Unofficialbmw.com

[Soup]

I recently had a check engine light on, I went to autozone and read the ODB-II code which gave me
P0740 Torque Converter Clutch Circuit Malfuction
I went to my dealer and asked them about the light. They told me the same code was pulled and a thermostat sensor or something being closed. (I never saw that code from autozone). They called a tranny specialist who told them that 95% of the time you need a new tranny with that code, and it would be about $450 to replace the thermostat. For like $3500 they would replace the transmission (not even looking if it needed it necessarily, i.e. I read about looking for metal shavings in the bottom of the tranny pan or something).

I drove the car for about 2 weeks off and on locally knowing this. I left the car running about 20 minutes on my driveway as I was going somewhere else in a few and came out and saw the car smoking and coolant was all over under the car. I shut it off immediately and lifted the hood and the coolant overflow tank was melted slightly or shredded either from the fan or the heat of the engine.

My question to you- Since the car engine was overheated for some X amount of time and was smoking. If I replace the thermostat, buy a new coolant overflow tank to replace the old one, I guess perform a coolant flush as well… What else should I look for or check to ensure the engine / oil / other engine parts are toast or need to be changed / checked before spending money and energy doing the following? Also, If I do all that and everything else seems fine, how difficult is it to manually check the transmission looking for metal shards that would indicate a replacement is required soon. The car is a ’98 BMW with 118k miles that is still in good shape and I would like to keep it since I spent about 2k on it over the last 2 years with new tires, new radiator, new brakes, etc….

Thanks for any / all help!!

[walshja]

you can easily replace the thermostat without removing anything but the fan shroud if I can remember correctly.

I would replace the thermostat and the housing, as well as the expansion tank, and check your hoses, and fill up with fresh 50/50 BMW antifreeze. make sure you bleed the system properly

then see what happens. that will only cost maybe $150 in parts, and a couple hours of easy labor.

BMW doesn't fix transmissions, they replace them. you may want to visit an independent transmission mechanic.
_________________
joe

1994 325iC, 195k miles
http://home.comcast.net/~walshja/index.html <--- check it out

[Soup]

Thanks. I will do that and see what happens. Flushing the coolant and replacing the thermostat look simple enough as I've seen a couple DIY's showing how to do this. Do you know any good links or resources to change the coolant tank? Or do you have some simple instructions, from peering at it from above it doens't look that difficult, but I have big thumbs.... Also, how important is it to use a torque wrench for these parts?

[yelcab1]

I think you do have to remove the fan, but that is not too bad. it is reverse thread, 32mm wrench needed, and a way to hold the hub stationary.

New transmision is needed. No one rebuilds BMW transmission for cheap anymore.