Folks,

I know that once we shut off the car the coolant stop flowing, which the temp could increase to 100c+ plus quickly.

Usually when in my garage, I have two fans blowing at my 7 after a drive; during some hot days I will even turn it back on to let the coolant flow for a bit then shut it back off.

But how do you guys manage to keep it cool if you are outside?

Ever since I have my 7 I have been extremely cautious about the coolant temp; or does it not matter how hot it gets after shutdown?

 

At home I pop the hood, but there’s really no need to do anything if you are out, as coolant temp going up after shut down will not cause any issue.

 

A vented hood is the solution here but otherwise dont worry about it. When you're home or somewhere "safe" you can just open the hood and let it breath naturally so it doesn't bake. If you're not somewhere you feel comfortable doing that then treat it like any other car. Its fine

 

does having an Ast make any difference?
I have a vented hood on my fd and it hit 240f pretty quickly after turning key off from 191
maybe 10-15 min?

 

No it doesn't. Whatever the water temp does when the car is off doesn't matter.

 

The previous owner of my car installed a turbo timer, which is unnecessary, in my opinion (he was a track instructor and time attack champion, though).

Just driving around for a few minutes is probably the best way to cool the car down... no drastic changes in temperature, and the coolant and fans can do a proper job before you turn everything off.

A lot of FD guys opened their hoods at the track, but I think it's a good idea to upgrade your cooling systems, fluids, ducting, brakes, etc. if you are going fast for long periods of time.

 

I saw somewhere that the water seals will starts to degrade at 110c+? If that's the case, when the coolant temp reaches 110c+ after shutdown, would it not hurt the water seals?

*I think I start to understand your point but just want to make sure what I am thinking is correct.

 

Just a data point: stock FD fans don't increase to High until 226F/108C!!! For me, the real question is how adverse would be to localize heating after a shutdown that starts at the temp. I SUSPECT that noting short of continuing to flow coolant (e.g. post-shutdown TT, EWP, et) will significantly lower the internal hotspots. Short of this worst-case scenario or improper proper coolant mix and pressure thermal protection, I doubt that post-shutdown cooling is that important for the seals.

On the other hand, post-shutdown cooling to prevent vacuum hose "Medusa" ossification is probably where the greatest good can be had.

 

I have an Davies Craig electronic water pump. When the car is shut off, it runs until the coolant reaches a set temperature. It's a nice feature.

 

Another ‘pop the hood’ if practical to reduce heat soaking plastics etc. Otherwise stop worrying, relax and enjoy the car.

Turning fans to blow on the engine and coming back every few minutes to start the car and circulate coolant? Well OK…certainly not going to hurt but that’s a little OCD…and I should know. Several years ago I used (IIRC) the diagnostic ground at the ECU to run the radiator fans for 10 minutes after shut down, ostensibly to reduce under-hood temps. Made no difference.

 

Like everyone else, I pop the hood at home. Other than that, just drive easy before you shut it off and it will be fine.

 

Can't remember but I think one of the major vendor, maybe Sake Bomb, sells a electric WP that I was considering, but I am unsure how reliable it is; maybe my next step.

Where did you get yours from?

 

My thought on this is, once the car is shut off, the combustion stops, which no heat is produce; though the coolant stop flowing which increase the coolant temp, but the block's temp should be stable and decreasing since there is no more combustion.. I don't know if that's a correct theory, please educate me if it is not.

 

That's correct - when combustion stops, the engine is no longer making more heat, so the coolant temp rises when you shut down because the heat remaining in the block is simply dissipating that heat into the non-circulating coolant. It will reach a maximum high temp point when the coolant & block surface contact temperatures equalize, and begin to drop from there.

 

If you really want post shutoff cooling: install a grounding switch for the cooling system recall that added the small black relay and jumper cable with the black female spade connector.
The grounding switch should go to the black female spade connector. Engage the switch a couple of minutes before turning the engine off.
If the engine is hot enough, the fans will run for 10 minutes for cool down.

This same switch if turned on while driving, it bumps up the fan speed by one for extra cooling.
This mod goes back about 24 years.

 

AFAIK having the fans running for 10 minutes after shut down will do two things…help cool the water sitting in the radiator and make you feel better…until you buy an infrared thermometer and actually check things. But it didn’t do much else for me. Probably why that mod seems to have been largely abandoned.

Just open the hood when practical. Done.

 

^Exactly, unless you also have an EWP to circulate the coolant after shutdown, running the fan only cools the coolant sitting in the radiator and does absolutely nothing for the engine. But doing do will put more wear & tear on your battery. Lose-lose modification.

Yup, that's what I do too.