. Bleed it once, let it run, let it cool off, then bleed it again. The temp sensor in the lower hose sounds suspect; change it, about $25 or less.

Originally Posted by theruined

Indeed, hindsight on DIY is always present once you've completed the job and were forced to pay for it since lack of preparation and such would deter someone from initially considering the DIY route. If I had enough balls to do a radiator swap myself I would've done it when mine burst ...

Can you provide some info on your radiator? Was it a leak that progressed? Did it "burst" and dump all fluid in less than 5 seconds? What part broke on the radiator; i.e. upper hose neck, end-tank broke off from the core, etc.?

I've probably seen most failures, and have experienced many first-hand. Would just like some data regarding radiator failures on the E46.

Originally Posted by marlin1881

Can you provide some info on your radiator? Was it a leak that progressed? Did it "burst" and dump all fluid in less than 5 seconds? What part broke on the radiator; i.e. upper hose neck, end-tank broke off from the core, etc.?

I've probably seen most failures, and have experienced many first-hand. Would just like some data regarding radiator failures on the E46.

Well I was in downtown San Francisco - and as I had previously mentioned the upper hot hose came right off - the one attached to the t-stat. The right side of the hose - going into the expansion tank - sheared right off of the hose clamp and it was an OEM factory welded hose clamp...the bugger of the problem was it wasn't even broken (the hose clamp that is) it just slipped right off.

So I reattached the hose using a hose clamp I had lying around and decided to fill 'er up with coolant only to find out I forgot to bleed the radiator entirely, so essentially I broke my own radiator - aside from the hose shearing off in the first place having to replace the expansion tank and radiator were entirely my fault - or at least that is what I am led to believe. This was before xmas of 2009 - as of now everything works wonderfully. I replaced the upper hot hose, lower hot hose and radiator + expansion tank. Aside from a smallll power steering leak everything under the hood is running like clock work.

Maybe you can explain to me why the pressure got so high in my radiator that it caused my hose to shear off of the expansion tank and spray all over my engine...To this very day no one could explain it to me and I can't find a reasonable explanation for it either.