Cooling Troubles...

[r0lf-]

Ok, I tried tuning my truck a bit to get my gas milage up a bit. Its been running like a champ, I messed with the carb a bit and advanced the timing a degree or two. But ever since I did that the temperature gauge has been all over the place.

Im not sure if the temp gauge has anything to do with me tuning it, but... I checked the radiator and it had a bunch of overflow in the container, so temporarily I added some fluid to it. Still the gauge is all over the place. My heater wont even heat up and its a brand new heater core (not even a year old).

Any Ideas what It might be? Temp sender? Thermostat? Radiator?

I know I need to flush my radiator and its in need of an oil change, but what else might be the problem?

[rockman20]

All over the place? As in the truck is getting way too hot, not hot enough, goes from cold to boiling to back down to cold, what?

If everything was fine before tuning, I would say undo what you did on the tune. An engine will get too hot if you have leaned out the fuel mixture too much. A lean running engine can be found by pulling the plugs and reading them. If they are white with no deposits on them, you are running too lean. They should be kind of a tan color if memory serves me right.

Timing can cause a hot engine as well. If you advance your timing too much, this can cause a hot engine as well. So if you increased timing and also leaned out the mixture, you just created two heat increases in an engine.

Want better fuel economy, replace the spark plug wires, distributer cap, rotor, plugs, air filter, engine oil, and you can even gain a bit by adding on or making sure that your cold air induction is hooked up. Make sure that the heat pipe from the exhaust manifolds to the air cleaner is hooked up, that the vacuum door in the snorkel is working correctly, vacuum advance in distributer is working correctly, and depending on the year of the truck, make sure that the converters are in good shape and that they are not plugged.

[r0lf-]

I really didnt do anything to the carb except make sure it was to factory specs. Its just running a bit hotter than usual. Its usually to the first tick on the gauge and now it sits around the second.

I have no clue why the thing wont heat up the heater either.

I have recently replaced the rotor in the dist and the wires and the plugs. The cats are new also. Its also a brand new radiator, this is why im so confused.

[r0lf-]

Oh... also its a I6 with 3 on the tree. Shouldnt be getting very hot with a radiator for a 350.

[rockman20]

How long ago did you replace the rad? Did the heating problem come about after this? Chances are you may have air trapped in your system somewhere that can cause heating problems and such. Or, you may of just got lucky and your thermostat may of went out.

When I replaced the rad in my Cutlass, I filled the rad and then started the car with the rad cap on, but not tight. Then I took the cap off and I watched it until the car warmed up. Once the thermostat opened, I watched the coolant run. I let it run for some time like that. I let it get up to normal temps and I did add some coolant in, but not full because when stuff heats up, it expands, hence why most cars run with overflow tanks. After the coolant level was up there a ways, I put the cap back on and haven't touched it since.

If you want to do this, make sure that you have your heater controls turned on in your truck and the heat is on hot. There is a valve in the heating system that actually stops coolant flow into the heater core when the temperature is set on cold in the truck. If there is air trapped in that system, it would never be purged if that valve is closed.

Sometimes air in the system can be a b!tch to get rid of. When I originally built my Cutlass, I did the above procedure about 4 times before it finally cooled the way it should of.

[rockman20]

Also wondering, how did you set carb to factory specs? I am guessing that this is a Quad we are talking about?

If you want to, I can give you run down on how to set the mixture screws on a Quad. It will require an external tachometer (or a buddy sitting in the truck or you walking back and forth all the time) and a vacuum gauge. This procedure takes a while, but it will get the idle mixture setup very nicely.

After the idle stage, there isn't much you can change mixture wise unless you start changing the jets and the metering rods inside the carb.

[r0lf-]

Im going to go ahead and flush the radiator. If this doesnt help ill be back for more help.

Thanks guys.

[rockman20]

Good luck.

[apstguy]

Did you replace the heater hoses too? Might want to take them out & see if they are clogged. With the engine running, turn on the heater and feel the hoses. If it suddenly is cold after a warm spot, you have clogged hoses.