Hi,

I've tried to solve the overheating issue on my 305 for quite some time now and made the following changes:

• 3 Core Aluminium Radiator
• Two Fans + Shroud
• Checked and corrected the Fuel Pressure (was running lean which also contributed to the Temps)
• New Water Pump (supposed to be heavy Duty, but thats probably only a buzzword)
• Cross checked my aftermarket temp gauge, its spot on

I live in quite a hilly region where we get around 100 degrees (Fahrenheit) on hot some days (or even a little more).

Made two test drives the last few day on nearly the same conditions:

• With heater on, but the heater fan working on minimum (not really any hot air getting in) + both radiator fans running
  • Even on long and step serpentine roads it will rarely go over 220-225 and will drop down to ~205 (or even below) as soon as the road is going downhill or a long stretch at constant rpm's
• Without the heater on + both radiator fans running (actually turned it off because who keeps it running in the summer):
  • Wouldn't cool down below 225 and went up + would have probably started cooking but I stopt to let it cool down

How can the heater water circuit make such a huge difference??

I know that the following issues are still on my list ot be checked, but how could they be connected to this whole heater business??

• Replace the EGR (may not work properly)
• I still have a vacuum leak somewhere (fixed a few already) because my vents inside won't work
• The Airdam is there but I really think its on the wrong position (its a little bit behind the front of the radiator, looks like it was always there, but it should be flush with the front or not???)
• I am not sure if I have a thermostat in there

Would be grateful for any tipps (also about the airdam position) and especially how the heater features into all of this
(At least I'm happy its not getting too hot anymore with the heater on)

 

The heater core is a small radiator under the dash, It works just like the 3 core you bought for the engine. The fan blows across it and it pulls heat out from the hot coolant and blows it on you. This is why your car runs cooler with it on, consider it your 4th core.

For your air dam, it should be all the way to the front of the lower radiator support. I have an A/C car and it is in front of the condenser. I also have a curved plastic shroud about 10" in front of the air dam that creates a 'AIR GAP" to direct the air through the radiator. Is this piece on your car?

Assuming all your plastic air directors are in place IMO you have a "flow" problem and maybe to much. If heavy duty is not a buzzword and it is a high flow you may be pushing the coolant to fast through the radiator. The coolant does not spend enough time in the radiator for it to pull the heat out. Not running a T-stat would be your issue so I would check that STAT. With that radiator you probably should use the stock 195. I don't think your EGR systems have anything to do with this. People remove the EGR valve all the time. A vacuum leak to cause the engine to run lean would also cause a high idle or something.

It could be system pressure which affects the flow. Make sure you used the proper pressure cap. I think 10-14lbs. Does your coolant tank fill when hot and get sucked back into the radiator? Not to familiar with those aluminum radiators but all systems have some sort of pressure/coolant overflow.

I found this "flow" out on my stock system. I repainted my T-stat housing and decided to not put back in the stock t-stat. I thought it would make the car run cooler right? Well I took it for a drive and drove that temp right up to red line! I let it cool. drove back home, reinstalled a new 180 and the car runs @ about 190 all the time and 210 with the A/C on.

.

 

Thanks!!!

That was a little bit of my theory too (about too much flow) but I would not have thought the heater system would make such a huuuge difference (the ventilation is still set on minimum so you won't even get hot in the car).

-I will definitely check out the Thermostat + my air dam is definitely too far back from your description (for testing purposes I still have my old banged up one, will install that where I think it should be)

 

Back in the day it was common practice to turn your heater on when sitting in traffic and it would keep the car from overheating. Here is a pic of my air dam and curved plastic in front.

 

Thanks again for the pic!! I will try to replicate it

The curved piece is definitely not there, but I'm not sure if this is maybe a difference between Camaros and Firebirds? (From what I've read it also depends on the spoiler package?)

 

I used to do that! Not a fond memory.

The temp gauge would rise toward the read area in my '90 Formula with a TBI 5.0 when I was stuck in traffic on the GW Parkway while heading to/from work in DC. I'd blast the heater and it would come down a bit. Don't know if I really had to do that, but seeing the gauge drop a bit made me feel better. In 95 degree, high humidity weather in DC, it made for some hot rides home. But when I was young, I rarely even used air conditioning and preferred to have the windows down.

Funny I never had to do that in my TPI 5.0 Formula or in my 5.7 GTA.

 

If your unsure it has a thermostat, First things first pull the thermostat housing and replace it with a stock temp thermostat.

Have you checked your ac evaporator to make sure the fins are not clogged up with dust etc? It could be simply that the air will not flow through the evaporator so your brand new radiator is not getting enough air flow.

If your AC works and has pressure I would pull the radiator and take a pressure washer at low setting and clean the evaporator from the back side spraying through to the front (the reverse of normal air flow to help blow out crud). If you AC doesn't work and doesn't have freon in it I would simply remove the evaporator and see if temps are better then replace it and fix the AC based on the temps you see in your area.

I live in north GA, it was 102F yesterday and hilly etc (you might be interested in Helen GA as it looks like it should be in your country)

Timing and Air Fuel ratio can also cause a otherwise healthy engine to over heat. But since your heater core pulls the temp down.

Exhaust leaks as well as clogged exhaust can also cause it to over heat because you are heating the engine bay or restricting the exhaust flow building up heat. If you are running the factory cat still might be worth testing it with that off the car.

The air dam only really effects cooling at speed, I can let my car idle indefinitely even during the summer and it doesn't get that hot. I also drove it for years with the air dam destroyed by a piece of big truck tire that went under the car. It still never over heated.

 

I was about 7 or 8 when my dad would take me to Mets games @ Shea and on those hot summer days sitting in traffic waiting to exit the interstate, he would always run that heater "just in case" I could never see the gauge or even know if our mid 70's Torino even had one.We always had the windows down back then also. My dad past a few years back and when I was reading this post that memory just came flying back. Because I was young and did not really know the concurrences of overheating in traffic on a 95 degree day, this is a pretty fond memory of this practice.