overheating

[selavia]

Haven't been here in awhile... new job, travel, etc... things have been fun and interesting. THis morning topped it. Getting on the I95 and the temp gauge started going above half way. Then started to climb to hot very quick. Puled over before the light went on. I gotta deal with this when I get off of work.

I felt both hoses; top right hose extremely hot, bottom left the temp of the engine bay, but not really hot.
No leaks during normal operational temp., but when it started to overheat, anti-freeze squirted out from the little black plastic screw right next to the radiator cap / resevoir cap.


THe water pump and thermostat where replaced over 5k miles ago.

I'm thinking possible problems:

Too little coolant

Blocked radiator

Fan

Fan clutch


Any thoughts?

 

[///M SPEED]

Could be a faulty or stuck thermostat Sean, good luck with fix....

 

[selavia]

I'm going to test the fan / fan clutch today after work.

I'm hoping it's not the thermostat; I just replaced that damn thing 5k miles ago, along with the water pump and the thermostat housing.

Thanks.


Any other thoughts?

 

[nadroj]

first, try to bleed the system, it sounds like you may have air in it. Second does your heater work?

 

[selavia]

My heater works... I think. I'll definitely try those two things before anything else tonight. THanks!

 

[nadroj]

Try the heater, if it doesnt it could be a blockage in the heater core, or it just need bled

 

[selavia]

Air in the system & too little coolant. It ended up swallowing 3/4 of a gallon of 50/50 mix when I was filling it up.

I never checked the coolant level after I drained and filled the block and radiator when I replaced the thermostat and waterpump. She hasn't over-heated since, so I'm assuming that was the issue.

Thanks, Sean

 

[nadroj]

Air in the system & too little coolant. It ended up swallowing 3/4 of a gallon of 50/50 mix when I was filling it up.

I never checked the coolant level after I drained and filled the block and radiator when I replaced the thermostat and waterpump. She hasn't over-heated since, so I'm assuming that was the issue.

Thanks, Sean

hah yeah low coolant will overheat your engine.

 

[selavia]

I have a related question:

When I did the thermostat and waterpump and drained the block, I filled the system all the way up until it spilled over; I ended up using a little more than what Bentley's said the capacity was for the radiator and the engine. Now 5-6 months later it overheats because the system was just about a gallon low on anti-freeze.

I mixed 50/50 (BMW concentrate antifreeze and distilled water); should I have used a different ratio; is it normal for this motor/cooling system to require over a gallon more than what Bentley's calls for? I have no leaks, but is the system loosing coolant through evaporation? Am I making a big deal out of nothing?

 

[Big Daddy]

50/50 is the correct mixture. Bentley's mentioned amount is really an average because it depends on how you drain the system and how much coolant you get out. I have had to add after a drain various amounts, but you do need to run the car to operating temps, let her cool off and recheck the coolant. Sounds like you got her fixed though...

 

[nadroj]

You should only fill it up to the cold line. do not fill it up to the top (your radiator could blow up!)

 

[selavia]

If I fill it only to the cold line, then how the hell am I supposed to bleed it? When she cools off tonight, I'll look at the level and see where it is; I imagine that even though I filled it so much that after it ran for a bit, it'll be right around the cold line.

Thanks guys!

 

[Big Daddy]

You are correct, fill the radiator until coolant flows from the bleed screw you removed. This from Pelican Parts Tech articles,

When the system is full of coolant, you will need to bleed air out of it. This applied only to the cars that have the expansion tank attached to the side of the radiator. Other BMWs with a separate, external expansion tank are self-bleeding. The procedure for bleeding these cars seems somewhat sloppy and not too slick. With the bleed screw removed, fill the expansion tank until fluid begins coming out of the bleed screw. Continue filling until there are no more bubbles coming out, as shown in Figure 13. This, of course will mean that plenty of coolant will spill all over your radiator, and down onto the ground. Have a catch pan ready to capture this coolant spill. When no more bubbles exit out of the bleed screw, tighten it to 8 Nm (71 in-lb).
Now, run the engine until it reaches it's operating temperature. Turn off the engine and let it cool down. Then, top off the coolant in the expansion tank to the appropriate level, if necessary

 

[chief]

You could always add another fan. You will find them via Summit Racing.com. Takes about 45 minutes to install. I did on mine for the aftercooler and haven't had any problems since.

Good luck,