2001 BMW 325i overheating issues

[Ah417]

Hi all, first post, though I have been here for previous issues.

So, title says it, my 2001 325i is overheating. Some time ago (probably a year or so) I had a low coolant issue (light would come on for a while, go back off), so I put some stop leak in, and the problem went away. A couple weeks ago the light started up again, then my heat was in and out, followed by no heat. Finally the car overheated all together. The expansion tank had a crack in it, and the thermostat had a bunch of crud around it, so I replaced both of those. But the car is still overheating. Only seems to be actually overheat once I start driving. temp gauge went up to a bit short of red, if that helps. Whats my next step? My brother suggested a coolant flush. I know you are supposed to use distilled water when doing the flush, but will tap water (city water) work?

Thanks in advance

[Vorsprung46]

you probably didnt bleed the system all the way. Use distilled, it prevents the corrosion build up like you saw. Also, use only BMW coolant (blue)

check this guide,
https://www.e46fanatics.com/threads/...system.689618/

and this covers the whole system

https://www.bmw330ci.net/maintenance...etecoolant.php

[Ah417]

Thanks, I think you may be right that I didn't bleed the system correctly.

I don't have BMW coolant, but the coolant I use is made for european models (including bmw) and is blue. Should be fine, right?

[MarcoZandrini]

What are the brand and version is the coolant? Always make a 50/50 mix of coolant and DISTILLED water.

[BimmrMeUpSnotty]

Your first mistake was not maintaining the car, your next mistake was shoving that stop leak crap in there. Your brother suggested a coolant flush. This would be the best thing you could do right away. Get all that stop leak crap out of the system as good as you can. I would completely dismantle the whole cooling system, check the manufacture date codes on everything, replace with new parts, good brand quality parts, unless you enjoy torturing yourself. Time is the most important part of your life. Use it wisely, purchase the good stuff and overhaul the whole system, that means even replacing the two plastic pipes underneath the intake manifold. That means replacing all the intake manifold gaskets, replacing all the CCV pipes, hoses that go all the way into the firewall for the heater core. Then jack up the front end of the car and bleed that system properly. You keep overheating that engine, the cooling system won’t be the only thing you will be replacing.

[Jabspine]

Ah417,

Typically, leaks will cause "low coolant" lights before over heating when caught depending on how big the leak is. Blocks or no flow will cause over heating (thermosrat/pump). Additives usually do not help or fix a problem. Coolant leak stop, oil additives, stop leak whatever... don't use it. If there is a leak it must be repaired.

You changed the coolant tank and thermostat. Look at the coolant pump next (water pump). My wife has a 2011 X3 35i which is mainly electronic, tons of modular parts. Once you do your homework, easy to fix.

1st it was pin hole leaks in different coolant hoses. Repaired. No over heating during leaks.

Coolant level still dropped with no over heating.

2nd- found a pin hole leak in the radiator. No over heating. I changed it. No coolant level drops since 2017.

Finally in 2020 over heating became an issue, then the pump went out as it was a total failure. Coolant levels were constant and never dropped.

I did purchase a Foxwell 510 code reader which allows for diagnostics and to clear codes.

The 2011 X3 35i (N55 engine) has a pump/thermostat housing which looks like a heart. Both electrical and fail. I changed them and no issues since with over heating.

I only use pink/purple capped Pentofrost coolant for BMW which I buy from Autozone. Only mix with distilled water. Nothing else. We are in South TX so I use a 50/50 mix.

In other words if your coolant levels are constant and your engine over heats, it most likely is a block or no flow. Blocks prevent flow which cause over heats. Leaks will cause over heats when not caught because there is no coolant.

With BMW problems can cascade and be adjacent to each other. Follow the line.

Flushing is only good to change the fluids out when using what is appropriate.

Sent from my SM-F711U using Tapatalk

[feels1]

Few years ago, I helped my friend on his 2006 E53 X5 engine overheat issue like yours.

The previous owner pour in coolant stop-leak solution like you as a temporary workaround to stop a radiator leak, only then replaced the radiator as the engine still overheating. His mechanic recommended him stop-leak as he wants a cheap fix, and save up $$$$ to repair later. This didn't addressed engine overheat, and the interior heat stop working (blowing cold air in winter).

The previous owner finally selling the car to my friend for $2k, as his mechanic(s) quote him $8k to replace the entire engine (which is same engine as E46).

I ended up helped my friend, as this is an opportunity for me to learn about BMW cooling system with INPA real time monitoring. I managed to fix the issue by replacing blocked hose for < $100, but spent ~ 5 days. Imagine the shop will charge $120/hr, and could be 8 hr full day, so ~ $1000 - $2000 charge for damage due to radiator stop-leak solution.

Before I start to share how to resolve it, I will strongly recommend NOT to use stop-leak solution for radiator, engine block, transmission, as this will leaks to various blocking issue later that is time consuming to identify (not cost justify for owner to spend), and resolve.

For E46, E53, or car of that generation that use the similar M54 engine design, the cooling system and interior heat core are similar. If you have 1 climate zone, then there is 1 electronic coolant flow control valve, if you have 2 climate zone, then you have 2 electronic coolant flow control valve. The rest are pure mechanics, and cheap to replace.

You must perform following preliminary flush with garden hose (regular water to save cost) to push out the crud (introduced by stop-leak solution) in various part of the engine + radiator:
1. radiator - put garden hose into "outlet" of radiator (lower radiator hose), and open up (disconnect) the "inlet" radiator hose by disconnect coolant reservoir
1.1. Crud accumulate from inlet, so this will push it out in reserve
1.2. Pushing it from inlet will "push" the crud much deeper into the radiator fin, and it will stuck forever
1.3. If you want to skip this step, then replace with another radiator, and forget about the crud blocking the radiator fin
1.4. This is first thing to flush as it is the main component to cool down the engine. Replaces if you want to skip labor intensive flushing time
1.5. Be prepare to spend several hours to flush
1.6. The back pressure (crud blocking) could be high, so you might want to be creative to make a good join with the garden hose
1.7. Avoid using high pressure water, but air compressor is acceptable
1.8. If garden hose can't unblock it, use bicycle air pump (large model), or air compressor to push out crud
1.9. If majority of the crud is removed, the inlet garden hose should not feel any back pressure
1.10. Stop when the outlet hose/port doesn't see any crud (stop-leak) debris, as well as water free flowing
1.11. This will be sufficient to keep the engine cool, but perform next step to clear out out crud.
1.12. Interior heater might still blocked by crud. Perform #3 to clear it out
2. engine's water pump area - put garden hose into lower radiator hose and keep upper radiator hose disconnected
2.1. There is no specific order to push the crud out as the coolant passage in the engine is very wide
2.2. The crud not possible to attach to the metal alloy engine block, so this is to stop crud to flow to other cooling system later
2.3. Remove thermostat to remove any crud that attached to it
3. Flush crud from heater core system. This will resolve cabin not blowing hot air
3.1. Keeps thermostat disconnected
3.2. Disconnect lower hose that go into coolant reservoir. Follow this hose and it will leads you to a electronic coolant flow valve that controls coolant flow OUT from cabin heater core
3.3. For each flow valve (if you have 2), there will be 3 hoses, i.e. out engine to valve, input to cabin heater core, output from cabin heater core
3.4. Attach garden hose to each of them (leave others detach) to push out the crud
3.5. When attach garden hose to engine outlet (to flow control valve), then the crud will come out from thermostat port
3.6. When attach garden hose to cabin heater core outlet (to flow control valve), then the crud will come out from heater core inlet hose
3.7. This is the part that my friend's car found the blockage that can't flush out with garden hose, or air compressor. From the engine block, the coolant flow through a solid plastic hose, then to rubber hose to electronic flow control valve. The plastic hose was completely blocked by crud. The crud was harden in the bending area that took 3 days, and can't clear it out. Part is shown below with 2 bolts attaches to engine (USD$32.19):
https://www.fcpeuro.com/products/bmw...in-11531705210
3.8. Replacement of above plastic hose will need to remove entire air intake system, which means very time consuming (more involving than CCV oil separator replacement)
3.9. Once you get no back pressure using garden hose, and the water come up clean without any debris, this system is clean, and you can stop
3.10. Detaches all hoses, thermostat to drain out the water
4. Assemble engine hoses, heater core, radiator together, and flush with proper BMW coolant
4.1. Detach lower coolant reservoir hose coming from flow control valve (indirectly, it is output of cabin heater core)
4.2. Blocked the lower port in reservoir to avoid coolant flowing out later
4.3. We will fill in fresh distill water from coolant fill cap at top of reservoir
4.4. Prepare funnel or water pump with 20L of distill water
4.5. Start the engine, and let water pump push out water
4.6. Fill in fresh distill water from the fill cap not to keep the coolant/engine dry
4.7. Do this for ~ 1 min, and entire system should fully flush with distill water
4.8. If you want to skip this, I still recommend to fill up the system with distill water, then drain it 3 times. This will keep the system with near to 90% distill water
4.9. Now entire system is filled with distill water, and ready to fill with BMW coolant
4.10. Drain out coolant from radiator, and reservoir. Fill it back with BMW coolant like regular coolant replacement procedure

Note 1: If you want to use distill water, then prepare (1) electrical water pump (2) 200L - 1000L of distill water
Note 2: Engine replacement is not needed, as stop-leak crud won't attach to alloy engine block

[Sapote]

I would completely dismantle the whole cooling system, check the manufacture date codes on everything, replace with new parts, good brand quality parts, unless you enjoy torturing yourself. Time is the most important part of your life. Use it wisely, purchase the good stuff and overhaul the whole system, that means even replacing the two plastic pipes underneath the intake manifold. That means replacing all the intake manifold gaskets, replacing all the CCV pipes, hoses that go all the way into the firewall for the heater core. Then jack up the front end of the car and bleed that system properly. You keep overheating that engine, the cooling system won’t be the only thing you will be replacing.

AFter all of these done, then OP find out the head is cracked and decides to junk the car.
I think he should fix the overheat first and if he found out combustion gas leaked into the coolant, then he needs to decide how far down the hole he wants to go.

[Sapote]

But the car is still overheating. Only seems to be actually overheat once I start driving. temp gauge went up to a bit short of red

What is the coolant level in the tank checked on cold engine?
Detail steps of your bleeding method?

[screenshot]

does every bimmer take the blue coolant or only some year models and does it have to be somekind of original bmw blue or any blue ones in the shop will do the job? and why does some shops even recommend a green color coolant which is supposed to be higher standards than the blue one?