I just flushed my coolant last month or so, and replaced the water pump, and t-stat at the same time. Jeep has been cooling to perfectly sense. Before I did my cooling system maint my heater would sweat me out and now it seems like the motor never gets warm enough to get the heater hot. The heater gets hotter with the motor, so I dont think its the heater core, I think the motor just isnt warm enough. I got a 165 t-stat, I had a 135 before. So if anything I thought it would get hotter. So I know I have three different sensors for various functions in my renix, IE the fan switch, the sensor for the gauges, and the sensor for my ecu. I am thinking I may as well just replace the sensors for the ecu and the gauges anyways, but what im wondering is, is the sensor on the top of the head drivers side back, is that the sensor for my gauge or my ecu? And any other input about what could be wrong with it? Perhaps a faulty t-stat? My temp gauge never gets above the first line, the previous owner gave me the sensor for the gauge and told me it was bad and I never replaced it.. Ran fine and was never a problem.. After the flush and what not it wont even enter the meter part of the gauge. Even after an hour plus of driving.

 

The sensor on the back of the head is for the gauge. Have you checked the actual temp of your engine with a thermometer? the gauge may just be wrong.

 

^sorry missread a few things

 

A 135 t-stat was replaced with a 165 t-stat?

 

Its alright, its a long jumbled post I understand.. No I have not used a heat gun. Is that something you can buy for fairly cheap? Or am I going to have to have a shop check?

 

Yeah, I wanted to go a little warmer to see if I could see a difference in performance and fuel economy.

 

I agree, what?

I've never heard of using a 135

 

You should be running a 195 thermostat not 165

 

you need at least a 185degree

 

The t-stat isnt really what Im looking to replace, the heater was plenty hot enough before with a colder running t-stat. Im just wondering what could be causing my heater/motor to not be running as warm or warmer then it was before. If my sensor for my ecu is bad, will it cause the motor to run colder or just run rich? Will replacing my temp switch help anything other then my gauge reading accuratly?

 

It may have been a 130 or something like that, cant remember exactly..

 

Well a thermo laser deal is only like $25-30 at harbor freight, but who knows how accurate it is.

Your sensor for the ECU really only tells it that it shouldn't be in enrichment mode or whatever you want to call it to have the engine warm up faster. So it wouldn't keep the engine from getting hot. You may check if your aux fan is always on. That may be making it harder for the engine to get hot.

 

I agree with running a 195, although that's not your problem. You did a bunch of cooling system work. After it's been running for a while, put your hand on the two lines for your heater core, see if they're hot (they're probably not) squeeze them, is there coolant in there? If it's cold (well, not hot like it should be) is it cold because the coolant is cold, or because there's no coolant in those lines. Same problem I'm dealing with, closed cooling system issues and air bleeding, not allowing proper circulation.

If it's not circulating, and there's air pockets. Then it could potentially effect everything you mentioned, temp gauge not registering, the ECU temp sensor, saying it's cold, and constantly running in warm up mode and running richer, and your lack of heat.

Like I said, I personally feel you should be running the 195, as that motor was intended to be ran with, but you still had good heat with a 135, because yeah, a fan blowing across 135 +/- coolant is still very hot. Read about older Renix and closed cooling systems on the forum.

 

Only motor I'm aware of that runs a 130-140 t-stat is a 3 cyl Evinrude outboard.

 

I think you misread the old t-stat - I bet it was a 180, not a 130.