would the temp needle read full cold?

I'm gettin' full cold readings as my rpms go up above 2500. From 2500 to 3000 is gradual (jittery/jumpy); from 3000 onwards is full cold. I'm guessing the thermostat is stuck open and temp is going to full cold with rpm's because of increased water pumping

coolant system just bled

4/27/2006 7:38:01 PM

yeah... especially if you're moving if you're stopped and its warm ( not 50 like today) you might eventually heat soak the radiator and it'll come off full cold but still be cool.

4/27/2006 7:39:42 PM

when my car is idling, the temp is right at half way between hot and cold. After i start driving it will drop down to almost completely cold. This is an automatic and sometimes it will cause it to downshift while doing like 70 on the highway, and it wont go into the highest gear for a while. what do you think the problem is?

4/27/2006 8:13:20 PM

Once the engine warmed up it would be normal. Sounds like faulty wiring (as mentioned on CN)

4/27/2006 8:33:07 PM

you want my old one? its stuck closed.

4/27/2006 10:45:11 PM

but yeah, if it's stuck open wouldn't it just take the car longer to warm up?

- My cooling system on my s14 fu(ked up too once

[Edited on April 27, 2006 at 11:26 PM. Reason : s]

4/27/2006 11:25:26 PM

It may NEVER warm up, unless in warm weather.

Not good from a sludging point of view.

4/27/2006 11:38:23 PM

if it's jittery then that sounds like an electrical problem. Stock coolant temp sensors tend to suck really bad. You could always pull the thermostat and check it out...

4/28/2006 2:03:42 AM

Quote :

"when my car is idling, the temp is right at half way between hot and cold. After i start driving it will drop down to almost completely cold. This is an automatic and sometimes it will cause it to downshift while doing like 70 on the highway, and it wont go into the highest gear for a while. what do you think the problem is?"

when my car did this i finally figured out it was the engine coolant temp sensor. replacing that might help.

4/28/2006 2:59:36 AM

you can feel the top hose from the radiator after the engine has run for a few to tell if its actually fuckin up....

4/28/2006 3:54:31 AM

Quote :

"It may NEVER warm up, unless in warm weather. Not good from a sludging point of view."

I just don't see how an engine can't warm up the water, even with the radiator stuck out front eating up all that cold air. Of course, I've always driven real motors, maybe 4 bangers just don't produce the heat that I am used to.

4/28/2006 11:27:30 AM

The car warming up and then getting cold again and not goin into drive is just a sticky thermostat. Alot of cars with automatics will not go into OD until the engine is at temp to help warm the engine up faster.

4/28/2006 11:38:44 AM

Quote :

"I just don't see how an engine can't warm up the water, even with the radiator stuck out front eating up all that cold air. Of course, I've always driven real motors, maybe 4 bangers just don't produce the heat that I am used to."

Well I have a Cummins 6cyl diesel, and the water in the radiator would get warm at best in cold weather before I swapped thermostats. Granted, diesels often run colder than gasoline engines, but still, operating temp is supposed to be 170 degrees.

BTW, I consider warm to be 180 degrees plus. Operating temp. I don't know what you consider warm to be.

4/28/2006 12:03:58 PM

Quote :

"diesels often run colder than gasoline engines"

not really.

4/28/2006 12:10:31 PM

Quote :

"BTW, I consider warm to be 180 degrees plus. Operating temp. I don't know what you consider warm to be."

Well, I guess in regards to sludging issues. But maybe you mean that the extra time while the engine is cool from having an open thermo. and not once the normal driving has begun.

4/28/2006 1:17:32 PM

Quote :

"not really."

Yes, really. Exhaust gas temps are lower as well, on the order of a couple hundred degrees.

You might think that all that extra compression generates a lot of heat, but in reality, it's the combustion process that generates a vast majority of the heat. A diesel's combustion duration is often quite a bit shorter than that of a gasoline engine, and there are no huge pressure spikes. Theoretically and ideally, diesel combustion is a constant pressure process, though there is some pressure spike, albeit much smaller than a gasoline engine.

Oh, not to mention, a diesel always runs lean under anything less than full load. That extra air also buffers combustion temps.

[Edited on April 28, 2006 at 1:49 PM. Reason : temps and such.]

4/28/2006 1:48:05 PM

you might be right, and I admit I haven't read a lot about engines ever since I studied them in 8th grade. But, what do you mean by the air providing buffers for combustion heat? I think the 25:1 compression in itself raises the temperature of the air to about 1300F. That and the fact that diesel fuel burns hotter than gasoline would make me believe that diesel engines are hotter than gasoline engines.

I dunno how long the power stroke is in a gasoline engine, but in diesel engines, the ignition takes the time it takes for a flash to go up.

Also, the fact that there are no pressure spikes basically mean that the pressure is always constant at maximum?

4/28/2006 3:25:53 PM

You are way out of your league trying to argue with zx. Just fucking stop now.

4/28/2006 3:41:21 PM

Quote :

"That and the fact that diesel fuel burns hotter than gasoline would make me believe that diesel engines are hotter than gasoline engines."

Doesn't burn hotter...just longer. Diesel is less volatile than gasoline, and is actually quite a bit denser. A lot of that heat energy created under compression goes to change the state of the fuel from liquid to vapor, and the combustion process in a diesel engine undergoes the same phase change as fuel is injected.

Gasoline, on the other hand, often completely changes phase prior to combustion due to its much higher volatility. Really, the biggest thing that controls the duration of a gasoline combustion event is flame front propagation, and this is dependent on mixture quality and, especially with new designs, mixture velocity and turbulence.

Compression temperatures have very little to do with actual flame kernel temperatures. Gasoline burns hotter, faster, but with less total heat energy released.

4/28/2006 4:20:13 PM