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Discussion Starter #1
My car has been running hot since I put the new head on it this past winter, and I’ve been having a lot of trouble finding the source because I changed so many variables at once. New head, rebuilt carbs, new thermostat, new coolant hoses, new coolant type. I reused my old rad because it seemed to flow water just fine and always kept the car at a solid 185F prior, regardless of weather or conditions. The rad cap is new.

Now the car runs closer to 200-212F, as indicated by both the coolant gauge and my infrared temp sensor (they match!). And the temp fluctuates +/- 10F during a drive, which it never used to do. Road speed and engine speed seem irrelevant to the temps.

After the new cylinder head went on, I filled the engine with Evans Waterless Coolant. It occurs to me that that’s another critical variable that could affect running temperature.

I’ve already spent about $200 to fill the motor up with this stuff twice (don’t ask). I’m gonna swap it for Prestone this evening unless someone has a better idea and see if the temps come back down.

Besides the Evans coolant, the only thing left I can think of is that there’s something not right with the new thermostat I got from Centerline. That seems unlikely. I tested it in boiling water to see that it works, but I didn’t check at what temp it opens.

I’m pretty confident I’ve bled the system well.

I know some will say that 210F is no big deal, but this same motor used to never deviate from 185F, so I know something’s not right. I’ll report back, but I’m open to any suggestions!
 

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But Mad North-Northwest
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Yes, Evans will make your car run hotter. If you do a search on the BB you’ll find details. Personally I think the stuff is a really bad idea.

In older Alfas I prefer conventional green coolant over Prestone. Prestone is now an OAT long life coolant. It is *probably* fine, but the green stuff works well and is definitely fine.
 

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Yes, Evans will make your car run hotter. If you do a search on the BB you’ll find details. Personally I think the stuff is a really bad idea.
IMHO, the Evans coolant is pure BS. If it is so good, why isn't it used in high $$$$ applications like Reno Air Racing planes?

The ONLY reason not to used ethylene glycol based coolants is if they are not allowed (e.g., motorcycle racing commonly requires plain water so the track isn't slippery after a crash).
 

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86 Veloce
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I live in an area that never really freezes hard and my vehicles are always garages so I really have no use for anti-freeze. IMHO, the best coolant is water. I run nothing but distilled water with a rust inhibitor and "water wetter". As far as I am concerned the only benefit to Ethylene Glycol is as an anti-freeze....
 

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Coolant wars! This is shaping up to be like the posts on Oil types, or if DOT5 is any good...

Your thermostat has the most direct influence on your coolant temps. Evans will run a tad hotter, but nothing like what you are seeing. Given the proclivity for aftermarket spare parts to be crap, you should put your old thermostat back in. They rarely fail, from what I've read on these forums. And given the expense of Evans, the thermostat change out makes the most sense per dollar.

If things work out, another owner in 10 or 15 years will pull the head and have NO issues with corrosion on the studs, and it will come right off! Ditto for water jackets.

Another thought- I'm not sure if Alfa sold thermostats for different climates like most other manufacturers, but you could have gotten a cold climate thermostat, or maybe they don't want to make different climates, so they sell 'one for all'.

I'd put in your old thermostat.
 

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Got an air pocket. Loosen the 14mm Brass nut above the thermostat and before put a towel around it. You must BLEED the coolant system and it's the only way. Also turn your internal heater valve on cause there is AIR in the heater core. Loosen the nut when cold PB bast it 1st, start the car and get her warm and loosen the NUT, you'll hear the air, may have to add additional coolant.
Coolant is all the same, I use store brand stuff.
Do this and write back?
 
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I use 50% green anti-freeze mixed with 50% distilled water in all of my Alfas. I do not own a new Giulia or 4C. I never thought about using Evans coolant in any older Alfa. I like to change the coolant every two or three years. I know that new cars require different coolant compared to old cars.
 

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But Mad North-Northwest
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Coolant is all the same
That is a provably incorrect statement. You should read up on the different technologies out there (IAT, OAT, HOAT.) Coolant ain't all the same any more.
 

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Well, here's my 2 cents. Burping the cooling system as Alfasrules described, is the way to go for removing air & lowering the temperature.
These are "old school" cars & they've just not caught up with modern technologies.:wink2:, so the "old school" approach just might work.
But who cares, it's just an opinion.
 
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Richard Jemison
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Evans Coolant???

By now you should have the Evans drained and the coolent systen flushed. With water how`s the temp??

Engine below has mods to prevent air and steam pockets from occurring.
Critical as increases in HP seriously raises the thermal load.
 

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After years of racing MG's then Brabhams, Elfins and Lotuses, my experience is nothing removes heat like water. If in a non freeze climate I use just water and an inhibitor. Some that have used Evans have gone back to water, I never did - don't like anything that increases running temps.
 

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86 Veloce
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Right on, Ed. All I have run for years in all my vehicles is water with Water Wetter which is a corrosion inhibitor and increases heat exchange. All this hulla ballou about "coolant" is nonsense. Anti Freeze, yes, when needed but "coolant" doesn't cool.....
 

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Discussion Starter #14 (Edited)
After replacing the Evans with Prestone there is no change whatsoever.

Is it possible that the new thermostat is incorrect? It’s this one:

https://centerlinealfa.com/catalog/thermostat-euro-1750-2000

My car was originally a US SPICA car, but a previous owner changed it to twin Dell’Ortos.

When I crack the bleeder open, hot or cold, only fluid comes out. An IR temp gun shows 185-200 on the exterior of all hoses, and there is heat in the cabin. The hose to the expansion tank is not blocked.

Still, the temp gauge shows a consistent 15-25F increase over the pre-top-end-rebuild temps.

If the car is parked with the engine running and the electric fan comes on, the temps drop verrrry slowly. I’d expect them to come way down in just 15-30 seconds based on experience with other cars, but it takes way longer. Same if I let the temps rise a bit then cruise at 50 mph — the temps don’t come down fast like I’d expect.

Is that a clue?

I really doubt the thermostat is defective. Could I have the wrong one? Unfortunately I no longer have the original.
 

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86 Veloce
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Other variables.... Howz the fan working? Blockages in air flow? Possible water pump issues? Put the coolant ridiculousness aside for a while and just run some water for a while and see if temps change....
 

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The radiator was flow tested, are there any cool spots (checking with the infrared sensor?) I typically have the rad core boiled out then flow tested.
 

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Cognitive dissonance
 

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Discussion Starter #19
I rechecked all the under-hood temps with an IR thermometer after a 40-mile run.

The rad is 210 at the top and 165 at the bottom. The bottom hose is also 165.

Even after 20 minutes above 70 mph the temperature gauge still does not get below ~195. Outside air temperature is 75F. Nothing is blocking airflow to the rad.

The fan is new and electric and is working.

I did not have anything done to the radiator, but it is the same radiator that always kept the car cooler than 185 previously. I did run water through it from the garden hose before reassembly, and it seemed to flow water well.

Do the symptoms above point more to a bad radiator or incorrect thermostat? Is it even possible to have an incorrect thermostat that fits perfectly?
 

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86 Veloce
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Your new electric fan.... did it always have an electric fan or did you swap out the mechanical one? Is it operating at top efficiency? Does I think have a shroud to direct air flow? Thermostats do come in different temp ranges but with the Alfas I don't know. Have you just removed the T-stat and ran it open? Keep plugging, you'll find the issue sooner or later...
 
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