For those who share my obscure (I think it's nifty) 4+3 transmission you know there is a Temp parameter.

I bought a Stant 195F to replace what was either a failed original or some idiot put a 160F in there (because racecar) not understanding that doesn't benefit a street car in any way.

Now that I'm still fighting putting this thing away in NY until 'real' winter hits, I've found that ever since it's stayed below 50F ambient this thing just won't hold enough heat to keep the OD on. As of now being in the 30's all the time it just bounces around in the 180's. The cut-off is 184. So I hit around 190, turn the OD on and within a mile I'm kicking out of OD on Low Temp. Does this new Stant T-stat SUCK?? There was an optional 205F NAPA could've gotten me which seems unreasonable but it gets that hot on a regular basis in town anyways. Would would you guys do? 205F option? AC Delco 195F? I would hate to put a different 195F in only to find out it'll keep dipping just below the threshold.

I did pay my mechanic to put this one in so changing it out again would be a waste of that labor cost. But I can't be making messes where I live. So it is what it is as far as that goes.

 

A 195 will be open at 195... usually I see +/- 10 degrees on my data logs with any stat. So that 195 can start to open at say 185 and given the discrepancy between dash sensor and ECM sensor, it can very well lock out overdrive. I never found a good one for my car when stock. A 180 would work for a while but eventually would dip into the 175 range. I tried a couple of different ones too.

 

I have said before I think thermostats should be described with two temperatures. One where it starts to open and one where it is fully open. I once tested a 190 AC Delco against a 190 fail safe in a pot of boiling water. Both started to open at 190 as advertised. The GIANT difference was at 195 the AC Delco was maybe 20% open while the fail safe was almost fully open. I used the fail safe and it reacts very fast. I know some here hate the fail safe but I don't. I would test any new thermostat in a pot of water before using. The AC Delco was not fully open until 210 degrees. Dan

 

Anyone who actually thinks a thermostat is fully open at it's rated number needs to put one in a pot and watch it. Then decide for yourself. Dan

 

How will blocking the radiator help....when the stat is already fully closed? Water in the radiator ain't moving....so, you're blocking air flow to water that isn't cooling the engine anyway. Cars make sufficient heat w/o covering radiators.

 

I agree. When the last thermostat had failed it stayed stuck open only a couple thousandths (small enough I didn't notice it when I first removed it) and that was more than adequate to keep operating temps in the 160 range at highway speeds, even with ambient temperatures in the upper 50s per my data logs. It really doesn't take much with the heater running.

 

What does "minimum" temperature have to do with anything when really driving your car. Say you had a 190 degree thermostat then yes the minimum temp will be 190. BUT, if it does not fully open until 260 degrees it will not work very well in real life notwithstanding its rated minimum temperature. Dan

 

Hey, Thanks, man! Appreciate the compliment. It's not that I like arguing, it's that I can't stand inane, retarded suggestions. The engine ain't air cooled. Car engines generate way more than enough heat to get to temp and run the heater....w/o cardboard. You were talking about 30F temps...right?

BTW...you know air also circulates up under/around the engine from below, too...right? Shall we card board all that off, too?

 

DING-DING-DING-DING!!! The brain just kicked in, folks! We have a winner. T-stat is stuck open if he can't reach operating temps in 30F weather.

 

Have you checked the trans fluid level in the DNE OD unit? Low fluid levels will show the same symptoms.

 

LW1, thanks for the suggestion to check the fluid. I had all other oils changed; I should just order the kit and have that one done. I was wondering if fluid in that could have relevance. I've seen 10k mile recommended service intervals for that. Which is really quite often. There's no way that has been done on time.

So what I'm gathering is the T-stat does not function well either due to debri (very possible, a coolant flush on this would be a good idea) or it's just not that good. I think I will flush the system, and try a GATES brand T stat. I was looking through different brand options on Rock Auto. Maybe Stant isn't good anymore. Someone I know bought a Stant gas cap recently and they were disappointed. They used to be a Go-To. I like Gates either way.

I would not want to block off the radiator in any amount. Here is why-
Which the blower on level 3, which is what I always set it at when warming it up, the Temp still hits 214/216 just sitting in the driveway. And when I'm sitting in a 10 car line at Dunkin Donuts by then I'm no longer blasting the heat and I'm hitting 228 & the fan is kicking on. This is at or around 30F so I definitely wouldn't want to block the fan's airflow even when very cold out.

To clarify- my OD needs 184F. I took this # straight from my 1984 owner's manual. I will read back through and make sure that is accurate but that's the only # I saw. This does coincide with my gauge. That is a VERY high parameter which is part of why this is so difficult. But I doubt the 350 in my Cadillac gets below that driving around all winter. No car should fluctuate that much.

On a side note, I never turn OFF the heat slider. It does not always come back for me. Something I need to fix of course, but obviously this should all work with the heat on, like any other car that maintains a normal operating temp during the winter. Sorry to start a debate!

 

The dash will say 184, the ECM is probably seeing 176. Being they are 2 different sensors they tend to read different.

When my stat failed it would be fine sitting as well because the only heat exchange occurring is when the fans come on. 228 is about right for that if I'm recalling correct.

I think you're on the right track trying another stat. I had no luck with mine but I only used a stant which had failed. Then I could only get a 180 and we're at where we're at. It was obvious that it was an issue with the car as GM lowered the temperature parameter in subsequent years.

Good luck.

 

Two things; The C4 DOES fluctuate a LOT. More than many cars and most other cars that I have owned. If the '84 has a 195 stat, that should be your min op temp....and it can go below that some but lets say 195 is the bottom. Your fan on temp sets the high end of the operating range; ~230*F. That sets a 35*F "normal" operating range, which is pretty large. Later LT1 cars were even larger, since they came with a 180 stat and a 230* Fan on temp....that is a whopping 50*F "normal" operating range!

With regard to your heat "coming back". I believe that the '84 used a water valve to close off flow of water (divert it back to the engine, actually) when the slide is in the 'cold' position. 84 4+3 mentioned flushing your cooling system and debris in it....I wonder if he's right and debris is affecting flow through that valve/through your heater core at times? Just a thought.

 

Why don't you over ride the ecm and just power the od through a separate circuit with a fuse of course. An 84 I had was always PIA until I did that. Other 84s I had worked fine . Make sure the ecm is showing the correct CTS signal also. Not what the gauge says , the cts that the ecm reads. If installed with Teflon tape you can get faulty signal. Use a sealing paste. or like Tom said....could just be a faulty T Stat.

 

ihatebarkingdogs said 140f for a 1985 car. Does this number represent the thermostat temp or something else. My fsm calls for 195F

 

Something else.

 

So sounds like a coolant flush is a good idea either way, didn't think about that making the heater valve stick. That makes sense as well.

But now someone mentioned what could also easily be my issue. I replaced the CTS (the one in the front for the ECM; 2 prong) and I USED TEFLON TAPE. Just got in the habit of that, given the stuff I do at work. Figures.

So I now have 3 things to try. I have a feeling the sensor is accurate tho, as it does coincide with what the gauge sender says as far as kicking OD on & off while I'm driving. I was thinking about just changing all the sensors when the coolant is out. But then new parts are often such poor quality now.

Thanks for all the help. When the weather is better or I drive an hour to use my friend's heated garage, I'll report back!

 

The ecm sensor shouldn't matter if you use tape on it. It's a two wire thermistor with the tip extending into the coolant passage. It requires no ground through the intake as that is supplied by one of the two wires on it... the temperature reading is taken my the tip of the sensor. I suppose it being bare threaded will conduct heat better and make it swing but ultimately it will reach equilibrium no matter what.

 

I hate misinformation...and I like clarity. Yesterday a circumstance happened that shed clarity, so I'm gonna share it.

I went to my winter "side job"/work yesterday, guys there wanted me to bring the Kart so they could see it. Weather was supposed to be sunny, low 50's which is a bit cold for driving the Kart, but not bad w/the sun. UNFORTUNATELY, when I left my house at 7am, it was neither sunny nor was it 50's. It was 25*F....and that made for a "crisp" drive out there. Now....the Kart's engine is completely exposed. No hood, fenders, inner fenderwells, no bumper, nothing. The engine is sitting out in the open completely exposed to the air/wind that could/would pull heat away and "air cool" the engine, preventing it from reaching operating temp. Right?





Can we agree that if ANY C4 were going to have trouble getting up to temp in 30* weather, due to "air cooling", it would be one with a completely exposed engine....in 25* temps?

The Kart didn't have any problems getting to, or maintaining temp. It has a 160 stat in it, it warmed quickly to 165ish and stayed at about 165 for the entire 40 minute trip to the "ranch". Even with all that 25* air circulating about the engine block/heads/pan/intake etc. Water cooled engines aren't air cooled. While heat is most certainly radiated from a water cooled engine into the surrounding air, the amount of heat is basically meaningless. Insignificant. Which is why, when we have cooling system issues, an idling water cooled engine will over heat in minutes...even w/the hood open in the winter. It ain't air cooled and the heat radiated from the engine into the surrounding air is meaningless.

If an engine can't reach operating temp, it's not b/c it's 30* out; and it's not b/c it's "air cooling" itself. Engines were designed to reach operating temps, even at -40*F and the t-stat is what makes that happen.