Issues (if any) w/ "free" revving-coolant light?
 

OK. Let me be clear... this is immature... I know. However, we wanted some new footage for our club media team and an exhaust flame is always nice to have on file. Well, being 1 of 2 cars in the club with a mid-pipe, I opted to do the deed. I normally don't "free" rev much (revving in neutral), but I needed to consistantly pop flames for the cam and this is the only way I can do it. I rev the car up to 8-9k let off and tap back on the gas quickly, keeping the revs 7-9k the whole time. In order to get good camera shots, I did this in 3 sessions at 10-15 seconds each( :slap: ) with a 30-60 second cool down in between. Well during the second session using a fully warmed car (heater on/ hood popped/ ambient temp 43 degrees) I got a 1-2 second illumination of the coolant light. :dunno: Perhaps my waterpump cavitated and created enough bubbles to momentarily trip the sensor? The car acts perfectly normal, but I will check the level tommorow as it is pitch dark right now. More to the point however is my concern about extended free revving. I would assume it to be less stressing than to have the car wind out to redline in gear as this would likely increase the flex of the e-shaft, no? I would think the thermal strain would be higher in gear as well, or am I nuts? Any thoughts/experiences? Did I kill her?

Checked coolant and everything was OK. Sorry for the rambling. It was late and I was tired. Any thoughts on what may have triggered the coolant light?

Did you do all the update to the PCM ? cuz if u dont you shouldn't be able to free rev at 8-9 K for that long ....

Anyway, there shouldnt be any damages ......

but after the revving, its better to drive it around to cool it down,instead of just sitting there.

Drive it around slowly will give it better airflow (simple physics, u know) and it cools down better.

Yeah, not the "official" recall flash (T) but I am on the S flash. (I thought iut had to be a steady RPMs at a longer rate for the "R" flash to cut revs.) I also noticed the cooling fans did not come on til after the last session.

I think the stock fan 1-on temp should be around 97c, which is pretty high if u ask me.

S flash should cut your revs .... but the flash's logic is pretty stupid if you rev it and back down and rev it back up right away, it wont limit it.

The difference is, revving in gear means the car is moving, and therefore shedding a lot more heat through the radiator and the oil coolers. Sitting still, you're more likely to spike the coolant temperature, and get localized hotspots. Combine that with waterpump impeller cavitation at redline and I'm guessing you had some localized boiling of the coolant.

I agree.

That and you should probably let it cool for more than a minute between runs. Espically if the car isn't moving.

When you get above 7,000 rpm, the water pump starts cavitating, and gets worse as rpms increase. That means it's not pumping nearly as much coolant as it should, and your motor can heat up FAST. When you're driving, air is coming past the engine and at least cooling it down some; but when you're sitting still, you're getting little cooling at all. Underdrive pulleys will help with the cooling above 7k, but bottom line, don't do it!

the coolant light is just your level sensor, your gauge would have told you if you were really overheating. during one of your 9k rpm pulls the level got low enough in your tank to trip the light for a second. take a look at teh difference in diameter of the inlet and outlet hoses for your coolant tank.... the outlet is larger than the inlet. which to me means that it can remove it faster than it can put it back

Where does the coolant hide when it's pulled out faster than it's put back?

Hint: flow is a function of pressure and diameter, not just diameter.

hint: pressure is constant in a closed system. so with that being equal we can go with diameter.
the coolant obviously hid somewhere... the low level light came on for a second
but where.. i dont know. expanding rubber hoses, air pockets from a previous service, maybe it wasnt as full as it needed to be