The Stovebolt Site Forums The Shop Area Engine Shop Unusual problem. Engine temp remains 160.

So my engine never reaches 180* unless it’s at idle on a VERY WARM DAY. Driving around it usually stays around 150*-160*.

I have a 5000 mile rebuilt 1964 230ci in my 1965 C10. I replaced the radiator with an aluminum version. These trucks came with 2 different versions of radiators. The tall narrow style (usually with an L6), and the short wide version (usually paired with a V8). Mine is a short wide aluminum. I have a 180* thermostat and an electric fan. I have an aftermarket electric temp sender to a Sunpro temp gauge. The electric fan NEVER comes on because I have the switch set at 200*.
I have a short piece of pipe and heater hose that I use to route the water neck coolant back to the water pump because I have deleted the heater. This hose/pipe exits the water neck BEFORE the thermostat. It certainly doesn’t dissipate much heat with that short piece of hose.
I’m of the opinion that my engine will run much better at 180*-190*.
Suggestions?

You did everything under the sun to keep it cool,
And now you want it hot,
It's runnin good, it's a happy motor,
We'all want what you got,
Don't worry, be happy.........
Don't worry, be happy

If you don't have a heater for some reason, you don't need those ports operational at all. Plug 'em off!
Jerry

Try a different temperature reading device.
Maybe the gauge is not reading correctly, i.e. defective or calibrated incorrectly.

bartamos,
The issue as I see it, is that very little coolant,if any at all is going to the radiator to be cooled. The thermostat is 180*. I personally tested an verified that it opens at 175ish and is fully open at 185*. It wasn’t open at 160*.
One possibility is that my sending unit isn’t reading correctly (reads lower than actual).
One possible solution would be to install a different thermostat (190* maybe).

HRL,
The loop of heater hose connecting the water neck and water pump is actually shorter than it was before I changed radiators. That can’t be the problem. The reason they are not plugged is because the water neck has a fitting for a hose with hose clamp. It seemed risky to remove it and plug it. Routing the coolant to the water pump was as easy as pie. Doesn’t look too weird either.

Use a short piece of hose from that nipple and plug it, then. You don't need to be bypassing that much coolant back to the water pump inlet. It's interfering with the operation of the thermostat.
Jerry

And the water pump port? Plug it too I guess. It’d just be simpler to put a plug the circuit to block coolant from traveling around the loop.

150-160? My GUESS would be you are not getting an accurate read. I would think it is really about the 185 of the thermostat. Can you look into the radiator once warmed up and see the water circulating? Might have to goose it. Is the electric fan the only fan?
Dennis

I have one of those infra-red temp guns and IIRC, the temp at the water neck (external above T-stat is 185*. The temp sending unit is located below the T-stat, so I might be getting an incorrect reading. That is my #1 suspicion.
I will open the radiator cap and use a good old fashioned thermometer on the fluid circulating. The radiator does get hot enough to burn you, but aluminum conducts heat very fast.

The190 deg thermostat should fix it. You do want the motor to be at operating temp for a lot of reasons. Those Harbor Freight infrared laser thermometers are a nice thing to have. $20 with coupon. From checking for a fever to the refrigerator temp to truck stuff.

If you want a little bit of bypass flow to prevent hot spots during warm up, put a restrictor in the hose with a 1/8" or 3/16" hole in it. If you've got a thermostat with a jiggle pin or a bleed hole in it, you don't even need that- - - -just choke off the flow altogether. To test to see if it makes a difference, put a C clamp or vise grips on the hose temporarily.
Jerry

Jiggle pin. So that’s what it’s called. Hmmm.
Well, my T-stat didn’t have that Jiggle pin, so I drilled a teeny tiny hole, maybe 1/16” in the T-stat instead.
I’ll pinch off the hose, use a thermometer, and run a few other tests and report back.

Bartamos, I have one of those HF temp guns. Works great. I had one of flat ones but got tired of the fact you couldn’t see the screen well while in use. Sold it and bought the much more convenient gun shaped version. Worth the few extra dollars IMO.

Seems like OE for 1964 230 is a 195 with alternates 160 and 180. With different altitudes, coolant mix and your improved system, you need to dial it in to be in the 180-195 range on gauge, for best performance and wear. May have to change radiator caps. Be sure the sender is in the optimum location near thermostat. Gauge and sender can be tested together on the stove using a chart to tell you what temp water boils at your altitude. The test on the truck, touching sender wire to ground, etc., only tells if its "operating" but not if it's accurate. Most gauges/senders are NOT very accurate. But once you do the stove test, you know how to read the inaccuracy.( I.E. What does gauge read when water starts to boil?). Interpolate from there. Forget ohm testing. You will go nutz.

It is possible:
If you just leave the heater set up alone, you will be fine. The system will be the system. Heater hoses all attached, plugs, partial, whatever.....it all becomes the system and operating temp is arrived. Don't start tweaking too many things at once. Pause at each tweak to test results...or you will be in a tweakin mess. Cwazy wabbits, can't get any west and wewaxation.

I have an aluminum radiator and my situation is the same. I have a thermometer on the radiator cap and an aftermarket sensor. I thought of forcing for a higher temp but most of my driving is highway driving between May and October and I don't need heat that much I am going to leave it alone.

bartamos,
I agree that I must find an accurate thermometer. I’ll test the infra-Red gun simultaneously with a regular thermometer. If the two match, then that’s gonna be pretty accurate verification that either one can be used as a standard. I’ll say this, I used the temp gun to read the water temp when I tested my thermostat in a can of hot water. The temp gun was reading 175* when my 180* T-stat started to open. That by itself seems to correlate pretty well but should be checked by another method.

The big downer for me is that I bought a really nice radiator electric fan control system, and my coolant doesn’t ever get hot enough to put it to good use. Fan never comes on cause it doesn’t need to.

So you don't have the motor driven fan? Just the electric? If your radiator works sufficiently you may never need the electric. Who knows. Time will tell.
Not to be disrespectful but how hot did you expect the 230 to get? Now the electric fan is just blocking your radiator
You better wait til summer before making any rash changes.

Here’s the story. Sit back with popcorn.
Bought a 1966 C10 parts truck and kept the good running 250 and the “better than what I had” radiator (short and wide). Replaced the 250 because it had low oil pressure. (I’ve since learned my lesson and know the proper ways to test an L6). Kept the radiator.

***Intermission**** and bathroom break.

Ran the truck into a guard rail. Radiator leaks. Looked for a replacement and decided to continue using a short wide version since my lower saddles, upper hold down clamp, and virtually new hoses would make it a drop in installation.

I live in SC and summer days can frequently reach 100*. Having an electric fan seemed like a safer upgrade than the mechanical version. Cools when needed and is off when not needed. Makes sense.

I think my entire problem will go away by switching to a 190* T-stat. We shall see.

Most OEM electric fans are set to come on at 220 degrees, and turn off again at 200. As long as the coolant isn't boiling and the radiator and heater core can stand 15-17 PSI, the coolant can actually get up to 250+ degrees without doing any damage to the engine. That's how 21st. Century auto makers get away with using tiny radiators- - - -make the engine a pressure cooker!
Jerry

Here's something to ponder about your looped heater bypass hose. Does the factory heater core for your model have the significant restriction in one of the core nipples in the form of extreme crimping of its end like what came in late '50s trucks?
This would give significant credence to HRL's recommendation
of adding a restriction in your loop.
Carl

just pinch off the loop and see what transpires. The short loop dissipates a lot of heat when it is bypassing the thermostat that way. We had generators up in alaska that never reached temp till they were under full load, so one day I started looking around and when they installed the block heaters, they had bypassed the thermostat with 1/2" hose. Bought the correct fittings and routed the coolant correctly and it worked perfectly.

FYI, those infrared thermometers read widely varying temperatures, depending on the surface you're pointing it at. For instance, if pointing it at a copper pipe carrying heated water (such as in a boiler system) that is shiny in one area and tarnished in another, the temperature reading can be 20F or more different. A flat black surface is the most accurate, so if you need a better handle on temperature, get a spray can of flat black and put a spot on what you want to measure.

Here are some pics of the engine and heater bypass circuit. At first glance, the circuit will seem that I could shorten it by half . . .
. . . so . . . just call me lazy, and get over it. LOL!
LINK HERE

While I can't disagree with your personal experience, I will point out that if I ran the hoses to the factory heater on the firewall (I've since deleted it), the circuit would have more than 5 feet of exposed heater hose. So I must politely disagree that the circuit is the problem. The circuit is BEFORE the thermostat, so I'm circulating coolant back to the water pump before it gets past the thermostat. Yet my temp sender (immediately after the T-stat) is reading 155*. At 155*, I don't think my T-stat has opened enough to allow more than a trickle of flow.

I'm still thinking it's an incorrect reading from my sending unit. I might find time to test it today.

I come from a family of seven kids, dad bought a used '66 289 Mustang for the oldest to drive. Each of us learned to drive in the Mustang, by the time it was my turn, #6 in line, the engine was so worn it wouldn't make heat. Dad cut off two of the four fan blades and blocked 90% of the radiator just to get enough heat to defrost the windshield. It was nothing to grab the fan blade and turn the engine over! I don't know the condition of your engine, but I do know a worn engine won't make heat!

My 250 makes all kinds of heat, I am betting the T-stat is partially stuck open.

Joe

I couldn’t find a second thermometer, or I was too lazy to go look for one. You decide.
At idle, the temp does get to 190* and high enough to eventually trip the fan switch which I have set at about 190*. When driving, the temp stays at 160*. I suspect the aluminum radiator cools so well that once the T-stat opens and coolant starts to flow, even a little flow keeps the temp down at 160*. The engine has maybe 4500 miles on the rebuild, so it’s not worn out or running poorly. Here’s a short video of today’s tests. LINK HERE

Lugnutz, lets forget about the heater bypass for a while. Lets talk about gauge and sender accuracy. You don't need a thermometer of any kind to test. You put the sender in water on the stove, don't let it touch the bottom of pan. Hook up the gauge to it. When the water boils, as in: bubbles-a-crazy starts, see what the gauge reads. Check online charts that tell what temp water boils at your altitude. Water boils at 212 deg only at or near sea level. Then you can see how to figure what a reading of 160 or any reading on your gauge, actually is, because you know how many degrees the gauge/sender are off.

I don't know if you have an electrical or mechanical sender.

I agree, the heater bypass is NOT throwing off enough heat to cool the engine down over 25*. While I appreciate your suggestion, I really don’t feel like removing the electric temp gauge sender. It’s nicely sealed and doesn’t leak. I feel that the IR gun confirmed the same temp reading as the temp gauge. That is enough to convince me that it is reading properly. The radiator system pressurizes properly. When I loosened the cap on the hot radiator, there clearly was pressure.
I will get a real thermometer and test the coolant temp through the radiator cap hole to give another confirmation.
Your way is more scientific than mine because it’s a direct measurement rather than using the IR gun as a standard reference, but the two did match.

Your new aluminum radiator is more efficient at cooling your engine than a stock radiator. You need a thermostat which does not go wide open at 160 degrees.
The temperature which a specific thermostat becomes wide open may vary from what temperature is stamped on it or what is written on the box it came in.

I think you have the right path to figure it out.