: Air-Dam / Belly Splash Guard importance on cooling your N*



Raze
07-22-09, 04:14 PM
Well it's been known on other GMs that if you remove the plastic air diverter from the front bumper to the radiator support you can have overheating issues, well guess what, same applies to your N* powered Caddy.

I did some testing while mine was out, and at 50-70MPH on the highway in 90deg ambient temp travel the temp would creap upwards of 220-230 and stay around there under light load, I never punched it as I didn't want to see how hot it would go. It also tends to lead toward unstable temps in around town driving, I can only assume because at lower speeds you don't end up getting any airflow leading to poor cooling, I did notice that just idling along the temps would stabilize as normal back toward 200-210.

I added the air diverter and guess the difference, now on a 90 deg day my ambient at 50-80 MPH remains at 197F, no matter how hard I push it, I ran it up to 120MPH and it actually got back down to 185F. Needless to say my around town driving saw much lower temps and it took me driving stoplight-to-stoplight like a turd to get it up to 224F to get the fans to kick on, but as soon as I'd drive it at more than 5MPH with the diverter in for longer than 30 sec I'd see 10 degree drops almost instantly.

Long story short, if you are having ANY cooling issues with your coolant system, add checking for the presence of your air-dam/diverter to the list.

I am positive that if it had not been in place and I had pushed the car on the highway I could have easily overheated it FWIW...

STSS
07-22-09, 04:47 PM
I am not questioning the importance of the "diverter", but I have been driving my STS without one for a couple months now (chasing down CKP sensor problems) and I still have not seen my temp go above 12:00, not even 12:01. I hit 125 on the way in this morning and temp never moved at all.

Submariner409
07-22-09, 04:53 PM
That splash shield/air diverter causes a significant increase in airflow through the radiator and over the engine - necessary in a sidewinder FWD installation. It may not be all that critical, but it is a help. Also notice the squishy air dam flap attached to the hood to seal the top of the radiator sight shield. (and the CAI modification people neglect to consider the high underhood temperatures involved when they junk the stock airbox and stick a cone filter over in the front corner - instant 30 - 50 degree increase in intake air temp.)

Raze
07-22-09, 08:50 PM
I am not questioning the importance of the "diverter", but I have been driving my STS without one for a couple months now (chasing down CKP sensor problems) and I still have not seen my temp go above 12:00, not even 12:01. I hit 125 on the way in this morning and temp never moved at all.

Turn on your digital temp readout on your DIC and then see how much it actually varies, 12:00 is 190F-220F...

STSS
07-23-09, 05:58 AM
Its an 01, I dont have a digital temp readout.

Submariner409
07-23-09, 09:11 AM
For a neat toy, take a look at www.scangauge.com. The ability to monitor coolant temps and intake air temps will bust a lot of myths. I usually monitor coolant, intake air, throttle percentage, and ignition timing. There are 8 other possibles.

This is posted in about a thousand threads, but once again...........

Why does the 12:00 tick cover such a temperature range ?? Because modern drivers go freako if a gauge actually moves in response to changes, as a gauge is supposed to. What do you think Deville Dan Ditso would do if an oil pressure gauge went from 10 to 60, up and down with engine speed, all day long ?? The dealers would be swamped with useless warranty work.

STSS
07-23-09, 10:07 AM
Well I can say for a fact that since I've owned my car, it has never been up over 210, not that I tried, but I do like to beat the snot out of her every once in a while.

Submariner409
07-23-09, 12:05 PM
Some new (used) owners are unaware that the fans run in slow any time an A/C function is selected, so the temp gauge should never move from 12:00 except in desert rush-hour traffic. With the HVAC system in a mode which does NOT call for A/C, including OFF, the fans will not run until the coolant hits 224, so it's entirely possible to see that gauge move a half notch in heavy traffic. Some of these Northstars have a PCM fan over ride which disables the fans above 45 MPH. You don't need them then. If, for some reason the slow fans can't cool enough they go to fast at 236 (coolant) or 305 transmission. Why 305 transmission ? Because that fluid temp in the radiator transmission cooler adds temperature to the coolant going to the engine, so you want to get that below 236 ASAP.

It's all magic.

hnettles
01-01-11, 03:29 PM
Why does the 12:00 tick cover such a temperature range ?? Because modern drivers go freako if a gauge actually moves in response to changes, as a gauge is supposed to. What do you think Deville Dan Ditso would do if an oil pressure gauge went from 10 to 60, up and down with engine speed, all day long ?? The dealers would be swamped with useless warranty work.

I used to own a 2000 Ford F250 with a 7.3L diesel engine, and did a lot of reading in forums specific to that truck / engine. There was a long thread about the oil pressure gauge in those trucks, and how it ALWAYS read either 0 or 3/4 scale, never the slightest variation. Someone with a good electronics background used a variable voltage source (or was it variable resistor? don't remember now, been several years). At any rate, the gauge was in reality, an on/off switch. Period. Either 0 or 3/4 scale, no other reading was possible. Worse than useless, in my opinion.

Submariner409
01-01-11, 04:31 PM
............same with my F-150: the oil pressure gauge is either at the zero tick or exactly halfway - no movement at other than engine:Start. The coolant gauge does cycle a bit, though.

The STS temp sending unit is, in fact, a variable resistor - the gauge and ScanGauge readouts move in 2 degree steps. Unfortunately there's no way to see oil pressure unless you T in an electrical gauge with proper sending unit.

mhamilton
01-01-11, 05:41 PM
Ford has been using those "dummy gauge" oil pressure setups forever... it's really is no more useful than the GM oil pressure warning lamp--maybe worse, because it fools the driver into thinking he/she knows what the engine is doing. Don't get me started on Ford's temperature gauges either...

One of the few production cars I've seen with real gauges are Mercedes. At least the older models (pre-1991, maybe also the 91-2000 series). A real oil pressure gauge that actually moves up and down with engine rpm, and oil temp. Plus a temp gauge that is calibrated in real numbers. Not that "90C" or "3 bar" means much to me, but the info is there :sneaky:

I've seen a few Eldorados with the bumper-to-core air dam missing... who knows how or why they were removed. In addition to the ram air, it probably also keeps hot air from circulating back in front when the fans are on (helping ac and engine cooling)