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-   -   Cooling System problems? (http://www.318ti.org/forum/showthread.php?t=39462)

KB_ActiveTI 11-19-2013 02:27 AM

Cooling System problems?
 
Whats up guys, i have a 95 that im working on with my father, need some ideas on a problem with the cooling system. when i turn on the car, it runs fine, but heats up as soon as i start driving. it only takes about 10 minutes for the needle to hit the red. I have kept the cooling fan in front of the engine unplugged until i drive, otherwise it will stay on. recently replaced the thermostat, also there doesnt seem to be any leaks. Anybody have any ideas what the problem would be?

1996 328ti 11-19-2013 03:27 AM

T-stat in correctly?
Do you see water circulating when you remove the radiator cap?
You sure you bled the air out of the system?

zoner 11-19-2013 05:27 AM

What caused you to replace the thermostat in the first place? Like Steven said- check for water circulating once the engine is warm. If no water is circulating, it's possible that it's the water pump, which is a common fail on these cars, especially if it's the original one.

Additionally, DO NOT keep letting the needle get to the red- you're going to end up weakening/blowing the head gasket and/or warping the head. Once it starts getting close to 3/4, especially if the fan is running, something isn't right- shut it down, let it cool, and reassess the situation. On a properly operating cooling system, the needle should not move from the 12 o'clock position once it is warm.

The radiator fan not shutting off is concerning as well. Is the A/C switch on? Could possibly be a stuck fan switch.


Welcome to BMW cooling systems... :)

KB_ActiveTI 11-19-2013 07:55 AM

yeah, ive installed the pump correctly. the reason i replaced it was because it had done this before, we figured it would solve the problem. i agree with the temperature gauge info, ive only driven it a couple times, and ive double checked the Head Gaskets just to be safe. i am going to check the water pump as well as all of the hoses around the block. there has to be a clog or faulty part somewhere. they are all original parts.

Also, is the fan behind the radiators for the A/C only? ive fixed an 85 325e with no AC before this project so im somewhat new to A/C systems, haha.

zoner 11-19-2013 08:28 AM

Is the arrow (embossed on the outward side of the thermostat) pointing straight up to the sky? This is critical.

There is only one fan on 318ti's- when the A/C is turned on, the fan runs constantly while the ignition is turned on. When A/C is turned off, the fan is controlled by the thermo switch in the radiator.

Are you bleeding the air out of the system correctly? Sometimes it takes several attempts to get it right and get all of the air out.

I'm out of ideas for the night...

1996 328ti 11-19-2013 02:58 PM

Easiest thing to look at first is to see if water is circulating by opening the radiator cap.

xxxJohnBoyxxx 11-19-2013 05:49 PM

My suggestion. Let car cool off till cold. Remove rad cap and remove bleed screw. Fill with water until fluid starts to run out bleed hole. Solid fluid this means no more air bubbles. Start car and rev lightly to remove additional air bubbles. add fluid as needed until only fluid comes out air bleed. Cap air bleed and rev a few time more and add any fluid to top off side tank and then put on rad cap. Drive car until it just starts to overheat (If it does now). Time it so you can pull in your driveway before the temp gauge is over 3/4's. Look for leaks under car. If no leaks let it cool and remove cap. remove bleeder and run car and see if there are more air bubbles in system of loss of coolant. If there are major air bubbles your head gasket is gone and allowing exhaust gas in the cooling system.

Also follow what Steven is stating about look for coolant flow. Without coolant flow it will always overheat.

KB_ActiveTI 11-20-2013 04:47 AM

i have a feeling it might either be an air bubble or a broken pump, sorry in my last reply i said pump instead of thermo. i installed the thermostat with the arrow facing up. we flushed the system today, no large particles came out, when i put new coolant in, and ran the car, the needle jumped to certain spots until it hit 3/4, (possibly an air bubble moving around?) another thing, the fan runs constantly. even when the car is off. i know some cars do this on shut off at certain times. my dads 325 does

KB_ActiveTI 11-20-2013 04:53 AM

we are going to try replacing the water pump tonight. hopefully it works out

KB_ActiveTI 11-20-2013 05:19 AM

CHECKED the coolant flowing through the Radiator cap... NO COOLANT MOVING! we will replace the pump first thing tommorow... does anybody think that might solve the fan issue?
its temperature controlled, soo if there is hot coolant sitting there, it should keep the fan on?

xxxJohnBoyxxx 11-20-2013 05:35 AM

Quote:

Originally Posted by KB_ActiveTI (Post 356694)
i have a feeling it might either be an air bubble or a broken pump, sorry in my last reply i said pump instead of thermo. i installed the thermostat with the arrow facing up. we flushed the system today, no large particles came out, when i put new coolant in, and ran the car, the needle jumped to certain spots until it hit 3/4, (possibly an air bubble moving around?) another thing, the fan runs constantly. even when the car is off. i know some cars do this on shut off at certain times. my dads 325 does


When you say the "needle jumped" is this a fast motion jumping around or a movement within a 10 second time frame. If it is jumping with quick movements then the issue is most likely in the gauge/sender.

Water pump might help if it is rotted or a plastic impeller that has come apart

KB_ActiveTI 11-20-2013 07:02 AM

yeah the needle progressively jumped upwards, no back and forth over 10 seconds. but it has never done that. only once

1996 328ti 11-20-2013 03:07 PM

When you opened the cap to see if water was flowing, did you unscrew the air vent plug?

I recently replaced my radiator and water didn't start circulating until the vent screw was removed.

You said you already replaced the water pump in post 4.
Did you mean t-stat? It's hard to see the arrow on the t-stat. At least on mine.

zoner 11-20-2013 05:51 PM

Quote:

Originally Posted by KB_ActiveTI (Post 356695)
we are going to try replacing the water pump tonight. hopefully it works out

It's sounding more and more like this could be the culprit... Impeller has probably disintegrated or is just spinning on the shaft.

Be extremely careful trying to remove the pump- they are often a major PITA to get out of there, especially if is has been frozen in there for 15+ years.

This thread may be helpful to you. I would advise against using any sort of prybar to get the pump out if it is frozen in there, especially if you are using the aluminum timing cover as leverage...

KB_ActiveTI 11-20-2013 06:20 PM

cool. yeah the plug was out. Thanks everybody for the help! the part should be coming in any minute now. ill post pics to the thread when i have time


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