[Missing Link]

Good day all,
Obviously my first "question" post. I'm new 'round these parts, so forgive me if I forget anything...I did an introduction a month or so ago.

I FINALLY finished up most everything on the car, got the frontend aligned and went for one little spin...about two or three miles. New motor, 350/330HP GM performance motor, new trans 2200 stall speed w/ a remote cooler, new radiator, new water pump, new thermostat, new hoses, new gauges and senders. Timing set at 10* BTDC per the owner's manual. HEI distributor.

Here is my predicament: The temperature gauge goes WAY high whenever I drive the car.

I can be at 160* one second and then up to 210* the next. Back down to 180* then the gauge pegs itself. Then it will come back down to 200* Since everything is new, this is scaring the piss out of me every time I drive the car!

There is a fan shroud on the radiator and I am using a 180* thermostat. When the gauge pegs the car does not over heat or "puke." It doesn't seem to make a difference if the car is idling, pulling a hill or running down the road at 40 mph. I am not using an electric fan. The 350 is brand new and I am using a short style pump with a puller mechanical fan.

I've busted my *** for the last year on this car and the last thing I need is to screw something up by running it over temperature.

I was thinking of pulling the thermostat out and taking a spin just to check things out and see if the gauge reads differently.

I am confused. Can anyone offer up any suggestions? They would be greatly appreciated. Thanks.

[347mustang]

sounds like maybe you have air in the system, or a bad gauge

[Missing Link]

I forgot to mention that I have no puke tank installed at this point. And I have slightly over 2" of space between the flex fan and the radiator. The shroud covers about 1/3 of the fan blade width at idle. (I will be installing a "boogie 'til you puke" tank within the next day or so...as soon as this bottle of Vodka is empty )

[Missing Link]

Originally Posted by 347mustang

sounds like maybe you have air in the system, or a bad gauge

Probably a dumb question, but how do you get the air out of the system?

[poncho62]

Drain the system down a ways, and refill slowly with the engine running. This should bring the air to the top.

[T-bucket23]

I had a similar problem with my 350. Wild swings in temperature. I have a high flow waterpump and what I found from reading on forums like this is when you run a high flo pump it actually puts presure on the thermostat and keeps it from opening soon enough. Finally when it gets hot enough to force it open the temp would drop way down. I had a 180 and the temp would go from 160 to 260 or higher and then back again. real scarry. I added a second gauge because I didnt believe the first one. They both read the same.

Now the 12 dollar fix, throw out that stock crap thermostat and get a Mildon high flow thermostat. They are imune to internal cooling system flow presure. It solved my problem immediatly. i can sit in 95 degree heat or run down the highway at 80 and it always runs arround 160 -180.


Dont run without a thermostat, it can actually make things worse because the water doesnt remain in the radiator long enough to get cooled and the unrestriced flow inside the engine also does not remove as much heat. There are several articles on this on the internet.

[Classix_Lover]

THANKKKK YOU TBUCKETTTT!!! I finally have found a person that actually understands the other purpose of a thermostat besides just opening and closing at the designated temp setting(I know other peeps know this too..). I can't tell you how many people say, "No, it's just supposed to open at that temp and nothing more..." and constantly saying you're stupid. It also restricts the water flow allowing it to stay in the radiator longer to cool off, even when it's fully opened up, like you have said. But anyway, back on topic now. Missing, that puke tank will definately help because if it is puking out coolant, you're going to lose it obviously. I used to not have one and was wondering why I was running hotter than usual, popped the cap off the radiator, low and behold I had more than 6 inches of empty space in the radiator. I went in, grabbed a fairly large plastic water bottle(not the throw away kinds) boom, works like a charm even though it isn't show material if your worried about that kinda crap . I would try and cover all of the fan area with the shroud by either getting a different shroud or a longer spacer just to get optimum cooling. Anyway, do what poncho says for purging your system of air, if there's any at all, and hopefully your cooling is just a few minor problems that are all working together making you sweat and panic. Gl with it all .

[sbchevfreak]

Getting a newer style pressure/vacuum rad cap will also help with airlocks. Fill the rad with the engine running, put the cap on, then (once you have it installed) fill the surge tank nearly to the top. Get theengine good and hot, then shut it down and walk away. The vacuum caused by the coolant contracting will actually purge the air out by drawing coolant from the surge tank into the rad and filling the empty space. Once this is done, top the tank off to the mark, and this will become an automatic function of the cooling system.

[T-bucket23]

There is actually a fiarly cheap kit you can purchase that consists of a Funnel that holds about 1/2 gallon of coolant and radiator cap like adapters. You install the adapter and insert the funnel into it. Fill it with coolant and let it run until it wont take any more. The funnel ends up higher than the rest of teh system so that it forces the air out. Air is usually not a problem unless the top of your radiator is lower than the higest point in the engine that holds water. You have classic thermostat cycling. Get a good thermostat and your issue will go away. I have the same crate motor you have and had the same exact problem. The problem is also prone to happen more if you are not running a heater core and have the heater hose connections blocked off. This also effects the circulation and presure in the system.

[johnsongrass1]

Dont run without a thermostat, it can actually make things worse because the water doesnt remain in the radiator long enough to get cooled and the unrestriced flow inside the engine also does not remove as much heat. There are several articles on this on the internet.

Now wouldn't you suppose that is the coolant stayed in the rad longer, it would stay in the engine longer and heat up faster?

Think about it, it a closed loop system,

Some day I will get people to stop thinking this

[T-bucket23]

the coolant needs to spend time in contact with the engine parts to draw away the heat also. Think about it, if you take a pan and heat it up to lets say 200 degrees on the stove and then dump some 70 degree tap water into it, the temperature transition will be very slow and eventually will balance out. If you were to just dump water into it and dumpt it right back out the pan would not get cooled and the water would not have transfered away much of the heat. The water needs to absorb the engine heat, once it gets hot enough to open the thermostat the water flows to the radiator to have the heat removed at the radiator by the fan or natural air flow. The cool water is then transfered to the engine and the whole cycle starts over.