95 gt running hot

texmirage · Mar 12, 2013

I have a 94 gt convertable. I just bought the car a week ago.
Mods that I can see so far....
exhaust from the headers back. (no cat)
Aftermarket throttlebody
K&N filter on the factory intake
MSD box on mounted on the firewall and distributer
underdrive pullies
Nitrious dry kit (150shot set up on it-- I won't be using it though)
Auto... I think 410 gears.
miles are unknown odo stopped at 130K
temp gauge runs little less that half and will creep up to half way and more when cruising around. I had this same problem with my last 94 gt. I never figured it out on that car.
Water level was good. Thought it might have had air in the line(nope). changed the thermostat. still doing the same thing.

any thouhght before I put a new water pump on it?

94GTCoupe · Mar 12, 2013

Get a real temp gauge.
The stock gauge is notoriously inaccurate.

texmirage · Mar 13, 2013

Good to know.

Dino Dino Bambino · Mar 13, 2013

texmirage said:
any thought before I put a new water pump on it?

Yeah, firstly drain the cooling system by disconnecting the lower radiator hose from the radiator. Then disconnect the upper radiator hose from the thermostat housing and separate the housing from the intake manifold. Insert a garden hose into the intake manifold opening and flush the engine out with fresh water until the water coming out from the lower radiator hose is clear. Then insert the garden hose into the upper radiator hose and flush the radiator until the water coming from the lower radiator neck is clear. Reconnect everything and replenish the system with fresh 50/50 antifreeze/distilled water mix. Remove the expansion reservoir and give that a good rinse to remove any sediments that have accumulated at the bottom. Then refill it with the same fresh coolant mix to the COLD FULL line, put it back in the engine compartment, and reattach the hose.
Leave the radiator cap off (better if you have a new 16psi cap anyway) and start the engine. The coolant level will drop so slowly add more while gently squeezing the upper radiator hose to evacuate any pockets of air. Once the coolant level rises up the filler neck and there are no more bubbles, put the cap on and take a drive for at least 10 minutes so the engine can get up to temperature and the thermostat can open. After you've finished the drive, shut the engine off for at least 4 hours so it can cool down completely. Then check the coolant level in the expansion reservoir and top it up as required.
DONE.

toyman · Mar 13, 2013

All Good Stuff ^^^ but the gauge readings do not appear to be out of the ordinary. The factory T-stat isn't fully open until about 205*F which will place the needle just a little left of half way. These gauges will vary so there is no defined point for a particular temperature.

ratio411 · Mar 16, 2013

texmirage said:
...temp gauge runs little less that half and will creep up to half way and more when cruising around.

I agree with everyone about the guages in these cars being less than great.
Also, that if the stock gauge is not in the 'red', so to speak, everything is usually fine.

However, are you saying that your temp goes up when the car is moving, then down when it is stopped?
If that is the case, and assuming your gauge is somewhat doing what it is supposed to, you might have a flow issue.
I would follow Bullitt's instructions on servicing the cooling system, mainly because that should be done from time to time no matter what, but it could also clear up any dirty radiator core issues if they are not too bad (which it doesn't sound like they are). Then check your lower radiator hose for excessive softeness, and make sure it has a spring inside. If it is not spongy, but doesn't have a spring, you can take the spring out of an old donor hose, or make one from a coat hanger.

The point is that the lower hose is a suction hose, and generally the only way your temp should go up when in constant forward motion is if the hose is collapsing when the rpms increase, cutting off some or even all coolant flow to the engine. I have had blown head gaskets due to this problem, and now I will make my own spring for the lower hose if it doesn't have one already. It keeps the hose from sucking shut.

ratio411 · Mar 16, 2013

Bullitt95 said:
Yeah, firstly drain the cooling system by disconnecting the lower radiator hose from the radiator. Then disconnect the upper radiator hose from the thermostat housing and separate the housing from the intake manifold. Insert a garden hose into the intake manifold opening and flush the engine out with fresh water until the water coming out from the lower radiator hose is clear. Then insert the garden hose into the upper radiator hose and flush the radiator until the water coming from the lower radiator neck is clear. Reconnect everything and replenish the system with fresh 50/50 antifreeze/distilled water mix. Remove the expansion reservoir and give that a good rinse to remove any sediments that have accumulated at the bottom. Then refill it with the same fresh coolant mix to the COLD FULL line, put it back in the engine compartment, and reattach the hose.
Leave the radiator cap off (better if you have a new 16psi cap anyway) and start the engine. The coolant level will drop so slowly add more while gently squeezing the upper radiator hose to evacuate any pockets of air. Once the coolant level rises up the filler neck and there are no more bubbles, put the cap on and take a drive for at least 10 minutes so the engine can get up to temperature and the thermostat can open. After you've finished the drive, shut the engine off for at least 4 hours so it can cool down completely. Then check the coolant level in the expansion reservoir and top it up as required.
DONE.

I would like to add that the heater should be running on the floor setting, with temp turned all the way to hot, fan on low, the entire time you are 'burping' the engine (running after servicing to cycle the t-stat a few times). If you don't have heat knob all the way up, with the heater set to the floor, you risk not fully burping the heater hoses/heater core (If you run defrost, you are running your A/C compressor, that's why you set it to floor only.). Run the car with the heat on before you flush it as well, turning the engine off with the heat going, so you make sure your flush gets into the heater core as well. I don't know if it helps or not, but I run my fresh water from the hose into the heater hoses as well, to make sure that water runs clear too.

When you run the hose through the engine, you don't have to seal anything up too well, the water needs plenty of escape routes.
City water runs at something like 40 psi in most places, and if it gets anything over 20 psi in your engine, it could cause a gasket or part failure.

95 gt running hot

texmirage

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94GTCoupe

texmirage

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Dino Dino Bambino

toyman

ratio411

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95 gt running hot

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