160 degree thermostat ???

[bladesC4]

My car runs hot. In fact at times with the heater on, it will only blow cold air and no heat. At some point it will "usually" change to heat. My fluid is fine so I am lead to believe it is my thermostat.
I have run at 230 before and hope to drop this. Can I install a 160 degree Thermostat ? and if so what else will I have to change ? Are there any performance issues from doing this ? Any help would be appreciated. Is anyone else running this hot frequently (85) ?ad

 

[bossvette]

try a 180 first, if you have plenty of antifreeze and you are running hot with no heater the thermostat is most likely sticking or you have air in your system.

BTW a 160 is a common way to trick the computer into thinking the engine is not warmed up and give it more fuel (and hopefully more hp) I run a 180 in my TPI setup

mine runs 180 all the time

 

[JonM]

First thing to do is clean between the AC condenser and the radiator. Make sure all the air is purged from your system. For the no heat problem check the valve located on the hose leading to the heater core box...have someone switch it on and off while its running...Its vacuum activated and you should see the little arm opening and closing the water flow. You may also have a clogged heater core (the outside of it) This post may give you a clue CLICK HERE

 

[bladesC4]

Thanks for the tip. I went to your link and ..........wow what a pile of crap was in there. I am going to check that out. I am also leaning toward a 180 degree thermostat as well. Got a 160 for Christmas. Cool.

 

[vettenick]

You cannot run a 180. The logic in the chip is set for a 195. If you use a lower stat, the computer will not go into 'closed loop'. That's where it controls fuel. You will have a drivability problem, and your fuel mileage will drop.
The other option is to use a chip that has been programmed for the lower thermostat.
Either way, I don't think that will solve your "hot" problem.

Good luck!

 

[VETTEX2]

if your car runs hot , get a real radiator

 

[oldace84]

240' is what it runs for the smog crap.
So what do you want?
I changed the chip, and the sensor, along with rebuilding the radiator.
The sensor is set at 180', cuts in the fan at 180'.
Always cool.
But then again I installed the FLOWKOOLER water pump.
You know Ive done alot of mod's.
E-Mail me for all the info.
tony

 

[bladesC4]

THANKS FOR THE INFO. I'LL EMAIL YOU VERY SOON. I AM A VETTE LOVER AND NOT A MECHANIC SO THE THOUGHT OF DOING MODS MYSELF CAN BE INTIMIDATING. I CAN BUILD A HOUSE,....... BUT A CAR //////// OH WELL. YOU MAY HAVE TO DO "MOD EXPLINATION FOR DUMMIES"

 

[GeorgeT]

I had a similar problem in another car - overheating and no heat. Turned out to be a bad radiator cap. It would not hold pressure.

 

[warren s]

DO THE 160 THERM AND INSTALL A MANUAL SWITCH FOR THE COOLING FANS

CHECK OUT MY WEB PAGE FOR PICS AND GENERAL DIRECTIONS

 

[c4cruiser]

No heat output can also be a clogged heater core or the diverter door in the heater box not opening properly. Coolant is always circulating thru the core.

Get the system pressure tested to insure that the correct pressure is being held. Test the cap too or simply buy a new one with the correct pressure rating.

You may also have a thermostat that is not opening at the right temperature. The "thermostat temperature" is where the thermostat opens not necessairly where the coolant temps will be once you install that particular 'stat. Idling in traffic, clogged passages in the radiator, debris in the cooling fins, air in the system or even a hose collapsing can cause temps to rise. Another possibility is the water pump starting to fail.

I have a 180 degree stat in my 87 and the computer will go into closed loop at that temp and I have the factory chip. No driveability problems and I get consistant mileage of 28-30 on the freeway with a small cam and some port matching, In cold weather, I see indicated coolant temps of 180-185 and on hot summer days, 190-200 or so.

230 for coolant temp is not really "normal" for cruising temps unless you are going slow in heavy traffic or not moving. Do you have a secondary fan in front of the radiator? Z51 and Z52 cars had them. Is the cooling fan coming on when the temps rise? The fan is controlled by a switch located on the right cylinder head down by the dipstick. Once it sees a certain temp, the fan is turned on by this switch.

 

[AUSSIEVETTEMAN]

We all feel your pain!

We had the same probs with our radiator in our 81. Mind you, it doesn't have the same electronic engine management that the later Vettes have, but it is still a pain in the ar$e when heating probs happen.

Ours was heating up in traffic and one day it heated up while driving on the highway at 110 KM/H. The problem was the bottom radiator hose.
When we pulled the radiator out for a flush, the core was cactus. We put a big block radiator in there with a 160 degree thermostat, two new hoses (top and bottom), new coolant (50/50 glycol water) and a new cap.

Heres the deal. Now when she first heats up in the morning, the thermostat opens at 160 and the temperature goes back down to around 130 or 140. Under normal driving conditions, she doesn't get over 180 to 185. In traffic after about 20 or 30 minutes with no air flow she will get to around 210 or 215, but the higher temperatures take longer to get to. Remember boiling temperature is 260, IF YOUR SYSTEM IS PRESSURISED CORRECTLY! IF NOT, THE COOLANT CANNOT DO THE JOB IT WAS DESIGNED TO DO!!
Coolant is designed to work under pressure by being pushed through the water and the cooling system, this raises the boiling temperature from water, which is around 225, to 260. If there is no pressure, then the coolant is a waste of time and boiling temperature will be lower than 260 degrees.
This means that you need no air leaks from the head gasket, cap, hoses and areas like that. A blocked system will also prevent coolant flow and different areas of the block will be different temperatures. This will cause damage as the sender unit that tells you what the temperature is, only takes the reading from one point on the engine.
I recommend you have the system cleaned and flushed and pressure tested. It will tell you want the problem is or at least the area to look. I also recommend that after you have any repairs done, your system should be able to operate smoothly without pressurisation. By this I mean design it so that when you add coolant, it is a 'buffer' or 'extra'. The system should be able to operate or cool the engine and not boil without coolant or pessurisation. That way if something goes wrong, you can get her home. Use the coolant and the pressure as a buffer!

Cheers

Tony

 

[bladesC4]

I guess for me I'll go through the simple things and then if I need to I'll bring it in. I am just working through this problem over the winter. I did order the Haynes Manual but it isn't very specific about many things. Some good stuff. Thanks for the info. This is a great forum.

 

[bladesC4]

Another note, I just found out from the previous owner that it was never flushed so I am going to add that too. I am sure it is more than ready for that.

 

[SKIP780]

no heat

my problem also but i fixed it. replaced the thermostat w/factory. 185 degree i think it was. still no heat. took off 2 heater hoses and put a garden hose to the outlet to back flush it.that cleaned it out and now it works fine.i believe pluggade is your problem and this is the cure. r/s frank

 

[Eagle85C4]

You might also want to check the vac controlled valve for the heater. Mine was slow to work, so I sprayed WD-40 into both sides of the valve which freed it up so now it works perfect. Also the same valve came decompose inside from all the junk in the system, sometimes even a good flush will not bring it back and it has to be replaced. The dealer last year wanted 115.00 for the valve and associated plumbing. I got one off of ebay for 35.00.
Becareful when moving the inlet and outlet tubes to the heater core. It does not take much to start it to leak and as you can read on here it is a bear to change the heater core.

 

[vettered91]

bladesC4,

Everything the guys have said it's fine for your vette, but first of all I don't think you have anything wrong-unusual with your temps. The ugly temp you said in your first post (230°) is normal for stop'n go traffic in a c4 (ugly normal stock vette temp)

The first fan in a 91 L98 turns on at 227° !!!!
The second turns on at 235° !!!

So; stop looking for something wrong!!!

It's fine if you do everything to keep it clean, etc. But if you want to run cooler (185°- 205°) NOTHING WILL WORK unless you change your Stat to 160° or 180° AND the prom chip to turn on the fans earlier or a manual switch.

With the 160° stat, 1st fan turning on at 184° off at 175°, 2nd fan on at 194° off at 185° in my LT1 my coolant temps are:
Very slow traffic: 210°
Highway: 173°
Engine oil temp: 185°-210° 99% of the time (no risk of open loop after warm-up)

 

[Eagle85C4]

Sorry...but I would have to disagree.....

If you follow all the suggestions so far it is quite possible to run 185-200° with a stock system and 195° stat.

Once I cleaned all the junk from the radiator cavity, did a flush, replaced with fresh green stuff, the stat and heater control valve mine now runs at 185°.
It will run up to 205 first off, then the stat opens and it drops fast to 185°. Once I turn the heat on...it drops to 179°. With the A/C on it will run closer to 200°....

Maintain the stock system and it will run fine. By using a 160° stat it only opens sooner, the engine will run up to temp anyway.
It is designed that way... One thing you can do to help is add a switch to turn on the fans manually, in traffic and stop and go it will climb to 220° or there abouts before the fans come on automatically, but forcing the fans on earlier will keep the temps lower...

 

[warren s]

Sorry...but I would have to disagree.....

If you follow all the suggestions so far it is quite possible to run 185-200° with a stock system and 195° stat.

Under perfect conditions, like a recently cleaned system and new antifreeze the system will still cycle between 195 and 230 in stop and go traffic.

If you use a 160 therm, it will take alot longer to run over 200 in stop and go traffic. You will still need the manaul fan control but with a 160 instead of the 195 stock therm you will not need to turn on the fans as much and sometimes not at all.

 

[Eagle85C4]

Again...I respectfully disagree...

Regardless of what you do...you will not lower the temp until you change the capacity of the system. Even adding different cooling media, ie...water wetter, only has a minimal effect. All of this is just plain ole logic....


The following excerpts are from...
http://www.dewitts.com/download/cooling.pdf


"THERMOSTAT:
Probably the most misunderstood component in the cooling system, the thermostat has absolutely nothing to do with controlling maximum engine operating temperature. Period.

What does it do? At cold start, it blocks the flow of coolant out of the engine until the trapped
coolant reaches the thermostat’s rated temperature, at which point it opens and
permits coolant to begin circulating. This aids rapid warm up, which reduces cylinder
bore and piston-ring wear by bringing the engine up to operating temperature
relatively quickly. Once it’s open, it modulates the flow of coolant through its calibrated
restriction so coolant temperature never drops below its rated opening point,
assuming the cooling system is efficient enough to cool the engine down to that
level. In most cars, it’s essentially wide open all the time, and only the heat transfer
efficiency of the radiator and the airflow through the radiator determine the
engine’s maximum operating temperature. If you have a 180º thermostat and
your engine operates at 220º, changing to a 160º thermostat won’t change your
operating temperature one bit – you need more radiator, more airflow, or both, to
reduce operating temperature. If you have an extremely efficient cooling system with
more heat-rejection capability than your engine needs (runs at 180º with a 180º
thermostat), changing to a 160º thermostat may result in reducing your operating temperature
to 160º, but this is rare except in cold weather. Furthermore, 160º is too
cold; OEM testing has proven that the rate of cylinder bore and piston-ring wear at
160º is double the wear rate at 180º, and a coolant temperature of 160º won’t let the
oil in the pan get hot enough to boil off condensed moisture and blow-by contaminants,
which then remain in suspension and accelerate the formation of acidic coolant sludge.
160º thermostats were specified in the 1930s for the old alcohol-based antifreezes,
which would boil off and evaporate at 185º; there’s no other reason for them. “Balanced-Flow” thermostats like Robertshaw makes (also sold by Mr. Gasket with their name on them) are calibrated
much more accurately than conventional parts-store thermostats, and if they fail, they do so in the open position. Conventional thermostats fail closed, which can cause a lot of engine damage in
a big hurry if you don’t spot the sudden temperature rise."