94 Nissan truck V6 running hot


#1

Hi, I just replaced the timing belt water pump, thermostat non factory 170 degree lower radiator hose and tensioner pulley. I was very careful with the timing belt marks. I even marked them with white marker. The engine runs fine but is now running hot but not overheating. I checked the lower after market radiator hose for collapsing and it looks ok. Has any one out there had trouble with stant after maket thermostats? Before changing the thermostat the engine ran to cool. Should I replace the thermostat with a Nissan 170? or suspect some other problem? I am the original owner it has about 180,000 miles.Any help would be appreciated.


#2

What do you mean by ‘hot but not overheating’? I had my Toyota truck running cool until I changed the thermostat. The old one was stuck open, and not letting the engine properly warm up. Once replaced, the temp gauge was on the slightly hotter side of center. I considered this good.


#3

I’ve NEVER used OEM thermostats…and never had a problem…EVER…It could be the thermostat…or the pump…I have had problems with cheap aftermarket pumps. What pump did you use??? I know it’s a pain to replace the pump if it is because you have to do the belt all over again.


#4

I used a Duralast pump from Autozone. The lower radiator is not as wide in diamter as the OEM hose. Maybe this is the culprit. Thanks for the input hopefully it is not the pump.


#5

use a temp gauge,and see how hot the coolant actually is, is it too hot? or did the stat fix the cooler running engine.


#6

Thanks! good idea. Should the coolant measure around the thermostat rating at 170 degrees when completly warmed up?


#7

thats when the stat opens,normal operating temp could be as high as 190degrees F, rec you find the real num in a manual,so as not to mis lead you. that num is aprox.and did you mix the coolant properly. some want 50/50,and some want 60/40.as in some mitsubishis.

good luck


#8
Only at the thermostat. It will be about that in the engine, but cooler elsewhere.  

Are you sure that 170? is correct?  Is that what the factory recommends?  It seems rather low to me.  It is generally not a good idea to use a thermostat rated lower than the factory recommends. It can cause additional wear and lower efficiency. 

I am really curious about that "running hot but not overheating"  Could you explain that a little?

#9

I doubt that there is ANY problem. An engine cooling system, with a radiator cap holding 15 psi (normal), won’t boilover until the coolant reaches 265F degrees. Of course, THAT would be too high.
If the thermostat required is a 190F degrees thremostat, use a 190F degree thermostat, not a 170F degree one. One too cool (I think that 170F is too cool) can cause problems.
Normal coolant temperature is 220F to 230F degrees. The thermostat opens, to allow coolant flow to the radiator, at 170F to !95F degrees; but, it’s NORMAL for the coolant temperature to rise to 220F -230F. You can measure the radiator and coolant temperature with an infrared thermometer. Repair shops have them.


#10

I have owned this truck since new. I removed a 170 degree factory thermostat when I repaced the water pump ,timing belt and lower radiator hose. The gauge comes up slowly when driving almost as usual. It reads about an eighth of inch away from the hot zone after being on the highway at 3000 rpms for 20 minutes. Thank You!


#11

I guess i need to do a little testing.I will check the temperature.


#12

two suggestions/reminders:

take apart the thermostat housing. ensure you put the thermostat in correctly. it IS possible to put them in backwards, in which case the water WON’T flow at all; or VERRRRRY little.

i would actually reassemble the housing WITHOUT the thermostat in it, to check up on the waterpump flow. you WILL have to reinstall the t stat, but running it without will remove or reinforce the t stat as a problem. its easy, and doesn’t cost much for a new gasket.