How hot is 'hot'?

[Adambravo]

A couple of times this summer, my HOT light has lit up on '63 (in 80+deg stop/go weather). Most recently, I was headed in a parade to a car show and the light went on as we pulled into the parking lot, so I was a bit anxious as I was slowly guided towards my parking place. The good news is that, unlike the '68 Charger and MGB that were part of our group, I didn't spew coolant all over the pavement once I came to a stop, and the car ran fine without issue on the way home. Since I'm used to a gauge, what's the guidance on the warning light? I know ideally the answer is "Stop immediately" but that's not always viable, so I thought someone here might have some guidance. Thanks in advance...

[RivNut]

You might hook up a direct reading gauge to the same port as the electric sending unit is. Check the temperature to make sure you don't have a faulty sending unit. Or if it hasn't been done in 20+ years, you might have the radiator rodded out. One other thing to check on is if your car has a/c, does it have a shrould surrounding the fan? If not, big issue. Without a shroud, the fan can't pull air through both the a/c condenser and the radiator. That's why the a/c cars have 5 bladed thermal clutch fans, shrouds, and 5 impeller water pumps.

It sounds like as long as you can push air through the radiator (driving it) you're okay but the fan can't create the same air flow idling as can driving.

Ed

[Guest Steeleco]

Hello,

My 63 with AC is missing fan shrouds. Although I don't drive it alot I have been running around in it with the AC on and although I have not spewed out any water I am currious as to wheather I am running to hot. Since the car is new to me I don't know if the Hot light works or not. I am interested in getting fan shrouds for my 63 if anyone has them. Secondly, how do you know if the clutch fan is working properly. (I swear I used to know this back in the 70's).

Thanks

[RivNut]

Steele,

Cars Inc. has repo shrouds for about $140.

With the engine off, you should be able to turn the fan without turning the water pump. When the temperature of the radiator gets hot enough ,the clutch engages, and you'll hear the fan roar.

It's been a while, but I think the idiot light should come on when you're cranking the engine. Someone who drives theirs frequently can verify or refute this.

Ed

[Guest Kingoftheroad]

I know some folks run an electric fan on in front of their classics radiator.

[Don McClair]

Adam, putting a bottle of water wetter in your cooling system can help too. Most of the manufacturers say it works best when there is only one gallon of anti-freeze in the system but in Michigan if you don't have a warm garage that could be a problem. I have used this in a couple of cars and it has dropped the operating temperature by about 10 degrees.

[Jim Cannon]

A couple of times this summer, my HOT light has lit up on '63 (in 80+deg stop/go weather). Most recently, I was headed in a parade to a car show and the light went on as we pulled into the parking lot, so I was a bit anxious as I was slowly guided towards my parking place. The good news is that, unlike the '68 Charger and MGB that were part of our group, I didn't spew coolant all over the pavement once I came to a stop, and the car ran fine without issue on the way home. Since I'm used to a gauge, what's the guidance on the warning light? I know ideally the answer is "Stop immediately" but that's not always viable, so I thought someone here might have some guidance. Thanks in advance...

Adam-

See shop manual, section 10, page 10-63.

HOT light comes on at about 248 degrees F. In my book, that is very hot. I would sure shut it down as soon as possible when light comes on.

The HOT light should come on any time you are cranking the starter. This provides you with a test of the indicator bulb every time you start the car. Get in the habit of looking for it when you start. Otherwise a burned out bulb will not tell you that your engine is overheating.

Unless you know how old the fan clutch is, I would recommend you replace it. It is easy to do and does not cost that much. Get the higher-cost unit with the little coil spring on the front face. The lower-cost unit with the smooth face is not adequate. I use Imperial #215049. The last time I needed one, AutoZone had it in stock. I was surprised. YMMV.

As Ed said in an earlier post, when the engine is hot, the fan should ROAR when you run the RPM up. While driving down the road, I can actually hear my fan clutch engage by the added engine noise of the fan roaring.

If you do not have one already, I recommend you add a coolant overflow bottle to your Riv. It keeps the radiator full, keeps oxygen out of the coolant (slows rusting in engine) and keeps toxic antifreeze off the ground.

If you ever decide you need a new radiator, have your existing one recored with a "4-row core" and you will never overheat again. You will have to find an old time radiator shop in the older part of town to do it. It will be a custom job and it will not be cheap, but it is worth it.

HTH. Please add your ROA member number to your signature.

[RivNut]

I'm going to chime in once more here. Don't try to fix your cooling problems with a bunch of band-aids!

Get to the core of the problem and fix it. In their hay-day, these cars were every day transportation. As such they performed flawlessly. Get the car back to basics and it won't let you down.

Chances are you're not the original owner of the car. Who knows what kind of short cuts one of the previous owners may have taken to save a buck. Perhaps the water pump is for a non-a/c car. If so, 40% of the needed impellers are missing - 5 impellers on a a/c water pump; 3 on a non a/c water pump. If the water pump was rebuilt, was a new impeller installed or were the fins on the old impeller "smoothed" out to make it look good. If so, there's too large of a gap between the impellers and the body of the pump. Water is not being moved, the impeller is just cavatating and not moving any water. Are the fins on the condenser full of bugs and dirt - no air flow to the radiator. Are the fins on the condenser bent over - no air flow to the radiator. Are the fins on the radiator allowing air to flow through it? Is the radiator painted with typical rattle can black paint? If so, the paint will not allow heat to dissipate. There's a special radiator paint that should be used. Lots of stuff on a 50 year old car that need proper attention. If a previous owner had the motor rebuilt, did he overbore it too far? If so, the iron in the block is not thick enough to transfer heat out of the cylinder wall.

Proper fixes are more than just adding something to the proper water/antifreeze mix or installing a different kind of fan.

Ed

[1965rivgs]

Dont trust the "hot" light. Indicator lights such as this are called "idiot" lights for good reason. Best way to accurately determine temp is thru a gauge or point and shoot thermometer. If you overheated the motor there would surely have been evidence like boiling over.

Barring any glaring problems in the cooling system I would install a new thermostat and proceed from there.

Tom Mooney

[63 Rivi]

To answer your original question, I drove my 63 Riv yesterday on a 75 degree day and got stuck in a lot of traffic in NYC. After 1 hour, the temp gauge made it up to 235 and then shortly thereafter the idiot light went on. I have run it up to 240 without any issues although I admit that makes me pretty nervous. I spoke to Dennis Manner about this issue and he assured me that these engines where run on dynos back in the day at that temp for quite some time without any problems.

BTW, this is an Auto Meter temperature gauge and I installed it where the ash tray used to be. Nice and stealth, no one knows it's there. I tapped into the head on the left side of the engine for the installation of the sending unit. (There is a pipe plug there so it can be fairly easily removed) I still have the stock temperature sending unit in the right side of the engine so my idiot light still lights up when I crank the engine and works properly.

[Jim Cannon]

That sounds about right. You put your temp gauge on the left head, in the back. The coolant flows from the back toward the front, so the stock temp sender on the right side head is reading coolant temp after it passes through the head. Your temp gauge is reading it before it goes through the head. So I would say that your reading of 235 back there corresponds to the book's number of 248 at the front of the head.

Pretty darn hot in my book.

[Guest dcdpgh]

Adam-

If you do not have one already, I recommend you add a coolant overflow bottle to your Riv. It keeps the radiator full, keeps oxygen out of the coolant (slows rusting in engine) and keeps toxic antifreeze off the ground.

Let me ask about retrofitting coolant recovery tanks in cars not originally designed with them. I understand the enviromental benefit of captuering overflow coolant, and the functional benefit of having the ability to visually monitor coolant level in the overflow tank, rather than waiting until the car is cool to remove the radiator cap to check coolant level. But doesn't this change (raise) the operational pressure of the cooling system? Say you have a pressurized system with a 15 lb radiator cap. Without an overflow tank, your radiator starts out cold with the coolant level a few inches below the fill neck. After starting the car, the coolant warms and expands (and if the engine is operting correctly) expands in volume within the radiator, so the cooling system never exceeds the 15 lb rating of the radiator cap. It operates somewhere between 0 lbs and 14 lbs. Only in an "overheat" condition would the pressure exceed 15 lb rating of the cap, and allow coolant to be relieved. If we introduce a recovery tank, and fill the radiator to the neck when cold, the pressure builds almost immediately upon start up, as the coolant warms and expands. The 15 lb cap lifts almost immdiately to allow the cooant to expand into the recovery tank, where the coolant level rises. Essentially we are now operating the cooling system at a constant 15 lb state, rather than somewhere between 0 and 14 lbs. I realize you need to use a radiator cap designed for use with a coolant recovery tank to make this work, but the pressure discussion is still valid. What am I missing?

[Jim Cannon]

You are essentially correct in your concept, but you don't really raise the operational pressure of the system with a closed cap. That pressure is still set by the cap. But you are right, you will get to that pressure more quickly when the radiator upper tank is full of solid liquid with no air space at the top. You will be operating at the cap pressure much more of the time. But I would ask: So what? That does not change anything. The system is designed to operate at that pressure.

Even without an overflow bottle, I think you would find that the pressure gets up to the design pressure of the cap fairly quickly (but not as fast as with no air in the tank, in a closed system with overflow) because the volume of coolant that is expanding is much larger than the volume of air in the head space in the tank.

[Guest Steeleco]

After the engine is warmed up what is the expected temperature the engine should be running at and what is the temperature the coolant should read at idle after warm up. Additionally, what is themperature the exaust pipes generaly get to at idle.

Thanks much!

[Guest dcdpgh]

You are essentially correct in your concept, but you don't really raise the operational pressure of the system with a closed cap. That pressure is still set by the cap. But you are right, you will get to that pressure more quickly when the radiator upper tank is full of solid liquid with no air space at the top. You will be operating at the cap pressure much more of the time. But I would ask: So what? That does not change anything. The system is designed to operate at that pressure.

Even without an overflow bottle, I think you would find that the pressure gets up to the design pressure of the cap fairly quickly (but not as fast as with no air in the tank, in a closed system with overflow) because the volume of coolant that is expanding is much larger than the volume of air in the head space in the tank.

Thanks Jim for the insightful reply. I guess the part I am struggling with is the notion of what normal/design operating pressure is - is it really the 15 lb rating of the cap? By my thinking that is the maximum pressure. In researching my 1968 Buick Factory Service manual, I found this passage in the Coolng System and Water Pump section which describes the function of the radiator cap - "The pressure valve is held against it's seat by a spring of pre-determined strength which protects the radiator by relieving pressure if an extreme case of internal pressure should exceed that for which the cooling system is designed". What caught my eye was the word extreme (was not italisized in the manual BTW). That passsage made me second guess what normal operating pressure is considered, and is the 15 lb normal, or the extreme case when it's time to relieve?

To answer the so what? question, I think about putting undue pressure on 44 year old motor (head gaskets, etc.).

I did a litle experiment with my '68. A previous owner retrofitted a recovery tank on my car. I've been running it like this (full rad cold, extra coolant in the recovery tank) and noticed that once the car was up to operating temperature and upon returning home and idling in the driveway, the radiator hoses are rock hard (let's say that represents the 15 lb condition). Note that I have replaced the thermostat, radiator cap, hoses, and coolant during my ownership - so I believe the system is functioning properly. The next time I took the car out, the following weekend, I emptied the recovery tank and drained some coolant out of the radiator, down to the factory fill level leaving about two inches of air space above the coolant level in the rad. Again took the car for a drive, got it up to operating temperature, and returned home to the driveway to find the radiator hoses much less than rock hard, in fact I was able to squeeze them (although not for long as they were hot!). And there was no coolant in the recovery tank, all of the coolant expansion had occurred in the radiator. So in this operating condition I concluded the system was functioning at something less than 15 lbs, because I could squeeze the hoses and the cap had not lifted.

I got two different pressure conditions in the two scenarios, that's what got me wondering if operating at the 15 lb condition 99% of the time is such a good thing on a car that did not leave the factory with a coolant recovery system.

[Jim Cannon]

After the engine is warmed up what is the expected temperature the engine should be running at and what is the temperature the coolant should read at idle after warm up. Additionally, what is themperature the exaust pipes generaly get to at idle.

Thanks much!

If you are using the stock 180 degree thermostat, you should be reading close to that when the engine is warmed up.

I have no idea about exhaust pipe temperature. Find someone with one of those fancy infrared thermometer guns and they can tell you.

[Jim Cannon]

You have a good point Dan and are correct about the pressure being less if you have air in the upper tank. But in my opinion it is more valuable to the engine cooling system to keep the air out as much as possible by keeping the tank totally full and using an overflow bottle. This reduces rust formation. If you want, you can use a slightly lower pressure closed system cap if you want to get the closed system benefits but not run the pressure as high as 15 psi.

[NTX5467]

I would suspect that a coolant recovery system would be more needed with a crossflow radiator rather than a vertical flow radiator situation. Obviously, the crossflows have more capacity than they need, as the "cold" level is down a good bit from the filler neck, usually . . . at least on the older copper radiators used back then. Keeping the crossflows full would mean more heat-exchanging functionality.

The non-contact infrared thermometers come in 500 degree models and OVER 500 degree models. If you're going to check exhaust temperatures, especially at the cylinder head, you'll probably need the OVER 500 degree model. I used a lower temp version one time to check exhaust manifold temp and it would read the actual temp for a split second, then error off. The higher-temp versions are getting more affordable all of the time, moreso when they get put on sale at the tool vendors. They've got LOTS of uses in troubleshooting vehicular stuff . . . and even checking your own bodily temp, too.

I understand the issue of the "expansion cushion" in the radiator tank vs. with a coolant recovery system. I concur that a full radiator is better than a partially-full radiator, although there might be enough reserve capacity built into the existing radiator to work pretty well. But, 15 psi is still 15psi whether it's controlling hot radiator "air space" or hot liquid coolant . . . to me.

Perhaps, the reason the Riv didn't puke coolant, as the Charger did, was because of the air space cushion in the radiator? If it'd been fuller, it might well have done similar? When my uncle bought a new car in 1963, he was concerned about some leaks and stuff. The dealer's service manager said they'd probably happen until "a level" for each component was reached, after when the leaks/pukes would stop and the levels would stabilize over time . . . in other words, to not really worry about it on a new car . . . unless they continued.

One time, on our '69 Chevy pickup (crossflow radiator), when it was newer, I had put an aftermarket coolant recovery system on it. It always seemed to empty the reserve tank, or had air in the lines, or whatever. I had the radiator cap off one afternoon, trying to get all of the air out of the system. I discovered that with elevated rpm, the coolant level would drop, although it was "full" at hot idle. So I put the carb on fast idle and topped it off, then replaced the raditator cap. Ah Haa!! I'd gotten it full! So I filled the line going to the recovery tank and adjusted the level in the tank. Several days later, it was back like it used to be. Seemed to be a loosing battle!

Seems like "modern stuff" temp gauges have the red starting at 260 degrees? If the system has 15psi of pressure, the resultant boiling point might be a little past that level?

Along about 1996, I rented a Grand Marquis for a trip to Houston. In reading the owner's manual for the RADIOS and the one for the CAR, seems that when the engine's temp gets to a certain point, a message comes over the radio . . . "MOVE TO A SAFE PLACE AND PARK THE CAR! SHUTDOWN IN 2 MINUTES!" After that warning, you'd better get the car parked pronto! The powertrain controller would stop the engine to protect it, so it claimed. But it seemed that after the engine cools down, then it'll be fine to operate again. Seemed pretty fancy to me! But it was an all-aluminum 4.6L V-8 . . . all 200 horsepower of it. No mention of "raising the hood" or if the coolant fan would run during cooldown? It was HOT that day, outside temp was over 100 degrees and the poor a/c was stuck on "HIGH" all the way down there. I-45 was a "parking lot at 85mph", it seemed.

Just some thoughts,

NTX5467

[RivNut]

If your engine is trapping air in a pocket and you can't get it to burp the air bubble, you could try this. (I did it on a '97 Sebring convertible and it worked fine. Problem w/ the Sebring was that the radiator cap was lower than the thermostat.) Remove your thermostat and drill a teeny tiny hole in it; this will allow air to pass through a closed thermostat. Then park with the nose of the car going uphill and loosen the radiator cap. Over night the air will escape through the hole in the thermostat and pass on through the upper radiator hose, and out the loosened radiator cap. The hole you drill in the thermostat will not be larger enough to let water pass through at a rate that wouldn't allow your engine to reach operating temperatures and stay that way.

Ed

Edited September 22, 2012 by RivNut (see edit history)

[Guest dcdpgh]

Thanks for all the insightful responses on the full radiator w/recovery tank vs. air space in the radiator w/o recovery tank discussion. Lots of good info to ponder.