[Old Bird]

After fighting heating issues with my 67 firebird with 400 motor and th400. I finally solved my problem with running to hot. I have read and studied and tried everything under the sun but like a lot of others my car would overheat in stop and go cruise traffic in the heat. The last few things I did keeps my car from not going over 190 degrees at last. First I put on a 4 inch water pump pulley in place of the 8 inch that was on. That helped a little. Then I ordered a Champion 3 core aluminum radiator and a Flex-a Lite Black Magic electric fan. The fan is mounted in a shroud that fits nicely over the back side of the radiator. It also has it's own adjustable thermostat so you can control the temp. This is a puller fan that is rated at 3300 cfm. I also ran a remote switch so I could turn the fan on from inside the car. I removed the belt driven fan from the motor and engine seems to like it also. I know some don't like the thought of running different set ups than what came from the factory. Nothing on this car is numbers matching so I was more concerned about being able to drive it in hot weather and not damaging the motor. Not sure but Just putting the elec. fan on the old radiator might have worked also.

[Old Bird]

Added a album with pics. of most recent work. Thanks

[Kenth]

An engine is not overheated until the "TEMP" lamp lits at 245°F.

Installing an electric fan is not the cure.
Replacing a 40-50 year old clogged radiator is.

Here is a good article on engine cooling:

http://mysite.verizon.net/vzezeqah/s...ingsystems.pdf

[74Grandville]

I also found fuel mixture to be a big factor at cruise. if you're running lean, the temp will go up.

[Old Bird]

Sorry but I would rather not have motor run at or near 245 degrees. To much invested in motor to damage it from running too hot. The radiator was not a 40-50 year old clogged radiator either. It was replaced a few years back. When the motor would get to about 210 and still creeping up the engine would start to run a little rough. Also I have worked on the tune of the motor trying to help with the temps.

[ta man]

Originally Posted by Kenth

An engine is not overheated until the "TEMP" lamp lits at 245°F.

Installing an electric fan is not the cure.
Replacing a 40-50 year old clogged radiator is.

Here is a good article on engine cooling:

http://mysite.verizon.net/vzezeqah/s...ingsystems.pdf

Hopefully that was a joke about 245 degrees?There is no way I would run my engines at 245 degrees...there is always a reason why engines run hot.Something is wrong!
I do agree with the clogged up radiators a good flush by a rad shop is essential.

[72LuxuryLeMansLa.]

Originally Posted by ta man

Hopefully that was a joke about 245 degrees?There is no way I would run my engines at 245 degrees...there is always a reason why engines run hot.Something is wrong!
I do agree with the clogged up radiators a good flush by a rad shop is essential.

I would say so. Something is wrong. Are the pistons down in the hole? IE wide to no quench. Has the engine been rebuilt lately? Older engines with tons of corrosion will prevent heat transfer. Engines can have a coolant related sludge/layer of crud because of bad coolant. I have a block that was recently machined for a rebuild but was obviously not acid dipped because there is still a layer of corrosion inside the coolant passages and I'm considering having it dipped before going on to assembly.
If a radiator/electric fan/ pulley change fixed the problem, I would think that something was not correct with the set up to begin with.

[68blackbird]

what amp rating is the alternator you have?

Rich

[Old Bird]

The engine was rebuilt a few years back and gets very few summertime miles put on it since then. I would say 500 miles give or take a few hundred. I did not do the motor work but know it was bored 30 over. Block was tanked and checked before rebuild. I run a 100 amp alt. on it and seems to work fine.

[Schurkey]

Originally Posted by Kenth

An engine is not overheated until the "TEMP" lamp lits at 245°F.

This depends on your definition of "overheating". There are three common definitions, and I'm not fond of either of the first two:

1. The coolant is actually boiling out the rad cap overflow hose. The temperature required to do this varies with system pressure and anti-freeze concentration. If the coolant is actually boiling out the overflow, the engine has probably already suffered some amount of damage.

2. The coolant temperature is at or above some specified temperature. Different people specify different temperatures. Some "hot" light sensors didn't trigger until 260F. Another issue is WHERE the temperature is measured. Sensors next to an exhaust manifold tend to read higher than sensors in the intake manifold coolant crossover. The engine is in imminent danger of damage.

3. The coolant temperature at or near the thermostat is more than 15 degrees above the thermostat rating, at idle or cruise. A thermostat is intended to set a MINIMUM operating temperature, not the maximum temperature. If the coolant temperature measured near the thermostat is more than 15 degrees above the thermostat rating, the theromostat has no control over system temperature. It has "lost control" of the temperature. The closer the system temperature is to the thermostat rating, at idle or cruise, the better. System temperature will increase somewhat for heavy-throttle or high-rpm use, but when the vehicle returns to idle or cruise, the temperature better go right back down to near the thermostat rating.

[68 Firebird]

Schurkey that was the best response I have read in a while.

Kudos

Gerry

[fatguyterry]

my 400 bored 30 over kb pistons, 268 cam, timing at 12 and all in at 32, b cool alum side to side flow, 19.5" fan w/clutch half way in shroud , w/p plate as per bulletin. check with inferred and glass runs at idle for an hour at the thermostat housing and intake at 185 and at the lower rad hose it is 155. the biggest change was the rad, side to side always cools better. that's why they are in ALL the newer cars. by the way the temp was 92

[BruceWilkie]

Originally Posted by 72LuxuryLeMansLa.

I would say so. Something is wrong. Are the pistons down in the hole? IE wide to no quench.

Fwiw millions of cars are built just like that and they dont "overheat"...
Most run in temp range they are intended for... usually minimum of 190... thats why they came with 190+ thermostats. Thats the minimum normal operating water temp the factory desired.

Agree lack of quench isnt so great for performance or combustion efficiency but its not likely his overheating issue.

Motor oils are speced for oil temps by the car manufacturers(engineers not your handyman friend/neighbor)... the coolant temp range is set to keep oil temp in range with oil spec.
Radiator cap pressure and boil over protection in the coolant are speced to run at those +190 temps as well. Nothing wrong running at 210-215 degrees coolant temp and briefly at 230 in severe conditions...
So yes, if you hit warning light temp(240+) at normal air temps/conditions then yes something is wrong.

Further more all your factory clearances/tolerances are all based on the factory speced operating temps for oil and coolant. Cool oil doesnt flow as well as warm oil... majority of engine wear is from oil not up to temp and flowing as it should.

Yes race cars deviate from this... they arent built to have the longevity of a street car and are tore down and inspected regularly.

[68gtoMN]

and did anyone here refer to the water pump threads dealing with aftermarket pumps (wrong impellers) and reshaping the diverter plates to be in correct tolerance to the impellers? It's AMAZING what a well-engineered cooling system can do when the proper parts/tolerances are used.

Read and learn...

http://forums.maxperformanceinc.com/...mp+overheating

Good luck.

[zeebo]

excellent response, schurkey..especially point number 3. i have argued that with people for years. your response is exactly the way i have been taught a cooling system/thermostat works..it sets the minimum temp, nothing to do with the maximum. for example, folks will write in "i have a 160f tstat and going down the hi way my temp gauge (sensor located in intake, not head) is reading 190 to 200f." if you are 40 degrees above the rating of your tstat, it is wide open and doing nothing to control temperatures--you are now controlling temps at the mercy of the ability of your radiator to exchange the heat, along with airflow and ambient air temp. and its not always a "radiator size" remedy, but a "coolant system physical" that is needed. scale and that white flaky corrosion not only plugs up radiators, but heater cores and block passage ways too-obstructing flow and making temps rise.


also, remember something about 195f tstats--back before emissions controls, cars were factory equipped with 180f tsats, or cooler. i will agree that a motor has to get up to a certain operating temp, not just to atomize fuel and run correctly, but to have the oil at a temp to be able to burn off the impurities like condensation, etc, and have it reach the temp where it can lubricate the best. that being said, when you raise an engines operating temp, you can tune it to run leaner--hence the 195f came about in the emissions era. you need a thermostat, but you dont need to cook your motor, either. my 2 cents.



i have a 2001 buick park avenue with the 3800--i run a 180f tstat with a good maintained cooling system--it has a digital readout of temp--when i am going down the road, (be it 40f or 80f out) my outlet temp is running between 180 and 187f. only when im in traffic and not getting alot of airflow (electric fans only) does the temp creep up--it immediately drops right back down to 180f ish as soon as i drive a few miles.

[72LuxuryLeMansLa.]

Originally Posted by BruceWilkie

Fwiw millions of cars are built just like that and they dont "overheat"...
Most run in temp range they are intended for... usually minimum of 190... thats why they came with 190+ thermostats. Thats the minimum normal operating water temp the factory desired.

Agree lack of quench isnt so great for performance or combustion efficiency but its not likely his overheating issue.

All the other stuff I wrote about the cooling system should have clued you in on the fact that I was not blaming the whole thing on quench. I'm well aware they were built that way. My point was that lack of quench can be a contributing factor to an engine that runs hot. One of the main things that tight quench does is to cool the chamber somewhat before the plug fires to help stave off preignition. If you don't think that has an effect on operating temperatures you are mistaken.

[BruceWilkie]

Water temp...Oil temp you guys may need to know more...
http://www.bobistheoilguy.com/motor-oil-101/

the following from above link is noteworthy.

"I think it is time to go over passenger car automotive engine oils in detail. I will be writing several articles to be published soon so I will try to get some of it out here. I feel this is a very general topic for all car owners on this board.
This is a very difficult topic to comprehend. Everybody including good mechanics think they are experts in this field but few understand engine oils. Most of what I hear is the opposite of the truth. It is however easy to see how people get mixed up as there is always some truth to the misconception.

Please forgive me if I am too wordy or even verbose at times. I will be redundant for certain. This will be in areas that people have to hear things over and over again to get it right. Some will never be able to understand these concepts unfortunately. I base my thoughts on those whom I have been listening to in various automotive chat rooms and discussion with mechanics. I will try to minimize technical terms and be somewhat vague rather than exact. I will round and average numbers to make the point simple rather than mathematically exact. Thickness has the same meaning as viscosity. Viscosity is a measure of the resistance of a fluid (liquid or gas) to flow. Fluids with high viscosity, such as molasses, flow more slowly than those with low viscosity, such as water. Again, I am trying to explain general principals as I know them.


The greatest confusion is because of the way motor oils are labeled. It is an old system and is confusing to many people. I know the person is confused when they say that a 0W-30 oil is too thin for their engine because the old manual says to use 10W-30. This is wrong.
More confusion occurs because people think in terms of the oil thinning when it gets hot. They think this thinning with heat is the problem with motor oil. It would be more correct to think that oil thickens when it cools to room temperature and THIS is the problem. In fact this is the problem. It is said that 90 percent of engine wear occurs at startup. If we are interested in engine longevity then we should concentrate our attention at reducing engine wear at startup.

Oils are chosen by the manufacturer to give the right thickness at the normal operating temperature of the engine. I will say this average oil temperature is 212°F, the boiling point of water. On the track that temperature is up to 302°F. It is important to realize that these are two different operating environments and require different oils.

I will discuss driving around town first. Everything I say will be based on these conditions. At a later time I will discuss track conditions. Everything I say will be as accurate as possible without looking everything up and footnoting. I am trying to be general not ultra specific.

One thing that is no longer important is the ambient temperature. Older automotive owner manuals often recommended one oil for the summer and another for the winter. This is still necessary for air cooled engines but is no longer a consideration in pressurized water cooled engines. These engine blocks are kept at around 212°F all year round. The oil is around the same temperature as well. This allows for a single grade oil all year round. Again, this is not the same as on the track where the coolant temperature is slightly higher and the oil temperature is much higher."

[Chris65LeMans]

Cooling issues are like discussing religion on here.

My takeaway from your original post was - "You had an 8" water pump pulley on there? I've never seen one that big!"

[Region Warrior]

68 up HP and non A/C cars used a 7-7/16" crk pulley w/a 7-15/16"(most just say 8") w/p pulley.

A/C cars used an 8" crk with 6-3/8" w/p.

There where a few different odd sizes in early 70's, but ratio's where very close to same as above.

Had/have no prob's use'n non a/c pulleys w/a 4 core radiator, shroud, factory clutch and/or 19-15/16" flex fan, 170-180 stats in my 67-68 FB's from 1975.
No front baffles or upr covers.