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Old 09-24-2008, 10:58 PM
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Overheating 454 Chevy

The 454 I have originally came from a 1978 truck and was rated for 250HP. The only changes to the original engine have been an Edelbrock maniforld and carb and HEI ignition. The engine was placed in the current car, a 1939 Plymouth about 15 years ago and few miles have been placed on the vehicle. No idea how many miles on the engine and it doesn't appear to have ever been rebuilt. Runs strong, no smoke.

It overheated when I purchased it a year ago and it showed signs of neglect:: the coolant was way past due for a change, the coil spring in the lower radiator hose was almost rusted away; the C.A.R radiator (seems to be sized appropriately) leaked. the 10 lb radiator.cap leaked, the overflow container and hose leaked, the mechanical fan was mounted completely inside the shroud (so it easily overheated at 65 mph), and the water pump looked to be the original.

Here's what I've done:

1. Radiator repaired and tested.
2. FlowKooler pump installed.
3. New hoses.
4. New sleeve-style thermostat.
5. Nasty engine flushed many, many times until it consistently ran clear.
6. 50/50 antifreeze and water and Water Wetter.
7. New VDO temp sender.
8. Radiator core mount rebuilt to place the fan 1/3 out, 2/3 in in relation to the shroud.
9. New 10lb cap.

In the course of driving 6 - 8 miles with a few stoplights, the water gauge rises to 200 (I've noted that the thermostat opens around 190 like it should). At the very next stop, the gauge will rise to 225. Within a few minutes, the gauge quickly rises to 250 and I stop the engine. A boiling sound is heard from the engine as the overflow tank itself overflows with bubbling. The amount of bubbling air has decreased with several repeats of this cycle and my not allowing the overflow tank to become empty as it gets sucked back into the radiator, hoping to purge the system of air. It will also go through this cycle just sitting at idle; just takes a little longer.

But I've been through this cycle ten times already and it has gotten a little better, but it hasn't stopped.

I 've never had this kind of experience before. I've heard that big blocks run hot (and have ignored the advice to use a restrictor instead of a thermostat; GM uses thermostats in thousand of these engines that don't overheat like this - remember, it's essentially stock).

The only thing that I have not yet changed is the exhaust. From the stock manifold, the pipe is reduced the 2 1/4 inches to th3 muffler, then 2" to the tailpipe (I know better, but I didn't build it). I haven't changed it yet because I have some Sanderson cast iron headers on order ( the factory has to cast them of all things; it seems so long that they must be mining the ore) that I will have ceramic coated, and follow them with 2 1/2 the rest of the way.

If it matters, power flows through a 700R4 with the clutch lockup wired correctly. There is a trans cooler (radiator and external B&M) and a Vintage A/C (hasn't been turned on since I've had the car; heater works too well).

So I'm open for suggestions, having exhausted my limited knowledge of what to do and look for about this aggravating overheating problem. I'm out of things to do. What's next?

Hoyt

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Old 09-24-2008, 11:16 PM
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Is the vacuum advance connected and functional? is the mechanical advance working? what is the timing set at? Is the fuel mixture too lean? Are you certain the thermostat isn`t sticking open? does the car have a air dam?
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Old 09-24-2008, 11:55 PM
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What type fan and blades? (Is it viscuos coupling drive?) I saw no mention of the fan type, that's why I'm asking. Also, is grille area of this vehicle of a sufficient size to allow airflow across the entire area of the radiator, or perhaps could it be somewhat restrictive of outer {perimeter} areas of the radiator, thus reducing it's effective size? The '37 Plymouth has somewhat of a "pointed nose", does it not? Just some additional food for thought.-Jim
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Old 09-25-2008, 02:02 AM
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A few things I would look at #1 is the water pump running the right direction
#2 is the thermostat housing above the radiator fill neck or close #3 when you hold the motor above idle will a 8x11 piece of paper stick to to front of the radiator (cks draw) #4 are intake gasket holes in correct spots #5 Did you ever flush block with lower block drains open?

Last edited by AJ Motorsports; 09-25-2008 at 02:07 AM.
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Old 09-25-2008, 01:00 PM
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You have air coming into the engine compartment, do you have air going out? Are the louvered wheel skirts in place on your '39 Plymouth? If you open the hood to the first notch, is the cooling better or worse?

Why only a 10# cap?... and not a 16#'r!

What kind of fan and how many blades?

I think, he has enough questions to answer now and he can get a few good ideas from the questions that were asked.

Here's some reading for you: http://www.crankshaftcoalition.com/w...cooling_system
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Old 09-25-2008, 04:53 PM
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Quote:
Originally Posted by hduff
The 454 I have originally came from a 1978 truck and was rated for 250HP. The only changes to the original engine have been an Edelbrock maniforld and carb and HEI ignition. The engine was placed in the current car, a 1939 Plymouth about 15 years ago and few miles have been placed on the vehicle. No idea how many miles on the engine and it doesn't appear to have ever been rebuilt. Runs strong, no smoke.

It overheated when I purchased it a year ago and it showed signs of neglect:: the coolant was way past due for a change, the coil spring in the lower radiator hose was almost rusted away; the C.A.R radiator (seems to be sized appropriately) leaked. the 10 lb radiator.cap leaked, the overflow container and hose leaked, the mechanical fan was mounted completely inside the shroud (so it easily overheated at 65 mph), and the water pump looked to be the original.

Here's what I've done:

1. Radiator repaired and tested.
2. FlowKooler pump installed.
3. New hoses.
4. New sleeve-style thermostat.
5. Nasty engine flushed many, many times until it consistently ran clear.
6. 50/50 antifreeze and water and Water Wetter.
7. New VDO temp sender.
8. Radiator core mount rebuilt to place the fan 1/3 out, 2/3 in in relation to the shroud.
9. New 10lb cap.

In the course of driving 6 - 8 miles with a few stoplights, the water gauge rises to 200 (I've noted that the thermostat opens around 190 like it should). At the very next stop, the gauge will rise to 225. Within a few minutes, the gauge quickly rises to 250 and I stop the engine. A boiling sound is heard from the engine as the overflow tank itself overflows with bubbling. The amount of bubbling air has decreased with several repeats of this cycle and my not allowing the overflow tank to become empty as it gets sucked back into the radiator, hoping to purge the system of air. It will also go through this cycle just sitting at idle; just takes a little longer.

But I've been through this cycle ten times already and it has gotten a little better, but it hasn't stopped.

I 've never had this kind of experience before. I've heard that big blocks run hot (and have ignored the advice to use a restrictor instead of a thermostat; GM uses thermostats in thousand of these engines that don't overheat like this - remember, it's essentially stock).

The only thing that I have not yet changed is the exhaust. From the stock manifold, the pipe is reduced the 2 1/4 inches to th3 muffler, then 2" to the tailpipe (I know better, but I didn't build it). I haven't changed it yet because I have some Sanderson cast iron headers on order ( the factory has to cast them of all things; it seems so long that they must be mining the ore) that I will have ceramic coated, and follow them with 2 1/2 the rest of the way.

If it matters, power flows through a 700R4 with the clutch lockup wired correctly. There is a trans cooler (radiator and external B&M) and a Vintage A/C (hasn't been turned on since I've had the car; heater works too well).

So I'm open for suggestions, having exhausted my limited knowledge of what to do and look for about this aggravating overheating problem. I'm out of things to do. What's next?

Hoyt
This sure has gotten to be a common sounding problem this year with these pre 1940 style hot rods. One is getting wonder if this is an effect of nuclear testing or global warming or what?

Clearly this is a situation of insufficient heat transfer, we'll start by assuming that the cam and ignition systems are timed properly in relation to the crankshaft's movements and that the carb isn't running lean nor if this has an automatic that there isn't excessive heat from internal slippage in the bands and clutches or from a loose (high stall) converter.

Those abnormal heat producing sources set aside and assuming the thermostat functions, you're left with;

1) Too little radiator capacity. This can be from too small for the job to plugged core tubes. Back flushing and chemical cleaning of the radiator core is inadequate to clean really grungy tubes and does nothing to open plugged tubes. The only solution here is rodding the radiator, which is removing the tanks from the core and passing the correct size rod thru the tubes to scrape off the gunk and force obstructions out of the tubes. Often radiators that need this treatment simply don't survive the process and their core has to be replaced.

2) Radiator size, these old cars just don't have space for large radiators, they didn't need it with a flat head 6, plus people of the era simply accepted the fact that cars overheated. They carried extra water, long hilly stretches of road included pull-off areas to allow engines a place and time to cool. Something today that is a lost memory except in us geezers. If the radiator is good and is as large as space permits, you often have to turn to tricks in these old cars. You can apply external coolers for transmission fluid and engine oil. These can take 20-40 degrees off the coolant temp. Copper pipe can be fastened to the inside of the frame rails and the engine's coolant circulated thru the pipe. This both reduces temperature by using the frame as a heat sink and adds capacity by way of the volume of the pipe. This would have coolant on the intake side of the radiator flow into the pipe first instead of the pump, then route back to the inlet side of the pump. This routing just looks cleaner than tapping the return line where everybody can see it.

3) You can play with the bypasses to force more coolant thru the radiator, This only works if the radiator has unused capacity. But if I had to put up hard cash, I bet on your radiator already being maxed out, so this will probably be an ineffective exercise, still this is simple and cheap so it's the typical place to start.

4) Getting the air out of the system, belching the system is an upfront activity that once done shouldn't need repeating unless there is a leak somewhere. Cavitation while creating gasses in the system should only be vaporizing coolant which should return to a liquid state once it cools. It is important to keep air out, this means making sure any overflow goes to a catch tank that is plumbed to keep the end of the overflow tube submerged in coolant. This way when the coolant expands when hot it will flow to the catch tank. When the engine cools and the coolant contracts a vacuum forms in the radiator and cooling jackets that draws the expelled coolant back. The cap must be at the high point of the system, otherwise you'll have great difficulty venting trapped gases out. A higher pressure cap insures that local boiling doesn't occur inside the engine. The temperature you see on the gauge is an average of returning coolant. Specific coolant temps around the sparkplug and the exhaust valve can be much higher, so high the coolant locally flashed to steam. Steam takes a lot of heat with it when the liquid changes state, but after that steam is a poor heat conductor and the metal surface next to a steam pocket overheats. So going to a 16-18 pound cap buys some space to prevent steam formation in the heads.

5) You'll find removal of the thermostat will have no long term effect other than causing the engine to take longer to warm up and increasing upper end wear from unburnt fuel wash.

5) Safety; a characteristic of pressure cooling systems is that the coolant is near, at, or over the normal boiling point of water. If you remove the cap from a hot engine, some to all the coolant will flash to steam and blast from the cap. You will be par-boiled if this stuff gets on you.

Bogie
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Old 09-25-2008, 07:14 PM
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i have a 40 chev with a 454 i had the same thing happen here is a few things that worked for me

aluminum radiator

be cool radiator hoses

electric water pump

electric fan
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Old 09-25-2008, 07:34 PM
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As soon as you said 454 and '39 Plymouth, my mind flashed to a very tight engine compartment with insufficient hot air exit area. You could install the radiator from a mining truck, but if the air ain't gettin' out, it ain't gonna work.
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Old 09-26-2008, 08:20 AM
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Body style aside....I would run a higher pressure cap. If nothing else it will keep it from bubbling over prematurely.

What did the tempertature guage say when it overheated?

Verify the timing is correct...alot of overheating problems in BBC's are actually timing problems.
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Old 09-28-2008, 01:05 PM
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Has to be AIR FLOW or WATER FLOW
Since you are having problems at low speeds, let's analyze this.

#8 = The fan is still too far into the radiator. 1/3 or less width INto the shroud// 1/2 inch into the shroud is better

Water pump/fan MUST be overdriven. Shoot for 120%.

You need all the fan pitch you can get. Consider a DeRale stainless steel flex fan of the maximum possible diameter you can get into the car. They are 2 1/2 inch pitch. Flexilite makes a stainless fan that is ok.

#9 = Minimum of actual 16# working pressure on the cap/ 20 preferred, TEST IT. New ones are never up to spec. I have had to buy 20# to get one that goes to 16-17#.

Drive it without the hood to see if the airflow changes.

It could be too small of a radiator, but regardless you have TOO LITTLE AIRFLOW.
Check that hot underhood air is not being sucked back into the front of the radiator.
Water pump must be overdriven. Shoot for 120%.

Check to see if the heater is full flow. If it is, put a shut off in the heater hose. Remember all the coolant flowing through the heater is NOT being cooled by the radiator.

The engine vacuum advance needs to be hooked to direct manifold vacuum and be giving you at least 30* advance at idle.

Evans Coolant is one solution that you might have to use if all else fails.

There is a custom outfit making special radiators that increase cooling more than 100% more than the new aluminum radiators, per unit volume. These radiators are made of brass tubes with no fine fins and hold 100% more coolant and have about double the surface area exposed to the air. But they are NOT inexpensive... but they work. I'll try to find their address and post it.
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Old 09-28-2008, 02:04 PM
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Is it ok going down the highway, if so you most likely have an air flow issue like not enough fan or poorly designed shroud. A 15LB cap is a good idea, it will help keep it from boiling over but it isnt going to change the temperature.
As mentioned above either the radiator is to small, the coolant is not circulating through the radiator quick enough to remove heat or your fan is not woring properly. If it is good while moving it is most likely the fan.

Chet
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Old 09-28-2008, 06:30 PM
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sounds like you don't have a bypass hose connected between the water pump and intake manifold. You don't need the bypass only if the T-stat is replaced with a restrictor (a t-stat size hole that is open all the time).

If you run a t-stat without the proper sized bypass hose, it will over heat just like you describe.

you could try cutting the guts out of a cheap t-stat and block off the bypass hose (if it isn't already).
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Old 10-01-2008, 12:39 PM
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Thanks guys for all the suggestions. There are certainly many things that can cause an engine to overheat. Many components have to work correctly and also work in concert with one another. The BB seems to start with the deck stacked against it since the cumulative effect of many smaller things seems to more easily cause it problems.

I'm still unable to purge air from the system and the radiator begins to push nearly 2 quarts of coolant into the overflow tank almost from startup. The radiator capacity alone is about 3 gallons, a thick core.

At this point, I suspect a defective head gasket as all the other items to check that have been suggested have been checked and ruled out.. Using a higher pressure cap caused a patch on the tank to break open, so the buildup of pressure in the radiator is pretty great.

I agree that the engine is physically too large for the engine compartment. It's been installed offset severely to the passenger side for steering clearance and the the 'pointy-ness' of the nose doesn't leave any space ahead of the engine to push the radiator forward to run an electric fan - there is no spacer between t he factory fan and the pump pulley and I've -just- got enough space to keep the fan and shroud oriented correctly, but the fan does pull well.

I'll do some testing later this week to see if the head gasket is the culprit and let you know what I find.
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Old 10-09-2008, 06:53 PM
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Problem Solved

After a trip out of town and some family problems, I was finally able to diagnose
the overheating problem.

As I mentioned before, the cooling system had been poorly maintained and thsi contributed to the problem.

The heads were warped, cupping between the middle two cylinders of each head. this allowed air to be pumped into the coolant passages, raising the pressure of the cooling system and pushing the coolant out through the overflow tank.

I had the heads machined and am now replacing them along with all the other components that had to be removed just to get the heads off.

I hope to have it put together and have the car at Myrtle Beach in a week.

Thanks for all your suggestions and comments!

hoyt
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