Another "Running Hot / Overheating" thread...

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Anonymous

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I've been trying to chase down a problem with my car running waaay hot... almost overheating on the interstate. Current setup is a Duraspark II, Holley 1940 (of questionable condition), Timing set at 6*, 160* T-stat, new water pump, hoses and coolant.

Around town it runs fine, temp remains just a hair below the midpoint on the gauge. I feel confident the gauge is okay as it has been replaced at some point by a PO (I base this on the fact that the gauge face is nice and shiny black and the needle is bright red/orange... all of the other gauges are faded).

On the highway (65-70 mph) the temp climbs up to the top of the gauge, just before the H... then I chicken out and get off the highway. At 45-55 mph, the temp comes back down almost immediately... pointing directly at the "p" of the word "temp."

With the DSII, I have now ruled out too much timing advance as the culprit... this leaves the following suspects:

1) Carb too lean
2) Lower radiator hose sucking closed.

Are there any other culprits I need to look into?

I will say that the previous lower hose had the spring in it and this new one does not... did I just answer my own question here? Can a spring be bought or are they integral to the hose?

Thanks in advance for your advice.
 
Most newer hoses are non-collapsing.

First up, you definitely need a secondary reading on the temperature. Either by stopping immediately and using an infra-red thermometer or by hooking up a mechanical gauge.

If you really are running hot, I'd suggest a clogged radiator and crusted up block. Acid through the block and a radiator rodding, should help you there.

Regards, Adam.
 
I would change out the hose immediately as this is a common problem with overheating.

Try to eliminate other types of problems by removing the heater hoses and either use plugs or loop one of them to the other side. This will take any problem with contamination from the heater tank out of the system.

Make sure all clamps are tightened securely and up clos to the nipple portion of the inlets/outlets. This is another problem as pressure can be lost and is a major overheating issue with various Ford engines.

flush your systen and observe the water exiting.

Check for lean conditions. Put all settings back to factory specs and see what happens.

Try another themostat with lower temperature than 180 degrees and observe the results. You can even take the thermostat out of the system which many have done in hot weather areas like here in Phoenix.
 
The radiator was flushed/rodded about 3 years ago by the PO. Am I hoping in vain that the radiator is probably ok?!?

Also, while looking around the engine bay last nite for leaks (found none), I did notice something... the a/c condenser. A PO had the car painted by one of Earl Scheib's apprentices who didn't remove/mask off the condenser when he painted. Hence, the condenser got painted. The condenser is also warped (bowed inwards toward the radiator to where they are actually touching). Would a clogged condenser, blocking the airflow to the radiator contribute to my "highway only" overheating problem?

I need to get this cooling issue sorted out before I put a/c back on this car.
 
just a thought , could the water be moving through the engine and radiator too fast on the freeway with the new water pump, maybe the new one is more efficient than the old.

otherwise i would stick with addo's suggestion that the cores are blocked and not cooling properly.

i wouldn't think that having the condensor infront would make much of a difference as you would notice this in heavy traffic situations. the air is being drawn through the rad more than freeway driving when the air is getting forced through the radiator.

these are only suggestions, if anyone can correct or rule these out might help.

p.s check the thermostat is opening all the way.
 
could the water be moving through the engine and radiator too fast on the freeway with the new water pump,
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That is an old tale. Higher coolant velocity leads to higher rate of heat transfer.

With the DSII, I have now ruled out too much timing advance as the culprit...
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Does the vacuum advance mechanism function properly? Are you getting enough advance at highway speeds? How have you confirmed this? Retarded timing has a huge effect on an engine running hot.

On the highway (65-70 mph) the temp climbs up to the top of the gauge, just before the H...quote]
This typically is a sympton of a radiator in poor condition and or blocked air flow. I had my old Pontiac out on a trip last week, and the temp climbed to 230deg when my speed was 75 to 80 mph. At 70 mph, it ran cooler at 220deg. It has run hot since I got it, but I know the radiator needs to be replaced.

And as has been mentioned, you can't make any assumptions of absolute engine temperature with the stock gauge even with new components. All they can really tell you is a trend such as your highway temp is hotter than around town temp. So unless you confirm temp with another calibrated gauge or other sign of overheating such as boiling over, you may not have an overheating problem. When I rebuilt my Mustang, I had bought a new temperature sending unit. The guage seemed to read much higher than I remember before my rebuild. So I took a temp sender off of another Ford six I had and the temp read back in the normal range. The point is, that new components do not necessarily mean the guage is going to read correctly. The new sending units are notorious for not having the same electrical response as the original units.
Doug
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On the highway (65-70 mph) the temp climbs up to the top of the gauge, just before the H...
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This typically is a symptom of a radiator in poor condition and or blocked air flow.
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I agree- if the bottom hose is in good shape a partially plugged radiator is the most likely problem. One thing you can do to test this is drive the car on the freeway until it's getting too hot, pull off a ramp, get out and feel the front (non-fan side) of the radiator with your hand- it should all be uniformly warm/hot if you feel hot and cool spots that will confirm it.
 
:D Get a good candy thermometer.Put it in the radiator.Start engine,and see where the thermostat opens.Got my candy/baking thermometer at wally world about 6 years ago for $9.95+ tax.Works great.
Leo
 
Well, I went to AdvancePePKragenZone today to get a mechanical water temp gauge (dreading the time it would take to install it... etc). When what did my wondering eyes spy but one of these:

http://www.thermocap.us/

I put it on and verified the following...

... my stock water temp gauge is fracked.

I took the car on a 25 min. highway ride at a steady 75. Stock gauge didn't get as hot as the other day, but it was within a hair's breadth of where it was then. Pulled over, got out, checked the thermocap, it was "dead on balls" at 190*. Drove it another 25 miles at 75 mph (and then some... fastest I've ever driven it). When I stopped, same result, 190*. I let the car idle and it came down to about 175* within 3-4 minutes. I'm going to try it again tomorrow in the heat of the day, but I don't expect the water temp to exceed 200*.

So, the moral of this story is that trusting a 40+ year old gauge and/or sending unit is foolhardy at best...

... and that you guys here at FSP know what the heck yer talking about.
 
my mustang has been in family family since it was new and it has lived in south florida its whole life and when i got it i noticed the same thing you do that the temp gauge gets very hot on the freeway i never bought a mechanical gauge but i got a 3 row rad from advance instead of the old 2 row original and now i can cruise on the highway dead of summer at 65 and it goes to about or a little under the half mark. However as for your mechanical gauge where did you take the head temp because the sensor for the dash gauge is on the back of the head which means its the last place to get coolant meaning the coolant will be hotter when it flows there giving you a higher temp reading.
 
I have not seen one of those thermo-caps. I may have to get one for the old Pontiac to see what the temp going into the radiator.

the sensor for the dash gauge is on the back of the head which means its the last place to get coolant meaning the coolant will be hotter when it flows there giving you a higher temp reading.
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After flowing up to the heads, the coolant has to return to the front of the engine to enter the radiator. The radiator is a downflow model so the hot coolant enters the radiator at the top. So I don't know that the rear of the block is necessarily the location of the hottest coolant. It could be hotter at the rear due to localized hot spots. But taking a reading at the top of the radiator should be pretty representative.
Doug
 
I bought my Dad one of these. He reckons the laser spot makes it easy to work out what you're actually measuring.



Summit sell a near-identical item.

Possibly a good tool for checking evenness of temperature in a radiator core, or finding hot spots in a motor.

Regards, Adam.
 
I had a similar issue- overheating on the freeway with a new hoses- I was able to buy about 5 springs at the hardware store- with a diameter just under the inner hose, and each 2" long- and popped 4 of them in the lower hose to exclude a collapsing hose as the cause. It made no difference but at least I knew the lower hose was not collapsing.
 
I wouldn't count on there being no overheating going on just because the water at the top of the radiator wasn't too hot. The stock sender is at the rear of the head and could have much hotter coolant than what you get at the radiator cap.

I had overheating at 60 mph and replaced the radiator after a bad motor mount took it out. Now my temp gauge never makes it over 1/4 of the way up. I am going to have to replace the thermostat that must be stuck partially open. The new radiator is thicker, but the old original must have been plugged up.
 
In the last ten years there have been innumerable posts on overheating. A couple of things that seem to run true:

1. Lower hoses "rarely" collapse from suction. Seems plausible, but almost never occurs. Any hose soft enough to close shut would be the consistency of warm chewing gum and would probably be swelling under pressure as well.

2. Ford gauges are notoriously inaccurate. The only conclusion you can reach on operating temp is "yes, I have some temperature".

3. An electric fan will not cure a poorly operating cooling system.

4. The most common causes for overheating are clogged, dirty radiators, clogged rusty water passages, stuck thermostats, blown head gaskets, and loose belts.

5. The stock cooling system has more than enough capacity for a stock engine. Most cars (unless you live in a 100F+ climate) do just fine on the stock 2 row radiator. 3-rows are not really needed and 4-rows may actually perform worse.

6. Adding a coolant recovery tank is a good thing to do.

7. Watter Wetter and other coolant additives are a crutch that may help a marginal system return to normal. A cooling system that is clean does not need it.

There may be more, but the point is, the original system works well if its clean. It is dead nuts simple and these cars were not prone to overheating when new. There's just nothing complex about how it works or what makes it malfunction. You may have had the radiator cleaned a few months ago, but if the engine has rusty crap in it, you'll have to do it again. Take care of the rusty crap, and the problem goes away.
 
You may have had the radiator cleaned a few months ago, but if the engine has rusty crap in it, you'll have to do it again. Take care of the rusty crap, and the problem goes away.
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This last from a man who cleared his block water passages of rust and casting sand with solvent and a good wire coat hanger in only a few short hours.
 
ludwig":3fkvdsnw said:
You may have had the radiator cleaned a few months ago, but if the engine has rusty crap in it, you'll have to do it again. Take care of the rusty crap, and the problem goes away.
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This last from a man who cleared his block water passages of rust and casting sand with solvent and a good wire coat hanger in only a few short hours.
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LOL, so? I did the same thing, steam cleaned inside the block and head and did a round of muriatic acid. You wouldn't BELIEVE how much junk is in there.
 
My bet is that it is a clogged/restricted flow radiator. I had a similar problem with my '68 Catalina; ran hot on the Interstate and cool around town. Pulled the rad and had it flow tested, it was 40% clogged. Put a new one in and the temp gauge went back down to its normal level.

Antifreeze actually has anti-corrosive compounds in it. They typically last two years. So that is why the cooling system needs a flush and fill every two years. Its not the "anti-freeze" part of the solution, it the corrosion inhibiters that go away.

Another reason why I think its your radiator is that the current t-stat is a 165, yet you are measuring the water temp at 190 :shock: The t-stat will crack open at 165 but somehow the water is picking up an additional 25 degrees of heat? Again, the radiator is not cooling the fluid enough; its new radiator time. If you do buy a new radiator repeat your hi-way temp test and tell us what the thermo-cap reads. I'm very interested in what you find.

tanx,
Mugsy 8)
 
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