Maybe my Water Pump

[beemarman]

Hi,
Am having some heating problem with my 2000 4.4 X5

I think I have a radiator blockage or maybe my water pump is gone
When I put some water in coolant header tank and after running the engine for about 30mins the water will start to boil over(Steam Over) from the coolant header tank, a lot of pressure gets released and I see a lot of bubbles and steam coming from the coolant header tank. It gets worse when the engine is immediately switched off, all the water just escapes underneath the car and the “low coolant” light on the dash come on.
The car does not overheat and the car heater still works. I had to replace the last coolant header tank because it cracked because of the pressure in the bottle.



Has anyone experienced this before please as am about to book the car in for BMW to have a look at it?

[withidl]

Your themostate could be stuck in the CLOSED position thereby only allowing coolant circulation within the engine & heater resulting in the symptoms you describe.

[vinuneuro]

Be careful with this as lack of coolant circulation could cause you some serious issues.

[alpac]

Originally Posted by beemarman

Hi,
Am having some heating problem with my 2000 4.4 X5

I think I have a radiator blockage or maybe my water pump is gone
When I put some water in coolant header tank and after running the engine for about 30mins the water will start to boil over(Steam Over) from the coolant header tank, a lot of pressure gets released and I see a lot of bubbles and steam coming from the coolant header tank. It gets worse when the engine is immediately switched off, all the water just escapes underneath the car and the “low coolant” light on the dash come on.
The car does not overheat and the car heater still works. I had to replace the last coolant header tank because it cracked because of the pressure in the bottle.



Has anyone experienced this before please as am about to book the car in for BMW to have a look at it?

It could be the thermostat not working and keeping the cooling circuit closed. I got the exact same problem with my 2000 x5 this summer. The coolant was boiling in the coolant tank which first resulted in a coolant hoose broken. Instead of looking for the underlaying cause the garage just replaced the hoose. 2 days later I got the same problem but this time they had to replace the entire cooling system (radiator, water pump, thermostat and hoses) . It cost around $4000 but it was covered under the extended warranty

[Bill K]

If it takes you 30 min to start overheating, then that is puzzling. A therm stuck closed would probably take less than 10 minutes to overheat as would a bad water pump. Is there any fluid lealking from the water pump? Either way, I would recommend replacing the therm and water pump. Once they are removed, flush out the radiator.

Have you tried bleeding any air out of the system? There's an air bleed screw for that.

Have you checked the oil to see if you have a head gasket leak?

[beemarman]

it really puzzling, the car does not overheat even after running for nearly 1hr. I spoke to BMW technican and he said that they could be a air lock in the system and to try and get rid of the air by unscrewing the little nob next to the cap of the coolant bottle.

I have tried this and notice a lot of bubble and air coming out - the problem i have now is how do i know when the air lock has cleared?

The pressure still builds up when the car is running but it's not as bad as before. I just need to know when the air lock has cleared.

[alpac]

Same for me when I had this problem of boiling coolant the temperature indicator did not show any sign of overheating at all.

[alpac]

here was my post on a very similar problem http://www.xoutpost.com/showthread.ph...hlight=coolant

[X5Flyboy]

How many miles? - someone in an earlier thread mentioned the water pump typically 'went' between 72k-84k (if I remember right) - might want to replace both water pump and thermostat, if digging in there (per Bill K)

[Bill K]

Originally Posted by beemarman

it really puzzling, the car does not overheat even after running for nearly 1hr. I spoke to BMW technican and he said that they could be a air lock in the system and to try and get rid of the air by unscrewing the little nob next to the cap of the coolant bottle.

I have tried this and notice a lot of bubble and air coming out - the problem i have now is how do i know when the air lock has cleared?

The pressure still builds up when the car is running but it's not as bad as before. I just need to know when the air lock has cleared.

You unscrew the bleed screw until all the bubbles run out and solid coolant is coming out. Then you shut it (dont overdo it--its only plastic). Also make sure that you have your heater turned all the way hot and that it blows full power as you bleed it.