BMW Forums : BimmerForums banner
1 - 20 of 38 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter · #1 ·
Bmw e46, m43 Cylinder head just came back from the engineers, had pressure test done and replaced the valves & guides. My car idle for about then fan goes and the top radiator hose feels firm but its only when i take it for a drive for about 3km or so then its starts heating up pressure building up on top radiator hose and it feel very hard. i had my radiator, water tank and water pump replaced. It builds up so much pressure that it leaks water through the hoses, you fix the one side it starts leaking on the other side..... Any ideas on what it could be or advise..... please.
 

·
Registered
Joined
·
1,058 Posts
I'd say head gasket is possibly leaking. Make sure you've bled the system properly, when you're filling with coolant, have the bleed valve open with keys in ignition turned to position 2, but engine not running, the heater on full with the fan on position 1. When it's full with no more air bubbles coming from the bleed valve then replace the filler cap and bleed cap, start the engine up and let it run for a few minutes with revs slightly above tickover, maybe 2000 rpm. Stop, let it properly cool down. Check coolant level again, it's possibly lost some coolant so top up with the bleed valve open, this time when it's full start the engine and watch the level. let it tickover for a while if all is well, close the caps and it should be good. If there's a head gasket leak I'd expect you might not be able to bleed the system properly and will always be getting air/gas bubbles coming through.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #3 ·
I'd say head gasket is possibly leaking. Make sure you've bled the system properly, when you're filling with coolant, have the bleed valve open with keys in ignition turned to position 2, but engine not running, the heater on full with the fan on position 1. When it's full with no more air bubbles coming from the bleed valve then replace the filler cap and bleed cap, start the engine up and let it run for a few minutes with revs slightly above tickover, maybe 2000 rpm. Stop, let it properly cool down. Check coolant level again, it's possibly lost some coolant so top up with the bleed valve open, this time when it's full start the engine and watch the level. let it tickover for a while if all is well, close the caps and it should be good. If there's a head gasket leak I'd expect you might not be able to bleed the system properly and will always be getting air/gas bubbles coming
I'd say head gasket is possibly leaking. Make sure you've bled the system properly, when you're filling with coolant, have the bleed valve open with keys in ignition turned to position 2, but engine not running, the heater on full with the fan on position 1. When it's full with no more air bubbles coming from the bleed valve then replace the filler cap and bleed cap, start the engine up and let it run for a few minutes with revs slightly above tickover, maybe 2000 rpm. Stop, let it properly cool down. Check coolant level again, it's possibly lost some coolant so top up with the bleed valve open, this time when it's full start the engine and watch the level. let it tickover for a while if all is well, close the caps and it should be good. If there's a head gasket leak I'd expect you might not be able to bleed the system properly and will always be getting air/gas bubbles coming through.
I'd say head gasket is possibly leaking. Make sure you've bled the system properly, when you're filling with coolant, have the bleed valve open with keys in ignition turned to position 2, but engine not running, the heater on full with the fan on position 1. When it's full with no more air bubbles coming from the bleed valve then replace the filler cap and bleed cap, start the engine up and let it run for a few minutes with revs slightly above tickover, maybe 2000 rpm. Stop, let it properly cool down. Check coolant level again, it's possibly lost some coolant so top up with the bleed valve open, this time when it's full start the engine and watch the level. let it tickover for a while if all is well, close the caps and it should be good. If there's a head gasket leak I'd expect you might not be able to bleed the system properly and will always be getting air/gas bubbles coming through.
Thank you... I will try bleeding out this way and see.... can the head gasket be blown again ? I did replace it a few days ago....
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #5 ·
Thank you... I will try bleeding out this way and see.... can the head gasket be blown again ? I did replace it a few days ago....
The mechanic replaced it... I dont know much of mechanical things but do think a pressure test at the radiator place will tell me if something is wrong with the head ?
 

·
Registered
Joined
·
1,802 Posts
If you have oil in coolant then possible headgasket problem.
And other issue's e.g. overheating, misfire etc.

Try what Greasy said first.
Or buy coolant dye and add to coolant system and see where it is leaking.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #9 ·
If you have oil in coolant then possible headgasket problem.
And other issue's e.g. overheating, misfire etc.

Try what Greasy said first.
Or buy coolant dye and add to coolant system and see where it is leaking.
Hi... I did do what Greasy said this morning but still doing the same thing. I did fix a small leak on one of the pipes but still the same when it builds pressure it will find another place to push out the water..... not sure water & oil is mixing my oil is still clear...
 

·
Registered
Joined
·
1,058 Posts
Hi... I did do what Greasy said this morning but still doing the same thing. I did fix a small leak on one of the pipes but still the same when it builds pressure it will find another place to push out the water..... not sure water & oil is mixing my oil is still clear...
Yes, you now need the coolant system pressure tested. You have no idea right now if the coolant system pressure is too high or not and if it is too high then why isn't the pressure relief valve in the cap not venting it out? Check youtube for how to test it, there are loads of videos, it doesn't have to be exactly your car, coolant systems are similar on many vehicles. Buy a pressure testing kit. I've seen people use bicycle pumps and home made caps for the radiator/expansion tanks etc, but I'd prefer a pressure test kit that reads the pressure accurately! You need to check your cars details for what pressure it should actually be at but it's between maybe 5 and 35 psi or so.

I would now also start looking at how good the pipes are, how new and how secure they are, if they're the push fit with a clip type, then better to replace with new. I've just replaced my radiator MY RADIATOR and a few hoses and the O-ring type seal inside the pipes gets flattened and maybe leaks, mine were OK, but I replaced them as they looked original on a 15 year old car!
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #13 ·
Yes, you now need the coolant system pressure tested. You have no idea right now if the coolant system pressure is too high or not and if it is too high then why isn't the pressure relief valve in the cap not venting it out? Check youtube for how to test it, there are loads of videos, it doesn't have to be exactly your car, coolant systems are similar on many vehicles. Buy a pressure testing kit. I've seen people use bicycle pumps and home made caps for the radiator/expansion tanks etc, but I'd prefer a pressure test kit that reads the pressure accurately! You need to check your cars details for what pressure it should actually be at but it's between maybe 5 and 35 psi or so.

I would now also start looking at how good the pipes are, how new and how secure they are, if they're the push fit with a clip type, then better to replace with new. I've just replaced my radiator MY RADIATOR and a few hoses and the O-ring type seal inside the pipes gets flattened and maybe leaks, mine were OK, but I replaced them as they looked original on a 15 year old car!
Hi ... all I know for sure its building up pressure which causes the water to drip out by the water hoses.... I just came from the radiator place they did some pressure test which didn't go with what I've heard how a test supposed to be done (no color or dye were used) only a 2lt bottle with water in it and a pump ! Going get the test kit and try it out myself🙈🙈🙉 I also thought of replacing my new water pump wich I bought a month ago maybe that one it faulty. Oh yes, the radiator man also said that the water in the radiator circulates then it stops but he couldn't pin-point to the proplem or give a solution.
 

·
Registered
Joined
·
1,058 Posts
The pressure shouldn't make the coolant drip from the hoses even at full and somewhat over pressure, the cap should vent first, so there's most likely a problem with the cap or the seals on the coolant hoses. It might be there are a number of problems underlying which also need to be fixed then.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #15 ·
The pressure shouldn't make the coolant drip from the hoses even at full and somewhat over pressure, the cap should vent first, so there's most likely a problem with the cap or the seals on the coolant hoses. It might be there are a number of problems underlying which also need to be fixed then.
Hi Greasy..... the cap is also new wonder now if that can be faulty.... anyway just gonna have to wait and see gonna put my old cap back then see what happens.
 

·
Registered
Joined
·
183 Posts
All the best. Cooling problems are the worst. I've had no end of them on mine. Burst hose. New hoses with a sensor that popped out. than bottle and now the new hose has gone bad.

Hope you get it sorted.
 

·
Forum Chatbot
Joined
·
3,708 Posts
The pressure shouldn't make the coolant drip from the hoses even at full and somewhat over pressure, the cap should vent first, so there's most likely a problem with the cap or the seals on the coolant hoses. It might be there are a number of problems underlying which also need to be fixed then.
LOL not a single one of the four caps I have had stopped the expansion tank blowing and one of these were a 1.3 bar.
 
1 - 20 of 38 Posts
Top