[gtorich]

Ok, had the car out today about 60 ish degrees, ran for a half hour of so, car ran between 172 to 174 ish..............checked hoses both the top and lower hose only warm at best................the other day in the 70"s both hoses were hot to the touch, running a 160 degree stat......................also today the waterpump and rad were hot to the touch, but not the hoses.............even after heat soak never got abobr 182, the other day while in the 70"s both heater hoses were hot.............any ideas on what to check here for.

Rich

[tempest1964]

Could the thermostat be stuck?

[gtorich]

I was thinking the thermostat might be stuck, replaced that a few years back, the water pump is fairly new, did all the clearances to it, the car did leak a little antifreeze over the winter sitting in the garage, but i topped that off before driving, just find it strange one day all hoses are hot then the next day lukewarm after driving.

Im gonna keep an eye on this for the next couple days and see what happens. I see i have this in the wrong section also, good thing you guys can read between my misspelled words, i was in a hurry.....lol

Rich

[steve25]

The stat is no moving as freely as it should.

Replace it before it hangs up closed on you!

Your not doing the life of your motor any favors by not having at least 190 degrees of coolant temp .

[Squidward]

That's weird. According to the gauge they should be uncomfortable to touch. Is your gauge in the crossover, or in the head?

I've been playing with my system (over in the Cooling section), and I've had some inconsistent results at times too. What I have concluded is that even tho you have a 160 Tstat, it doesn't mean it will flow enough to keep it at 160. At some point the tstat will be open as far as it can go, and then air flow and radiator size become the determining factors after coolant flow to the radiator is maxed out. I removed my tstat recently, and got a roughly 30 degree drop in temp. I'm happy with that drop, but I want to run a tstat so I can get up to normal temp quicker.

I'd be curious if you put a laser temp gun (available cheap online) on those hoses while running. A functional radiator should make the lower hose relatively cool to the touch.

[mgarblik]

Most likely a goofy thermostat is the issue. Been seeing more and more inconsistent, malfunctioning thermostats in the last 3-5 years than in my entire career. To try and combat this, I tried several of the safe-T stat type thermostats. That did not solve the issue. Just ended up with them latched in the open position. So that's not a fix. If a fresh thermostat doesn't seem to fix it, consider purchasing an infra-red temperature gun for better diagnosis. They are a handy little tool and Harbor Freight has decent ones for around $40.00. A good working cooling system should have about a 20 degree drop on the inlet hose, (lower) vs the upper hose once up to temperature. I doubt the water pump is the problem in this situation. If you have a quality pump, cast impeller, decent plate clearance, good, tight fitting rubber sleeves in the transfer tubes, there really isn't anything else in there to give you trouble.

[peters23]

I would just replace it with a new one, its cheap insurance against a meltdown.
Might want to test the new one in a pan of water on the stove with a thermometer.
I always drill a small hole (maybe 1/16" or less) in the thermostat flange to ensure some flow to help trigger it.

[gtorich]

Hey thanks guys, will pick up one of those thermo guns, and replace the thermostat, was reading up on some old threads about air in the system, right now my upper hose is about level with the radiator cap, its on a 66 gto, can't cut it any shorter without it sitting on top of the alternator. Can't remember if i drilled a small hole in the thermostat flange, but i will check, thanks for the help guys i appreciate it.

Just in case someone asks, i have a cold case radiator, 7 blade clutch fan, proper shroud, think i have a slant super stat in there, will get one for sure. One thing, don't know if it matters or not i don't have a coolant recovery tank, just run the hose down the side of the rad, been this way for many years, never gave me trouble before, i can throw one on if anyone thinks that would make any difference

[steve25]

You will only have an issue with air in your system if your rad cap sits lower the the thermostat which is not the case in your car.

If you want to be anal about it and to confirm then start the car cold and when the coolant gets hot enough to reach the overflow tube below the cap then slam the rad cap on.

[Squidward]

Originally Posted by mgarblik

If a fresh thermostat doesn't seem to fix it, consider purchasing an infra-red temperature gun for better diagnosis. They are a handy little tool and Harbor Freight has decent ones for around $40.00. A good working cooling system should have about a 20 degree drop on the inlet hose, (lower) vs the upper hose once up to temperature. I doubt the water pump is the problem in this situation.

I got this one, worked well:
https://www.amazon.com/dp/B0CH6LKBSZ...fed_asin_title

I did the temp sensor cal with it on my FiTech, and it matches within 2-3 degrees of my digital cluster temp sensor, both located in the coolant crossover.

Interesting you mentioned the temp deltas. I would like to start collecting some IR data for inlet/outlet temps on various components. It'd be nice to know what expected temp deltas should be for a good working system. When it came to troubleshooting these issues, someone could throw $19 at an IR gun, and get real performance data before throwing $$$ at new pump/radiator/fan/deluxe tstat. I've personally taken that boat ride before.

[dataway]

I love projects like that, real world data.
Back in 2000 I was on a forum for a particular new motorcycle that came out, as various different exhaust systems were offered by the Aftermarket, owners wanted to know the sound level for each new offering.
I bought a decibel meter and we shipped it all over the country to people with the various products installed. Each person used the same testing method and shipped the meter off to the next person. Another forum member posted all the resulting data to a webpage.

With the questionable quality of many vintage car parts these days we might have to start doing our own testing.

[Schurkey]

Originally Posted by gtorich

today about 60 ish degrees, ran for a half hour of so, car ran between 172 to 174 ish.

Seems high for a cool-ish day and a 160 thermostat. Not harmful, of course...but with cool air going through the rad, I'd have expected the dash gauge reading much closer to 160. That thermostat is nearly, or completely wide-open at 15 to 20 degrees above it's rating...and you're nearly there.

Thermostat reliability has taken a plunge. Start there. If it still runs well-above the thermostat rating in cool-ish weather, you have cooling system problems, (clogged radiator, dirty radiator air-fins, blocked air-flow, scale in the engine, faulty fan, eroded water pump impeller, and so forth) or you have engine-running problems (Lean fuel-air ratio, incorrect pulley ratio on the water pump, retarded timing, etc.)

Notice that NONE of the major manufacturers, and NONE of the thermostat companies leave bigass holes in the thermostat flanges. Some 'stats have a "jiggle-valve" that CLOSES as soon as the water pump develops pressure, and Robertshaw stamps a tiny lil' vent into the side--enough to bleed air without passing much water. A drilled thermostat might be needed if you've disabled the OEM coolant bypass system, otherwise it's a waste of effort, and somewhat counterproductive.

Beware the "dirty little secret" of infra-red thermometers: They're only accurate if the surface you're measuring the temperature of has the same emissivity as the infra-red thermometer is calibrated for. Very few infra-red thermometers have adjustable emissivity calibration, and you're just guessing at the emissivity of the item you're trying to judge the temperature of.

[Squidward]

Originally Posted by Schurkey

Beware the "dirty little secret" of infra-red thermometers: They're only accurate if the surface you're measuring the temperature of has the same emissivity as the infra-red thermometer is calibrated for. Very few infra-red thermometers have adjustable emissivity calibration, and you're just guessing at the emissivity of the item you're trying to judge the temperature of.

The ir gun I got (cheap) has a correction instructions for different materials. True, the reflectivity/emissivity will affect accuracy, like painted or cast metal vs shiny polished.