Car overheating

First, check that the air was bled out of your system when they replaced the water pump and radiator.

Then as your car warms up, check the temp of your upper and lower radiator hoses. Both should be hot. If one is and the other is not, then your thermostat is stuck closed.

If that checks out good, then I'd say you have a blown head gasket. Sometimes you'll see signs of water mixing with your oil and leaking out of your tail pipe, sometimes you won't.

What will happen is, exhaust gas is pushing its way past a small leak in the gasket and into your coolant. The hot bubbles eventually get trapped in the highest points in the heater core and radiator, which creates a lock that your water pump can't push past.

A quick way to test for this is to remove the radiator cap (or overflow tank cap if your radiator doesn't have one), and while someone revs your engine to at least 1,500 rpm, look at the coolant. If theres large bubbles (same time as engine revs), then that is the exhaust gas.

See the guides below for external leak check and head gasket check

https://www.2carpros.com/articles/head-gasket-blown-test

https://www.2carpros.com/articles/radiator-pressure-test

Do you mean there's a vacuum leak around the o-rings where the injectors plug into the intake manifold? That won't cause overheating but it can cause a high idle and a hesitation.

The head gaskets would have been my first suggestion. You might still consider having a mechanic perform a leak test at the radiator cap with a special tool.

Next wuld be to check if the radiator fan is turning on. A fast way to do that is by unplugging the two-wire coolant temperature sensor while the ignition switch is on. That should cause the fan to run. If it does not, there might be a blown fuse for the fan. The best way to diagnose it is by using the DRB3 scanner to command the fan to run.

Sorry for taking so long to reply. The site stopped working on my regular computer. Just want you to know I'm not ignoring you.

Yes, it helps deflect air flow. However, you mentioned it overheats when sitting in park.

You have replaced and double checked everything. The only things left is a timing issue and there still could be a head gasket leak even though it was checked. Have they done a compression test?

An air pocket can prevent the thermostat from opening. Thermostats open in response to hot liquid, not hot air. You should see a bleeder screw on the thermostat housing. Be sure to open that after the thermostat was replaced.

Feel the lower radiator hose when the engine is hot. If that hose is cold, coolant isn't flowing. You might consider removing the thermostat to see if that makes a difference. If there is still no evidence of circulation, suspect a problem with the water pump. One possibility is the impeller can be worn away or it can be cracked and spinning on the shaft. Also check the tension on the timing belt since it runs the water pump. A loose belt will slip over the pump's pulley.

If you repeatedly find air coming from the bleeder screw, suspect the head gaskets are leaking. When those gaskets are replaced, the heads must be checked for cracks and for warpage. Warpage must be checked at an engine machine shop or by a mechanic who has a straightedge. The maximum allowable warpage with aluminum heads is.002" in any direction.

To check for leakage, first look for the presence of bubbles in the reservoir when the engine is running. If you see any before the engine has warmed up, suspect the head gasket. The clue is the engine isn't hot yet and there's no steam with those bubbles. Most mechanics can perform a test for you that involves a glass cylinder with two chambers partially filled with a special dark blue liquid. Air from the reservoir is drawn through that cylinder. If combustion gases are present, the liquid will turn bright yellow. Those gases will create that air pocket again that prevents the thermostat from opening.

This is a tough one. I have a couple more questions. First, and I know this may sound odd, was the thermostat replaced with a 195 °F thermostat? I have seen situations where lower temp t-stat was used, opened fully when the engine was at 165 ° and the coolant circulated so fast, it never had time to cool in the radiator. The reason that popped into my mind is because your car does the opposite of what most do. It overheats when driving rather than sitting.

Next, when it overheats, does it ever boil over where coolant is coming from the overflow? I ask because you could have a bad temp sending unit and you are not seeing the correct temp from in the car. They actually make a thermometer to check coolant temp in the radiator.

Finally, when it is overheating, has anyone checked to make sure that both the lower and upper radiator hoses are not collapsed? I have delt with hoses that will pinch shut at higher RPM's causing an overheat situation.

Let me know.

Joe

Nope. The EGR valve allows exhaust gas into the engine at highway speeds only. While that gas feels hot to us, it is "inert" and takes up space so less fresh gas and air fits into the engine. That means less heat is produced in the engine and less fuel is burned.

A knock sensor picks up pinging in the engine, and in response, the Engine Computer retards ignition timing a little. In a very severe case, some of that fuel and air might finish burning in the exhaust manifold rather than in the engine. Heat from the exhaust manifolds doesn't transfer into the cooling system so it won't cause overheating.

Not sure what you mean by a "BP" valve.

I'm not aware of a bypass valve but there is a bypass passage. That gives the coolant someplace to go while the thermostat is closed.

When the overheating occurs, feel the lower radiator hose. If it is real hot, the heat is not leaving the radiator. That can be due to air flow blockage, a fan that's not turning on, a fan that's wired wrong and blowing the wrong way, a missing shroud that lets the hot air go back around and through the radiator rather than drawing cool air in. Related to that, look for a missing rubber strip under the front edge of the hood. That is a seal that forces air through the radiator.

If the lower hose is not hot, the coolant may be not circulating properly. Check the water pump impeller and be sure the timing belt is tight and not slipping. You may have to flush the cooling system and try removing the thermostat to verify it is not sticking closed. If the coolant is not circulating, the air from the heater will not be as hot as normal.

A clue to a fan-related problem is the overheating will not occur while driving at highway speeds.

Double-check that the fan is turning on and blowing the right way. You said you replaced the radiator. Was that a new or used one? If it was used, check if the cooling fins are rotted away. That will reduce its ability to give off the heat to the air.