Car cooling issues? maybe?

Might be paranoid or it could be the exhaust fumes getting into the car but anyway...

I noticed that when im at low speeds or stopped with the fans on the car sits at about a hair under 180*F to about 185*F. When im driving at speeds over 25mph, it actually starts to get a little warmer.

The commute to work was okay, freeways getting about 195 degrees at maybe 55 ambient temps.

I noticed yesterday during my commute home from work, doing freeways speeds (65-70) the car got rather hot like 230-235*F. Or is that even reallly THAT hot? this was flat ground, no hills. Hills caused a little creep, but not much. Outside temp was 95 degrees. Fans on or off didnt make too much difference. This was the same situation the weekend of the Idaho Rally driving in to the mountains. Not even really "getting on it" the car just got hot going up hills but cooled down once i was flat or going down hill in neutral.

I had no ducting around the radiator AT ALL. Nothing. So im thinking there is less resistance for the air to go around the radiator than through it at higher speeds. So last night I made some ducting from aluminum. Need to support the lower part since it bent down on the freeway (doh!) and the one side was rather complicated so i want to use rubber there instead of Al.

Going to work this morning, its cooler outside (55ish) and the temps where better at about 195. So it could be the bent ducting on the bottom, but not really looking too different. I'll see on the way home.

thermostat is 180*.
miata 1.6 engine
saab 900 turbo radiator and fans
nothning fancy about the coolant
4,78 gears


thoughts?

---

First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023

Are the fans moving air in the correct direction?

---

Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

yup, confirmed that a while back.

i also run with the fans off on the freeway because technically, they shouldn't be needed

---

First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023



Edited 1 time(s). Last edit at 06/18/2013 08:54AM by Gravity Fed.

Head gasket. Time to well it. Or just add some water wetter.
It's convertible? Open roof, turn heat on high.

---

Grant Hughes

its the rally car.

your thinking headgasket, eh? what do you mean well it? might explain the utter lack of power the car has (and maybe the consumption of oil) but its not consuming coolant at all.

---

First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023

Sell it. Stupid phone.
I always just say it's the head gasket.
Merkur would get crazy hot which was why I could never run more than 10 lbs of boost in competition. It was way more fun at 20 lbs but I figured 10 lbs was better learning anyhow.
Combination of huge spaces around the radiator and huge skid plate leaving nowhere for the air to leave under the hood.

---

Grant Hughes

Ducting. I recently ran into this after taking my under-bumper panel off in October. First time it got warm this year, car starting running 220 on the highway (instead of 160-165 like it should) and would take a LOOONG time to cool off.

After installing a new 'stat and backflushing the radiator/washing the fins to no effect, I put the underpanel back on and poof - no more running hot.

It's NEEDED otherwise the air'd rather go through the wheelwells because air is lazy.

The clue for me was after I took off the stock-type struts and installed the not-quite-Super-Bitchin-but-still-8"-of-travel FrankenStruts which raised the front end maybe two inches and the problem got severely worse. Like pushing 230 just driving at 60mph at NIGHT.

---

Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.



Edited 1 time(s). Last edit at 06/18/2013 01:24PM by Pete.

There are many articles about getting airplane motor cooling to work correctly, one point I always find interesting is the need for much larger area for the air to leave than to enter the cooling system. (air cooled motors mostly)

Air needs a path to leave the back side of the radiator, and this path likely should have more total area than the total area of the front side of the radiator.

I expect careful internet searches will bring up some details on the ratio etc.

---

In the long run reality always wins.

Quote
derek
There are many articles about getting airplane motor cooling to work correctly, one point I always find interesting is the need for much larger area for the air to leave than to enter the cooling system. (air cooled motors mostly)

Air needs a path to leave the back side of the radiator, and this path likely should have more total area than the total area of the front side of the radiator.

I expect careful internet searches will bring up some details on the ratio etc.

Quick search from memory bare out whacher saying--let air out, utilise low pressure/high pressure differentials and remember inverse realtionship between speed and pressure:

Oh what are those triangular holes there immediately behind the rad?

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

just 'cause I'm bored, I dug up some pics.





We need pics of the newly ducted rad, stat!


I thought the ducting in the later WRC focii was pretty interesting


but looking at the fiestas, they appear to have dropped all that in favor of a simpler setup:



(I think the answer may be: solid ducting + bigger hole in the hood to pull that air out)

---

KF7RWG
http://www.utahrallygroup.com

I stink pretty surely I told him to close off the gaps. Force the air in thru the rad.
Rubberoid sheeting would do for the most part, but often for the ease and price, a nice bucket chopped up works good if its the right color:


Chop it up, cram it in and then
duct tape sealing the edges.. Duct tape comes in lotsa nice colors including some appropriately Sooper Bitchin ones:


It'll be a thing of beauty.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

We used to pin the back of the hood up a bit on the 7's to keep them cool with rotaries. No ducting is bad juju as pictured. The air will just roll around the edges of the radiator. The bottom valance or lip provides a low pressure area for the radiator to exhaust the air from also.

Then in other news, in a properly functioning cooling system your symptoms describe a slightly plugged radiator. They will cool ok around town but lack the capacity to cool at the power required for freeway speeds.

Quote
heymagic
We used to pin the back of the hood up a bit on the 7's to keep them cool with rotaries. No ducting is bad juju as pictured. The air will just roll around the edges of the radiator. The bottom valance or lip provides a low pressure area for the radiator to exhaust the air from also.

Then in other news, in a properly functioning cooling system your symptoms describe a slightly plugged radiator. They will cool ok around town but lack the capacity to cool at the power required for freeway speeds.

Good point. It was a junkyard rad, but unlike here where it really doesn't get very cold and saab owners are lazy on keeping good fresh coolant in the car, he got his rad over there where its snowy for 7-8mo/yr except when its baking hot..Means better care with coolant so probably not too plugged---although on the 3rd hand the saab rad is a "high efficiency" rad with more tubes and more fins and those tubes are smaller ID..
BACKFLUSH!

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

well the ducting doesnt seem to be doing much of anything. Also, if im cruising along at 60, and push the clutch in so the engine speed drops to 800 or so, the temps plummet immediately.

I wonder if i am running too much timing...

---

First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023

If you don't have an IRT get one, or two, they are cheap these days. Check the temps along the hoses and such with it. Look for cold spots in the radiator or run you hand over the core. Cold spots indicate plugging. Usually at the bottom 1/3 of the radiator. If you find cold then pull it and take it to a shop and have it rodded out, backflushing rarely works well on plugged radiators.