[Blue '66]

An A/C car?Does it have all of the baffles around the rad?One of the biggest differences others have noticed is when the baffel between the rad and core support is there.

[dave bolduc]

yep////baffles in....no ac compressor....

[meanolegoat]

FWIW--Are the tubes/seals present in the timing chain housing??? Mine did great at idle and stop and go but would climb to 220 on the highway. Found out some jack-ass had left em out!!
"mean"

[george kujanski]

Dave: either your system can't get the heat out or you are putting too much in.

Heat out: need airflow thru rad; need circulation of coolant, no trapped air, System needs to be sized to dump the normal engine heat.

Too much heat in: Engine not running efficiently, etc.

The above general conditions are what need to be examined in detail. There must be an answer.

George

[70 lucerne lemans]

I had the same problem,mine would creep up to 225 on the highway.I tried a flowcooler pump and high flow t-stat,nothing worked.I finally installed a griffen universal aluminum radiator and problem solved!I actually had to change from a 160* t-stat to a 180* because it ran too cool.Now she stays at 180-190* all the time.

[dave bolduc]

thx for the replies....has had me pullin hair out....the car ran great for 4 yrs before having it painted...it sat for nearly a year in a shop.....did lots of retro...new panels, disc brakes, bushings etc. when she was don being painted, the tubes and side vents had been opened...to have it run cooler~!..Had her flushed like i do every spring, put her on the road...heat on hiway...did the whole iron impeller search, couldnt find one...put in new pump anyway...same prob...finally found used pump...changed clearnce again....same prob...went back to new pump..speed shop messed with mixes, put on another carb...same prob...guess ill pull the a/c unit in front of radiator..see if it helps since i dont have AC in yet anyway.
radiator seems great...i see flow in all tubes. The only other thing was changing from flex fan to new clutch fan..
will the aluminum radiator work better than my big assed orig????

[Blue '66]

Have you been able to find the pulleys OPH?

[gtochism]

Have you checked to see if there is a coiled spring in the lower radiator hose? I've seen hoses installed without the spring suck almost closed at hi speed but not at idle.

[dave bolduc]

ya...that was in george's thread last summer...thx....replaced hose/spring anyways...no help

[Blue '66]

In the race section several have noted cooler temps when the block is filled to the bottom of the lowest freeze plugs.Not that that is something easy to do........

[dave bolduc]

finally resorted to the most basic of fixes for heating at 65 mph +

My car is a clone with T/A hood snorkels open. When I taped closed the tubes, the 230+ temps stoped....she tops out at 210 or so now. Sadly have to close the tubes perm now. I had thought the increased air would help COOL the engine.

thanks for all the ideas guys

I ended up:

1. replacing pump with cast impellar - tightening div plate gap
2. checking fan shround, distance fan sits in it
3. drilling 3 small holes in my 160 degree new stat
4. replacing my bottom hose, checking that spring was intact and not bent
5. installing a bottom spoiler as an air dam
6. making sure my baffle plates were installed
7. power flushing my entire system at a shop
8. adjusting my timing and mix

answer.....2 strips of duct tape on tubes....

still gonna try the "Y" on the return hose....\\You guys have been great..thanks again

[HWYSTR455]

I run all the A/C pulleys from a donor '68 Cat on my 71 LeMans, and used to have a creap problem on the highway. I've got the 7 blade clutch fan, and actually changing to a different clutch is what fixed mine. I had a clutch for a 455 application, then chose a clutch for a 400, seems to engage more, and even at highway speeds. Sure, over 50 I hear everyone say a fan doesn't do jack, but I swear it did for me. I can hear it partially engaging on the highway and dis-engaging. It's a thermal, and can get the part number if anyone's interested. The full time flex fans actually block air after a certain RPM, and I hear the best factory fan to use is actually the 5 blade. The 7 blade can block flow as well, almost a cavitation thing going on in the shroud area, if that makes any sense....

[dave bolduc]

would love part number...

[scratch the itch]

Rodney RED Radiator is supposed to work. I will let you know in a couple weeks

[Geeto 67]

Here is the problem I have, At idle at a stop light the car will creep to 240. It does this regardless of what fan is on it (I have used electric and various clutch fans, current is a 7 blade and hd clutch). When I rev the car up to about 2 grand the car then begins to cool down. The pulleys are the stock pulleys on the car from the factory (1967 GTO, non-ac car). This is the kind of problem that a pulley swap will probably cure. the question is, where do you get an a/c pulley. for a 67.

the reason the crank pulley is larger is not to help the wp spin faster but to take up the slack in the stock belt that occurs when you go to a smaller WP pulley size. A smaller pulley will also cause the fan to spin faster increasing airflow at slower speeds where it is most needed.

[Brad B. Hillebrand]

Some ideas:

Cast impeller? or try a Flowcooler pump (works very well for me)

Use a Stewart High flow T-stat to help get more water thru at higher speeds.
http://www.stewartcomponents.com/. Start at 160 to get water flowing as soon as possible. You could also remove the stat as a test to eliminate it as a possibility. I assume your hoses are new or newer? No need to mess with drilling, just buy one already done...

I would eliminate the anti-freeze unitil the issue is solved. Go to straight water w/water wetter and 16 oz. No rosion (for anti-rust). It works better and that's proven.

Use the stock 19" A/C fan with a new clutch, your old clutch might not be stopping at higher temps and reducing air flow. Napa HD Police Interceptor clutch works fantastic
A/C fans are on E-bay all the time and work very well....push air big time

If you have A/C take the belt off the compressor

If you have headers see if they are close to the oil filter, if so, wrap it as a test.

If auto, make sure trans lines are away from heat.

Install RR radiator - my car runs too cool at times and that makes me worry a little....never gets over 185, even in 100+ temps. In spring and fall, car sits at 175....



What kind of engine are we talking about?
Auto/stick
Rusty water passages?
What temp gauges do you have beside water? Oil/Trans?
Rad. type? copper?
Lots of other idea depending on car....shroud, shroud kit to increase air flow.

Brad

[Geeto 67]

Brad,

not sure if your questions are directed at me but i'll answer them anyway.

Got the case impeller water pump, helped a lot (the car used to really overheat). Run a high flow 160 T-stat. Run mostly water in it right now with some royal purple corrosion stabilizer and temp reducer. I have the napa hd clutch (I have gone through 7 fan clutches looking for the best one). I am pretty sure the 7 blade I have is an A/C fan. No A/C ram air exhaust manifolds. Auto and the trans lines run the factory route away from the heat.

Engine is the original 400 rebuilt 5000 miles ago. The block was hot tanked and checked for crossion in the passages and came up clean. The car has a ram air IV cam, 670 heads, stock manifold, 69 H.O. quadrajet. Car has a shroud. Radiator is a factory harrison 4 core. Right now I only have a water temp gauge but it is easy to know when the car is overheating, it runs differently (usually a little hesitation).

I have been battling this heat problem with the car since I bought it. I just have to accept that this car runs hot (210-230). about the only thing left is to do the Rodeny red radiator but that is big money for me right now, espically when I am contemplating taking the car off the road to do the bodywork.

[Malky]

dave, I agree that overheating at highway speeds is more likely a water flow problem than an air flow problem. Since you have ruled out the pump and rad, it may just be a sticky thermostat (not uncommon), or collapsing lower rad hose starving the pump at high rpm. Check if hose has internal spring to prevent collapsing.
Also, like others have suggested, timing could be really retarded at higher rpm. Check the centrifugal advance weights aren't rusted solid and the vacuum advance is working. This is easy if you have a timing light. Running retarded will cause overheating and also give you terrible gas mileage.

[Brad B. Hillebrand]

Geeto 67 -

Couple questions:

You are not running the stock A/C pulley, you mentioned the one you are using now is smaller. Earlier you said that a pulley swap might solve the problem. Are you saying going to the larger A/C WP pulley might solve the issue?

What is the diameter of the crank pulley you are now using?

What is the diameter of the wp pulley you are using now?

Who makes the high flow t-stat you are using?

About the radiator...it's a stock 4 core unit right? Did you have it tanked and cleaned? When I put my trans temp gauge on I was shocked at how hot my trans ran, it runs cool for a while then really gets hot. I have the RR rad so it can handle it, I can't discount hot trans fluid in the rad. especially in a stock unit. I'm wondering if the trans fluid temps is also causing some issues as well.

You mentioned that at idle you have the issue then at 2K the car cools down, at normal highway speeds what happens?

Spinning the fan at higher speeds increases water flow in additon to air flow. The faster you move water thru the system, more heat will be removed. The rad. needs to be able to keep fast moving water cool. I'm not sure yet but it appears that the setup you have is not moving water fast enough at idle, your pulley ratios might be incorrect, your WP might be running slower than you think at idle. Assuming the rad. is cleaned and working as it should.

Brad

[Geeto 67]

Originally Posted by Brad B. Hillebrand

Geeto 67 -

Couple questions:

You are not running the stock A/C pulley, you mentioned the one you are using now is smaller. Earlier you said that a pulley swap might solve the problem. Are you saying going to the larger A/C WP pulley might solve the issue?

What is the diameter of the crank pulley you are now using?

What is the diameter of the wp pulley you are using now?

Who makes the high flow t-stat you are using?

About the radiator...it's a stock 4 core unit right? Did you have it tanked and cleaned? When I put my trans temp gauge on I was shocked at how hot my trans ran, it runs cool for a while then really gets hot. I have the RR rad so it can handle it, I can't discount hot trans fluid in the rad. especially in a stock unit. I'm wondering if the trans fluid temps is also causing some issues as well.

You mentioned that at idle you have the issue then at 2K the car cools down, at normal highway speeds what happens?

Spinning the fan at higher speeds increases water flow in additon to air flow. The faster you move water thru the system, more heat will be removed. The rad. needs to be able to keep fast moving water cool. I'm not sure yet but it appears that the setup you have is not moving water fast enough at idle, your pulley ratios might be incorrect, your WP might be running slower than you think at idle. Assuming the rad. is cleaned and working as it should.

Brad

- I am using the stock NON A/C Pulley which I think is larger than the a/c pulley. The reason I think this will solve the problem is if I am at idle the car is creeping. If I rev the engine to 2000-2500 rpm the car begins to cool down by about 10 degrees. If I rev it to 3000 it doesn't cool down. I think this isn't an airflow problem because this happens when I am moving and I am stopped. I don't think the wp is turning fast enough at idle to cool the motor. I also happen to think the radiator is too small for the car and that is why it heats up at 3500 rpm or above.

- don't know who makes the t-stat I am using right now, I bought it 2 years ago from my local speed shop.I've gon through a bunch of them this was the one that worked the best.

- The harrison radiator I have is a stock unit. I had it recored when I was working at a radiator shop, we flow tested it and it checked out perfect. For all intensive purposes it is a new radiator.

- The tranny cooler might be contributing to the problem.

Today I really cooked the motor. I got stuck in traffic and pegged the temp gauge in the 6'o clock position. considering the gauge only reads to 240 I figure the thing was probably at 260-270. I had steam coming out the overflow hose. I have a feeling the valet parker I had to give the car to today overheated it parking it in the garage as I could hear him beating on it up the street (spun the tires a little) and that caused a lot of the overflow to spill out so for my drive home there just wasn't any water in it.

Anyway, I really need the car right now to drive but five plus bills is a lot to drop on a radiator right now.