Bleeding cooling system.

[OhOneSnake]

I changed my thermo to the 170deg that was sent to me when I ordered the Diablo Predator, but I'm not finding the bleed valve screw (if we even have one) like I used to use on the Corvette to bleed the air from the cooling system after a refill.

What's the trick to it?

 

[Dano]

You need to "burp" it. Do a Search on it ... there have been dozens of posts on it. Look in the past posts, too. It's pretty much straight forward - filling thru the cross-over tube.

Yes, you have to also fill it from the crossover tube. You can fill it most of the way by just filling the reservoir tank, but you have to take the cap off the crossover tube and finish filling from there as well. The crossover tube is too high for water just to flow in there from the reservoir.[/quote

Steve Snake Driver:Also make SURE you 'burp' the coolant system through the fitting on the upper hose manifold (looks like a socket wrench fits into it).
Fill the system and the overflow tank and then turn the heater on full blast. With the 'burp' fitting off, fill the system through the fitting as its idling and ensure that hot air is coming out of the heater. If not, there is air trapped in the coolant system and you will have overheating problems.[/quote



Dan

 

[Vinnie T]

If the cap has never been off, I'd suggest putting some WD-40 or similar on on the seam to loosen it up. I couldn't get it loose the first time without damaging it with just the 1/4 drive, so I let the dealer give it a try. They promptly stripped the drive hole, and then had to turn it off with vise grips which ruined the cap. And then they found out that you couldn't just order a new cap. You have to get the entire crossover pipe with it. Oh well, it was their dime back then since it was under warranty. Just use some anti-seize on the threads, and don't over tighten it. It's not the tightness that makes the seal, it's the O-ring.

I'm curious, why does it require such a cold thermostat?

 

[OhOneSnake]

It doesn't REQUIRE such a cold thermostat, but I'd like to get the regular temp down from 210ish to 180ish. I switched to 15/85 % Anti-freeze/Water and use Royal Purple "Purple Ice" coolant additive.

By lowering the stat, and having the fans come on sooner, I hope I can stay under 200 in the swealtering DC heat and humidity.

 

[Vinnie T]

Originally posted by OhOneSnake
It doesn't REQUIRE such a cold thermostat, but I'd like to get the regular temp down from 210ish to 180ish. I switched to 15/85 % Anti-freeze/Water and use Royal Purple "Purple Ice" coolant additive.

By lowering the stat, and having the fans come on sooner, I hope I can stay under 200 in the swealtering DC heat and humidity.

I'm wondering if you are going to affect your engine negatively? They're designed to operate in the 195-210 range normally, so it would seem that the electronics are going to be constantly compensating for colder than normal readings. And having such a light anti-freeze mixture will lead to a much greater corrosion probability.
I live the central valley of CA (near Sacramento), and air temps of 90-105 are common in the summer. I certainly haven't had any negative affects of running the stock 195 thermostat and 50/50 anti-freeze.
Oh well, good luck with your endeavor :burnout:

 

[OhOneSnake]

With the additive, a 15% antifreeze mix is all thats necessary for corrosion protection. While most newer cars are designed to run hotter, its only because they run "cleaner" that way.
Cooler is better (obviously to an extent) for performance. I don't plan on drop-kicking the temps all the way down to a ridiculous 160deg like I see some try. I figure 180 constant on the highway will be high enough to not negatively effect wear, and low enough to cool faster when I drive it to the track.
Where I race, if you don't show up early, and get into the staging lanes right after inspection, you won't get more than 2 runs in.

 

[Dano]

I have to agree with VinnieT ... I've read that the alum block engines are designed to run at a higher temperature - that's why the fan is designed to kick in at about 205 or 210. On my '95, the temp runs around 210 average. With the AC on normal, no blower going, the fan kicks in and keeps everything normal. I have an OEM radiator (cleaned & rodded) and the same w/pump that's been on there for the 3 years I've had it.

Anyone else dissagree with the high temp theory?


Dan

 

[biminiLX]

Cooler temp will make more power if tuned correctly.
I believe the OEMs use higher temps for better emissions? Not sure but a GM mechanic told me that when my brother and I were working on his GFs GrandAM, which actually has a temp guage with #s and runs around 200-210.
Anyway, to expand, the lower thermostat and cooler temps WILL make more power if the computer doesn't think somethings wrong. That's why they (and Hypertech, and others) send a different thermostat--they advertise more HP, and if the computer is tuned to this lower temp, you'll make more power. Later, J

 

[OhOneSnake]

Correct, hotter running cars burn cleaner. This, combined with the need to heat the cats for them to work better, is the reason you should run your car for at least 30 minutes before showing up to a state dyno-emmisions test.

Cooler is better

 

[Vinnie T]

Originally posted by OhOneSnake
With the additive, a 15% antifreeze mix is all thats necessary for corrosion protection. While most newer cars are designed to run hotter, its only because they run "cleaner" that way.
Cooler is better (obviously to an extent) for performance. I don't plan on drop-kicking the temps all the way down to a ridiculous 160deg like I see some try. I figure 180 constant on the highway will be high enough to not negatively effect wear, and low enough to cool faster when I drive it to the track.
Where I race, if you don't show up early, and get into the staging lanes right after inspection, you won't get more than 2 runs in.

I realize that they are tuned for max. efficiency when it come to MPG and emissions, but this is the first that you've mentioned the racing aspect, which I can understand. I was looking at it from a day to day use standpoint, which seemed like major overkill. My original question/point was that the cool temps may cause a negative reaction with the cars electronics that ends up offsetting any gains you get from running cooler. If your fuel/air mix isn't burning as completely as it could, you're going to be losing some power that way. However, if your electronics package advises the use of the cooler stat, then it must compensate OK.
I'm not familiar with that particular additive, but have seen enough damaged cooling systems, blocks, heads, etc. from weak or low % solutions of anti-freeze to just mention it.

 

[OhOneSnake]

Back to the original question I had for this thread, thanks for the advice. I had no problem screwing off the cap, and it worked out great. I am declaring success.

I couldn't get the temps to go above 196 no matter how hard I tried, and at cruise on the highway, they sit in the 180s.

I am having it dyno tuned soon, shortly after my SLP x-pipe gets off backorder from LM Performance. Most likely I'll just be adding some timing and leaning it up a little bit (which the lower temps help allow)