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70 454 correct temp

8K views 42 replies 15 participants last post by  71350SS 
#1 ·
Fellas, just picked up my first Chevelle about 2 months ago. Love it! Few minor things here and there, but I'm getting genuinely concerned about the water temp. So, it starts, idles, and drives great! Once it gets warmed up, it runs right around 210-215. I have stock gauges, stock fan, stock rad, stock Tstat (that I know of). When I'm cruising, it stays pegged at 210-220. But as soon as I get in traffic, it climbs pretty quick to 230-240. The other day I was in downtown and lot of start and stop to take pictures, and at one point it read 250. I turned it off, popped the hood, and nothing smelled like it was burning, no steam, no overflow on the ground. So, I started it back up, still at around 240, and started driving down the road and it cooled to around 220-230. Should I be concerned??? Seems a bit hotter than it should be... Temps have been in the low to mid 60s around here. The coolant does look old, so I'm going to do a flush this weekend and see if that helps. But, otherwise...what would you suggest next? Lower Tstat?? I have done a bunch of research and it seems the stock Tstat is a 195, but I get mixed reviews on which to run (195 or 180, even some suggest 160). That would make sense then to see 210 temps with a 195 Tstat. But for it to climb to 240-250, I'm not sure what is next. The car is for the most part in a stock setup.
 
#2 ·
Adam, if it has a stock fan and clutch assembly, check the clutch. It should spin pretty freely by hand when the engine is cold, and with resistance when hot. If it spins freely with hot engine, replace the clutch with a Hayden 2747 heavy duty clutch. Of course you may have radiator problems or a bad thermostat, but the clutch is an easy thing to check. I run a 180 stat in my BBC, no problems.
 
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#3 ·
I would replace the thermostat with a colder one 180° or maybe 160° (like in my car).:yes: Even though the factory one is a 195°, for years it has been a common practice to replace it with a cooler one as big blocks have a tendency to run a little hot… BUT… going anywhere over 220° is definitely too hot!:eek:

Claude.
 
#5 ·
I would replace the thermostat with a colder one 180° or maybe 160° (like in my car).:yes: Even though the factory one is a 195°, for years it has been a common practice to replace it with a cooler one as big blocks have a tendency to run a little hot… BUT… going anywhere over 220° is definitely too hot!:eek:

Claude.

Yep, I think I will pickup a 180 stat at Autozone and swap it out when doing my radiator flush today. Hopefully that helps cooler her down. Again, she runs great, just seems to get a bit hot when in slower moving traffic.
 
#9 ·
I bypassed my regulator and went with a standard 10SI on mine. I have to ask, is Humdingers restaurant still open there on Bemiss road? lol
 
#16 ·
I have to ask, is Humdingers restaurant still open there on Bemiss road? lol

Haven't heard of it, so maybe not. Do you remember Rockin Rodeo, with the mechanical bull by the Liquor Store on Bemiss...ya it burned down, so now it's just a slab of concrete, haha.
 
#10 ·
Couple things come to mind.
1. Is there a fan shroud on it? Is the shroud proper for the fan and is the shroud positioned properly?
2. Where is the temp reading being taken from. Is it from the head or the intake. If taken from the head it could read as much as 20 degrees hotter than the intake . However 250 seems a little hot.
3. Nasty colored coolant certain ly won't help. Might want to flush out system and change coolant.
4. What kind of shape is your radiator cap in? If it is not holding pressure it will lower the boiling m point of the coolant thereby creating higher temps.
5. What about the shape of the radiator. If the coolant is nasty maybe the rad needs clearned out.

My big block has never run higher than 210. Even in 90 degree weather.
 
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#15 ·
Yes, same car haha. I've only had it a month so I'm still working out all the kinks. My buddy (same buddy) has a timing gun. Coming over this weekend and gonna crush some beers and see how the timing is. But, if it was grossly out of time, I would expect to run rough. It doesn't...but, would a few degrees cause it to run lean and get that hot...?
 
#12 ·
First and foremost before throwing money at it, verify if the temp gauge is reading correctly. An IR temp gun is your friend here. Shoot it at the temp sensor.

A 160 stat will not make it run cooler. All it will do is open earlier than a 180 or 195. Usually whatever temp the stat is, is the temp it starts to open. Add another 10-20 deg for fully open.

If you are truly running up to 250 I doubt a stat change will make a difference, unless your current stat is bad. You can check the operation of a stat on the stove in a pot of water and a temp gun/candy thermometer. Just don’t tell the wife.
 
#14 ·
First and foremost before throwing money at it, verify if the temp gauge is reading correctly. An IR temp gun is your friend here. Shoot it at the temp sensor.

My buddy is sourcing one for me. Hopefully we can use it this weekend. I'll keep everyone posted.
 
#13 ·
Flushed the radiator, added new coolant. Pulled thermostat and it was a 160. So, I thought maybe it had gone bad, so I picked up another 160 tstat at Autozone for $12. Put it in and buttoned everything up. Test drive, still was cruising at 210, and in traffic bumped up to 230. The sensor is in the stock location, just above the left side exhaust manifold. The shroud looks to be correct and hugs the fan tightly. The radiator looks to be in good condition both on exterior and the interior (from what I can see with a flashlight). The overflow tube is clear. I also ran the heater to clean out the heater core, and it was producing heat like it should and the lines were warm. The 7 bladed fan has some resistance when engine is cold, and slightly more resistance when engine is hot.

But, I'm still thinking the gauge or sender is suspect... This car was recently restored/rebuilt and it runs like a dream, but according to the gauge, it runs at 240+ if sitting in traffic. I've stopped several times, popped the hood, no burning smell, no steam, no boiling, nothing coming out of the overflow, fan turns fine, nothing coming from tstat housing, nothing coming from any lines, nothing leaking on the ground. I'm not a Chevelle expert, but I'm scratching my head at this point.
 
#18 ·
As already suggested, an IR temp gun is worth having. I still suspect you have a bad fan clutch.
 
#20 ·
Randy, I guess I'm a bit confused on the clutch operation... When engine is stone cold, it should completely free wheel...as in turn several revolutions before stopping? Because right now, if it spin it, it will turn maybe one or two fan blade widths. It behaves basically the same way after it's been running and warmed up. Are we on to something here? New tstat, new coolant, fan shroud in place, radiator in good condition, fan itself in good condition... So, you're thinking it's just not spinning at the right rate when it's supposed to? When cold, it should free wheel to a degree, and take load of the engine so it can warm up. Once warm, should the fan clutch essentially be fully engaged?? Just thinking out loud here before I throw more $$$ at it.
 
#21 ·
The fan clutch when hot should be close to fully engaged. I suggested the heavy duty Hayden 2747 clutch because it engages at a higher percentage of engine rpm for better airflow.
 
#22 ·
Upon further inspection, the ends of the blades look like they have been ground down...why would that be?!?!?! wrong fan? wrong shroud?

Hmmm, the fan and shroud look to be stock due to the correct mounting holes and whatnot.


Again, this is my first Chevelle, so if something looks out of place, please tell me! It won't hurt my feelings!


What kind of fan clutch is that...stock??
 

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#25 ·
Interesting...so my dash cluster is all stock. Did they come that way in 1970, with the water temp at the head? If so, then I'm actually right where I should be then, right? Like I said, when cruising, it stays pegged at 210-215. Sitting in traffic, that's where it creeps up to around 230-240.


Again...my first Chevelle, but this looks like a water temp sensor to me, and the right location. When people talk about water temps in the 180-190 range, where do they have there sensors plumbed into? Manifold?



Like I mentioned in the first post, I find it hard to believe that I'm "overheating" due to the lack of any normal symptoms. But then again, I'm no Chevelle cooling system expert.
 

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#26 ·
That’s the right spot for the sensor and where you get the highest reading. The boiling point of 50/50 EG water is 265F at 15 psig. As long as you are reasonably under this (220F), not boiling off coolant, and your idle mixture and timing suit the temperature you should be OK.

It is certainly preferable to operate cooler (190F full time would be great) but it may just not be practical. A 220F head reading might read 200F or so at the intake? This would be considered acceptable for me, but I know others here have a lot of differing opinions.

I have a fresh 496 in a 67 that I haven’t had on the street yet, but at idle after 10 minutes or so it sits around 210. I am reading from the same sensor as yours.
 
#30 ·
An engine with 70,000 miles on it is different then a brand new engine with 100 miles on it. Combustion chambers get smaller so compression goes up, cooling system passages also get caked up, so things need to be changed with use..

Those engineers are hand cuffed by a one size must fit all rule when they design these cars. The owner isn't bound by those restraints and is allowed to tune for best performance based on climate and terrain. I think you are handicapping your car by using stock specs, especially front end tire alignment, these cars were spec'd with negative caster!! Surely you don't use negative caster and positive camber but these cars were spec'd that way..
 
#35 ·
Something also to consider,,,,,,,,,,, Your fan blade. It is not a 3947772 blade. Not sure what fan blade it is. A 1970 -396/454 with VO-1 cooling or some call it H.D. The fan blade is a 3947772 and it is STAMPED with these numbers.
This way you have NO doubt what fan blade is on your car.
Why this fan blade and why are the numbers stamped on it???????
This blade was designed for the B.B. cars with A/C and or H.D. cooling.
Also this 394772 blade has the correct pitch to draw air through the heat exchanger and " Also very important",,, It will remove the SUPER HEATED AIR from the engine bay. ( everyone blames vapor lock on EVERYTHING else. Most of time your engine bay is NOT like it left the factory. Parts are MISSING,,,,,The Super Heated air is staying under the hood and " NOT " being EXPELLED!!!)
My one owner 70 SS 454-M/22 car has the VO-1 with A/C, The 3947772 blade was part of the FACTORY Pkg. The org. clutch was made by EATON, You will hit the Lottery before you find an Eaton Clutch!
I am a Geeser, I would do Four items.
1- Heat Gun
2- A new Mech. Temp. Gauge. ( the first time I did this, I duct taped a mech. gauge to the windshield and go for a ride) Write down speeds & Temps.
3- Get a correct fan blade and make SURE your clutch is working.
4- correct any out of order items. Thermostats, I have a 180 & a 160 in Two different cars both with Q-Jets, Other than warm/up time=" NO DIFFERENCE " Thats your call.
...........................................................................................................
If you revert back to the factory Org. cooling system set up, Your system will function properly. Over the years items get changed, Then you have issues. Take it " One step at a time ".
Good luck
Bob
Trivia:
The- O.E.M. fan blade AKA 3947772 has curved tips WHY? The REAL O.E.M. 772 blades with curved tips match the radius of the plastic 1970 fan shroud. Do the Repo. blades have curved tips? The Repo I bought Did not and it MACHINED a hole in the Factory fan shroud. That blade did not make it to "door stop" statis,,, It went to the F^!%$EN scrap!
 
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#36 ·
Bob, thanks for the input!! Definitely gonna tackle this one by first figuring out what temp it ACTUALLY is. The gauge is stock, but the PO said it was rebuilt, so it could have the wrong resistor...? I don't know honestly. But, we'll see what the gun says tomorrow!
 
#38 ·
I agree Randy. Chevrolet designed it to do a job. So far for me , The last fifty years that I have owned and driven my LS-5/M-22 El Camino. No issues so far, So I do believe Chevrolet got this right...:thumbsup:
P.S.:
My one owner SS 454 and my FAKE SS 454, AKA(468), both have O.E.M. cooling systems. My 468 driver has over 41.000 Highway miles on, So far So good. Yes I do have an Electric fan, I blows the KOLD AIR through the Evaporator to the inside of my wagon...:laugh:
Bob
 
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#40 ·
I've had cooling issues with my BB in the past and now I run a constant 170 +/- driving, 190 while idling.

This is what I`'ve learned on Team Chevelle from mechanically superior minds than my own.

First, a 180 t-stat should work just fine. The reason why; a cooling system has to work in cycles. Once the t-stat opens, it cycles the coolant into the radiator where the cooling takes place. T-stat will close and the radiator does its job, (as long as it's clean and the fins aren't crushed)

Running a 160 might not get you the proper cycling you need due to the t-stat remaing open at higher temps. The t-stat needs to close to optimize the cycling. This is why that old myth of not using a t-stat at all will keep the coolant constantly moving through the system is better. Totally wrong.
Your 195 may not have been working properly.

Try the 180 and get your timing right.
I also run full manifold vacuum to my vac adv. FWIW.

Only trying to pass on what I've learned and what worked for me.

Nice 70 :thumbsup:
 
#42 ·
Welp, my buddy came over today with his timing gun and thermal gun. Checked timing and it actually wasn't too far off. Set the idle timing at 14* and it seemed happy there. Other than a 276 cam, the engine is stock. That seemed to be the recommended advance for the cam in a stock engine. Radiator cap is 16 psi.

Took it around town, ran it pretty hard, and the temp gauge stayed around 210-220 while cruising and around 230-240 if in traffic for several minutes. Pulled back in the driveway, my buddy hoped out, popped the hood, and I shut it off. We shot several places...

Intake manifold: 182
Thermostat elbow: 176
Top of radiator: 178
Bottom of radiator: 172
Engine head at stock sensor: jumped around in the mid 200 range

So, with that data, I feel WAAAAAAAAAAY better. Sounds like the cooling system is doing what its supposed to, and that temp gauge is reading the head temp, and not a true reading from a water jacket. I have a 160 tstat, so the temp at the elbow being within 20 degrees makes sense.

Down the road I would like to install some aux gauges, but seeing that data makes me not cringe every time I'm sitting in traffic and it creep up to 240-250.

Thanks for all the input fellas!!!!
 
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