Hey guys. I have two motors. One in my carbed 85 and one in my efi 89. the 85 has always run cold. Barely into the normal temp range but the 89 seems to run hot. Its been straight up on the temp gauge. A few weeks ago it got really hot while idleing for a bit. I changed out the fan clutch figuring it just wasnt pulling enough air through. I just wanted to see about what temp your trucks run at and if im just paranoid. I really like my 85 running cold but im sure the sending units are different.
thanks

matt

 

An engine is the most efficient at the higher operating temperatures this is why trucks since the 1970's and up run a 185 to 192 degree etc. Thermostat. The very old trucks use to use a 160-degree units as started to raise the operating temps they also started taking the degree readings off the dash temp gauges. Substituting cold, normal and hot, because people had a harder time getting use to fact that the new engines are were now operating at a much higher temperature.

So how hot is your engine running is it boiling over or dumping coolant out? If not it is probably not too hot. Are your radiator fins clean? Are the hoses in good shape check for collapsing when it’s hot, is the radiator flowing good and Thermostat opening?

 

im not sure if the tstat is open but the hoses are in good shape and the fins on the fan is fine, and as stated i just replaced the fan clutch. The coolant is not boiling over but about a month or two ago it go so hot that it did boil over and since then ive just kept a closer eye on things.

thanks for the reply

 

The hottest my gauge ever shows is straight up and thats with the A/C on in heavy stop and go traffic and 95 degrees outside. I got an 88 EFI. Im running a 180 degree stat and my fan clutch has two setting for the temp spring and its set to come on sooner than later. Most of the time the needle hangs around the" N " in normal.

 

Sometimes you can tell if and when the Thermostat or Stat opens. From “cold” run the engine with the Radiator Cap off watch the coolant (if you can also have someone watch the temp gauge to find out this temp reading you could make your self a reference mark with some tape or paint daub). Like Tranzmaan said close to straight up is were many run. When the engine reaches operating temp of the Stat you will notice the coolant will start to flow, before that it is still. On a cross flow type radiator you also be able to get an idea of the condition of the core by the amount of flow and its speed (a radiator in good condition has quite a bit of flow and speed). If it is not flowing very well then the core could be plugged up and will cause it to over heat. One way to be sure Stat is working is to take it out then put it in a pan of water than heat and with using a thermometer can see the temp it starts to open also watch for a smooth easy movement as they open and if it shows any signs of sticking. I can tell if they are bad just by looking at them and by pushing on the center if they don’t move or don’t move straight I replace them. Item you should also check is the cap and look at the seat in the neck of the radiator (has a raised bead for the seal) to make sure it is clean of any crude, the caps seals should have an even seal line all around, any signs of splits, if the rubber is deteriorating, or has become spongy then its replacement time. Sounds like the rest of your cooling system is probably ok. A stuck thermostat is one of the biggest causes of over heating, sometimes bad caps or if the wrong type of cap was installed i.e. a coolant recovery cap Vs a standard cap.

 

when u buy a t-stat for a 300 it comes as a 192, even if u ask for a 180 u will get a 192

 

My 84 F150 has a carbed 300 with a 160 degree tstat, it runs around 170-180 normally, it has gotten up to 190-200 on really hot days (90+ deg. 90% humidity) when I get caught in traffic. My 95 GMC Jimmy with a 4.3 Vortec, it runs 190-210 deg...I have noticed EFI vehicles run hotter. My girlfriends dad's 90 F150 300 EFI runs right in the middle of the normal bar a on the temp gauge.

 

if you guys realy want to know how hot your truck are running, install a new mechanical temp gauge. Ford dumby gauges simply don't work good (if at all most of the time) . I have a 1988 300-6 with the stock single core radiater a newer better fan and new fan clutch and my truck will run at just over 190 with the stock new 190 t stat all the time. That is unless i sit in traffic long enough (30 mins or so). If you sit still long enough i have had mine go up to 230* at which point i turn it off or speed up to get more air flow. I beleive the only problem with mine though is it only has the top part of the fan shroud on it. Anyways g/l with your overheating problems. Btw on an efi engine stick with the stock t stat you atomize fuel better at a higher temp so stick with the stock t stat. If you keep overheating get a better fan and new fan clutch if you still are overheating get a 2 3 or 4 core radiater. I can get a good brand name 3 core radiater for only like 150$ at autozone. If your to cheap for that go junkyard shopping and find you one .

 

Well, I'll have to differ with you on this one. The reason for the hotter running engines of today is due to the emission standards required by the EPA. The hotter the engine, the cleaner they run. The Feds have gotten so carried away with this garbage that power and fuel economy have become secondary to the manufactures. Hince the lower fuel economy and horse power in California's vehicles in particular.
Personally I've found that cars and trucks seem to perform better more towards the cold side. Not dead cold, mind you, but warmed up enough to no longer need the use of a fast idle, choke, or the richer mix in FI engines. Or if a vehicle is warmed up completely and driving in a cool environment they preform better. That's the reason for the air intake tube on the air cleaner, to take colder outside air into the intake instead of the hot air in the engine compartment.
I usually will run a 180 T-stat in most of my cars and trucks except anything that's late model. If they're made for the 200+ T-stat there's no point in trying to confuse the computer any.
Just my 2 cents.

 

i run a 160 in everything i can. especially in my turbo car. you just have to make sure where your temp sensors trip the computer for your enrichment mode like chevy eater said. Alot of newer cars with larger motors are set to run 200+ even in the 220s. id rather run a colder motor, less oil break down, less expansion of parts, better power. have to make sacrifices somewhere though