[JFMetter]

Thanks for looking at this.

I have a restored 1966 GTO - 389 Tri-power. The engine is rebuilt and I am at 100 miles in the break-in. My past experience with a GTO back in 66 I know these things run hot. So early in the break-in I'm pressed to understand how this one is acting., But it is running around 200 degrees. So I think I need to do something. But what?

Shroud? But my fan is 19 inch seven aluminum blade with a 15 1/2 core So I will need to replace it to fit correct shroud. OR

Try Evans waterless coolant. Not a lot of testimonials out there about this stuff. OR

New aluminum radiator.

All these fixes will cost $200/$300 +, so I'm trying to decide which a good first shot.

Thanks!

[ZeGermanHam]

190-200 degrees is normal operating temp.

[JFMetter]

Thanks. But I think I'm doing a little positive thinking saying it's running around 200. On a cool fall day with no traffic OK. But on a normal summer day the temp gauge is hovering around the 3/4 mark. Now I know these guages are not exact instruments, but I'm thinking it's showing a 210 - 215 reading and trending in the wrong direction. I'm hoping as I break the rebuild in a bit more the temp will settle down and I won't need to worry about it. My "year in Vietnam" GTO never really ran that hot, but it used as I remember seven quarts of oil to help keep it cool - Pontiac's attempt at cooling the engine a bit more. This rebuild only has five quarts capacity, so that's that's not going to help. Maybe I have nothing to worry about. But anyway, which of my three options from experience would be the best intitial attempt at aiding engine cooling?

[gtospieg]

Did you clearance the waterpump plate when you assembled the engine? That is the first place I would look.

[tom s]

if mine the first thing I would check is timing.Retarded timing causes higher temps.Second I would get a lazer temp gun to see how accurate your gauge is and also you can see how efficient your radiator is on how much temp decrease you have where it goes into and out of the radiator. You can also see if there are hot spots on the engine such as the thermostat area.Tom

[Ccass]

Today's fuels cause the engine to run hotter.

you probably have a 3 row original radiator? Pontiac realized almost immediately that the 3 row radiator was inadequate for most GTO's. They created a dealer installed fan shroud and 7 blade clutch fan almost immediately. Those two options may solve your problem. If not, you need a bigger radiator. Add a 4 row HD radiator or a 'Big' 2 row aluminum if originality is not real important.

That should get you down to 180-190 range even in hot driving conditions.

[JFMetter]

This rebuild installed a "DESERT COOLER - 4-Core (just counted this) Radiator" from AMES (part P119AC). Its brand new in the car so its not clogged or anything. Its not aluminum but should be a pretty good cooler. The fan is a 19 inch seven aluminum blade clutched fan (while I found the radiator info from rebuild paperwork, I can't find anything on this fan). So maybe I'm overacting here and should do what TOM S suggested - use a lazer temp gun (whatever that is - will find out) to checking to see if I really have a problem.

[tom s]

The guns are avail at auto stores like Pep Boys for about $20-$25.Tom

[Lee]

RE: the Evans Coolant

I know one guy that uses that stuff. Other than making your wallet significantly lighter, I do not see benefit. He still runs hotter than he wants to.

[Ccass]

Originally Posted by JFMetter

This rebuild installed a "DESERT COOLER - 4-Core (just counted this) Radiator" from AMES (part P119AC). Its brand new in the car so its not clogged or anything. Its not aluminum but should be a pretty good cooler. The fan is a 19 inch seven aluminum blade clutched fan (while I found the radiator info from rebuild paperwork, I can't find anything on this fan). So maybe I'm overacting here and should do what TOM S suggested - use a lazer temp gun (whatever that is - will find out) to checking to see if I really have a problem.

If you have a 4 row Desert cooler and are running around 200 degrees without a shroud, then all you need is a shroud. Make sure you seal the shroud all the way around the perimeter to create a better vacuum affect.

You also might need to switch out the 7 blade fan for another if that 19" fan doesn't fit in the factory shroud. Ames has the non ac shroud for about $115 I believe. Do not get the $70 shroud! It's so flimsy, it doesn't let you create suction without the shroud collapsing.

Doing this should lower your temps to 190 which is totally fine.

[Ccass]

Originally Posted by Lee

RE: the Evans Coolant

I know one guy that uses that stuff. Other than making your wallet significantly lighter, I do not see benefit. He still runs hotter than he wants to.

talked at length with the Evan's guys and while I have no first hand testing, I am skeptical of the benefits.
I do know that with Evans, they admitted that your temps don't actually come down when using their product. They had an explanation for that but I was a little confused.

[rwarnerjr]

The big thing with Evans is much higher boiling point and never needs changing, also you can't add water if you have a leak or whatever so keep a gallon or more handy. Must get all water out of block, they have an cleaner for doing that.

[AdamIsAdam]

Originally Posted by rwarnerjr

The big thing with Evans is much higher boiling point and never needs changing, also you can't add water if you have a leak or whatever so keep a gallon or more handy. Must get all water out of block, they have an cleaner for doing that.

Exactly. 375° boiling point and much less pressure on the system because of it. In fact, you need a lower PSI cap. I like the idea of that margin of not overheating out blowing as hose.

Evan's is exceptionally good for aluminum parts. Watch Jay Leno's review on it.

Lastly, they say the temp gauge might actually read higher because it's extracting more heat from the engine amber causing the gauge to read higher. Or so they say.

So far, I've had it for a few years and am pleased.

Getting back to the original question, I had much success using the Severe duty clutch fan with the modified spring to make it engage earlier. I don't even use a shroud because I'm running cool, plus engine masters tests showed no should picked up some horse. Odd, but true.

[JSPONT]

Clearance the pump and put a shroud on. Timing can make it run hot but I have my timing locked @ 25% my car runs @ 170 all day long.
Make sure you carb is not way lean or way rich.

[JFMetter]

Think I've got it.

Checked timing and is 6 BTDC.

Get a laser temp gun and verify temperatures

My Desert Cooler radiator good.

Put on shroud (part from AMES) sealed around edges and swap out fan if too big for shroud.

Use of Evans coolent questionable solution.

Guess I kind of knew shroud was the answer. Good to know what radiator I have too. One less thing to worry about (or shell out more money to replace).

Thanks

[JSPONT]

You can add water wetter sold at parts stores for around 10 bucks.

[JFMetter]

I put in, I think it's called Wetter Water. Interesting stuff. I hear it's like the liquid you can put into dishwashers that makes water less tacky and causes it to slide off dishes. In a radiator I guess this will cause the coolant to slide over the hot water jacket surfaces more and theoretically pick up more heat in the process - ever so slightly. It helps, but in my car not a big difference.

[dhcarguy]

Originally Posted by JFMetter

Think I've got it.

Checked timing and is 6 BTDC.

Get a laser temp gun and verify temperatures

My Desert Cooler radiator good.

Put on shroud (part from AMES) sealed around edges and swap out fan if too big for shroud.

Use of Evans coolent questionable solution.

Guess I kind of knew shroud was the answer. Good to know what radiator I have too. One less thing to worry about (or shell out more money to replace).

Thanks

6* ??? should be higher I think.

[JFMetter]

Originally Posted by dhcarguy

6* ??? should be higher I think.

The 66 Tempest Chassie Manual specifies 6. When I firsts checked the timing (vac advance plugged and rpms as low as I could get it - specs say 600 but I can't really get below 900 without stalling the motor ) it was very high, guessing 15 or so (the timing plate by the fly wheel mark only reads an advance of 8). So I dropped it to 6 and drove it. Before I had a little pinging at operating temperature (I am very very early - less than 200 miles - in the engine rebuild break in. So I'm still trying to understandstand this motor. And I've been away from one of these things for 40 years too). This pinging is now gone. The motor feels real good now (it's hard to stick to breaking it in and not lay a little rubber). And at operational temp while idling a lazer temp gun pounted where the temp guage sender plug screws into the manifold reads 185 - 190. So I now better understand what my temp guage is really telling me. I probably don't have a problem with overheating. But I'll keep in my back pocket the idea of a shroud just in case.

But - if I have misread the timing settings here please tell me to go back and get it right. I do not overestimate my skill and experience here and appreciate any advice.

[judgeman6970]

I usually run my gto's at 9-12 btdc, approx. 34-36 total. Also, there are different fan clutches that you can use. If yours isn't brand new, I would go with a more heavy-duty clutch. You can look up specs online, and see that some units lock up "more & sooner", helping the engine run cooler...