e46 gets hotter the faster you drive - BMW Forum

marko.j.t · 07-23-2008, 05:45 AM

hi guys,

new to the site and looking for some advice.

i drive a 2000 320d the 136bhp model. it is not an se and therefore doesnt have a/c.

i previously had problems with the cooling system after i changed the coolant but resolved that problem by eventually bleeding the system properly, however for the past couple of weeks the operating temperature seems to sitting slightly higher than it should. also when driving the car slightly more agresivly (revving up to 3000rpm) the temperature gauge steadily increases as i increase my speed. it does not go into the red but does go very high. if you slow back down to normal cruising speed it will drop back down, after a short period of time, to it being what i think is slightly higher than it should be.

the heater is not blowing any hot air. i was advised to change the heater valve which is done but has not resolved the problem. both hoses leadind to and from the valve are hot. could it be the auxillery heater?? could this have anything to do with my high temperature problem????

witeshark · 07-23-2008, 08:50 AM

Has the water pump been checked? There could be something restricting the coolant flow also.

darkhorse737 · 07-23-2008, 09:45 AM

i have a funny feeling you don't have enough coolant in your system. Have u checked coolant levels?... maybe check fan operation if yours is electric.

the temp going up and down tells me.. your pump, thermostat, radiator are fine.

RE: heater-lines TO & FROM are hot means valve is operational. If yours is the model that uses an auxiliary pump, then i suggest you test that first. Other than that, the only other fault u might have is the plenum or blend dorrs inside your cabin not operating in-step with ur climate control switches

and NO, this issue has nothing to do with HI-temp... UNLESS, you have a leak in the heater core or heater lines ;-)

darkhorse737 · 07-23-2008, 10:32 AM

ADDENDUM: i forgot to add, air pockets in cooling system especially in the thermostat head will also cause the symptoms you are seeing. Try refilling your cooling system and re-bleed. I squeeze the radiator hoses while bleedin to purge all the air, and then 1 final squeeze and HOLD the hoses in squeezed position- close and tighten the bleed screw; then release hose.

:-) Cheers