Overcooling, but overpressured cooling system
Hey all. I've got an L33 swapped into my BMW and have been having some strange cooling system issues lately. A little back story:
I had tried to make the truck water pump work with this swap (it did, initially), but I eventually wound up having problems purging the cooling system of air, since the WP outlet was the highest point in my cooling system and the BMW uses a closed system. I tried to bleed it for hours...some of the air was coming out as bursts of steam, indicating that I still had significant air in the block/heads.
The bursts were pretty violent and I feared that my radiator or hoses might blow, so I gave up and ordered what I thought was an F-body WP, swapped the pulley, etc. I reused the truck thermostat and housing (separate pieces, since the motor is from '05).
Now, the car stays around 150* while driving at highway speeds, but warms up to ~200 when stopped. I can smell coolant as soon as the motor gets some heat in it. Figured the t-stat was failed open or stuck partially open...no biggie. But when I removed the rad cap the next day, there was pressure in the system and my reservoir (which had around 3-4" of space above the coolant line) was completely full and there was a small puddle under the car.
I did some reading and found that you are supposed to use the thermostat style from your WP...well, my truck t-stat and housing fits my car style WP exactly the same as it did the truck WP. I must have a newer version of the F-body pump. I pulled the thermostat and it is not stuck open at all. It seems fine.
WTF? At first it was overcooling and not a big deal...but it is showing symptoms of having been overheated all of a sudden. Is it feasible that when I had tried and failed to bleed it previously, that hot spots were created that warped/cracked a head or blew a HG? What else could this be? Bad rad cap? Doesn't seem to fit the scenario...
I've got to be missing something...any ideas?
Also, I am new to V engines...how do you tell which head has a problem, if there is a HG/cracking problem? I only ask because one head could probably be pulled easily...the other requires the drivetrain to be pulled.
Cliffs: car runs too cold, but also has overpressurized cooling system. T-stat seems fine.
I had tried to make the truck water pump work with this swap (it did, initially), but I eventually wound up having problems purging the cooling system of air, since the WP outlet was the highest point in my cooling system and the BMW uses a closed system. I tried to bleed it for hours...some of the air was coming out as bursts of steam, indicating that I still had significant air in the block/heads.
The bursts were pretty violent and I feared that my radiator or hoses might blow, so I gave up and ordered what I thought was an F-body WP, swapped the pulley, etc. I reused the truck thermostat and housing (separate pieces, since the motor is from '05).
Now, the car stays around 150* while driving at highway speeds, but warms up to ~200 when stopped. I can smell coolant as soon as the motor gets some heat in it. Figured the t-stat was failed open or stuck partially open...no biggie. But when I removed the rad cap the next day, there was pressure in the system and my reservoir (which had around 3-4" of space above the coolant line) was completely full and there was a small puddle under the car.
I did some reading and found that you are supposed to use the thermostat style from your WP...well, my truck t-stat and housing fits my car style WP exactly the same as it did the truck WP. I must have a newer version of the F-body pump. I pulled the thermostat and it is not stuck open at all. It seems fine.
WTF? At first it was overcooling and not a big deal...but it is showing symptoms of having been overheated all of a sudden. Is it feasible that when I had tried and failed to bleed it previously, that hot spots were created that warped/cracked a head or blew a HG? What else could this be? Bad rad cap? Doesn't seem to fit the scenario...
I've got to be missing something...any ideas?
Also, I am new to V engines...how do you tell which head has a problem, if there is a HG/cracking problem? I only ask because one head could probably be pulled easily...the other requires the drivetrain to be pulled.
Cliffs: car runs too cold, but also has overpressurized cooling system. T-stat seems fine.
Last edited by TurboSportTSi; Nov 19, 2013 at 07:26 AM.
