Just shoot me...

So here is the story - car started overheating so....

Changed:

T-stat
all the hoses
water pump
brand new radiator
fan clutch
coolant sensor

Bled the air from the system

Today driving into NYC it was fine on the highway but as soon as I got to sitting in traffic (maybe 20 min into it and it was over 90 degrees out) the needle started climbing up. The AC was on. I noticed that if I turn the ac off and turn the heater on and rev up the engine (i can hear the fan) it cools off right away. No antifreeze in oil. So I am wondering if the fan is working properly - I can hear it when I accelerate and the car is hot but I dont really hear it when I am sitting in traffic. Is it the heater core? I mean how many more parts to the cooling system are there? I am ready to blow this thing up at this point. Any suggestions?

Alan

98 Discovery 70,000 miles 4.0

 

I'm no expert by any means, but did you replace the electronic fan in front of the radiator? I just bought one to replace mine. It is the AC condensor fan but also helps in cooling the engine in extreme conditions. It is located in front of the radiator, and behind the grill.

 

thats what im thinking too... with the ac on, does that front fan work. also does it overheat with the ac off?... your heater core wont cause an overheat, you also need to check for co2 in youre coolant, but check the cond fan first

 

Oh yeah those fans are cranking away no problem. CO2 in my coolant - oh boy! Is that something I can do myself?

 

the c02 coolant test is just showing if you have any exhaust in your coolant which would be an indication of a head gasket or something along those lines.

I'm not sure how much the test kit is, but it's a pretty easy test.
You get this turkey baster looking deal, add the catalyst crap to it, stick the turkey baster into the radiator fill and suck in the air from the coolant. If you have exhaust in the coolant than the catalyst in the baster will change color.

You can stick the turkey baster deal up to your exhaust pipe and suck in some exhaust to see what it does. Should probably be able to buy the kit at napa.

 

Check your serpintine belt for tightness. If it is lose the water pump wont turn fast enough to cool the engine.
You may just need a new belt.

 

try flushing out your radiator, seen these things get partially clogged and cause problems with insufficiant cooling when airflow is lower, use a flush additive, not just a drain and refill. im sure someone on here knows a good one to use, but most that you can get at the parts store will do the same thing

 

Do a chemical block test to rule out an internal exhaust leak from a bad head gasket.

 

The water pump isnt turning fast enough at idle, when he reves the engine it moves the coolant fast enough and the fan pulls enough air through the radiator to cool the engine.
His belt is loose, or maybe it was put on wrong when the water pump was replaced.
http://www.roverparts.com/TechTips/s...g_defender.cfm
Check your belt routing. There is more than one way to put a belt on aDI but only one way is the correct way.

 

The belt is new and was replaced 3 weeks ago. The pump was replaced a week ago and the fan clutch 2 weeks ago. Now that I think of it - the back of the belt is shiny but the tensioner definitely needs effort to move. I have to use a breaker bar to move it since a regular box wrench was waaay too difficult. So I am going to change the belt this weekend and do the CO2 test on the coolant.