My car over heats on the freeway after I drive more then ten miles. It over heats more when there is a load going up a hill and also when i get off the freeway and come to a stop. My upper radiator hose gets extremely warm while the lower hose stays relatively cooler then the upper. My first assumption was the thermostat was not operating correctly so I replaced it a few days ago. After that the same problem occurs and have not noticed a difference yet. My next guess was to test the flow of the water pump. Has this problem happened to anyone? Does anyone have any suggestions? I really need to get this problem fixed since it's my daily driver.

 

Coolant / antifreeze level?

My dad's friend ran his car from work to home with NO WATER OR COOLANT. His engine was fried when he got home, all of the cylinders were warped.

Be careful...

 

There is no coolant being lost, it has remained full. That was the first thing i checked.

 

What about the thermostat?

 

In my original post I stated I already replaced the thermostat because that was my first guess. ....can anyone help?

 

Water pump might be bad....

 

Probably the water pump. Before you do that, when was the last time you flushed the system?

 

Yep, that's what I was thinking. That or a blown head gasket but if coolants not being lost then maybe not. Try a flush and fill to see what happens.

 

Check the flow of the waterpump first. You haven't run it with plain water without antifreeze have you? That'll corrode the fins off the pump in a pretty short time. All you'll be left with is a post spinning around not moving any coolant.

Try taking the cap off and running the car till it heats up. Have someone rev it up and see if the coolant moves around with each rev up. If it stays still you have some kind of flow problem, probobly the pump. The car is pretty new to have a clog or need a flush bad enough to cause problems.

I'm sure you know but for the sake of anyone not too experienced I'll say it DON'T REMOVE THE CAP IF THE CAR IS HOT

You could also try running it without the thermostat to totaly rule it out.
How many miles on the car?

 

Had the same thing happen to me over the summer. I couldn't figure it out and even brought it to East Coast Nissan or Nissan of North Plainfield, whatever their name is. They told me it was normal for my needle to be near the H. Tells you something about the brain surgeons they have working over in that dealership . I ended up replacing my thermostat also, but I still have the same problem. Luckily it's winter time here in Jersey so I should be good until next spring/summer.

 

I had same problem w/ my 91 Sable. It was a bad water pump

 

Can a faulty rad. cap cause overheating? I so, u may wanna replace that. Should be inexpensive.

 

I flush my coolant every year on my vehicle so the coolant is fine. I'm going to check the water pump in a couple of days when i get a chance. Thanks guys.

 

Only way the cap could cause overheating is if it were leaking and causing a low fluid level. He's already checked that. My $ is still on the pump.

 

Did you bleed the system of air?

 

I was thinking the exact same thing at first, but he said the two hoses where way different temperatures, which to me would indicate a lack of coolant flow..........+1 for the water pump...Also could be a possible plugged radiator.
On another note: If the radiator cap was bad, and the rubber seal was deteriating not allowing pressure to vent, that could cause overheating too. (probably not the case since the hoses are different temps.)
If it does end up being the pump, I hope you got $$$ or tools and time)......The pump is driven by the timing chain.

 

I obtained the water pump today after a special order from Nissan. I also ordered a tool from Matco, which I didn't have, to bleed the cooling system. That should be here early next week. Once I obtain that, I'll be set to rip it apart. I ordered a timing chain tensioner, hoping it will solve my rattling noise which is occurring due to the excessive oil loss. Does anyone have suggestions of other components I should change as take apart the engine to access the timing chain and water pump area? I appreciate your help guys.

 

Replacing the tensioner will not get rid of the rattle if it's due to low oil. You have to keep the oil level up to get rid of that. Trust me, I buy a quart with every fill-up now.

 

are you guys talking about the rattle when you first start the car up i nthe mornign after it has been sitting for a while? like htese is a rattle for a couple of seconds and then it goes away? if that is what you guys are talking about its the vtc. i have a set both elft and right for sale of the updated version. the updated version hold the oil in the vtc so it doesnt drain over night.

 

I'm a little curious how this works. Correct me if I'm wrong but isn't the VTC mounted somewhere near the cams? The way I understand it is that the VTC basically adjusts the amount of oil being pumped into the VTC assembly then allows it to just drain back into the engine...If that's correct wouldn't the only way to fix this to be by somehow having a valve that prevents oil from draining back into the engine after it sat for a long time???
Please explain to me how the VTC actually goes bad???

 

There is a TB applicable to the Gen. 5.5s that addresses noise from a VTC sprocket/s on a cold startup. I doubt that your overheating problem is caused by the pump. After starting the engine check the heater return hose/pipe. It should get warm/hot fairly quickly indicating that the pump is pumping coolant at least around the bypass system. After changing the thermostat did you crack the bleeder bolt on the top of the coolant flow control valve housing and get coolant? The coolant flow control valve could also be suspect. The lower rad hose feeling cooler than the top hose is normal. It should be cooler than the top hose when the system is operating normally.

 

the vtc doesnt go bad. there is nothign wrong with yours either. there is a tsb for it though that calls for replacing the vtc sprockets. the older version has a drain hole in it that drains oil out of them when the car sits. so when you start the car up, they rattle becasue there is no oil in them. now the tsb states that you listen to which side makes the noise and you replace it. the new design doesnt have that hole so the oil stays in there so no more noise when the car has been sitting.