Technical Radiator cap and getting hot

Twenty8. I pulled the 180 yesterday and ran it for close to an hour getting carb and timing dialed in better. I just boiled that 180 stat and it opened after the pan of water started boiling! Fml! Another defective stat. I have a few coming so will know more when they come. Thanks for your post

 

So it opens when in a bucket of hot water......... but does it open when it is installed in the housing.??????
Go back and read @FrozenMerc 's post #20.

By the way, where are you reading the temp from (where is the sensor)?

 

Here are a couple of snippets that might change your thinking about operating temperature ....................

"Internal combustion engines operate most efficiently at relatively high temperatures, typically above 80°C - 85°C (176°F - 185°F). Wear on the moving parts is reduced and thermal efficiency is increased by operating at this temperature."
https://www.davidboettcher.com/thermostat.php#:~:text=Internal combustion engines operate most,by operating at this temperature.

"The hotter the engine runs, the more efficient it is, that why modern cars run at 230 degrees. Remember, if you have a 195 stat, it just starts to open at 195, it isn't fully open until it's much hotter."

As you can see, 220 degrees is actually desirable as the operating temp. The trick is to set up your system to maintain it there under different conditions.

 

Twenty8. I’m not sure what you are meaning by something not making sense. I ran a 180 stat and the engine hit 220 and kept climbing. So I pulled that stat and ran it without one yesterday dialing it in better. Never got over 160. I boiled the 180 tonight in the house and it opened after the water started boiling. The sensor is in the intake manifold

 

Twenty8. I understand exactly what you’re saying! I do. This is my first project and don’t want to start over. I know my engine will perform better at a hotter temp. I just don’t know what exactly that temp is. Trial and error but I’m trying to err on the side of caution. I know a fresh rebuild will run hotter for maybe first 1,000 miles or so also. As a side note, the original stat was a 165. And I understand the technology difference from then to now and efficiency. I appreciate your comments

 

Twenty8. The 180 stat didn’t appear to do anything when installed in the housing as the temp just kept climbing before I shut it down

 

Yeah, sorry, I deleted that post after re-reading it myself.

Re sensor position, if your sensor is at the intake, and the thermostat is not opening as it should, you will see the high temp gauge readings, but you will not know what the radiator reading is. It would make sense to see if your radiator temp stays relatively low as your engine temp goes high. This would definitely indicate a thermostat problem.

 

180 to 220 seems to be a widely accepted range. Modern engines are up at 230 or a bit more. I would aim for around 200-210 if it were me. Just be aware, maintaining your operating temp is very important, no matter where it is dialed in at.

The quicker it gets up to operating temperature the better, especially in cold weather. This is related to the thermostat. The original 165 thermostat does this job.

And your system should have the capability to keep it relatively constant in hot weather/hard operating conditions. This is all about the cooling system as a whole (water flow/air flow). The thermostat should be getting towards fully open at the preferred operating temp. It is desirable to have a little more opening go though, so if the temp rises higher, it can open a bit more and allow more flow.

A lot more to the humble thermostat than many are aware of.............

 

Twenty8. I totally agree. When I had that 180 stat in and ran the engine, I couldn’t get it to idle for me to get out by the engine and hit areas with a heat gun

 

Twenty8. Pop on up and give me a hand! I appreciate your wisdom and your thoughts are all right on track. I need to not be such a pussy when the temp starts rising and just see what it does! Finally I can take it for a spin if the temps start freaking me out! Thank you buddy!

 

I'm just curious, what kind of fan do you have and do you have a shroud?
Also I am having a real hard time figuring out if you are having this issue with the truck running down the road and coming up to stop lights or are having it sitting still in the driveway.

If the truck runs at the temp you think it should or just above thermostat temp running down the road at anything over about 35 but starts climbing right after you slow down or are in stop and go and then drops right back down when you hit 35 and above it is pretty well an air flow issue and not a thermostat issue.

 

Get it sorted while standing still before driving it. Being winter up there it should pretty well hold operating temp sitting at idle (test at night if needed). I really think your thermostat may be fouling inside the housing, preventing it from opening to where it needs to be. Lets get this right before you place any load on the engine/cooling system.

When you do test drive it, be very cautious. Overheating and cooking an engine is a very expensive exercise.

 

As far as I can work out, this is all happening while at a standstill. At least that is what I am basing my suggestions on.

 

Lots of guys are missing the fact that he had a thermostat that was not not designed to work on his motor's thermostat housing. All he had was an old original stat that does not match the two he is trying to replace them with.

If he has not yet purchased a new thermostat that is designed to work with the thermostat housing on his motor, he will continue to have problems.

If he has purchased the correct thermostat for his motor's housing, and that thermostat is the one that is not opening in a pan of boiling water, it is defective. The correct way to test a thermostat is to put a string under the flap that opens, and suspend the stat in a pan of water by the string. Then you measure the water temp (in degrees, not boiling or not). At the water temp the stat opens enough to drop off the string, that is that stat's opening temp. News flash, nearly every thermostat opening temp varies a couple degrees from what is designed to open, it may be less or it may be more degrees required to open it. Any other thermostat test is inaccurate at best.

He needs the correct thermostat for the housing on his motor, and he should test that stat in the water to know what temp it really opens at. If his new stat does not have the air bleed, drill an 1/8" hole (or 3/16" hole like mentioned earlier) before the installation, it won't effect the motors temps very much, but it will sure help get the air out of the system. Gene

 

^^^ YEP ^^^

Also, the thermostat should have the right hysteresis to suit the operating temperature of the engine. Hysteresis is simply the temp range from when the thermostat first starts to open to when it is fully open. For example, a 180 * thermostat will start to open at 180* (+/-), and should be fully open by somewhere around 195*. The operating temp should be within this range, best is about 75% open. This allows the thermostat to react and rectify flow rate to counteract temp rises and drops.

I will put this up again as it is an excellent read on the subject, especially the last section - "How Does A Thermostat Work". Sorry it is using centigrade, but the principles remain the same.
https://www.davidboettcher.com/thermostat.php

 

Wait a minute here. If he has an actual problem then it isn't working correctly. If it is working correctly then he won't have an actual problem.

Or have I misunderstood what you are saying?

 

Run as much timing as you can, until the engine struggles to start while hot. Another option is a RobertShaw style thermostat, has a larger opening. Don't overlook the water pump, pully size. I've learned, NOT all water pumps are created/rebuilt equal!

 

As long as it moves water, it is good!






Bones

 

Mr48chev. I have the original fan and shroud. It moves a lot of air! I have yet to drive it down the road so all previous running has been in driveway. It’s road ready now just not registered

 

Twenty8. Yes it’s not driving yet but real soon

 

Hold on a moment! The timing has been advanced some and has ' changed tune' (which I take to mean has increased idle speed and is running smoother) and has been idling (car stationary) thermostat-less for an hour ( as stated) with no ill effects ( my assumption / interpretation). That being the case get that thing down the road some!! The thermostat situation should resolve when the correct fitting and properly working item is installed. Paranoia was admitted to earlier! Nothing wrong with some caution though!

Chris

 

Winterfronts and shutters!
Budget36, did your dads trucks haul dirt? Fancy paint jobs and lots of chrome?

 

Lol. You know the type
Polished SS and Aluminum!

 

Yep I thought so. Small world.

 

Happydaze. You are correct on everything you posted. It is now road worthy so just waiting on the stat. Then I’ll take it for a ride

 

He’s looking at a temp gauge running 220F with no pressure cap. That’s the original problem statement. Water boils at 212F at atmospheric pressure. I suspect his gauge is showing steam temperature, not water.

So, put a cap on. The system is supposed to be pressurized. Use whatever the radiator is spec’d for. Then run it and check the gauge.

Added later, he may also have a dud thermostat. If it’s marked 180 and isn’t opening until water boils, that’s also a problem.

 

Awful lot of speculation going on for a situation that may or may not exist ...

 

I got the knowledge from a few different places. I am a Mechanical Engineer by trade. I got my B.S. from the University of North Dakota. North Dakota is coal fired power plant country, and most of the professors had a thermodynamics or fluid dynamics specialization because of this. I think I took 6 or 7 thermo or fluids based classes before I graduated, so my degree was biased towards those disciplines. I also worked for many years as a Cooling System design engineer for a power sports company. I learned way more than I wanted to about radiators, pumps, and heat exchangers at that job. I have built and tested with my own water pump dyno, instrumented and tested ATV's, Side-by-Sides, and snowmobiles with more thermocouples, flow meters, and pressure transducers than you can imagine, and spent 1000's of hours in the field, or on dynos testing cooling systems.

One interesting anecdote. During durability testing of a new side-by-side vehicle, we were seeing a high rate of failure of the water pumps. These pumps were manufactured with a plastic impeller molded onto a hardened steel shaft. The impellers were actually coming loose from the shafts for some reason. Turns out, that problem was initiated by the driver splashing through a large puddle. The splash of cold water on the radiator would cause the thermostat to slam shut. The rapid closing of the thermostat produced a large water hammer effect in the cooling system, and that pressure wave would be enough to knock the impeller off the shaft. It took a few days of instrumentation and data collection, and splashing through mud puddles, to find that root cause.

 

Internet diagnosis is like that. I think it's great that most are willing to try and help...............

 

FrozenMerc. Pretty vast knowledge and education in your field. You have a great way of articulating what you want to get across. Keep the info coming, I appreciate you!