[trshman]

I have a '66 LeMans with a "70 GTO/400 block and D-port heads from a '78 TA. Compression is all 160 except 1 & 3 which are 155. Runs around 200 in town (S Fls-85deg temp/w/o Air on) but runs up to 210-215 on hwy running about 80. 4 core stock radiator just removed/cleaned/thermo-hoses-belts-ok/ Milodon 7 qt pan put in last week and Flow-Master pump today-no change). Dwell checked-timing-etc. all ok. Any suggestions? In summer temp will averag 95 plus you need to run the air/ must find a way to get her to run cooler. All help is appreciated.
RG

[trshman]

I have a '66 LeMans with a "70 GTO/400 block and D-port heads from a '78 TA. Compression is all 160 except 1 & 3 which are 155. Runs around 200 in town (S Fls-85deg temp/w/o Air on) but runs up to 210-215 on hwy running about 80. 4 core stock radiator just removed/cleaned/thermo-hoses-belts-ok/ Milodon 7 qt pan put in last week and Flow-Master pump today-no change). Dwell checked-timing-etc. all ok. Any suggestions? In summer temp will averag 95 plus you need to run the air/ must find a way to get her to run cooler. All help is appreciated.
RG

[berrygoat]

What temp thermostat are you running and what type of fan ?

[gtoguy1967]

i have the same problom, seems the faster you go the hotter it gets. i tryed to run 80 once, the car went to 230 i backed it down quick my car runs hot but on the highway at speed say 65 it will run 205 or so somtimes more. i don't like to se those temps so i try to stay 55 or under and just cruise. i have tryed evry thing i can think of and no changes. you might try some water weter its an aditive to the coolant it claims to bring it the temp down some i cant say i have realy seen a dif though. good luck and let me know if you ever figure this out.

[trshman]

berrygoat,
Thanks for the response. Fan is stock, or so it appears to be. Clutch is new as is the shroud and rubber shroud "seals". Thermostat is 160 or 165, can't remember which, however it's an "off the shelf" unit. Flow-Kooler's website recommends using a thermostat by Robert-Shaw Controls, Inc. Could this all boil down to using their recommended thermostat? [img]/infopop/emoticons/icon_smile.gif[/img]
Thanks in advance.
RG

[trshman]

don,
Sorry you're experiencing the same thing but glad to know I'm not alone. Yours sounds a little worse, hitting 230 I mean. I top out at 215 on the hwy on a steady 80mph (+ -) run. Don't know where you live but here in So Fla it averages 95+ during the summer, only a month or so away. When I start running the a/c then it'll only get worse. I'd go for an alum radiator if I felt confident I'd get the results but after installing the Flow-Kooler and getting "nothing" I'm unsure an alum radiator would be money well spent. On the other hand I've spent a fair piece of change doing everything else,what's a few more bucks. At least I'll know I tried everything [img]/infopop/emoticons/icon_smile.gif[/img]
I'll keep you posted. Have a good one,
RG

[Lemans1]

Have no fear of the aluminum radiator....they work EXCELLENT!! I had that problem in 71 Formula I had. 455 w/Torker II, decent sized cam, Holley 750DP, headers, duals, and 3.73s. Car ran hot as hell, couldnt get it to stay under 215-220 to save my life. If I got caught in traffic it was big trouble on hot days. Put a Griffin aluminum radiator in----2 1" rows. From that point on the car was NEVER over 180. Just cruising on cool days it just stayed around 160, rising and falling a little with the thermostat opening and closing. I couldnt believe it myself, quickly got rid of the stock 4 core I was using and never looked back! It is money very well spent. I hope this helps your decision....

[berrygoat]

Switch to a Mr Gasket or Robert Shaw 180 thermostat. The coolant is circulating too quickly with that 160. It should help.

[mike nixon]

what rear gears are you running?

check you radiator cap,it needs to hold at least 12lbs of pressure.

use a 60/40 antifreeze mix for the best cooling.

install a "puke tank" and make sure that you radiator cap is a compatible unit [sealed systems push the coolant out and then pull it back in when the car cools down].

check the a/c condensor to be sure it isn't plugged with dirt / bugs. an air hose works well to clean it out. blow from the radiator towards the grille for best results.

is your clutch fan temp controlled or a centrifigal unit? i've had better luck with the centrifigal units or the oem type flex fans.

have you checked you carb mixture? if not you may need to richen up the primary jetting.

make sure the timing advance works properly, both mechanical and vacuum.

if you don't have a fan shroud find one and position the fan so the blades are about 1/2 way into the shroud.seal off the core support so that the air has to go thru the radiator.

also check to make sure the fan pulls air through the radiator and doesn't push out thru the grille.

mike

[trshman]

LeMans1,
I'm glad to hear aluminum worked that well, that's what I was told to expect. I found a place called "Muscle Motorsports" in North Carolina. They purchase parts from NASCAR teams and resell them. Most of those guys only use parts once and then toss them. I bought a 3 row/Fluidyne alum radiator w/oil cooler for $150 plus shpg a couple of months ago but couldn't make it fit, not without explosives. Just too big. Some fins were bent and it had no filler neck but other than that it was a beauty. Had no trouble selling it. I check with them every week or so hoping they'll get in something that will fit in mine. Whether I solve this or not eventually I want put aluminum in the car.
RG

[trshman]

[Berrygoat,
I bought a Robert Shaw 160 yesterday and was going to install it today. Glad I caught your post first. I'll try the 180 and let you know how it works.

I also want to apologize to Flow-Kooler for speaking too quickly. Their pump did make a difference. Temperatures are all about the same but around town it doesn't heat up as fast as it used to. If I caught 2 or 3 lights close together and temp was 85 or higher she used to get up to 220-225 w/o air REAL fast. That doesn't seem to be happening anymore plus she cools off faster. It looks like their claims of more circulation at idle and low rpm is true. Also one of their techs suggested that if the radiator was painted by the previous owner it could be preventing air from passing through it OR the fins have separated from the core decreasing heat transfer. I'm going to check that too. Geez, somethings got to work here [img]smile.gif[/img]
I'll keep you posted.
RG

[trshman]

Mike,
Thanks for all the suggestions. There's some I haven't tried. The rear end is a 2.93. The 2 previous owners lived in Las Vegas and I'd guess top end was more important-I know I'd prefer that if I lived there.

The cap is rated at 15lbs and is in good working condition.

After reading an article in Car Craft I run straight distilled water plus some anti-corrosive type product. It was their opinion that was the best combo for cooling. That doesn't mean it's right for this engine but their argument made sense and like most people I assume those guys know more. I have a copy of the article and would be happy to email it if you'd like to look it over. But if you feel strongly that the 60/40 mix is better then I'll try it. I'm leaving no stone unturned [img]smile.gif[/img]

The clutch is centrifugal and I have a shroud and shroud seals and the fan is stock and that's as much as I know. I haven't done the remaining things you listed but will over the next week and let you know. Again I appreciate your help, everybody's help for that matter. I'll keep you'all posted.
RG

[Lemans1]

For the record, I got my Griffin from Summit for $189 including shipping. It is a nice piece and only needed some minor mods in my core support for a nice fit.

[llucas]

RG, sounds like you have an airflow problem. Replace the fan clutch with a Hayden 2797 and you should be good to go if what you have IS an airflow problem. The typical failure for stock fan clutches is that they don't spin fast enough around town and thus you have low airflow and bad cooling, AND they don't freewheel good enough on the highway and thus you have low airflow and bad cooling there as well.

[Jim Doran]

I have had a hard time finding the hayden clutches at my parts stores. Where is a good source for them ?

[llucas]

Try Pepboys.

[78 GHOST]

RG: Interesting issue you have,where exactly is your temperature sending unit and what type of gauge do you have (elec. or mech.)?

On my 78 T/A, the factory location for the temperature sending unit is between #3 & #5 plugs in the block. The typical location on a Pontiac is in the intake manifold water return passage. I've been meaning to study the difference in position relating to indicated temps.

FYI, my T/A is bone stock, the only aftermarket add-ons are a K&N Air Filter (save your money), and a Stewart Warner mechanical gauge in the stock location.

When it's butt ass cold (20-30's) this car runs at 190-200 indicated. A few days ago (first warm day since new gauge install) I ran for a long while on the freeway and the temp stayed at 220-225 very happily. With A/C on, the temp went to 230 and stayed put (for 3 1/2 hours) with no apparent ill effects. No pinging, no nothing.

Early on, I was concerned and stopped to double check the car wasn't overheating and with it indicating 240-245 (immediatly after shutdown) I popped the hood, plenty of coolant, and the hoses, radiator, etc. all felt to be at a normal operating temperature to the touch. No coolant puked out the radiator into the overflow bottle while I was stopped.

BTW, I had another car once with a cooling problem and you could not touch the hoses or radiator right after shutdown.

I think my car is "happy" at this apparently high temp. but when considering the sending unit placement, that might be totally normal.

-Matt

[gtoguy1967]

uh 220 is to hot for me as a normal operating temp. i would be happy with 190 and 200 max .

[David Holmberg]

High temps at idle/low speeds is a fan/air flow issue.
High temps at speed, 3000+ RPM's is a water capacity/circulation issue.

I had the same problems as Matt has on my 77 TA. Around town it would stay at 180 but hit the highway (3.42's = 3200 rpm) and it would hit 220+. I checked the hoses and it felt fine, so I put it off to a faulty gauge. Then I added a Autometer temp gauge and it read dead even with the factory gauge.

I fixed mine this way..
1. I installed a Mr Gasket 180 stat that is exact.
2. (Made the most difference) Took the Q-jet off (that was lean) and installed a Holley 750 DP (slight rich) and now the temps never go above 200 even at the track.
3. Bought a griffin aluminum Radiatior and CSI electric water pump for the new motor...

[455Dave]

Dave,

I need to add a few points. Air flow can be a factor at speed, either diverted or blocked. An AC car with clogged condenser fins can cause overheating at speed as well as diverted air flow.

Another speed issue is a blown head gasket. I just went through this on the wife's car, at 80 mph tempurature climbed at would not peak. Found the No. 5 cylinder had a small leak, not enough to make the engine run rough, but made the cooling system operate at a 212 degree boiling point.

Funny, my T/A indicates around 160 in south Florida, 170 or so with the AC on.

During some recent testing, the radiator cap burped at an indicated 240 to 245 degrees so my temperature gauge is pretty accurate if the new 15 lb radiator cap is set properly from the factory.

Dave