[DanC]

I don't understand all the concerns I've read on this site for years about 210 and 220 temps being to hot The factory thermostats, as far as I know, have always been 195, and that is just the point when the poppet is fully open.

All of my V8 Pontiac's, past and present ('68-'78, 350 - 455) have always run 210 and some up to 230 on the interstate and 180 - 210 in traffic w/ ac on. Never seemed to matter if I had a 160, 180, or 195 thermostat the 210-230 temp results were the same and I've never had a problem. But I admit I get a little concerned when it goes above 220. Yes the engines are always running cooler, even with the a/c on in stop-n-go traffic than on the interstate for me. This common occurance leads me to believe that at higher rpms the flow through the rad is too fast and does not allow enough heat exchange to take place. So IMHO I would think the wp pully diameter is where I'd start to get lower temps by slowing down the flow.

I know water boils at 212, but in a pressurized system the temp at which water boils is much higher. Which is why we have a pressure rated radiator cap.

My daily driver Roadmonster wagon with the "corporate 5.7 LT1" runs a consistant 210 no matter the load or weather condition and seems to be the point when the factory electric cooling fan kicks in. I don't know what the wife's 4.7 aluminum V8 Toyota runs since it only has a "C to H" range gauge, no numbers. My son's all iron 4 banger Nissian runs 200, fan kicks on, drops to 190ish.

DanC

[Region Warrior]

Tried every temp over 36 yrs.
7 different combos.
All ran best mph/et at 190-210.

[DanC]

Originally Posted by Region Warrior

Tried every temp over 36 yrs.
7 different combos.
All ran best mph/et at 190-210.

That is what I've understood about internal combustion engine thermal efficiancy. "Hot" engine & cool fuel delivery.

DanC

[george kujanski]

If you are going to slow down the flow to get better cooling why not slow it down to zero flow????????

I'm being sarcastic...doesn't happen. You need more flow, both coolant and air for better cooling. There is no 'sweet spot" from high flow to zero where the cooling is better, physics doesn't work that way.

George

[GT182]

Newer cars these days are made to run with temps of 205 to 210. I guess it's because of the emission controls.

I didn't mind so much that my car got up to 210, it was the 230 and 235 temps that worried me. But now with the correct impeller is on the pump with correct divider plates that match the impeller, it's running at 180 to 190 depending on the outside temps and time sitting in traffic. Running down the road at 3000 rpms it stays at 180. Sure I could put a 190 in but why.

Our point all along has been, "why are they overheating now when they never did back in the 60s and 70s"? The only conclusion was the rebuilt pumps we've been buying have the wrong sized impellers on them... they've been shaved down. Which in turn causes cavatation in the pump and contributes to hotter temps. Take that problem away and they run fine again. But everything must work together... timing, pump, radiator and all the other respective parts involved. Just my .

[Region Warrior]

BTY, mine's a 68 FB, no a/c, or any upper or side baffles.
Just a 19.5 flex fan and factory shroud.
But guess i better change out the smaller crank/large water pump plly to large crk/small wtr pump(a/c style) pllys then, huh George?

[72LuxuryLeMansLa.]

Originally Posted by GT182

Newer cars these days are made to run with temps of 205 to 210. I guess it's because of the emission controls.

I didn't mind so much that my car got up to 210, it was the 230 and 235 temps that worried me. But now with the correct impeller is on the pump with correct divider plates that match the impeller, it's running at 180 to 190 depending on the outside temps and time sitting in traffic. Running down the road at 3000 rpms it stays at 180. Sure I could put a 190 in but why.

Our point all along has been, "why are they overheating now when they never did back in the 60s and 70s"? The only conclusion was the rebuilt pumps we've been buying have the wrong sized impellers on them... they've been shaved down. Which in turn causes cavatation in the pump and contributes to hotter temps. Take that problem away and they run fine again. But everything must work together... timing, pump, radiator and all the other respective parts involved. Just my .

Gary,

What do you mean by "overheating" ? Do you mean a specific temperature limit or boiling over? I fully understand that things should work correctly and I just want clarification on terminology. I couldn't tell you how these cars ran back in the day since I was born around the same time that Charles bought his GTO.

Karl

[DanC]

I'm being sarcastic...doesn't happen. You need more flow, both coolant and air for better cooling. There is no 'sweet spot" from high flow to zero where the cooling is better, physics doesn't work that way.
George

I'm no engineer, but if the coolant had more time in the heat exchanger (rad) even by just a few seconds wouldn't it cool down more? Or is it that the coolant in the engine would offset it by heating up the coolant more as well. You certainly would have overheating if there was zero flow! At any rate my original comment on the flow was just a thought.

Our point all along has been, "why are they overheating now when they never did back in the 60s and 70s"? The only conclusion was the rebuilt pumps we've been buying have the wrong sized impellers on them... they've been shaved down. Which in turn causes cavatation in the pump and contributes to hotter temps. Take that problem away and they run fine again. But everything must work together... timing, pump, radiator and all the other respective parts involved. Just my .
GT182

I can definately understand where the impeller design, clearance, and cavatation can cause problems. As an aircraft mechanic I definately know how timing and air/fuel mixture makes a big differance in cylinder head temp on an air cooled engine and I know it will affect a liquid cooled as well, but probably not quite as noticable.

My original post was just addressing the point that it seems to me folks posting here in this topic are thinking that 210/220 is overheating! I don't recall anyone mentioning 'boil over'.

DanC

[Pontirag]

The overheat now like they never did back in the day. I think chit waterpumps play a part, but cam choices do to and karap gas and ignition issues.

[arrowem]

Originally Posted by DanC

My original post was just addressing the point that it seems to me folks posting here in this topic are thinking that 210/220 is overheating! I don't recall anyone mentioning 'boil over'.

DanC

So are you saying 210/220 is not too hot? This is the perfect topic as I took mine for it's first real drive today (this year) and it would go 190 at slow speeds and got up to 210 at cruise (60@2300rpm) and I was getting paranoid.

[DanC]

Originally Posted by GT182

I didn't mind so much that my car got up to 210, it was the 230 and 235 temps that worried me. But now with the correct impeller is on the pump with correct divider plates that match the impeller, it's running at 180 to 190 depending on the outside temps and time sitting in traffic. Running down the road at 3000 rpms it stays at 180. Sure I could put a 190 in but why.

I agree with you 100%. You did what you had to to make yourself comfortable and able to enjoy your ride. At the same time 230 was not "Overheating", but a very "uncomfortable" temp.

I admit I "worry" at 230, and I'm "uncomfortable" above 210. But even 'back in the day' (1978) when I had worn out everything in the 10 year old, 90k+ mile '68 FB 350 on the interstate the thing would hit 240 and never experiance boil over / steam. And I didn't have the sense then to be worried about it as I was only 17. I dang sure would not want to see 240 today, as that would be way beyond my threshold of comfort.




My point of post is just to bring to discussion the statement of the "Running Hot" posts in this forum.

Is it a matter of the individuals "comfort zone" or of actual "boil over / steam emission" that these posts are being made?

And if it is just their comfort zone, then let's help ease their worries, as no one can enjoy anything if there is worry or doubt!



DanC

[DanC]

Originally Posted by arrowem

So are you saying 210/220 is not too hot? This is the perfect topic as I took mine for it's first real drive today (this year) and it would go 190 at slow speeds and got up to 210 at cruise (60@2300rpm) and I was getting paranoid.

Correct, in my opinion with 33 years experiance of driving original Pontiacs.

1968 FB 350 w/ ac (currently own)
1969 Bonneville 428 w/ ac
1971 TA 455HO w/ ac
1972 Formula 400 w/ ac
1973 GP SJ 455 w/ ac (currently own)
1977 FB 301 w/ ac (in Germany on the Autobahn!)

The '68 Firebird is the car I bought in '78 and still have. It would run as high as 240 on the interstate. In 1993 even after total resto, a 180 t-stat, new everything, it ran, and still runs 190 in traffic (205 w/ air on) and will go up to 220 on the interstate with or w/o air on.

And as stated in an earlier post, they all have had the same cooling results. With the exception of the '77, which just had an "idiot light", that never came on except during the bulb check of starting. And never "steamed" or boiled over.

DanC

[Tripower455]

This is actually a great discussion! Maybe I am being too paranoid about running on or even near the thermostat.

[Pepi]

Just think of the cars without gauges, and with the idiot light. You wouldn't even think about temps unless the light came on.
I know gauges are better, because the light tends to come on too late...pretty much telling you why your engine seized. LOL

[DanC]

I found no referance to any "normal" operating temps, but did find these two tidbits of info:
------------------------------------------------------------------------------------
"WARNING - THE COOLING SYSTEM IS DESIGNED TO BE OPERATED AT 15 P.S.I. PRESSURE & TEMPERATURES EXCEEDING 200' F. CAUTION SHOULD BE EXERCISED WHEN REMOVING PRESSURE CAP OR SERVICING THE SYSTEM" BYW: I'm not 'shouting, bold caps is the direct quote from the SM.

Ref: Fig 6A-1 Cooling System Diagnosis Chart Pg 6A-2

------------------------------------------------------------------------------------
"RADIATOR CAP"

"A pressure-vent cap is used on the cross-flow radiator to allow build-up of 15 psi in the cooling system. This pressure raises the boiling point of coolant to approximately 258'F at sea level."

Ref: 'General Description' Pg 6A-5
------------------------------------------------------------------------------------

Also in my AMA Specifications that came with the PHS for my '68 FB. In the cooling system specs it just states that the thermostat begins to open at 190'F.

DanC

[JohnS66GTO]

I know I've read multiple times that thermostats START to open at the rated temperature and are not fully open until 10 - 20 degrees above rated. Just can't find the info right now to substantiate it.

Since thermostats on some cars (especially newer ones) are such a pain to replace, I never put a thermostat in a car without testing it in hot water with an accurate thermometer first. So far I've never had one that was anywhere near fully open at the rated temperature, unless it was stuck open. FWIW.

John

[Pepi]

Originally Posted by JohnS66GTO

I know I've read multiple times that thermostats START to open at the rated temperature and are not fully open until 10 - 20 degrees above rated. Just can't find the info right now to substantiate it.

I've heard stuff like that also, where a 165 thermostat actually runs at about 180, and 185 at 200, and so on. 15 degrees hotter than what thermostat is stamped it what I was taught/told.

[GT182]

The Stant thermostats I've been using, 160 and 180, run the coolant at the temps marked on them. No 15 to 20 degrees over that. Car now runs at 180 except for sitting at a long long traffic light where it goes up to 195 on a hot day. Once moving again it drops back to the temp the guage is.

One thing I was told for the 'warmer climates' is not to run a 50/50 mix. Use 30 to 35 % antifreeze to 70% water. And it does seem to help. A bottle of Water Wetter supposedly helps too.

[Tripower455]

Originally Posted by GT182

The Stant thermostats I've been using, 160 and 180, run the coolant at the temps marked on them. No 15 to 20 degrees over that. Car now runs at 180 except for sitting at a long long traffic light where it goes up to 195 on a hot day. Once moving again it drops back to the temp the guage is.

One thing I was told for the 'warmer climates' is not to run a 50/50 mix. Use 30 to 35 % antifreeze to 70% water. And it does seem to help. A bottle of Water Wetter supposedly helps too.

Ditto on the Stants. Every one I've tested was right on the money, within a few (less than 5) degrees.

[Region Warrior]

Considering Pontiac used 195* stats since 66, 210*-220* should be normal.