what is wrong with my jeep?

i have a 1995 jeep Cherokee 4x4 V6 and it recently started over heating. we changed a cracked freeze plug and it did fine for a day. within the next couple days we changed the thermostat and it, again, did fine for a day or two. All my fluids are good and my fans are good. it starts to over heat when i drive over 35mph and cools down when i go below 35mph. i cant think of anything else that would be wrong, can anyone please help?

 

Several things but probably a blockage. Id start with making sure the lower radiator hose isnt full of gunk. Otherwise when was the last time the radiator was serviced? Ever use any kind of stop leak?

Does the heater work? If you run the heater full blast does it still overheat as quickly?

 

Also, is there water coming out of the seep hole on the waterpump?

 

we never put a stop leak in it and we flushed the radiator about two weeks ago and made sure everything was clean. as far as i know there is nothing in the hoses. what else is there to service on the radiator ?

 

and the heater was working and i used to use it to keep it cool and it would help but that went out to, it only blows cold.

 

When you say "flushed", how? Professionally, pool acid, off the shelf product...

Water hose?

Radiators can build up calcium and other deposits that don't come out without a good acid bath.

Water pump could be corroded also and not efficient.

 

it was flushed with a water hose until the water came out clear. is there a certain cleaner that is good to use or professionally is the best thing? also do you know of a way to test the water pump or a way to tell if its bad?

 

1. 4.0 is a straight 6. Not a V6.

2. If your heat is blowing cold then you either have very low coolant, a clogged heater core or a bad heater control valve. (The only one of these that would cause your engine to run hot is the lack of coolant.)

It costs next to nothing to go all the way through the entire cooling system.

I'm betting the water pump needs to be replaced.

I'd do new hoses, new radiator and a new water pump.

10 bucks says you need coolant right now. Either that or you have some serious air in the system. I'd suggest removing the coolant temp sensor from the back of the head while filling it. When water starts running out of the port hole then it's full with no air.

 

Don't forget if it still blows cold while you are driving down the road, and the valve is proved to be good, you have a bad water pump.