I got a POLY in my '54 Dodge Royal. There is only about an inch and a half between the pulley and the radiator. For that reason, I'm running an electric fan, pushing air through the radiator. The thermostat is new (less than 50 miles)The temp gauge is as low as it can go, then shoots up past 250 degrees. This is before I take it out on the road. And that scares the crap out of me. Any ideas on where to start?
Well you scared everyone away when you mentioned POLY! Now if it was SBC you'd have 2 pages of replies and info. I think there's probably only half a dozen on here who talk the Poly talk and I'm one of them. Re your problem I've got a "late" model 318 Poly in my 32 coupe, standard engine running single 2 barrel 97 at present and with a 14" pusher fan and I can do a lot of driving before the fan cuts in at say a traffic light. One thought is the temperature sender-is it the correct one for the gauge as that could be an explanation. Have you had your radiator cleaned out-rodded? Also is the radiator in good shape? I was the same as you when I first got my car on the road and the temp was looking too high but the radiator hoses weren't hot. Best of luck.
That is way too hot. I ran a 318 poly for years in my Studebaker truck and the hottest it ever got was 200 in a traffic jam in the summer. Are you sure that there isn't air trapped in the block when you filled the coolant? Try drilling a small hole in the thermosat body to let the air bleed out of the block. Also it's possible that your new thermostat is bad right out of the box. Is the radiator clean on the inside or full of sediment and scale?
I have a new aluminum 3 core radiator. I doubt its the radiator. A guy at work mentioned my sensor may not match my gauge. Sensor is new, the gauge I bought at the swap meet. They are both electric.
What do you know about the condition of the block? The last 318" poly I pulled down, when I removed the core plugs, there was solid sediment behind them. Hardly any water was circulating in the block. jack vines
One of four things when you have an idle-low speed over heat. Thermostat sticking, air pocket, water pump has poor circulation do to the impeller slipping on the shaft or the spacing is wrong to the back of the housing or wrong pulley or the temp gauge is bad. Fritz
The action of your gauge suggests that you have an incompatible sender. I suggest you get a new gauge with a matched sender. Could be a cheap one from the local auto parts store that you can replace with a better one down the road. You need to know that your monitoring indicator is accurate. Otherwise how can you be sure you do or do not have a problem?
Today, I ran the engine for a good 10 minutes with the radiator cap off. The thermostat opened up, the water circulated. The water in the radiator was nowhere close to 100 degrees. What I know about the block is, the guy I got it from, bought it from an old lady. It was cool to see all the documentation. Even a dealers receipt for a light bulb. It was in a 1957 Plymouth Fury. It doesn't have 60k miles. The guy had no reason to B.S. me, and seemed like a straight up guy. He just happens to be a big block guy. He had 6 or 7 street rods, all with big blocks. I haven't really changed anything, other than the electric temp sender and removing the power steering pump. It has the pulley it came with. I've never heard of an air pocket in the engine. How would I get rid of an air pocket?, Other than drilling a hole in the thermostat (I'm not opposed to it). And if doing that is my best option, where do I drill the hole? How can I tell if I have the right gauge for my temperature sending unit.
Park it nose up on an angle should get rid of a pocket. as was said buy a gauge & sender that you can use to see if you get normal temp readings. Car is/was a 6 volt system......
If the thermostat opens and the water circulates from the block to the radiator and the coolant level is at or near normal then you have no air pockets (rarely happens anyways). I do suggest just hooking up another gauge even if it is a mechanical gauge from Harbor Freight. If you were near me I'd lend you one. Something that works that is a known-good reference so you know what is what. Knowing what is what is the first thing you need to do here. Same way the first step in investigating a suspected charging issue is to get and use a known good voltmeter (I have three!).
You have about a 90%b chance your gauge and sender do not match! Buy a new matched set! Best of luck Gary
This may sound like I am asking a dumb question but did you get a sending unit that it calls for to fit the car or the car the motor came out of? Sounds to me like maybe you installed a sender for a light instead of a gauge. If that isn't the problem, I would revisit the air in the cooling system problem. As the air (or steam) pocket passes the sender it can cause the gauge to jump up real fast and if you allow it to run, will drop down real fast also as water hits the sender. Not an uncomman problem at all in fresh filled systems. You might try taking the heater hoses loose at the firewall and hold them up as you fill the system, that will help air to escape.
Cooling is cooling for any water cooled internal combustion engine, GM, Ford, Dodge etc. First things first, check and make sure that your timing is spot on, too much lead or too much lag either one will lend itself to cooling problems. Lead is the worse of the too. Now make sure that the air has to travel though the radiator core, if the air can travel around the radiator core it will do that as it is usually the path of least resistance. No air through the core no cooling. Loose the electric gauge at least for diagnosis. If you can't find a good mechanical gauge you can snag a candy thermometer, calibrate it with a pot of boiling water if you want to be dead nutz, then fire the pig up. With the cap off the radiator you can check the temp of the water leaving your engine and see if you have just been fooling yourself. While you have the radiator open look and see if your pump is really moving water or just stirring it. Those old impellars rot away and too much clearance in the pump will render it almost usless. you probably won't find a hot rod pump for your poly but flow cooler makes a kit to make any pump move more water. A worth while investment. On an old engine I like to chemically flush then back flush, until I am getting clear water out of it. Go to your local auto supermarket and get a can of radiator flush and follow the instructions. If your block is totally plugged it won't work well for you but on most engines it will make a world of difference. I also don't use an off the rack T stat in any of my engines. Stant T stats are even crap these days. Mr Gasket, TRW, Moroso to name a few all make good fast acting T stats and they only run about 10 or 11 bucks. All that and it still gets hot? better start looking into mechanical problems, blown head gasket of cracked cylinder wall or head etc.
The non-contact infrared thermometers work well in cases like this. Check the temp of the coolant when you can see that the thermostat is open. Soot it at any place and you can tell the temp differences, from side to side front to back, etc.
Agree that your sender and gage seem incompatible. As for the real temp, the non-contact infrared guns are a great tool to see the temps as 30dodge suggested. Cheap at Harbor Freight, get one and then you can see what is really happening. Once the thermostat opens up, it will generally purge air out of the system, unless your enginie is higher than the radiator, which should not be the case on your car. As p'n'b suggested, cooling is basic process for any engine, nothing about a Poly that is special. If you want to do a heavier cleaning of the engine, get some oxalic acid (look for wood bleach as common name), mix about 16 oz with water and run it in the engine for 15-30 minutes, thermostat removed. Flush with clean water until it runs clear. Reinstall thermostat and fill with coolant/water mix, using the old style green ethylene glycol coolant, not the new universal stuff.
X2 on a candy thermometer held in the radiator tank as a check. Looking forward to your updates and slide a few pix in as well, for fun!
sounds like the so called sensor is actually a idiot light switch not a true thermoresistor , as you have lower than normal (open contact= no current ) then goes to 250 ( closed = full current) . put a ohm meter across it to see how it reads as its warming up as it should be a nice gradual scale not abrupt .
Like they said 1. Air pocket...park it in an uphill to get the air out...I put a small bleed valve on my engines at the highest point. 2. Electric Fan ~ 1-2 HP ...stock fan is close to 10 HP = more air...worked on my duster. 3. Fan Shroud, Make sure the air is actually going through 1 time and not re-circulating. 4. Crud...My poly blocks where full of it!...cause they're old.
the water pump impeller in my 1963 Plymouth 318 was made of plastic. all the impeller blades had broken off. this caused the engine to run hotter than normal. not sure what years mopar used plastic impellers in their water pumps.
Many aftermarket gauge companies use different ohm ranges for their electric senders. Most likely the sender not maching that gauge you bought. Get a cheap auto parts store gauge with mechanical tube and use that to check the engine.
First thing to do, get yourself a non-contact temp gun, as said above. I bet it will save you a lot of pointless wrenching.
Used a kitchen gauge I got at the 99 cent store. Ran the car about twenty minutes with the cap off. Put the gauge in the radiator before the thermostat opened up, and didn't go over 180 degrees the whole time I'm just glad it's not over heating. The next task is to put a multi meter to the sensor and hope it gradually changes instead of going from one extreme to the other. The sensor came in a universal kit I got. The sensor $28, the kit was $30. It made more sense to get the whole kit, it had everything.
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