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Discussion Starter · #1 ·
Hello there!
I recently got overheating problem on my bmw 318i E46 AUTO (N42 engine).
I started with checking the colant level and it was ok. Then i started with changing the thermostat and its same.. cold air inside and engine overheating ( i had bleed the system manu times)
So I bought another orginal termostat and its same .. car overheat and coldair inside.. so i took my hammar and started hitting the heater controll water valve and booom the temperature dropped and the air inside become hot as hell.
But when I started driving 10-15min the car was overheating again! (The air inside still hot)
Any suggestions!?
 

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How many kms on the cooling system? Are you buying cooling system parts that are made by the suppliers to BMW?

The cooling system is the Achilles heel of the E46. It’s made mainly of plastic. It ages with the passage of time and repeated heating/cooling cycles. The consensus here and on other bimmer forums is that the cooling system needs to be overhauled every 100k miles/160kms.

It sounds like your problem is either low coolant flow through the radiator or a massive air pocket in the engine. How hot is the lower radiator hose? If it is a lot cooler than the upper radiator hose the problem is low circulation. That can be caused by a bad water pump or a an air pocket. We did not get that engine in the US, but I bet the bleeding procedure is the same as E46s sold here. Search this forum.

Oh, the installation of aftermarket cooling system parts is strictly verboten!
 

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Discussion Starter · #3 ·
How many kms on the cooling system? Are you buying cooling system parts that are made by the suppliers to BMW?

The cooling system is the Achilles heel of the E46. It’s made mainly of plastic. It ages with the passage of time and repeated heating/cooling cycles. The consensus here and on other bimmer forums is that the cooling system needs to be overhauled every 100k miles/160kms.

It sounds like your problem is either low coolant flow through the radiator or a massive air pocket in the engine. How hot is the lower radiator hose? If it is a lot cooler than the upper radiator hose the problem is low circulation. That can be caused by a bad water pump or a an air pocket. We did not get that engine in the US, but I bet the bleeding procedure is the same as E46s sold here. Search this forum.

Oh, the installation of aftermarket cooling system parts is strictly verboten!
The thing i didn’t understand why the engine temp dropped to normal when i started hitting the water valve controller?
 

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Hello there!
I recently got overheating problem on my bmw 318i E46 AUTO (N42 engine).
I started with checking the colant level and it was ok. Then i started with changing the thermostat and its same.. cold air inside and engine overheating ( i had bleed the system manu times)
So I bought another orginal termostat and its same .. car overheat and coldair inside.. so i took my hammar and started hitting the heater controll water valve and booom the temperature dropped and the air inside become hot as hell.
But when I started driving 10-15min the car was overheating again! (The air inside still hot)
Any suggestions!?
If the water was not flowing you cannot bleed it properly replace heater valve and bleed again
 

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Discussion Starter · #7 ·
Tell us in detail the steps in your bleeding process. As other said, I also think the cause is bad bleeding and air pockets are inside the engine.
Opened ET and bleeder screw, then switch position 2 heater on highest temp and fan low.. then started fill coolant untill water came out from bleeder screw. Closed the screw and left the car 1-2min then closed the ET and started engine.
 

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Opened ET and bleeder screw, then switch position 2 heater on highest temp and fan low.. then started fill coolant untill water came out from bleeder screw. Closed the screw and left the car 1-2min then closed the ET and started engine.
Bad steps no wonder why it didn't work. Here's why:

1. It has too much coolant in the tank. IOW, you had overfilled the tank too high and this can cause ruptured tank and other parts.
2. With engine not rev up during bleeding, air pockets might still be in the head.

Try this:

My method:
1) engine cold, car head up on slope driveway or flat ground level is fine.
2) remove bleeder and tank cap, fill coolant to the MAX marker on the tank using the popper rod as indicator. Do not fill up to top of tank.
3) close the bleeder and screw the tank cap by one turn to avoid coolant shooting out later when running the engine.
4) Set heater to hot and fan low, run engine at idle, then rev it up to about 2500 RPM a few times to push out any air pockets into the upper hose. Important: Do not let engine running more than 7 minutes total while the tank cap is not closed, to avoid damaging the cylinder head. Keep engine idling.
5) Crack open the bleeder to let air out and close it when no more air bubbles. Top off the tank to MAX marker. Close the tank cap.
6) Test drive and check for having heated air in cabin. Done.
 

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Discussion Starter · #9 ·
If the water was not flowing you cannot bleed it properly replace heater valve and bleed again
Little update here... i replaced the waterv valve and now.. when heater is ON the engine temp is perfect.. but as soon you turn off the heater the car start overheat..
 

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Little update here... i replaced the waterv valve and now.. when heater is ON the engine temp is perfect.. but as soon you turn off the heater the car start overheat..
You fixed the heater valve but engine overheat issue still there.
when it starts overheat, grab the radiator lower hose (one with the temp sensor) and see how hot or cold it is.
 

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Discussion Starter · #12 ·
You fixed the heater valve but engine overheat issue still there.
when it starts overheat, grab the radiator lower hose (one with the temp sensor) and see how hot or cold it is.
It have have been always cold, no matter how much you drive!
 

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It have have been always cold, no matter how much you drive!
This means no coolant flowing through the radiator.
Did you verify the Tstat opened in hot water? Did you try a different bleeding method -- Sapote method Rev1?

Sapote method, rev1:
1) engine cold, car head up on slope driveway or flat ground level is fine.
2) remove bleeder and tank cap, fill coolant to the MAX marker on the tank using the popper rod as indicator. Do not fill up to top of tank.
3) close the bleeder, set heater to hot and fan low, run engine at idle. Important: Do not let engine running more than 7 minutes total while the tank cap is not closed, to avoid damaging the cylinder head.
4) Crack open the bleeder to let air out and close it when no more air bubbles. Top off the tank to MAX marker. Close the bleeder and screw the tank cap by one turn to avoid coolant shooting in next step when rev-ing up the engine.
5) Rev it up to about 2500 RPM a few times to push out any air pockets into the upper hose. Keep engine idling for next steps.
6) Crack open the bleeder again to let air out and close it when no more air bubbles. Top off the tank to MAX marker. Close the tank cap.
7) Test drive and check for having heated air in the cabin. Done
 

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Discussion Starter · #14 ·
This means no coolant flowing through the radiator.
Did you verify the Tstat opened in hot water? Did you try a different bleeding method -- Sapote method Rev1?

Sapote method, rev1:
1) engine cold, car head up on slope driveway or flat ground level is fine.
2) remove bleeder and tank cap, fill coolant to the MAX marker on the tank using the popper rod as indicator. Do not fill up to top of tank.
3) close the bleeder, set heater to hot and fan low, run engine at idle. Important: Do not let engine running more than 7 minutes total while the tank cap is not closed, to avoid damaging the cylinder head.
4) Crack open the bleeder to let air out and close it when no more air bubbles. Top off the tank to MAX marker. Close the bleeder and screw the tank cap by one turn to avoid coolant shooting in next step when rev-ing up the engine.
5) Rev it up to about 2500 RPM a few times to push out any air pockets into the upper hose. Keep engine idling for next steps.
6) Crack open the bleeder again to let air out and close it when no more air bubbles. Top off the tank to MAX marker. Close the tank cap.
7) Test drive and check for having heated air in the cabin. Done
I changed the termostat for 2 times now, so differently not t-stat… and yes i tried your method same..
there are 2 bleeders.. should i open both or only the one next to ET?
 

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I changed the termostat for 2 times now, so differently not t-stat… and yes i tried your method same..
there are 2 bleeders.. should i open both or only the one next to ET?
Sapote method Rev2 has an extra step to make sure the water pump has enough coolant to pump, so check it again.
Where is the 2nd bleeder?
 

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Discussion Starter · #16 ·
Sapote method Rev2 has an extra step to make sure the water pump has enough coolant to pump, so check it again.
Where is the 2nd bleeder?
Second bleeder is on the oil filter housing. Im not 100% sure that the water pump is working probably.. didnt notice any noise or so.. but is there anyway to check it? I also have been told that the radiator could bee clogged.
 

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Second bleeder is on the oil filter housing. Im not 100% sure that the water pump is working probably.. didnt notice any noise or so.. but is there anyway to check it? I also have been told that the radiator could bee clogged.
So car has coolant in the oil filter housing? Well, if you're sure it's coolant bleeder, then bleed it just the same as the upper hose bleeder -- do it after finished the upper hose bleeder.

Re water pump status: to know for sure, remove it and see if the turbine is not loose on the shaft.
Re clogged radiator: remove the bottom right hose and the top left hose, then add water quickly into the top left and if water pouring out at the bottom hose then it's not clogged.

Easy isn't it?
 

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Discussion Starter · #18 ·
So car has coolant in the oil filter housing? Well, if you're sure it's coolant bleeder, then bleed it just the same as the upper hose bleeder -- do it after finished the upper hose bleeder.

Re water pump status: to know for sure, remove it and see if the turbine is not loose on the shaft.
Re clogged radiator: remove the bottom right hose and the top left hose, then add water quickly into the top left and if water pouring out at the bottom hose then it's not clogged.

Easy isn't it?
I ordered a new pump already, my only fair is that head gasket is blown, i checked the oil and there wasn’t milky mix.. also no bubbles in the water, i will hope my problem is water pump. And by the way thank you for the info you giving 🤗
 

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my only fair is that head gasket is blown, i checked the oil and there wasn’t milky mix..
bad head gasket is easy to check: the coolant upper hose should not be super hard after 10 minutes drive. It should feel like 15 psi soft tire and should not feel like 30 psi. 2nd method: drive it to operating temp, then park car overnight and remove the top plastic covers. Next early cold morning, remove each spark plug and look for water condensation on the plug tip; check all of them. Show the plugs pics too.
 
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