Car Running hot When a/c is on

[Stevens 325I]

i just installed a new head on my car and im currently running no thermastat and the car runs hot when i cut the a/c on and when i shut it off its borderline of normal temp...is this a sign my waterpump is going out or needs replacing? when i take the hose off the upper part of the radiator the pressure isnt that great its a slower stream of water i thought this m ight be because im not running a stat and its not building pressure but i have been told otherwise..any help will be much appriciated!

[Stevens 325I]

anyone have any idea?

[strad]

Thoughts:

Is system bled properly? Nose of car = highest point, heat on full hot.
Is thermostat functioning properly? It can be tested.
Is water pump functioning properly? It can be inspected.
Is fan clutch operating correctly? It can be tested.
Is auxiliary fan operating properly? It can be tested.

In that order.

edit: just noticed you're not running a thermostat. While that's not a great idea, I guess you can eliminate it as a cause!

[Stevens 325I]

Thoughts:

Is system bled properly? Nose of car = highest point, heat on full hot.
Is thermostat functioning properly? It can be tested.
Is water pump functioning properly? It can be inspected.
Is fan clutch operating correctly? It can be tested.
Is auxiliary fan operating properly? It can be tested.

In that order.

edit: just noticed you're not running a thermostat. While that's not a great idea, I guess you can eliminate it as a cause!

i bled the coolant system because my heat was not working and after i bled it it worked great and didnt run hot all day yesterday and then today its a little hotter than the day before and i turned the a/c on and i watched the temp gauge rise..i dont have a mechanical fan i replaced it with a fan that runs all the time aswell as the aux fan its running all the time aswell...


What are the "proper" steps the bled the system?
How can the waterpump be inspected?

[ekib]

For coolant bleeding do a search. People swear by different methods. Try them all and see which one works best for you (or a combination of them).

So, does the car run hot when moving or is it just when you aren't moving?

Not sure if you can tell whether a water pump provides enough pressure. You could see leaks around the shaft but that doesn't really tell you whether it's pumping enough coolant. You could take it out and see whether you have any broken blades.

You could have an obstruction in your cooling system for whatever reason. That could also make you believe that the water pump isn't providing enough coolant flow. Checking the radiator for obstructions is easy... take the fan out and check for cold spots: http://forums.bimmerforums.com/forum/showthread.php?t=1064187

[Stevens 325I]

i burped the system by taking the radiator cap off and squishing the lines and running the heat on full blast...the only thing i didnt do when i burped the system the other day was turn the heat on fullblast.. i believe the heater core had a air bubble in it or somewhere nbot allowing it to cool effeciently.. i had it sit for 15mins with the a/c on full blast and the temp gauge didnt move so i will check back in a few days and let you guys know if the burping method fixed the cooling issue...

[Stevens 325I]

ok still happening.only with the air conditioning though.as soon as i get in traffic or in the city with redlights it gets hot but if im on the open road its fine...i pulled the waterpump and its the metal one and spins fine..any thoughts?

[Bimjam96]

you can tell if the pump isnt functioning correctly if after running the upper radiator hose is hot or not. if its hot, your pump is fine. if its colder than the lower radiator hose them the pump is broken. you said your pump was okay but if thats still the case then maybe something is clogged. for example the old plastic impeller shattered and pieces are in your system and finally got lodged up to cause a blockage. other than that, try bleeding your system again. or try putting the tstat back in and see if thats the issue

[Stevens 325I]

the head is rebuilt so i know nothing is in the block...both hoses were hot as hell when i took them off..i will try the t-stat but dont see how it would be a problem..

[ekib]

If both hoses are hot as hell you likely have a clogged radiator which won't provide enough cooling so the temp difference between the hoses isn't great. Check it for cold spots (take the fan off first).

[Bimjam96]

the head is rebuilt so i know nothing is in the block...both hoses were hot as hell when i took them off..i will try the t-stat but dont see how it would be a problem..

yea i agree but you never know. the only difference it should make is take longer for your car to heat up to normal operating temp

[Stevens 325I]

ive never noticed this before but the lower part of the radiator is cold and the upper part is hot..and the car overheats just sitting there...this is really getting on my nerves...i know for a fact there are no obstructions on the head because i cleaned it myself...

[RNCaropreso]

Try replacing the t-stat. They aren't too expensive.
My friend thought he blew a head gasket and it turned out that the T-stat just wasn't opening.

[Stevens 325I]

thing was i wasnt running a t-stat when i had the overheating when a/c on..i installed a t-stat i had and the car started to overheat pretty quick..i replaced the head so i know it isnt the head gasket because thats new and there is no oil in coolant or water in oil

[randomy]

aux fan running when A/C is on?

[inked666e36]

ive heard (from a mechanic) that for a cars cooling system to work properly it needs a Tstat, not running one is your problem, as the engine needs it to cool down, if its just not there then there is no cool down function which the engine relies on. try getting a 82 deg one and see if that helps your issue. good luck

[ekib]

ive never noticed this before but the lower part of the radiator is cold and the upper part is hot..and the car overheats just sitting there...this is really getting on my nerves...i know for a fact there are no obstructions on the head because i cleaned it myself...

Yeah, it shouldn't be cold. It should be cooler and cooler as you move from upper right to lower left part of the radiator but not cold. If it's cold, that means that there is no coolant flowing through that part because it's clogged in that section.