hello,
i am having a issue with my temp rising. when i am driving the temp is about half way but when i stop at the first light, it rise up to 3/4, the line before the red line. so after i set for about 3 - 5 min. the temp goes back down to line before half and remain there until i began to drive again and it goes to normal running temp. i have change my water pump, temp sensor, flush radiator, new thermostat, new fluids, all change with in the last year. i do not know what else to do. please advise. oh my car is a 2005, with a 3.4 liter.

 

Possibly a head gasket or cracked head. If you can locate a cooling system pressure tester from a parts store you can test. You need to pressurize system about 12 psi and watch gauge , if pressure rise's it means pressure from cylinder is getting into cooling system causing your overheating issue. Good luck

 

As Jeff mentioned, it could be a head gasket. And the 3400/3100 can be a tricky one.
Start with a radiator pressure tester. This allows you to safely inspect for leaks (look, listen and smell). I believe the system is designed to hold up to 13 or 15 PSI max (verify with the radiator cap). I have seen a bad head gasket NOT cause a drop in pressure with these testers.

If you have no leaks that you can find, I can tell you something I ended up doing years ago... Get a ratchet and socket for the bleed valve on top of the heater tube (comes up from the water pump housing). Ensure that the car is properly bled of air. Next time the temp rises, pull over somewhere safe, pop the hood, open the bleed valve. If it shoots air for a moment and then coolant, this is lending to a head gasket issue. What is happening is that the cylinder compression is higher than the pressure of the cooling system. Combustion gases are being pumped into the cooling system, creating an air pocket (and potentially over pressurizing the cooling system). You might also develop a small rough idle when you start it after it sat over night (or multiple hours) and the rough idle might disappear on its own after a few seconds. This is all related. But, you won't see the tell tale white smoke until this problem escalates further.

Even if the signs look like what I described as a head gasket, at that point, it might be worth having someone experienced with the 3400 do a review of the engine before ripping into it.

 

Okay thanks, i do experience the ruff idling in the morning and clear up seconds later. thanks for the info.

 

Make sure you don't have a leak - check the fluid level first and foremost. Might have pockets of air bubbles in there too.

 

I was just told about some stop leak for head gasket leaks. Is it safe to use?

 

hello,
i have replace the head gasket on my 05 monte carlo 3.4 eng. i have receive some new codes since the replacement. P0101, P0108, P0340. please advise