I am leaning toward a radiator issue at this point also. Nothing else would really make sense given that I've been through the whole system at this point.

I have done some research on new radiators, and there are a lot of options for me to consider. I'd love to get an aluminum radiator and be done with it, but the higher cost may prevent it. When it comes to the brass/copper radiators, I can apparently get a 3 row or a 4 row version. I would certainly be willing to spring a little extra cash for the 4 row, but I am curious if the decreased space between the larger radiator and the AC condenser will have a negative impact on airflow to the radiator.

More advice wanted....

LO PHAT

 

I'm not sure if the stock radiator was 3 or 4 row, but as I have said before, mine never gets to 200 degrees with the original radiator. I have a fairly modified engine, cruise at high speeds in high heat with air conditioning on. I also drive in traffic on hot days with the A/C. The original system is plenty, but an aluminum one would be cool.

God bless, Sensei

P.S. I assume you don't have a head gasket problem!

 

At this point I'm not assuming anything....

LO PHAT

 

It ends up being cheaper not to guess.
To check the radiator efficiency you must take some test readings of the inlet and outlet temps with either an ir gun or a pyrometer. You are looking for approx a 15min to 30° temp difference.
If not, the rad is plugged.
If so, your problems lay elsewhere.

The condenser coil will have little effect on either a 3 or 4 row. They came both ways oem.

 

Take the thermostat out of the cooling system and see what happens. There will be ample people disagree with me on this, but I suspect that your new, high-flow water pump is just making a lot of heat trying to pump more volume through a 'standard' sized stock cooling system. If taking the stat out fixes your overheating problem, that pump is just to big for what you have. [it probably won't run much under 200F, but it may not head toward 240F]

If removing the stat makes no improvement, there is a blockage or a component malfunction somewhere...

 

I will give this a try when I get home from work this evening.

LO PHAT

 

The water pump is new, but it is not a high flow unit. I went with an OEM equivalent for this very reason.

LO PHAT

 

Correct!

 

It may be correct, but it is also unnecessary.
The boiling point of plain water in a pressurized cooling system @ 15psi is over 250°F.
I personally have no intention of operating my car at that temperature anyway.

 

OK. Water pump is not "hi-flow" type, so no wasted pump work. But, I still think taking the stat out and seeing what happens is a good test. You could have a "bumb" [new] stat that won't open. That test also guarantees that there is no blockage in the system (unless something is not assembled correctly). If that test also fails [engine still gets hot], it almost has to be a bad pump. {When it gets warmed up with the radiator cap off, can you see coolant flowing, or is it just stagnant?}

 

Lo Phat

lets start with the basics one step at a time.

Do you have the lower airdam in place
all radiator and core support seals in place

If so, than FIRST confirm an actually overheating issue with an IR temp gun, do NOT go by what you see on your dash gauge as they are notorious for being wrong.

IF you confirm a real problem via the IR temp gun:

Idle or low speed cooling issues are typically caused by:
1. bad fan or fanclutch
2. incorrect timing
3. inoperative or incorrect vacuum advance set-up

Highway cooling issues are typically caused by:
1. airflow restriction
2. coolant restriction
3. insufficient radiator capacity

Now you can go thru and check areas one by one to diagnose your problem

 

You can be as respectfull as you want, but you're dead wrong. Antifreeze does not conduct heat as well as water.

 

I doubt that the thermostat is defective, and let me explain why. When I start driving the car it begins to heat up at a normal rate until it reaches about 185 degrees (180 degree thermostat). At that point the temperature increase levels off. From there it takes a much, much longer time for the temperature to continue to climb. (It does continue to climb though ... always up to about 240 degrees.)

With the radiator cap off, I can see coolant flowing. For this reason I doubt the water pump is defective either (although anything is certainly possible at this point).

Regardless, this weekend the new 180 degree thermostat is coming out and a new "factory correct" 195 degree thermostat will be going in.

LO PHAT

 

OK ... let me go through this list.

- The lower air dam is in place (and the car also has a front spoiler that funnels air directly to it).

- All of the radiator seals are in place.

- I used my temp gun and took readings on a bunch of different locations throughout the cooling system (except the lower hose since the car was on the ground). The readings were all over the place to say the least, but at the inlet to the radiator the temperature was consistently around 238 degrees.

- Idle cooling issues versus highway cooling issues cannot be separated. Once the car is hot, it stays hot regardless of what sort of driving or idling I'm doing.


* * *

I stopped in Checker Auto Parts on my way home from work today. A radiator, upper and lower hoses, a radiator cap, and a 195 degree thermostat will be available to me Saturday morning. Nothing is paid for yet (and doesn't need to be if some other issue is found to be the cause), but I really want to get this resolved this weekend.

LO PHAT

 

By the way, I want to once again thank all of you who have been posting with your thoughts and suggestions. I'd be lost (or maybe just throwing money at random parts) without the help of members on this board.

For those of you still debating the coolant versus water versus coolant/water mix versus water wetter ... Keep going, guys! I'm interested in the argument, and I suspect a lot of others are too. If nothing else, you are helping to keep my post near the top. LOL!

Thanks again,
LO PHAT

 

I don't know if any of this information is useful, but I'll share anyway....

I just finished letting the car idle in the driveway for a solid 15 or so minutes. It was nearly the same as driving it. The temperature quickly reached the desired 190 degree range. From there the temperature climbed VERY SLOWLY (more slowly than when driving the car) to above 220 degrees before I finally shut it off.

I took temperature readings again at the radiator. The top of the inlet tank was roughly 222 degrees (the upper radiator hose was cooler) while the top of the outlet tank was roughly 212 degrees. The lower I went on the outlet tank, the cooler the temperature seemed to get, but once again readings were all over the place.

LO PHAT

 

why are you going back to a 195º t-stat? Do you still have all the factory emissions equipment on your car? If so than it's fine as that is the correct t-stat, but if they have been removed a 180º is great.
Regardless, changing the temp level of the t-stat is NOT going to make any difference at all how hot the car runs, it only controls it's MINIMUM operating temp. So now if you swap to a 195º unit it's will simply stabilize your temps at 195-200º (rather than your current 185º) before the temps start to climb up as you say they do.

Before you start just throwing a lot of money at parts such as a new radiator, all new hoses, etc pinpoint the problem!
For example, radiators are expensive, are you POSITIVE, without doubt, that the rad is really the problem? Upper radiator hoses rarely go bad so unless it's dryrotted with big cracks in it why replace it.

Check your existing lower radiator hose to make sure it has the internal spring in it. If it doesn't the hose can collapse under the pressure of the water pump causing a coolant flow restriction.

Have you tested your existing t-stat to make sure it's actually opening fully? The fact that the temps stabilize around 185º at first indicate that it's opening, but it may not be opening fully which would cause a coolant flow restriction which could allow temps to start to rise.

Fan clutch working correctly?
Timing and vacuum advance correct?

 

You are correct in all of this, and I am aware of the thermostat's function in the cooling system. My car still has all of the factory emissions equipment installed. I'll likely start by pulling the thermostat completely out and testing the car that way before replacing it with the 195 degree unit.


I again agree. That's why I commented that the parts will be available. I haven't committed to purchasing anything yet.


There is no spring in the lower hose. Interestingly enough, most people are recommending that I don't want one. Modern hoses are made to a far higher standard than the hoses made 25 or more years ago. That said, I do believe the lower hose to be rather soft, and that is why I will be replacing it. At worst, however, the current lower hose wouldn't be collapsed while the car is idling in the driveway. This seems to rule out the hoses....


Another good point. This is also a reason I will be pulling the thermostat.


How do I test the clutch fan?

My understanding of timing and vacuum advance is that these would primarily cause overheating during a situation of long idle. Am I wrong? They could be slightly off, but would it matter much in a street or freeway driving situation?


Thanks for the help,
LO PHAT

 

anyone that would recommend a lower rad hose without the internal spring is simply wrong! You need it.

to test the fan clutch bring the car up to operating temp than shut the motor off while watching the fan. It should stop within 1-3 revolutions. If it does it's good. If it takes much longer than that or just freespins it's bad.

Incorrect assumption on the timing in regards to overheating. If the timing is off or if the vacuum advance is not set up correctly it can cause overheating easily during driving and/or idle.
Make sure your total timing is right around 36º (with the vacuum advance cannister disconnected and hose plugged), than with the vacuum advance cannister reconnected make sure it's connected to full manifold vacuum

 

I double check these things tonight. Thanks!

LO PHAT