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By 62bigwindow - 9 Years Ago
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My car seems to run too cool. I have a 180° Robert Shaw thermostat in it but the engine will only get to 160-170°. And that's on a 90 plus degree day. The only time it will warm up is if it idles for long periods. I have a four blade fan on it with a water pump pulley about the same diameter as the dampner. Should I switch to a 3 blade fan or a smaller pulley?
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By Lou - 9 Years Ago
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I can't see a problem here. Sounds like it's running fine, leave it alone.
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By Baby Blue 57 - 9 Years Ago
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Ok time to chime in here, First I would check the poundage of your radiator cap! Yes it does make a difference if you don't believe me check it out on line because if you read it on the internet it has to be true! Just a little humor thrown in. It's a simple and inexpensive test or fix I just did it the other day with a friend with a scruby that was running way too hot as he thought using a 165 thermostat but then he told me he just installed a new aluminum radiator and used the cap that cap with it. No poundage indicted on it, I told him to try a 13 or maybe 15 lb cap he did and it reduced his temp by 5 degrees. Small difference but in the right direction for him, so I would check the cap first and read up on whether to go up or down in poundage on the cap.
hey just fuel for thought.
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By Baby Blue 57 - 9 Years Ago
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Baby Blue 57 (9/3/2016)
Ok time to chime in here, First I would check the poundage of your radiator cap! Yes it does make a difference if you don't believe me check it out on line because if you read it on the internet it has to be true! Just a little humor thrown in. It's a simple and inexpensive test or fix I just did it the other day with a friend with a scruby that was running way too hot as he thought using a 165 thermostat but then he told me he just installed a new aluminum radiator and used the cap that cap with it. No poundage indicted on it, I told him to try a 13 or maybe 15 lb cap he did and it reduced his temp by 5 degrees. Small difference but in the right direction for him, so I would check the cap first and read up on whether to go up or down in poundage on the cap. hey just fuel for thought.
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By Baby Blue 57 - 9 Years Ago
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It's not a scruby it's a scruby!!!
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By 62bigwindow - 9 Years Ago
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I have the temp gauge sender in the water pump. The only hole I could find it would fit. I have a infrared temp gun that I'm using to verify temperature. I checked several places water flows and 9 out of 10 times the warmest I find is 170ish. I was worried that if the thermo wasn't opening the engine water wouldn't flow through the block correctly. I'll check into the rad cap. I am using a 3 row aluminum from Champion and never changed the cap. And Lou you may very well have the right idea. Maybe I'm worried about nothing.
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By DryLakesRacer - 9 Years Ago
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A word about caps. DO NOT TRUST WHATS WRITTEN ON THE CAP. We run a very high # cap on our dirt track engine; after many failures we bought a tester and four 3 different caps that were over 25# would bleed at less than 10#. We now test every one and scribe what they are. I use a 7 psi cap on a heavy duty 3 core brass/ copper rad in my 56 with a 160 thermostat. It runs 160-170 at the top hose at idle and a little lower when running on the road.
Always check your water movement at idle with the cap off, if you don't have any install a smaller pulley.. Good luck.
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By slumlord444 - 9 Years Ago
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Every Y block I have seen has the sending unit in the back of the drivers side head. Threaded hole there. Most of us wish we had a too cool problem!
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By 62bigwindow - 9 Years Ago
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The stock sender is in place. I put a mechanical gauge in because the factory gauge doesn't work. I have a replacement now so maybe it will be more honest about the temp.
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By CK - 9 Years Ago
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It could be the new gauge or was it in before you changed the radiator?
Maybe you need to alter the pump pulley size to slow it down?
I read it should run between 180-210*
I have the gauge at the rear head port and a radiator cap with a gauge and they both read the same.
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By 2721955meteor - 9 Years Ago
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charliemccraney (9/3/2016)
The water pump is the worst place for a temperature sender. The coolant is just coming out of the radiator so at best, you will get a reading that is a few degrees higher than the cooled coolant coming out of the radiator. The coolant still has to pass by 8 cylinders and over 8 combustion chambers. From that perspective, it is no surprise that you are getting a lower than expected reading. The best place to check the temperature is right behind the thermostat, on the intake. If the device you use to measure is known to be accurate and it is only 170 there and and does not get hotter, then your thermostat is defective or perhaps is was mispackaged, or maybe it is a 160 and poor eyes made it look like 180. The thermostat is opening.The engine simply will not stay cool if the thermostat does not open. You should see the temperature increase as you measure along the flow of the coolant. The pump will be coolest, the middle of the block will be warmer, the stock sender location will be warmer, the thermostat will be hottest. Do you see that?
corection,withe the by pass working in the right situation(cold weather)the engine will not over heat stat closed
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By CK - 9 Years Ago
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http://www.hotrod.com/articles/davies-craig-reinvents-the-electric-water-pump/
It's a little modern but seems perfect.
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By oldcarmark - 9 Years Ago
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My experience with the Robertshaw Thermostat was similar to Yours. I tried 2 of them thinking the first was defective. Neither One would get the Engine warmed up in reasonable Time. Went back to a standard 160 Stat and it worked as its supposed to. Never figured out why the Robertshaw Stat didn't work properly. maybe both were defective? I also installed a mechanical Coolant Temp.
Gauge. Drilled and tapped the Intake Manifold just behind Stat Housing to the left on the flat area of Manifold. I also have the original Temp Gauge operating.
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By oldcarmark - 9 Years Ago
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The 2 I tried were Mr. Gasket. Did not realize there was a difference. Maybe thats why they failed.
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By 62bigwindow - 9 Years Ago
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The thermo works. I tested in in a pan of water before I put it in service. It is possible that it's a 160° instead of a 180°. It was a NOS unit that did not have the original box. I'm sure my gauge is reading correctly. It is within 10° of the readings I get with the infared gun. I just had the car out tonight and the temp never rose above 160. I think I'll try to find a 180 and swap them out and see what happens.
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By GREENBIRD56 - 9 Years Ago
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My trusty old '56 Ford manual (right or wrong) shows the OEM thermostat spec - "standard" = 157-162. So a new NOS could be just that.
The engine tuning - standard equipment - had a number of features that facilitate warm up. One is the "no vacuum advance" at idle and retarded initial timing settings. When using other tuning schemes - the engines may run quite a bit cooler at idle than the OEM - but warmed up and running, it should get to the t-stat rating as a minimum.
NAPA used to have a conventional 170 degree, 2 inch thermostat with the larger size (1-1/2"?) opening but I've lost track of the part number. Is it still available?
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By 2721955meteor - 9 Years Ago
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for what its worth, charley in correct, i don't by the pressurcap storey,pressure in the system stops water from boiling,boiling water causes cavitation hot spots in the engine,so some pressure is important. cavitation will give false readings on gauge.(that is why bypass hose is critical so pump keeps flow in engine when stat is closed. my ranchero runs 160 at ford temp location and170 at therm housing.little to no flow to rad till 170 at stat when it opens. yes i need a new stat to keep temp close to 180.
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By 2721955meteor - 9 Years Ago
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charliemccraney (9/13/2016)
I don't know what the pressure cap story is. It is important to understand that the thermostat is not simply an on or off device. It opens gradually, starting around the thermostat rating, being fully open at some point after the temperature rating. So your observations are correct. When the system has cooled sufficiently. the thermostat will return close to a closed state, preventing the flow of coolant, at which point it begins to heat again and open, allowing coolant through the radiator to cool. The fact being that if the thermostat does not open, the engine will not stay cool, no matter the weather conditions. You acknowledge that yours opens at about 170. It would not maintain a temperature around 170 if it did not open. The temperature would only climb. I acknowledge that in colder weather, it could take longer to reach that 170 degree mark, but it most certainly will and must.
_40 at idel will take some time before opening happens,we all know that the therm will open at some point
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By ian57tbird - 9 Years Ago
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Just as a side note, I always test a thermostat in a pot for opening temp and fully open temp with thermometer before installing. Both figures should be available. Too many stories of faulty units out of the box to take a chance.
The pressurised system will mostly come into effect when water temp reaches unpressurised boiling temperature. I do believe it might help to supress boiling near hot spots within the engine.
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By charliemccraney - 9 Years Ago
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If the thermostat is rated at180 and is functioning properly, then the engine is a minimum of 180 degrees. The factory gauge sender location will indicate a temperature that is about 15 degrees lower than the actual temperature. The reason is because coolant has to travel over 3 more combustion chambers from the location of the sender. Where are you getting the 160-170 reading?
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By charliemccraney - 9 Years Ago
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The water pump is the worst place for a temperature sender. The coolant is just coming out of the radiator so at best, you will get a reading that is a few degrees higher than the cooled coolant coming out of the radiator. The coolant still has to pass by 8 cylinders and over 8 combustion chambers. From that perspective, it is no surprise that you are getting a lower than expected reading.
The best place to check the temperature is right behind the thermostat, on the intake. If the device you use to measure is known to be accurate and it is only 170 there and and does not get hotter, then your thermostat is defective or perhaps is was mispackaged, or maybe it is a 160 and poor eyes made it look like 180. The thermostat is opening.The engine simply will not stay cool if the thermostat does not open.
You should see the temperature increase as you measure along the flow of the coolant. The pump will be coolest, the middle of the block will be warmer, the stock sender location will be warmer, the thermostat will be hottest. Do you see that?
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By charliemccraney - 9 Years Ago
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2721955meteor (9/11/2016)
corection,withe the by pass working in the right situation(cold weather)the engine will not over heat stat closed
If the thermostat stays closed, the engine will not stay cool, no matter the weather. The bypass only recirculates coolant through the engine, bypassing the radiator. This means that the coolant can only absorb heat. If it cannot transfer that heat to the air via the radiator, it will overheat. The engine block and heads will not be able to transfer that heat effectively enough to stay cool without the radiator.
I haven't had any problem with American made Robert Shaw style thermostats. I did have a Mr Gasket (Chinese) fail prematurely. I never thought either took longer to warm up.
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By charliemccraney - 9 Years Ago
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I don't know what the pressure cap story is.
It is important to understand that the thermostat is not simply an on or off device. It opens gradually, starting around the thermostat rating, being fully open at some point after the temperature rating. So your observations are correct. When the system has cooled sufficiently. the thermostat will return close to a closed state, preventing the flow of coolant, at which point it begins to heat again and open, allowing coolant through the radiator to cool. The fact being that if the thermostat does not open, the engine will not stay cool, no matter the weather conditions.
You acknowledge that yours opens at about 170. It would not maintain a temperature around 170 if it did not open. The temperature would only climb. I acknowledge that in colder weather, it could take longer to reach that 170 degree mark, but it most certainly will and must.
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