1983 944 Cooling System Upgrades

[AC130Tron]

I posted the following on the PCA tech forum; any additional thoughts would be appreciated.

I have an ’83 944 that I’ve had since it was a year old. I do most of my own work on it. I replaced the original radiator and water pump with upgraded OE parts years ago. I live in San Antonio and the cooling system cannot keep up with the Texas heat when I’m in heavy urban traffic and I can’t use the AC for more that few minutes unless I’m at highway speeds. I often must turn the heater on full blast to keep the engine from overheating, especially in stop-and-go traffic (this is not a new phenomenon).

I’m wondering if there are any cooling system mods/upgrades, such as a racing radiator, that I can do so it’s not so miserable to drive in the Texas summer?

[v2rocket_aka944]

...are the fans working right?
even in Texas the stock 944 cooling system, when all working right, is capable enough.
Here in inland CA we get comparable temps to you...today was 90+ and come July it will get to 100-110 regularly...no issues

[thomasryan]

...and at lower rpms, a dribbling injector can run the other three cylinders lean which can make the engine run hotter.

[fiily]

I had an issue with my 85.5 where it was overheating and I had new wp/belts, lindsey silicone hoses, and bled properly.

It was the thermostat, new one fixed it all.

Junky beck/arnley piece which was replaced with a wahler and car runs cool as a cucumber now. Took all of 45 minutes and I refilled/bled the cooling system in that time.

[AC130Tron]

Thanks for the replies!

Re fans: they seem to run and cycle appropriately, and run at full speed. I have two 10” aftermarket ten-bladed fans that seem to flow much more air than the original three-bladed or even the later six-bladed fans that I’ve had on the car.

Re injectors: I replaced them about 3 years ago, so I hadn’t thought about a maybe having a bad one.

Re thermostat: I’m not sure when I last replaced the thermostat, but the coolant (50/50 distilled water/coolant with Water Wetter) is about 3 years old. Maybe I’ll replace the thermostat, just for grins. Did you use stock opening temp or a lower one?

[Alexb944]

what aftermarket 10" fan did you use? and last summer i used water wetter and 50/50 coolant it didnt actually seem to cool any better then using only 50/50 pentosin and distilled water. if you would like to save the $10 or so the water wetter is.

[v2rocket_aka944]

you might be surprised at the capability of the stock fans - they are slightly larger than 10" but the paddles are so big they probably flow 50% more than any aftermarket fan does.

the same fans (with a different shroud) were used in the 944 turbo and 968 and people don't have cooling issues with them at even past 500hp...

[fiily]

Originally Posted by AC130Tron

Thanks for the replies!

Re fans: they seem to run and cycle appropriately, and run at full speed. I have two 10” aftermarket ten-bladed fans that seem to flow much more air than the original three-bladed or even the later six-bladed fans that I’ve had on the car.

Re injectors: I replaced them about 3 years ago, so I hadn’t thought about a maybe having a bad one.

Re thermostat: I’m not sure when I last replaced the thermostat, but the coolant (50/50 distilled water/coolant with Water Wetter) is about 3 years old. Maybe I’ll replace the thermostat, just for grins. Did you use stock opening temp or a lower one?

Stock 160 deg., I took out the old thermostat, put it in a pan and it opened @185-190 deg., I also found that the opening was actually smaller when fully open on the beck/arnley thermostat than the wahler also.

Better coolant flow and the new one actually opened @ 160 deg., imagine that, a thermostat that opens when it should.

[AC130Tron]

The aftermarket fans are two Hayden 10” with eight scimitar blades, rated at 650CFM each. I used the OE fan shroud. I’ve been using WaterWetter, but I don’t know if it really does any good.

I’ve had this problem for many years, but since the car wasn’t my daily driver, it wasn’t a big deal. My wife’s car was totaled by a hail storm, so she’s driving my Acura daily until we can afford a new one for her. I have to drive my 944 several times a week for now.

Maybe I’ll try a 160º thermostat to give the system a head start on getting the heat out.

[v2rocket_aka944]

different thermostat only sets a temperature FLOOR but does *nothing whatsoever* related to running hot.

as long as its not close to or in the block to the right you're ok...of course cooler is better but not really a big deal until you get close. 105C is where things start to get interesting...

[AC130Tron]

Things get interesting, i.e., approaching 105º C a lot. That’s my problem. As the temp gauge inches towards 105º C, I shut off the AC (if on) and turn on the heater full blast. Not fun in the San Antonio traffic!

[9FF]

It sounds like your fans are not coming on soon enough, a bad or mismatched thermoswitch will do that?

There are various temperature variants of the thermoswitch and iirc they are matched a little higher than the temperature of the thermostat.

[thomasryan]

Synergy......and overlooking the obvious signs of a bad radiator cap))

Pressure test the cap and system.

Get an infrared thingy and see what the temperature drop is across your radiator.

Weak coolant flow can be from a sheared or corroded impeller.

Freon temps and 'round here, BUGS. I was coming down from hot springs/max patch the other night and the bugs sounded like rain on the windshield. I actually had to pull over and scrub therm off with a towel.

[sausagehacker]

I live in Houston and also have an '83. Believe it or not, I actually only run with 1 fan year round, and daily drive the car in the city. It never even reaches the middle line - that's with a new WP, Wahler T-stat (lower temp but only because water temps rise quickly in this climate), and the fan switching controlled by my Megasquirt. I tell them to come on at about 180F, with 10F hysterysis.

[AC130Tron]

I got an IR thermometer and checked temps all around the cooling system as the car warmed up, the thermostat opened, and the fans came on; the thermostat and fans came on at appropriate temps (OE temps). After reaching operating temp, I ran the car for about 10 minutes on a 90°F day. The temps remained pretty stable and the fans did not shut off. I recorded the temps on a cooling system diagram from Clark’s garage. I was surprise by two things: 1) the temp at the inlet hose going into the radiator was 205°F, but I measured 230°F on the front of the radiator on the inlet side; 2) I measured 190°F on the front of the radiator on the inlet side, but temp at the outlet hose going out of the radiator was 205°F. I don’t really understand what’s going on there.

I haven’t tested the radiator cap yet, but I will.

[djnolan]

Did you measure on a black surface or a metal surface? I have read IR thermostats are more accurate when shooting against black.

[AC130Tron]

The radiator itself is black and I installed a screen in front of it to protect it from small road debris (and it’s clean).

[v2rocket_aka944]

Well, based on the temp readings and your gauge description..the gauge is working

Is all the original ducting present between the front spoiler and the radiator?

[Jfrahm]

Try removing the screen?

[v2rocket_aka944]

Originally Posted by Jfrahm

Try removing the screen?

Yeah, depending on how tight the screen "holes" are you might be surprised at how much airflow a screen actually blocks.