Radiator replaced but have problems with coolant oberflowing

[318ti_IL]

Hi guys, hope this is right category to ask...

My radiator broke and I got a new one but coolant is overflowing bottle (going back). Everything seems to be fine except one thing:

Coolant is reaching thermostat (hose before thermostat is hard and hot) but not passing thru it (hose feels empty and cold behind thermostat). I am guessing thermostat is closed (locked) and not opening so temp is pushing coolant back ? Temp gauge stays in the middle.

Should I worry about water pump and how to check it is it good or not? If helps to figure out - small line (size of straw) on top of the bottle is sending coolant to bottle but pressure is weak.

[dave45056]

Check your water pump.

The water pumps have been known to fail (plastic Impeller breaks off). I had a similar situation happen to me and it is relatively easy to check. You don't need to replace any gaskets if it's not the culprit, too.

Drain your coolant at the radiator
Take all of the bolts out of the water pump.
With large channel lock pliers, grab the body of the WP, and give it a twist in both directions.
Then try to pull it out. Use the jacking screws if you need more leverage, but only after twisting the WP to free up the housing.
When you re-install it, be sure to clean the bore and use o-ring lube or vaseline on the o-ring.

[318ti_IL]

Originally Posted by dave45056

Check your water pump.

The water pumps have been known to fail (plastic Impeller breaks off). I had a similar situation happen to me and it is relatively easy to check. You don't need to replace any gaskets if it's not the culprit, too.

Drain your coolant at the radiator
Take all of the bolts out of the water pump.
With large channel lock pliers, grab the body of the WP, and give it a twist in both directions.
Then try to pull it out. Use the jacking screws if you need more leverage, but only after twisting the WP to free up the housing.
When you re-install it, be sure to clean the bore and use o-ring lube or vaseline on the o-ring.

Thanks for your reply but how to check pump once when is out ? Look for broken plastic parts ? I was thinking to try car with out thermostat at all, what do you think about that idea ?

[dave45056]

Originally Posted by 318ti_IL

Thanks for your reply but how to check pump once when is out ? Look for broken plastic parts ? I was thinking to try car with out thermostat at all, what do you think about that idea ?

Just check the water pump. It's so easy to do it.
If the impeller is broken, it will be obvious.
If this is not the problem,move to the thermostat.

My guess is that the failed water pump killed your radiator.

[318ti_IL]

Thanks I will try it, and once when I get results will post them here.

[318ti_IL]

Didn't have time to check water pump but thermostat is bad (not opening). When I got home my dad took thermostat out and tested in hot water, so he's bad 100%.

[dave45056]

I would still take out the Water Pump just to check it. Especially since you already drained the coolant. To look at it and put it back requires no gaskets to be replaced.

By the way, make sure your dad boiled the water. The thermostat opens at 92*C which is close to boiling. The reason I ask is that these thermostats fail more in the open position than closed.

Also, what year is your car? The thermostat on the M44 is integrated into a plastic housing, but the M42 is seperate with an aluminum housing.

[cooljess76]

don't forget to properly bleed the cooling system:
http://www.318ti.org/forum/showthread.php?t=27983

[318ti_IL]

dave45056: Car is '97 and yes thermostat was bad. Looks like he caused radiator to overheat and crack as well. Thanks for help.

cooljess76: I didn't forget and and seems to be fine. Last time when I replaced heating line I did same thing so I know how to do it. Thank you anyway for reminder !