[dean7276]

I've searched the term "too hot" and couldn't find what Im looking for,so sorry if Im asking a question that's been asked over and over.

What temp is too hot? When should I pull over and shut er down?

78 Trans Am 400/auto. Alum rad,7 blade 19" clutch fan w/elec.pusher fan for a little help on those hot days.
Car ran "normal" all spring 190-205 range.Today was around 80 something degrees and I was pushing 220 at times.Got hot at traffic lights,or typical rush hour stop and go.Would cool back down to 205 when I got a little speed/airflow over the rad.
Im in Texas and it's not gonna get any cooler here for the next 5 months or so.
So what is TOO HOT? What is an acceptable scorching summer/stop and go traffic temp?

[GOAT8U2]

Too hot IMO is 220+, water boils at 212 and hopefully your running antifreeze to move that temp up. For those of you guys who run 215+ I'd run 50% antifreeze to be on the safe side until you figure out how to get the temps lower.

You have an upgraded rad so aside from getting a great electric fan, I'd start with your
1) Timing setup ( ported or manifold, vacuum advance, initial and WOT timing )
2) How old and what LB is your rad cap

[guccieng]

i would:
check tuning; retarded means heat.
up your idle for more water flow.
make sure radiator is clean.
run more water in your water/coolant mix.
water wetter won't hurt (lowers surface tension of the water).
give careful consideration to your oil (if it's too light, the heat will reduce it's lubricating quality).
make sure your clutch fan is actually working (run with a spacer and see if there's a difference).
with your cooling system description, i would think somthing internally may be wrong; that fan+aluminum rad+electric fan=very hard to get hot, but you're still doing it.
where is your temp coming from (temp sender location)?
and of course: water pump impeller to divider plate clearance.
just my $.02. good luck and let us know what works!

[66Mutt]

I would verify the accuracy of your gauge with a second mechanical gauge or a IR thermometer. I would not worry about the temp until the temp got to 240 F - 245 F or above range.

I don't have my coolant manuals with me, but I found some notes. At atmospheric pressure a 50/50 mix of coolant has a boiling point of 225 F. If you ran 100% water with a 15 psi radiator cap, it would have a boiling point of 245 F. A 50/50 mix with a 16 psig cap raises the BP to 265 F.

The higher operatating temps will necessitate the more frequent coolant and hose changes, but if you do it at 3 to 5 year intervals you will be fine. I would imagine you likely change the oil regulary and don't shoot for the extended oil change intervals. If so, then you should have nothing to worry about on the oil side.
Doug

[1967Tempest]

Well My :
My car always ran too cool after the spacer mod etc.. I recently bought a digital timing light and found the timing was SOOOO far advanced that I was surprised it ran at all.
I hace 15* initial timing now and on the highway doing 65 - 100 mph she runs 170-172 all day long. But she has seen 190 at idle.

Im running a 18" fan aluminum rad, 50/50 mix, 160 t-stat and an electric pusher in front.

I would check the timing first. I was shocked how much SMOOTHER she ran at 15*. I am going to bump her up to 17* initial to see if she cools down and stops being sluggish when I mash it.

Timing light I got.
http://www.actron.com/product_detail.php?pid=16315

Here it is on ebay.
http://cgi.ebay.com/ebaymotors/Actro...motiveQ5fTools

Hope that helps.

Dave

[kate`s67gto]

Do not discount the transmission. It can add to the high operating temps as well. Also you might be running too lean of mixture. Also the grade of gas used can add to the problem, try 89 or 91 if using 87 octane. I would not operate a car over 230*. Read the thread chalk one up for the cast impeller. That thread is tops on information . Just send George Kujanski $1

[getmygoat]

Originally Posted by 66Mutt

I would verify the accuracy of your gauge with a second mechanical gauge or a IR thermometer. I would not worry about the temp until the temp got to 240 F - 245 F or above range.
Doug

Sorry - but 240 is way too hot for any length of time.. Its one thing if it goes there after you shut the car down... But the car should not be over 220 for any steady period of time while running. (maybe at a stop light in the middle of summer with the A/C on - ok)

Will the car run at that temp? Sure, for a while at least - but its not good for longevity. Not only from the heat itself, (tighter clearances, thinner oil, etc) - but also you are likely to experience detonation at that temp, which can REALLY be bad for rod bearing life, etc.

If you do a search on this site, there's a lot of info on here... I think the general consensus is anything constant over 210 is something to look into and work to reduce.

Pontiac designed these engines to run between 195-205.

[lust4speed]

The antifreeze addition is a push at best. The more antifreeze added the higher the running temp. so it boils at a higher temp, but will reach that temp easier. I always started to worry when running temps went over 230°. I've lost fan belts and saw momentary temps pegging the gauge over 260° as I threaded my way out of traffic to pull over, and the engine didn't suffer any permanent damage - Scared me though. Don't give up on finding your problem. I've managed to get all my cars running at thermostat, but a couple were a hefty challenge.

[66Mutt]

If the engine is running that hot, I would definately work on finding the problem. There is no reason an engine with a cooling system in good condition and in proper tune should not run much cooler. My point is that you are not going to melt down the engine or have any serious damage running at 240 deg.
Doug

[cosgrove]

Originally Posted by getmygoat

Sorry - but 240 is way too hot for any length of time.. Its one thing if it goes there after you shut the car down... But the car should not be over 220 for any steady period of time while running. (maybe at a stop light in the middle of summer with the A/C on - ok)

Will the car run at that temp? Sure, for a while at least - but its not good for longevity. Not only from the heat itself, (tighter clearances, thinner oil, etc) - but also you are likely to experience detonation at that temp, which can REALLY be bad for rod bearing life, etc.

If you do a search on this site, there's a lot of info on here... I think the general consensus is anything constant over 210 is something to look into and work to reduce.

Pontiac designed these engines to run between 195-205.

I agree. Motors live longer at these lower temps. They also make more power. Dyno operators like that 160 degree range for the most power. As far as what is too hot? 220 for a short period is nothing to worry about. In stock car racing, we could run pontiac motors 240+ to finish a race with out immediate ill effects. We could usually keep it at 180 but dirt in the radiator from dusty track or bent ducting from contact could cause overheating. If you start to push water out all bets are off. Temp will go out of control, the gauge won't show it and your motor will be junk in short order.

[GT182]

Here's a thought I've had with overheating. Dumb maybe, but think about it.

Do you have a front license/vanity plate that is blocking airflow thru the center of the bumper. Plate attached by it's lower bolt holes so it sticks up higher and closes off the center of the bumper, and it's acting as an air deflector. Everything else can be as it should, but it sure looks to me like it's restricting airflow. Just my

I'm looking to find a way to lower my front plate and try it out. It sure won't hurt to let more air thru that bumper IMO.

[1967Tempest]

That license plate idea sounds great actually. How many times have we seen a BIG diesel RIG or school bus with cardboard or a sheet over the grille to get the BIG motors to WARM UP in the winter!!!

Hmmmmmm,........

[GT182]

Tempest, give it a try and see if it helps. Just take the front plate off first tho. If it works, then do the drilling. I don't want to see anyone drill holes in their bumper if it doesn't.

[gtome]

Not to jack, but mine seems to run really cool? Havent varified temp with a IR gun, but I run 165-170. Is there such thing as too cool?

[GT182]

Originally Posted by gtome

Not to jack, but mine seems to run really cool? Havent varified temp with a IR gun, but I run 165-170. Is there such thing as too cool?

Are you running a 160* thermostat? This is just my , but I wouldn't think so. Cooler is better IMO.

[1967Tempest]

TOOOOO late!!!! My bumpers were really bad any way. I drilled it and added the plate in the holes so there is a bigger gap.. My car always runs at 170* even at 100 MPH on highway.

Im currently running a 160* t-stat, 18* initial timing with 36* total, 18" flex-a-lite fan, 2 core aluminum radiator, an 8 inch crank pulley with a 6 1/4 water pump pulley, .025" gap on the plate/ water pump and an electric 16" pusher fan with a 50/50 mix with distilled water.

So I will see if it helps. I am only worried about the idle temps. Running temps NEVER get over 175* even in 100* weather.

Thanks

Dave

[GT182]

Charles and I were talking on the phone earlier and he asked if I had a fan shroud and clutch fan. It's no on both counts. And as he said to me, they were on these cars from the factory for a reason. And looking back my 1st GTO and the 2nd one, both had shrouds and clutch fans.


These being gone must have some impact on overheating I believe. So.... it's time to get a shroud and clutch fan setup on mine. I assume she had both, but for whatever reason they were removed. She'll have them back again..... asap.

[gtome]

I think I have a 180* Tstat and no shroud or clutch fan, no water wetter. I did notice it got up to 180* today at a long light and 90* ambiant temp, still ran bout 160* otherwise.

[GT182]

Dean, I didn't mean to hijack your thread, but I figured it wouldn't hurt for another idea to help cool your temps.

And Happy Easter guys.

[1971GTO]

After looking at the obvious(water & the 50/50 mix), and if the water pump's in good shape(not leaking water...right?),

I'd first look seriously at all aspects of the engine tuning. Timing really affects my 455's temp's so I really have to play with it; make test runs to see where it run the most moderate. Start over at factory timing if motor is near stock, or where motor just sounds nice at idle if modified seriously. Spend some time making the same fairly slow drive somewhere close to home, while noting how the temp is acting with each moderate change in timing. Once you've found a place where the needle don't go more than just over half way on the dial in just about any driving situation, i'd stop there and write down where the timing is at. Re-verify with another test drive.....maybe something a bit different like higher speeds. Then if the air/fuel ratio needs a bit of tweeking to run a bit smoother, go there. Then adjust the idle to where it won't "deisel" when shut down. You should then be all over it!

This timing/tuning/testing aspect I feel is he biggest player. Just kinda be thinking how much harder the motor has to work to burn at less that optimum timing as you do this.

It takes alot of trial and error on my part sometimes to get things running nicely. Oh, you'll burn some gas, but I think it'll better put you right there with what that motor really wants for settings. You're probably very close right now, just have to dial it in closer.

Oh....I found that using the 160 degree thermostat give you a little more range in tuning, might help to just put one in as others have stated, it's cheap and easy!

Also, I can drive in the fall and winter out here but find myself having to adjust the timing and tuning just a little to get it to run best season to season. Likely because of the 10% Ethanol in the fuels. But tuned, it'll burn 87 octane. I do put Sea Foam in the tank though as stabilizer for when it sits.

Have fun tuning!
Didn't mean to ramble.