Getting ready to do the hoses on my Cad and want to change the Thermostat. 1. I don't know what year engine it is. From what I understand most 472-500 cads interchange almost everything except the bottom end. Is this true of the thermostats too? Can I just pick a year and go with it? 2. Will there be any adverse effects if I use a lower temperature thermostat? I think factory temp. is 192-195 degrees but I've seen some years have a 180 and even a 160 degree thermostat. But I also know that some years like to run "hotter" and other "cooler."
Most of the thermostats should be the same as far as fitment as long as you stay within the engine series. Use a lower temp. The higher ones were only used to lower certain emissions for EPA regulations, and they kept you very close to boiling over all the time. The engines are much better when they are cooler.
Awesome. That's what I was wanting to know. The 1967 472 has a thermostat rated at 160 degrees. SHould I go with that? I ask because the part #'s for the 1970-1974 engines are all pretty similar but the early ones are different. Like you said though, the fit should be the same right? Thanks for the help.
The big Cads have an internal bypass under the thermostat in the block. It requires a Cadillac specific thermostat that closes the bypass when the thermostat opens. Do yourself a favor and put a soft plug in the internal bypass opening and drill an 1/8" hole(just to bleed trapped air) and run a much easier to find Chevy style thermostat. For more info or pics do a search here: http://www.cadillacpower.com/forum/
I just went thru this on my 472 and found out that these engines run a 180 and was also told that they run at 190 to 195 and need this to function, So the real fix was the radiator cap, so you might check that and if you are running a old radiator, you might not want to exceed 7lbs. Also Ramblur has the right idea, I had a problem finding the right Thermostat
Well, they got me a cap down at O'reilly. It's 180 and if what I'm hearing is right, it should fit. I was also going to put a higher pressure cap on it like you mentioned. I think it is the original rad but it shouldn't be a problem. My old man's running a 16 lbs or so cap with his hopped up 350 an using the original Model A radiator if you can believe that. Guess we'll see what happens. Thanks for all the knowledge.
The 472-500-425 thermostat is used on some IH truck applications also. 180 is the coolest normally available. Use the specified stat for quicker warm up, with the internal by pass open. When the thermostat opens it closes off the bypass to pull coolant off the heads more effectively. These motors commonly spent hours idling with the A/C on in commercial service. Get a 15# cap if your radiator is good and everyone will be happy. I drove my '69 Eldo to the top of Mt. Evens in Colorado 14,258ft elevation and no radiator overflow. The sensor on the right head is a ground switch that allows the heater fan to come on when the engine is warmed up about 130F. The sensor on the left head is a metal temp sensor that indicates mechanical malfunction about 285F. These are blind holes that do not go to coolant and should never have sealant on them. The coolant temp port is under the thermostat behind the steel timing cover plate. A mechanical "bourdon tube" sending unit will fit with patience and the A/C compressor removed for access.
... Cooler, within a "normal" operating range, is better because you have less oil thinning, less bearing heating, less gas boiling, slightly higher power output, and a host of other reasons. You want it warm enough to steam off the acids, water vapor, etc from the oil, but you do not want to thin it excessively. Cadillac 472s and 500s are rugged engines IF you can keep the heat from hurting things. They throw off a HUGE amount of heat. The thermostat temps were raised on almost all cars at the beginning of the smog era to temps that brought on lots of problems that they didn't have before. You will have less of a problem with spark knock, thinning oil, cooking starters, carb boiling, vapor lock, and a host of other things if you run the engines a little bit cooler. The higher temps offer NOTHING of value except for a reduction in ONE of the EPA emission concerns (was it NOX?), and brought on a whole list of new problems related to heat and deterioration. A thermostat with the lower "pre-smog" temperatures is best.
Are you aware that an engine produces more power the hotter it is right up to the point of self destruction? 160 degrees makes sense with a non pressurised cooling system. But if you are going to use a 16 lb cap to raise the boiling point to 250 degrees, why not take advantage of it? I will guarentee a 20 HP difference from 160 to 195. Also better fuel mileage.
Fry it, burn it, cook it, melt it, have at it...... you're the expert. Anyone remember those ads only a few years ago where they were advocating a super-coolant and hot hot thermostat for really high temperatures, 300, 350 and higher saying the engines ran REALLY, REALLY, very efficient at those temps? I wonder, did that one catch on like they said it would, or did those evil oil companies buy it up and hide it away with the 150 MPG carburetors??
Just try to keep it as cool as you can. The engine will try on it's own to do the opposite. The Cad motor will try to get really hot and you should try to prevent that. Radiated underhood heat and water temps will be your biggest concerns. Watch the oil temperature. And, YES, engine temperature does have an effect on oil temps. If you let the oil temps climb high, the oil will thin and the bearing life will be much shorter. I put an oil temp gauge on mine, and was surprised at how the different brand oils worked. There were some name brands that hit 300 degrees quickly and kept climbing when towing. Bearings won't tolerate that for very long. Certain other brands like Valvoline and Castrol ran very much cooler in my Cad engine. I learned what my favorite brands should be in order to keep the crank bearings cooler and last longer when towing. It helped me a lot to put a heat shield around the starter to allow air around it while deflecting the engine heat to keep it from cooking. A barrier between the exhaust pipe and the starter will help too, but don't surround the starter so it does still have access to cooler air flowing under the car. One of those remote solenoid kits that are often used to help GM starters with their hot-start problems will help a lot also. It made a huge difference with mine. There were a few threads on it here that you can probably find in a search.
Actually it worked, but not at a price that was competitive in the market. Ford is still pursuing it. It takes exotic materials to make it work at this time. The point is, an engine is no more prone to overheat with a 195 degree thermostat than it is with a 160 degree if the cooling system is properly designed and maintained. Horsepower makes heat, and if you are not making heat, you are giving up horsepower.
Yep, cooler does NOT make more power. Now a cooler intake charge does. And I have to say I have never ever seen a 160 degree theremostat make an engine run cooler than a 190 degree. IF the engine is prone to overheat the thermostat does not change this, it merely lets the water circulate sooner.
This is actually getting quite funny. Lets boil em, fry em, melt em, percolate em, all those other things people with problems mistakenly try to cure... You tell them to enjoy those problems, they are good for the engine. ! Do what you want. I have better things to do than watch this nonsense.
what's funny? engines have an optimal running temp, hell if you read the factory manual for the 401 and 425 nailheads it says 190-220 is the operating temp for the engine. I shoot for 195. And they do run better then they do at a 180 let alone 160. You're answers seem to be lacking any real understanding of what is going on. Maybe if you could back these answers up.
Ignore the drama. Run the Cad themostat. I've been around and around with my '68 472 (if your engine is a '67 it's NOT a 472, they're '68 up). Stick with the 180 t'stat, make sure your radiator is up to the task, 15-17 lb cap, that you've got enough airflow and it's properly shouded. My '36 Fordillac (where the 472 currently resides) was almost undriveable with the radiator I had in it initially, a tiny 3 row '65 Mustang copper one. The cure was an aluminum 2 row "high performance" radiator for the Mustang application. My grill shell is sectioned 10", so there's not much room. It's the shit. Runs 190 normally, idling in traffic on a REALLY hot day will push the temp gauge to 205-210, but it comes right back down. I only have room for a thin profile 14" fan, I'm sure with a bigger one, a 16", I'd be a little better, but it's no problem. I speak from experience, I've been running this particular engine, in two cars, since 1974, so I know a little about keeping a 472/500 cool. Enough radiator, 16lb cap, 180 degree thermostat, and plenty of fan. Brian
Right on. Thats the direction I've been leaning anyway. Already bought a 180 stat, and I'm using the 472 radiator (for now). I'm gonna throw a 16lbs cap on it and see what happens. Shrouding will be the next step. I'll have to fab something up but shouldn't be an issue. Hopefully, that will do it. Thanks. Chris
Ditto. Plenty of air. Big radiator. I have been running a 472 as a family car, travelling car, and trailer tow vehicle for many years. I had my copper radiator re-cored with a 4-row core. It's over 20years so far. I think the next one will be aluminum, when the copper one gets old. They put out huge amounts of heat and need lots of cooling and fresh air. Be careful of heat around the starter. Don't let a muffler shop run a pipe too close, and make sure it gets fresh air also..
Hey it's funny you keep mentioning the starter. After I run it for a while...it seems to be real weak. You say there is a thread on here for building a heat sheild?
There are at least a couple threads on here about using a remote solenoid for the starter. It is not Cadillac-specific, but a fairly common GM problem. In case someone else comes running over to pick a fight- there were quite a few complaints of GM starters cranking sluggishly, if not quitting altogether when the engine (Chevy, Cad, Olds etc) was hot. I am not making it up, and more heat is not the answer. There were remote-solenoid kits being sold to cure the hot-start problem. Others thought it was a problem too. Basically what it is, is a Ford style starter solenoid mounted on a fenderwell away from starter heat, and the GM starter-mounted solenoid no longer being asked to do the heavy-current switching. I made my own "kit" by just jumpering across the GM starter solenoid connections, and using a Ford/AMC starter solenoid away from the engine. It worked like a charm. Several places sell those kits. I don't have a name handy. I would do a search for Chevy starter problems, or hot-start troubles or something like that. Maybe "solenoid" or "remote solenoid" would be a good search term. The heat shield I made was a simple thin sheetmetal piece between engine-and-starter and between exhaust-pipe-and-starter. that simply let the hot air on one side of it stay separate from the cool air on the other side of the tin. That kept the starter from getting washed with the heated air. As long as there is free-air space on both sides of the tin, there is not much heat transfer. It just keeps the hot-air side from mixing with the cool-air side. That made a big difference in hot-cranking power even before the solenoid fix.
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