Is anyone still using the original 195 degree temperature thermostats in their 2nd generation Oldsmobile engines. All the resources I look at says Oldsmobile put 195 degree temperature thermostats from the factory starting in the 1964 with the 330 engine and ending at the end of production with the 307. Since it was used in 1964 that tells me it was not because of emission standards. From my understanding a cooler thermostat is used for more power and a hotter one would be used for efficiency. If you are using a 195 degree thermostat, what temperatures are you seeing on your gauges? If a 195 degree thermostat starts opening at 195 degrees, I would think 210 degrees could be typical on a gauge. At what temperature would yo consider the engine to be overheating?

Thanks,
Noel

 

Most of us use a 180* thermostat, and the temp would be in the 190ish range. To me overheating is around 230+.

 

I have a 195 in my '72 U code Supreme and even in the SE VA summer heat, I never see above 200-205 on my gauge.

 

What gauge are you using to determine your coolant temp? Is it just a parts store cheapie?

 

If you're asking me, I have Equus. Been using the same set for over 5 years now and haven't had any issues.

 

I have the SunPro 3 gauge cluster mounted under the dash, which is now Bosch.

 

Once the t-stat is fully open, it has zero effect on overheating. The radiator and fan are the limiting factors.

 

While that is true, I've found the normal operating temps of these engines to be around 190-195 in summer with or without a 180* or lower thermostat, however with a 195* the thermostat will still cycle and temps will run in the 210-215* level.

 

Noel,
Yes, still using the specified temp stat. The engineers put some time into its design for a reason. The cars operated as intended reliably for years with this configuration.

Just from being on the planet for 50+ years, I have learned a 190-192-195° Stant HD T-Stat works the best in an Oldsmobile V8.
It will maintain a tighter temp band and allow a healthy cooling system to do its job...maintaining 195-205 maybe 210 on a really hot humid day.
160-180° (IMO) is not hot enough to get an IC engine into its optimal operating temp range.

That said this is a very dynamic question and you will get thousands of opinions some right some not.
Step up and purchase a good stat, not a $10 chineese POS. Inspect/service the entire system as well.

My 68 400 would run hot when I first bought it in California. Hot was 220-230. I troubleshot the entire cooling system and found the radiator was plugged. Did a re-core (4 core) new hoses, water pump (was leaking), fan clutch, full flush, refill with 50/50, installed a 180° stat. It still ran hotter than I liked, 210-215ish.
Put in a Stant 192° stat. Problem solved. It rarely ran above 200°...only when climbing the Donner Summit on RT80 at 205°

Just replaced it a few years ago with the same Stant T-stat

Overheating in a second-gen Olds V8 would be 225-230°

Steve

 

At 15 psig, 50/50 water/ethylene glycol will boil at 268. GM thought the operating range of the cars could go to 250 and it says that in some owner's manuals. The car will run safely until boil over as the pressure is released in a controlled, safe, manner. Once the system hits boiling, you will have runaway gaseous coolant mixture escaping however it can, and then boiling more as it returns to 0 psig.

Like Joe says, the thermostat is simply a regulator on the system, just like a house thermostat is a regulator on your home HVAC. In a properly operating cooling system, the capacity of the radiator plus airflow (either fan, or road draft, or both) should exceed the heat generation of the engine. Fortunately, as the coolant increases temperature, the cooling capacity of the system increases due to the larger difference of temperature between the coolant and ambient (in other words, a hot radiator is more efficient at dissipating heat than a warm one). However, it is possible to get into a situation where your coolant temp is above the thermostat's value because the radiator can't keep up at that temp, but, due to the increased efficiency of a higher temperature gradient, it CAN keep up at a higher temp. This is commonly called "running hot" and, while it works, it is not as designed. The temp will stay at whatever the radiator can do until the heat is stopped.

A thermostat regulates this by opening and closing based on the heat it sees. Performance thermostats have a bigger hole, which, ostensibly, allows more flow (if it is the flow restriction in the system, of which I have my doubts). This was complicated by "low emission" thermostats which ran the engines hotter to make them run cleaner because a hotter engine does run cleaner on emissions. These came in about 72 or so and were about 195 deg, to my understanding. 180 is a correct range for these cars. 160 degree thermostats are just to be bandaids.

Verified by two mechanical gauges that matched, I saw the following on a small block Chevy.

Temp Highway, Temp in town, Thermostat, Radiator.
250, 220, original low emission 195 thermostat, gunked up 45 year old 2 core.
220, 200, Stant Superstat 160 thermostat, gunked up 45 year old 2 core.
185, 180, Stant Superstat 185 thermostat, nos 3 core radiator, new water pump, hoses.

My old Chevy was gunking up its bent (from a wreck) 2 core and running very hot. I bandaided a Stant 160 and did bring everything down 20 degrees, but would have a 25 or so degree swing from highway speeds to rolling around town. The water pump went, and I put in a NOS BBC specced Harrison 3 core, rebuilt water pump, and a 185 thermostat. It stays at 185. In fact, I had gotten into a water jacket intake manifold bolt doing valve gaskets (had to move a throttle bracket to get the valve cover off) and created a leak. I think that this kept the system at a much lower pressure than the thermostat, and it still stayed at 185. It's now fixed, and I am not really sure it gets up to puke it out the overflow into the bottle temperature much as that radiator is for a 454 and the little 350 is under-taxing it.

 

I was wondering what brand gauge the OP was using. Equus and Bosch are both reliable well known brands.

 

Thanks for the input on temps. I have owned my car for 25 years and all that time I ran a 180 degree thermostat with an idiot light and never had a problem. Recently I upgraded to a throttle body fuel injection and on the advise of a mechanic I put in the stock 195 degree thermostat. The fuel injection requires a minimum of a 180 degree thermostat and the mechanic said the engine would run more efficiently at 200 degrees. According to the fuel injection temperature sensor the car was idling around 201 and when on the freeway around 75 mph it would get up to around 216. I am using a re-cored original 3 core air conditioned radiator and clutch fan with all the correct shrouds along with a new water pump. The fuel injection sensor I have are known to be off by a little. I used a temperature probe with a multimeter in the idiot light sensor's NPT hole to verify. On the lower end of the scale it read a little warmer than the fuel injection sensor but at 75 mph it read around 207 degrees. I am currently getting ready to install a Speed Hut gauge pack, I am wondering how accurately that will read.

 

You have zero problems, it aint broke......
Dip strip the system every year to track PH. Flush accordingly.

 

Agreed you are concerned about nothing.