Need advice.

[air1jpg]

What I think, if you've drove it over 20-30 miles it's probly already mixed!! If your cooling system is Full of coolant with No Leaks or Air Locks (Like it should be!!) and if you have no Leaks in the line going to the Coolant reservoir (Like it should be!!) Every time you start it and get it to running Temperature it has already pushed a pint or more out into the Reservoir!!Don't believe me just take that little line off right by the Pressure cap going to the reservoir and start it up and run till it gets to 200* and watch it "U-riya-nate" out on the floor! Water,Antifreeze,40 Below,Water Wetter,Liquid Cool don't matter it all Expands as it gets hot and contracts as it cools down!! Now lets say your driving around town and it's running about 220-225* in traffic and you head down the Interstate and it comes back down to say 200*as it's cooling down it will be sucking the coolant back into the cooling system as the coolant inside the engine contracts!! This is how a Closed Cooling system works!! In the old days the systems didn't have a reservoir and had a upright radiator 8-12 lb pressure cap and as they got hotter they would Puke it out on the road and eventually be to low of coolant to circulate and then get Hot!! Now as far as dropping the operating temperature below 195 or so,alls thats going to accomplish is create more Condensation, Sludge and Harmful Deposits inside your engine,More Emissions, and will effect your economy some!! There is a reason that they designed them to run as hot as they do,ever see the inside of a Old 283,327 or Big Block after 100,000 miles!(Get the Bucket,Scoop Shovel and Jack hammer!!) I have a customer with a 86 that has 248,000 on it and still going strong,we finely put valve cover gaskets and timing chain in it last fall and I was amazed at how clean the engine was inside!!

Junk,

Wouldn't it be best if we just left the coolant/engine temp alone and let the engines run at the temp GM intended them to run at? When the engine is at 225 or so, doesn't that help the engine burn off deposits and junk like that? My stock LT1 engine didn't get much past 235 last summer.

 

[JAKE]

At the risk of starting a back and forth on this cooling system issue, my understanding is:

In order for coolant to be forced into the over-flow reservoir, pressure in the cooling system has to exceed the pressure of the radiator cap. When pressure DOES exceed the cap's rated pressure, it pushes up on the inside of the cap, causing the spring in the cap to contract/depress/relax.

This then allows the pressure and coolant to flow through a hose which is connected to the over-flow reservoir, thus releasing the pressure.

Once the engine begins to cool, a vacuum is created which, upon restarting the engine causes coolant to be drawn back into the cooling system/engine. So it's a sucking method. Pushes out, sucks in.

Now, if the engine's coolant system never creates enough pressure to exceed the radiator cap designed pressure (although on the LT1/4 the cap isn't actually on the RADIATOR), no coolant will flow into the reservoir.

So, if coolant IS being forced into the over-flow reservoir I suspect the cap is faulty.

Here's an example: This morning I drove my son's 96 LT1 Vette all around the Dallas metroplex doing some shopping. When I finally returned home, after about 50 miles or so, I popped the hood, removed the cap from the reservoir and stuck my finger inside to get a feel of the temp of the coolant inside. The coolant temp was very COOL, the same as the ambient temp. So none of the engine coolant, which was over 200 F, had entered the reservoir.

There are two hosed located just below the "radiator" cap on the LT1/4. It's the upper of the two hoses that is connected to the reservoir. In order for coolant to flow through that hose and into the reservoir, the radiator cap has to be in the open position.

Jake

 

[Paul Higg]

Jake, now THAT'S troubleshooting and using you old noodle! I NEVER would have thought of doing that, putting your finger in the coolant tank. Great real-world test. Your description of how the cap works was very good too. But the temp of the tank coolant seals it for me. I replaced the cap on mine when I first got it as it was rusty so it is brand new.

Thanks for that Jake.

Paul

 

[JAKE]

Junk,

Wouldn't it be best if we just left the coolant/engine temp alone and let the engines run at the temp GM intended them to run at? When the engine is at 225 or so, doesn't that help the engine burn off deposits and junk like that? My stock LT1 engine didn't get much past 235 last summer.

Sure you could do that. But in Texas, during the summer months when the temps are at 100F+, sitting in traffic with the A/C blowing full-bore, the coolant temp needle gets within a hair of turning on the WARNING light. Dangerously close to the little black and white hash-lined box.

I expect it makes most driver's very nervous to see the needle climb and climb, I know it does me.

I can't recall how many Vettes I've seen stopped on the side of the road with the hood up during days like those, but there have been a LOT. Remember, our cars are ground breathers, so without the airflow created by movement of the car, the fans are hard pressed to keep the temps down.

Coolant temp and heat soak has a profound effect on engine power too. The most recent edition of Engine Masters magazine speaks to that very point. Grab a copy; lots of good info in it.

Jake

 

[Tuna]

Besides Water Wetter, I have a 160 thermostat, reprogrammed computer chip that turns the fans on sooner and I use a "Big Mouth" radiator scoop to direct air to the radiator to keep things cooler.

 

[Paul Higg]

Tuna, I plan on having mine reprogrammed too but where do I get a 160 thermostat?

 

[Tuna]

Tuna, I plan on having mine reprogrammed too but where do I get a 160 thermostat?

Eckler's, MidAmerica, your local parts store, etc.
Using a lower temp stat needs to work inconjunction with reprogrammed fans. You don't want to reprogram the fan turn on temps lower and have the fan and the stat fighting each other.

Others will tell you that the 160 stat never lets the motor get up to temperature properly to heat the motor and the oil properly. For short trips, I agree.

Right now, with outside air temps in the 50-70, I see coolant temps in the 175-180 range and oil temps about 5-10 degrees warmer. I can live with that.

In parades and traffic jams, having the fans turn on sooner adds a little piece of mind. The Big Mouth really directs the air to the radiator once you start moving and cools down the motor quicker. The only issue with the Big Mouth is parking at curbs. You can't afford to touch a curb with the Big Mouth since is can be shoved back in to the A/C and radiator. Not usually a problem or issue for people that have been driving Vettes for a while.

 

[Paul Higg]

Thanks Tuna. Yeah, I know what you mean about parking. When I first bought it I thought I'd have to install some of those big-rig vertical poles with the lights on the top to know when to stop. <grin> I don't want any smashed air dams.