spedrcr

I'll consider myself a newbie to the C55. Had it for a few months now and really enjoy driving it on a daily basis for work. My name is Nic and I live in the north end of Seattle. Above is a picture of the car. Still learning how to post on this forum so my apologies if its too big...

Coming from a highly modified '93 Audi S4 with a 5 cyl 20V turbo, I have concerns about slowly cooling down the C55 engine once I've shut the car off and park. On my Audi, I have factory thermostatically controlled after-run coolant pump triggered by a temp switch which runs coolant through the block, head and turbo until a certain temp internally is reached. I use an underhood ambient temp switch from an older VW to trigger the coolant pump and in this case the low speed fan. In over 8 years, I've never had a problem with the battery dying and the pump and fan run every time I turn off the car, even when I just run up to the corner for a six pack of my favortie IPA.

Can the same scenario be achieved on the C55 using what appears to be the same small coolant pump which is attached to the coolant expansion tank? To this day, and we are having some HOT days for Seattle, I've never heard or witnessed the pump or fans running after the car is shut down. In fact I really don't know the operation of the pump hanging off the expansion tank.

Thanks in advance. Great forum, even better search function-very user friendly. I searched but couldn't find any info on this topic.

AMGPirate

Ha. Nic - nice to see you over here. Looks like great minds think alike! (same color too).

-S4Pirate from QW.

BF_JC230

Upgrade the HVAC unit to one with [REST]...it should pump water thru the system trying to keep the cabin warm...thus pulling ambient heat off the block...but will the MB system not allow such a feature to be used....say about 40 degrees Fahrenheit?...I don't know...I use [REST] in cooler months...I have though...used that pump to circulate water/air bubbles when I do a coolant flush with [REST]...so...

K3nD

welcome o the forum nick.. I see your from seattle - maybe i'll see you on i5 on of these day. I've had mine for a little over a year now and ive only seen about three c55 in the seattle area. have fun with it!

spedrcr

Thanks for the idea on the REST feature. I'm hoping to make this a passive feature with the temp control under the hood rather than in the cabin.

AMGPirate-do you still have the S4? I'm keeping mine for now but I really do enjoy the rear wheel driving experience these days!

K3nD-an uncommon car for sure. I always see a silver one in DT Kirkland and thats about it. How far north do you travel? Happy to meet up some time.

BF_JC230

I agree...but that is an easy way to turn on that pump OEM...what you do after that is up to you...hopefully this is a lead.

spedrcr

When do you suppose that pump does run? I don't even know its duty and timing. Based on its location, it would only be a secondary/after-run pump. All other times the water pump would be pumping coolant thru the motor. I imagine it could be used as a helper pump for the HVAC...hence the REST function.

Accidental L8 apex

Personally, I don't think it's needed unless you're running a turbo. What exactly are you trying to prevent from happening by doing this? No oil cooking to sludge in the turbo is the only reason I've ever heard for these setups.

spedrcr

Just trying to cool down the engine and fluids slowly. Put it this way; back in my SCCA racing days, I would always let the car run for 15 minutes or more after I came off track from a qualifying session or race. Just good practice and everything lasted longer, coolant, oil, the engine.

Now I'm not comparing competetive racing to driving on the street but its a huge, hot running engine in a small, well insulated space that heats up before it cools down after shut down. Why not try slowly cool it down???

Then again, MBZ and AMG engineers are in fact WAY smarter than I...

gwin

you dont need to do this for naturally aspirated cars. Unless you really want to sooth your obsessive compulsive tendencies.

If people at the AMG factory couldn't factor in cool down, they'd be producing pretty ****ty cars. that's why high grade and forged material is used on the blocks.

The parts that tend to suffer heat and cool issues are the rubber bits, hoses and electrical insulation. Of both which having a 15 minute cool down running the engine makes no difference at all.

Accidental L8 apex

I used to auto-x SCCA and did the same at times, mostly just popped the hood though. In the C55, I try and baby it home the last couple of miles before putting it in the garage.