What thermostat to choose for 350 and quadrajet

[kikkegek]

guys,

my 350 seems to be running rather cold! about 145-150F.

the thermostat is closed at cold start, I checked that, and after a couple of highway miles it has opened and I can measure a temperature at the thermostat-housing of 165F.

I have been searching the internet and found:

ACDELCO says the standard thermostat is 195F for my engine

and I find some topics on other forums that state that the normal operating temperature would be 195-210.

is this correct?

what is the standard operating temperature of a SB 350

btw, I live in the Netherlands with an intermediate/sea climate. normal summers and winters.

[Tx Firefighter]

Either a 180 or 195 either one is a good choice. Colder climate guys like 195 for a better heater output in the winter.
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[Slonaker]

I run a 195 in mine, and always have. That is stock for my '86.

Slonaker

[billnorman]

I run a 210. I have not found any deleterious effects.

[allengator]

Originally Posted by Tx Firefighter

Either a 180 or 195 either one is a good choice. Colder climate guys like 195 for a better heater output in the winter.
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agree

[kikkegek]

thanks guys. I am gonna go with a 195F then!
thanks!

[Prerunner1982]

I agree with the higher temp thermostat.... may also make your truck run better.

[496 BB]

Look on the copper part of the t stat u take out and see if it says 160 on it. May have had one in there.

[rblcori7]

My truck runs a 195

[solidaxel]

Originally Posted by kikkegek

thanks guys. I am gonna go with a 195F then!
thanks!

I would think over there in the winter you will never see 195* on your temp gauge.
Your engine will love you!!

[kikkegek]

Originally Posted by solidaxel

I would think over there in the winter you will never see 195* on your temp gauge.
Your engine will love you!!

:-)

[mooseknuckles]

195*

[kikkegek]

thanks!
I ordered a 195F and gasket yesterday. Will probably be in next monday!

I will report back on the result.

for now!

Merry christmass!

[kikkegek]

oke, got the thermostat today and replaced it (195F)

first disconnected the upper hose on the radiator. check out the dirt that came out. If you take into account that I just had the cooling liquid refreshed this summer. Shouldn't it be a lot less dirty?




I cleaned the thermostat houding and took a good look. NEver had this piece loose yet.



here you can see hoe dirty the cooling liquid is. about a quart came out of it. I tried to catch as much as I could in a little bucket.


when it gets warmer and the days are longer I am gonna have to rinse my cooling system....damn its dirty....previous owner probably had wather in it for a while I think? or never changed it...

these two bolts??? weer holing the thermostat housing. for now I reused them, but I want to change the housing and bolts this summer sometime.


anybody ever heard of Restone Thermostats? I got it at a local shop.



this bucket was clean when I started. Look at the dirt!



the old thermostat. Seemed to be a 180F.



the new thermostat, 195F




just cane back from a testdrive. Al stays dry. So that makes me happy. Now I a will keep an eye on the temperature the next few days and see if the engine gets warmer!

[kikkegek]

okay.
I did some driving around.

mostly 12km rides (about 7.5miles) the temperature goes up to about 155F on the gauge, so about 10K higher then the previous thermostat, but still thats pretty cool, dont you guys think?

should the temperature rise when you come of the highway after 5 miles of 60mph , stop at a traffic light and then drive about 3-4 miles though town? mine stays at 155F all the way through town.

Could this be my flexfan? constantly cooling at low RPM?

how can I check that the thermostat is not opening to early? I read something about closing the big hose to the radiator by hand after a ride and then letting it open up slowly and listening if you hear water running? is there no other visual check?

it is about 32F over here at the moment. could the outside temperature cool the engine soo much it doesnt get up to operating temperature?

[Shawn5488]

Hard to say when your not running a stock cooling fan and shroud, as well as most importantly a stock fan clutch that wont have the fan kick in and hurt the mileage as well as not allow the temps to come up.

You need to use a cooling system flush kit and let it work for a good while to flush all that crap out of the cooling system.

Very hard on oil to not get it up to temp, tends to sludge up and break down very soon.

[solidaxel]

With the ambient temp. at 35* and 60mph you will be very lucky to get the engine up to temp of 195*. The gauge is telling you that 155* is as hot as it is going to get, try a peice of cardboard in front of the rad. and see if it will get hotter, BUT keep a eye on the temp gauge
Prestone is a good brand of thermo.

[kikkegek]

today after a little drive i checked with the IR thermometer. about 176F at the thermsotathouse and the same at the top part of the radiator.

this is the IR thermometer I am using:



tech specs:

for contact-free measuring of surface temperature,
easy to use,
response time < 1 sec.,
display of current and highest temperature during the measurement,
hold and lock function,
stopwatch,
measuring range: -33 °C...+220 °C (-27°F...428°F), reversible °C/°F,
accuracy 0...50°C 1.5°C, otherwise 2°C or 2%,
battery CR 2032 button cell included
75 x 48 x 24 mm; 80 g

last time i checked, with old thermostat I got, 165F. So there is improvement. But still pretty cool.

And isnt it strange that the radiator is hot, while I only measure 176F and the thermostat is 195F....so the radiator should be cool, because the thermostat should be shut tight?

[Shawn5488]

Thermostats don't shut all the way and always flow a little coolant even when cold.

Sounds like it is cold where you are and you need to use card board to cover the radiator if you want the full temp.

I would be perfectly happy with167*

[454HO]

Not sure if you are aware or not, but the heater core bypasses the thermostat. I see in the second photo of post #14 that one of the heater hoses is hooked up to the intake manifold water passage just to the left of the thermostat housing. Since you do not show an overall pic of the engine bay it is impossible for me to see if that hose goes to the heater box on the firewall and then a second hose goes back to the radiator as it is supposed to. Assuming it does, that is definately a path for coolant to flow and potential source of heat loss, especially if you have the cabin heater on while you are driving.

[kikkegek]

Originally Posted by 454HO

Not sure if you are aware or not, but the heater core bypasses the thermostat. I see in the second photo of post #14 that one of the heater hoses is hooked up to the intake manifold water passage just to the left of the thermostat housing. Since you do not show an overall pic of the engine bay it is impossible for me to see if that hose goes to the heater box on the firewall and then a second hose goes back to the radiator as it is supposed to. Assuming it does, that is definately a path for coolant to flow and potential source of heat loss, especially if you have the cabin heater on while you are driving.

I know which hoses you mean!
they are for the evaporator of my LPG-system.

here's a overal pic of it. but thanks!
ignore the two red arrows please.

[Mkcustums]

Those extra hoses are gonna cool it down a bit too, acting as an extra heat sink. To what degree I don't know, but I assume it would have to.

[staggerd86c-10]

Im in miami and im not running a thermostat at all... Is that bad?
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[ironroad9c1]

Ditch the Flex fan and get a stock clutch fan..then it will warm up and you will reduce your chances of the fan coming apart and destroying your fan shroud and radiator. Flex fans suck.

[454HO]

Originally Posted by kikkegek

I know which hoses you mean!
they are for the evaporator of my LPG-system.

here's a overal pic of it. but thanks!
ignore the two red arrows please.

Wow... guess it helps to have the whole picture of what you are dealing with.

Unfortunately it looks like there are a couple things going on. I think your number one issue is that LPG does not contain the same BTU's as gasoline. It is a known fact that an LPG powered engine will run cooler than the same engine powered with gasoline. Not much you can do about this.

Next, as previously mentioned the cabin heater and LPG evaporater are robbing some heat from the coolant. PLUS, they are allowing coolant to bypass the thermostat which will delay, if not totally prevent, the thermostat from doing it's job of regulating the temperature.

I am not an advocate of flex fans either. I have seen the damage they can cause when they explode. And I am sure that since it is not on a thermostatic clutch it is drawing air thru the radiator all the time which is compounding you other issues.

Personally, I think you need to do a couple of things. First thing would be to put a restriction in the heater hose line. I would use either a 1/2" ball valve or gate valve between the nipple on the intake manifold and the 'T' that split the flow between the LPG evaporator and the heater core. Or if you want, you could put 2 seperate valves after the 'T' and control flow thru each circuit.

Second would be to ditch the flex fan and get an electric radiator fan. You can control it with an adjustable thermocouple mounted to the radiator. This should help limit airflow thru the radiator in slow moving situations, but if you travel on the highway a lot then you may also need to block some airflow.