can someone help

[aceifty]

i know this is a E30 forum but can any one help with my E39 523ise 1996 n plate
I have plenty of heat from about 4000+ rpm, but at low revs it cools down and gives cold air

[e30-EVN]

due to the freezing temps ect it could be just that mate tbh, either that or an air lock.
have you done any maintanence with any of the cooling system??

[eltel]

could be water pump failing hence more revs needed to push coolant round..but i would say it maybe the heater matrix blocked or air in the system.

any temperature issues or recent work done?

[eltel]

sorry e30-dk..must have posted the same time as you..didnt mean to duplicate.

[leeparkes]

Does it take a long time to get up to temp?

[e30-EVN]

sorry e30-dk..must have posted the same time as you..didnt mean to duplicate.

your ok mate, we seem to be on the same level of thinking which may help the op

[aceifty]

could be water pump failing hence more revs needed to push coolant round..but i would say it maybe the heater matrix blocked or air in the system.

any temperature issues or recent work done?

temp stays on half and no work has been done to the cooling system, the only thing i do is top up the water once a month.

[e30-EVN]

on tick over, is the heater output sort of luke warm and then hot when revved?
if so this could be fairly normal due to the freezing temps outside ect,

when revved the water pump obviously spins faster and pumps fresh ''hot'' water through the matrix which then gives off heat.

as long as the heater output is not 'freezing' on tickover i wouldnt worry to much, and halfway on the temp guage is about right!

[eltel]

if youu're topping it up once a month you may have a slight leak somewhere...i dont top any of my vehicles up that regularly and the level stays the same.

if you do have a slight leak you may have a bit of air in your system.
if you have no leaks monitor that coolant loss to ensure it isn't the head gasket.

but as e30-dk says it is cold and wouldn't worry about tick over heat is luke warm

[e30-EVN]

if youu're topping it up once a month you may have a slight leak somewhere...i dont top any of my vehicles up that regularly and the level stays the same.

keep your eye on that, i hope its a 'slight' external leak for your sake rather than 'internal'. but bmw's seem to find there own level in the coolant tank and stay there.
suggestion..... when it reaches the point you normally top-up, mark the tank with a pen and watch it for a few days (without a top-up).

how low does the level go when you decide to top-up?, out of curiosity

[Jim320i]

Anti Freeze...

[stbaz]

impeller on the water pump ..... thermostat...... or more common of all check to see if the bottom of the radiator is "bowed" if it is id be changing the radiator...dont ask me how but we have changed double figure amounts of bowed bm radiators curing the same symptoms you have

baz

[Greeny]

thermostat is stuck open.

[eltel]

baz..thats interesting about the rads, worth a look

[harry_p]

on tick over, is the heater output sort of luke warm and then hot when revved?
if so this could be fairly normal due to the freezing temps outside ect,

when revved the water pump obviously spins faster and pumps fresh ''hot'' water through the matrix which then gives off heat.

as long as the heater output is not 'freezing' on tickover i wouldnt worry to much, and halfway on the temp guage is about right!

rubbish! even at -10 or -15 once the engine is up to temperature (which it should be within 5-10 minutes is the thermostat is working correctly) the heater should be producing lovely hot air.

if it needs to be revved to do so then the coolant can't be circling properly, which means either the water pump or it's drive aren't working properly. even at idle there should be a decent flow of coolant.

a slow / stuck open thermostat could cause similar symptoms as more revs = more heat = warmer cooling system, BUT if the thermostat was suspect it would take ages for the car to warm up and in low temperatures the gauge may not ever make the halfway point.

if you decide to change the pump you'll be draining the system anyway so you may aswell go the whole hog and flush out the radiator and heater matrix while youre there.

[aceifty]

i was trying to remove the airlock and the temp gauge was on half, the car was running for an hour but still not giving heat, as i had revd it to about 3000rpm it gave heat but the temp went up to three quarters. it has never overheated.

[Rich_W]

I'd go for Water pump personally. Take the little return pipe off the header tank aim it into the OPEN neck of the tank. Start the car up and run it. Water should be pumped up constantly. If it isn't then the pumps at fault.

Might be thermostat, but unlikely. To rule the stat out start the car up let it run for a bit then check the hoses going to the radiator. When they are hot. a couple of them will be stone cold. Then after a while the stat will open and they will ALL be the same temp.

The level dropping a bit would indicate a leak, but it would need to be a substantial one to draw an air lock that wouldn't self bleed out.

[aceifty]

iv just checked the water pump and the thermostat and both are fine but still no heat and now the temp goes up to 3 quarters, it has never overheated as i turn the temp off when the temp goes to 3 quarters. but the car still drives fine.

This is doing my head in need it sorted asap.
can someone help?

[stbaz]

ive already posted this but seriously .....CHECK THE RADIATOR!!

if its bowed at the bottom...change it .

from previous post...
impeller on the water pump ..... thermostat...... or more common of all check to see if the bottom of the radiator is "bowed" if it is id be changing the radiator...dont ask me how but we have changed double figure amounts of bowed bm radiators curing the same symptoms you have

baz

[aceifty]

got it sorted, was just an airlock.