1970 455 Heating up.

[jonstringer]

My car does great on the highway. Never heats up, whatsoever. In town driving can be a different story. If I'm stuck in traffic, or stop at every light, it will climb to over 210 degrees. Once I start moving again, cools down very slowly.

Is this common with 455s?

What I've done to correct it... I have ordered these two items, and they are in the mail as I type.
1. Fan Shroud. (the guy i bought it from ditched it.) I ordered a new one.
2. Aluminum High Volume Water Pump. (currently it has a stock water pump.)

My Cutlass already has a 4 core radiator, so i'm not springing for an aluminum one just yet. I want this car to have the capability of being a daily driver. Not that it will be, but if it's faced with bumper to bumper traffic, I want it to survive. Am I on the right path with these add ons? Any other suggestions?

[Oldsguy]

I think the fan shroud should fix it. If your coolant system isn't stopped up anywhere you should be fine. Is the thermostat correct? Cheap insurance.

[Bubba57]

Having pulled my hair out with cooling issues, I would also check the fan clutch. When the engine is cold the fan should be hard to move as in stiff. If the engine is not equipt with a fan clutch then the shroud should fix it as Oldsguy mentioned.

[Lady72nRob71]

Adding the shroud should fix it as has been mentioned twice.

Although the fan clutch may be somewhat stiff when the engine is cold, it may not be thermally engaging (providing it is a thermal type with the coil on the front of it).
The old fan clutch in my 72 was like this - engine at 212 degrees but very little air flow from the fan at idle. Replaced the clutch with one from the Part Place and now after a good drive, it is blowing a LOT of air (enough to be blowing any loose papers out of the garage...) It sounds like a small helicopter as well.

[Rallye469]

I must be blessed...I haven't had a cooling issue in years.
And I never ran a shroud.
I do use a flex-fan though.
Yes, those fans that everyone who knows about them
swears to never ever use.

What temp. thermostat are you using?
When was the last time you flushed your system?
What are you running for coolant?

[jonstringer]

Originally Posted by Rallye469

What temp. thermostat are you using?
When was the last time you flushed your system?
What are you running for coolant?

1.I'm not sure about the thermostat. I will check on that a buy a new one. What is the factory temperature suggestion for a 455? I use a 195 degree thermostat in all of my sbc engines.

2.I flushed the system when I picked the car up. I have only had the car for two weeks. When I picked it up, I flushed all of the fluids, inspected the hoses , belts, plugs, wires, cap, etc...

3.Water and Antifreeze mixed half and half. Should I be using something else?

[Rallye469]

1. The factory is probably 180...I think I usually run a 160.
(some will argue a 160 will move the water through your radiator too fast-
they could be right...I guess)
2. If you've flushed everything, that's good. Radiator look clogged?
3. I think 50/50 is not the best mix. I run 100% water because I go to the track. That and a little water pump lubricant is the best.

Other things you should try.
-Tune your carb. Lean conditions can raise an engines heat range dramatically. Also, gas...what octane are you running?

-Timing. Advance it a little. Not to the point of pre-ignition- that will cause
detonation, which will also raise engine temp. But too retarded will raise
temps. It's a fine line, but a cheap one to play with. Bump a few degrees and take it for a spin.

-Have a trans cooler? It'll move hot(170-220 degree) fluid away from your
coolant. Your radiator is already taxed...lighten the load.

[Rallye469]

I'll amend my last post a little...
I think the trans cooler is kinda like a patch...
it's not fixing the problem, but it will help...and it's really good for your trans.

I drove my car, 469cid with a TH400 and 3500 stall converter, 3.90 gears...
96 miles to the track last august. 90 degree+ weather and raced it all day with the following set up:
-3 core stock radiator (at least 7 years old-bought used)
-aluminum water pump and stock pulleys
-trans cooler
-flex fan
-100% water
-160 thermostat
No shroud, water wetter, anti-freeze or electric fans.
175 degrees all day long.

[jonstringer]

The factory thermostat is actually 192 degrees. I found that out a the parts store. I went with a 180 degree thermostat, which is what it had in it in the first place, until further notice. Here is what I have done so far to solve the cooling problem...

1. I added an Aluminum High Volume Water Pump.
2. I replaced the clutch on the fan. (Thank you guys for recommending that I check that. It was shot to hell, and needed replacing)
3. I used a cooling system additive, basically water wetter.

My car is behaving a better in town, but oddly enough my car sits a temperature a few degrees higher than it did before the mods while on the highway. Appx. 195-200 degree average while on the highway, which is fine, but I thought I'd see a drop, not a raise. I just received my fan shroud in the mail yesterday, and I plan to install it later today if time permits. I'm hoping that this will be the end of this heat issue. I'll keep you guys posted.

jon

[joe_padavano]

You should definitely run a fan shroud and a 6-7 blade clutch fan. Overheating a low speeds is all about airflow through the radiator. A high-flow water pump is not necessarily the answer, since it is possible to circulate the coolant through the radiator too quickly and not allow enough time for heat transfer.

Having said that, 210 deg is not really a problem. Keep in mind that with a 15 psi radiator cap, water boils at about 250 deg F. That's the whole point of a pressurized system. Also keep in mind that temp gauges are not necessarily all that accurate.

The fact that you have a 180 deg thermostat (for example) doesn't mean that the engine won't go above 180.

[jonstringer]

Originally Posted by joe_padavano

You should definitely run a fan shroud and a 6-7 blade clutch fan. Overheating a low speeds is all about airflow through the radiator. A high-flow water pump is not necessarily the answer, since it is possible to circulate the coolant through the radiator too quickly and not allow enough time for heat transfer.

Having said that, 210 deg is not really a problem. Keep in mind that with a 15 psi radiator cap, water boils at about 250 deg F. That's the whole point of a pressurized system. Also keep in mind that temp gauges are not necessarily all that accurate.

The fact that you have a 180 deg thermostat (for example) doesn't mean that the engine won't go above 180.

Water boils at 212 degrees, and the only reason I know this is because I'm a bill nye the science guy nerd, but I follow what you're saying. I will install the fan shroud today, no matter how annoying it is...

I do have a 7 blade fan w/ new clutch, so I seem to be good there.
I didn't think the high volume pump would be potentially worse for cooling, but that does make sense. Too bad, because my iron water pump has less than 2k miles on it. No way I'm tearing back into it to reinstall the stock one. I'll probably just give the stock one to someone on the forum.

[joe_padavano]

Originally Posted by jonstringer

Water boils at 212 degrees, and the only reason I know this is because I'm a bill nye the science guy nerd, but I follow what you're saying. I will install the fan shroud today, no matter how annoying it is...

Water boils at 212 deg F at standard atmospheric pressure. Boiling point increases as pressure increases (it also decreases as pressure decreases, which is why cake mixes have different high altitude instructions). As I said above, at 15 psi ABOVE atmospheric (which is what you have with a 15 psi pressure cap), the boiling point rises to around 250 deg F. Better check with Bill Nye again.

[jonstringer]

technically we're both right. my statement is correct. your original statement left out said facts, but now we have come full circle. that's rather interesting, and I want to say that this is something that I should have learned in school. thank you for explaining. I've never had more fun learning about boiling points of water.

[Lady72nRob71]

-and none of this explains why I burn the water whenever I had tried to cook...


One other thing was to make sure your lower rad hose has a spring in it. New hoses now days omit them to save money. Cheaper hoses are thinner which may collapse during higher RPMs. My 86 Olds 307 hose has a spring.
If it collapses while driving, the temp can go up and come down again at idle. I think this is the issue with my 72 as it has a cheap hose on it.
Also i am going to pull the block drains and flush it well. Timing needs checking as well.
I like the 180 degree Mr Gasket high flow thermostats (otterzone part). I have one in the Ford and the 86 Olds. Both read 180-190 on the gauges and with my IR thermometer (which is a good way to check gauge accuracy.) Let us know what does fix it in the end...

[jonstringer]

I will for sure check my lower hose. Thank you for the tip.

I added the shroud yesterday, which certainly assists in highway cooling. In town, i'm still experiencing a climb in temperature. Although, it has decelerated some, and seems to plateau at a safe temp. I haven't really tested it. I left it running for 15 minutes in drive at idle, but this was a night with cool air. It climbed to 210, maybe 215. A true test will be sitting in 5 O'clock Austin TX traffic.

Side note: I had seen it before, but never inspected it. I have an electric fan on the front of my radiator. It's not hooked up, but it looks new. I might route this fan into my car and hook it to a toggle to test it out. I'll tell you what happens.

Thank you for all the help.