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Running High Temp On Highway???


fred

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Hi all, I have a 47 Chrysler Club Coupe with a 218 Canadian 6 cyl engine, 3 spd trans and 3.73 rearend.

Work to date on cooling system, remove freeze plugs and flush block, remove water distribution tube and clean out, new water pump (it works well), good t/stat 160, new coolant 25 % Prestone 75 % deionized water, and 1 bottle of redline Water Wetter, timing set at 2 ATDC.

My heater siser is in the seized positon of cold, which of course is directing all the hot exhaust to the base of the carb, this will be fixed ASAP.

When the outside ambient temps are around 65 and over, and driving on the highway at 50 plus mph, the engine will rise up to the 200 range,in a short time, few miles, I usually pullover, never let her boil over. It never does this at cooler temps 60 and lower.

The bottom rad hoses are in great shape, the rad is a honey comb, but has good flow,was boled out once, it will empty in 10 to 15 seconds in a flow test.

Will the heatriser if it is running hot exhaust through the intake help this engine overheat on wrm to hot summer days.

No brakes are dragging, the engine runs great at highway speed.

Any ideas, what point am I missing on solving this problem................Thanx Fred

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Guest elmo39

have you checked your themostat , a good way to test it is place it in a pot and slowly bring it to the boil and checking to see what temp it opens

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<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: elmo39</div><div class="ubbcode-body">have you checked your themostat , a good way to test it is place it in a pot and slowly bring it to the boil and checking to see what temp it opens </div></div>

Hi, yes I have tested the t/stat it appears to be working fine, and you can see when it opens in-car, that there is good flow across the top of the rad......................Fred

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How about the radiater itself? They can get plugged up but still flow water. (just not enough) I've had this happen on a couple of my old cars.

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Guest simplyconnected

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fred</div><div class="ubbcode-body">

...My heater siser is in the seized positon of cold, which of course is directing all the hot exhaust to the base of the carb, this will be fixed ASAP.

When the outside ambient temps are around 65 and over, and driving on the highway at 50 plus mph, the engine will rise up to the 200 range,in a short time,</div></div>Fred, this is exactly what the heat riser is supposed to do, and it appears to be doing it well. But this point, the theromostat and heat riser should open. One diverts heat out the exhaust, the other diverts heat to the radiator.

Your cooling system can only disipate btu's based on two things, outside temp and the amount of heat your engine generates. I will assume air and water flow are good.

Exhaust is so hot, it will turn your manifold cherry red, running properly (open the hood at night, on a long trip and you will see the glow). With the condition of your heat riser, you are asking the coolant to get rid of that heat, but your cooling system doesn't have the capacity.

Free-up the heat riser, your radiator can't compete with exhaust heat. Fixing this will solve your problem.

Install a new (recommended) radiator cap. A 16 pound cap will raise the boiling point of plain water to over 250-deg. F. Using antifreeze, the boiling point will be even higher. - Dave Dare

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Do not agree with putting a 16 pound cap on because if the radiator sees that much pressure it will blow it apart.

Make sure you have the correct water pump. They changed around 1950. Also, if it is for a Dodge truck, they are different.

Check your vacuum advance diaphram at the distributor. If this is not working to advance the spark at high speed, the engine will run at a higher temperature.

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<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bob Kinker</div><div class="ubbcode-body">How about the radiater itself? They can get plugged up but still flow water. (just not enough) I've had this happen on a couple of my old cars. </div></div>

Hi Bob, thanx for the reply, I agree, you can have flow and still be partially plugged or have poor heat transfer.

The rad was boiled out last summer in a shop, tested, it was deemed to be good, not excellent but good.

I just did a flow test, this is a big 1948 Chrylser rad, it empties between 10 and 15 seconds, has about a 4 inch geyser going ou the botom outlet, there is no crap in the rad.

A recore would dtill be better, but I don't have money to burn right now, so I am trying to figure out the root cause of my heating first before spendin the money on a re-core...Fred

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<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: simplyconnected</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fred</div><div class="ubbcode-body">

...My heater siser is in the seized positon of cold, which of course is directing all the hot exhaust to the base of the carb, this will be fixed ASAP.

When the outside ambient temps are around 65 and over, and driving on the highway at 50 plus mph, the engine will rise up to the 200 range,in a short time,</div></div>Fred, this is exactly what the heat riser is supposed to do, and it appears to be doing it well. But this point, the theromostat and heat riser should open. One diverts heat out the exhaust, the other diverts heat to the radiator.

Your cooling system can only disipate btu's based on two things, outside temp and the amount of heat your engine generates. I will assume air and water flow are good.

Exhaust is so hot, it will turn your manifold cherry red, running properly (open the hood at night, on a long trip and you will see the glow). With the condition of your heat riser, you are asking the coolant to get rid of that heat, but your cooling system doesn't have the capacity.

Free-up the heat riser, your radiator can't compete with exhaust heat. Fixing this will solve your problem.

Install a new (recommended) radiator cap. A 16 pound cap will raise the boiling point of plain water to over 250-deg. F. Using antifreeze, the boiling point will be even higher. - Dave Dare </div></div>

Hi dave, there is good flow, cleaned out water jackets, t/stat isverified, the heatriser is seized, it does not allow the exhaust to flow out freely but is diverting it under the base of the carb first, adding to the heat in warm weather.

The rad i a 1948 non-pressuire design, it is a honey comb core, it cannot be pressurized, no matter what cap is put on, as the overflow tube is at the top of the rad, not in the filler neck, it si designed this way, as the Mopar rads all were till 1950 or 1951.....thanx Fred

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Guest simplyconnected

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: simplyconnected

Install a new (recommended) radiator cap.[/quote</div><div class="ubbcode-body">

Do not agree with putting a 16 pound cap on because if the radiator sees that much pressure it will blow it apart.</div></div>That's odd, my wife's 2001 Dodge has one on a plastic bottle. I just looked out the window, and, yep... hasn't blown up, yet.

In any case, install a "RECOMMENDED" cap.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fred</div><div class="ubbcode-body">The rad is a 1948 non-pressuire design, it is a honey comb core, it cannot be pressurized, no matter what cap is put on, as the overflow tube is at the top of the rad, not in the filler neck, it is designed this way, as the Mopar rads all were till 1950 or 1951.....thanx Fred </div></div>Fred, what did Chrysler's do in high altitude? There, water boils at under 200-deg.F. Hard-boiled eggs won't harden because they never get hot enough. I'm not questioning Mopar's design. I just don't know how they could stay under 200 degrees. In any case, I would rather you don't have a heat riser at all, than to have one that's stuck shut.

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<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: simplyconnected</div><div class="ubbcode-body">[quote name=simplyconnected

Install a new (recommended) radiator cap.</div></div>

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: hwellens</div><div class="ubbcode-body">Do not agree with putting a 16 pound cap on because if the radiator sees that much pressure it will blow it apart.</div></div>That's odd' date=' my wife's 2001 Dodge has one on a plastic bottle. I just looked out the window, and, yep... hasn't blown up, yet.

In any case, install a "RECOMMENDED" cap.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fred</div><div class="ubbcode-body">The rad is a 1948 non-pressuire design, it is a honey comb core, it cannot be pressurized, no matter what cap is put on, as the overflow tube is at the top of the rad, not in the filler neck, it is designed this way, as the Mopar rads all were till 1950 or 1951.....thanx Fred </div></div>Fred, what did Chrysler's do in high altitude? There, water boils at under 200-deg.F. Hard-boiled eggs won't harden because they never get hot enough. I'm not questioning Mopar's design. I just don't know how they could stay under 200 degrees. In any case, I would rather you don't have a heat riser at all, than to have one that's stuck shut.

To tell you the truth, the Chrsler falthead 6 was no known to run super hot like the Ford flathead V/8, so folks probably used 160 t/stat and in summer the engine temps were probably running between 160 and 180, a 20 to 40 degree margin of error in higher altitudes. No doubt thats hwy a number of old highways throughout the USA and Canada, would have barrels of water along the highways in the Mountain regions for this very reason, not sure though, because I was not born till 1961.

The Heatriser I plan to place it permanently in the warm position, allowing the exhaust to flow out, this I can change back with a heatriser kit, if I feel so inclined at some future point, but idoubt it, as I want to go to dual carbs and split exhaust at some point..........Fred

Hi, I seeyour point, with every lb you get an extra 2 to 3 degrees above the normal 212 boiling point. When Chrysler switched over to pressurized cooling systems, they were 4 lb rad caps being used, I have used that type of rad with 7 lb caps, without p[roblems.

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Okay, I went for a drive tonight, it is cold here tonight around 38.

I went for about a 15 mile ride doing speeds of 45 to 55 mph on an old 2 laned highway, temp was dead on at 160, so because the outside ambient temp is cool, I cold not get an accurate test for the engien running a high temp, I will need to wait for temps in the high 60s or low 70s to test it again.........Thanx Fred

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New car radiators and associated equipment are designed to take higher pressure. Your argument is like the one the radiator shop used when they tested my radiator to 16 lbs to check for leaks. They blew a 1 inch hole in it.

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Guest simplyconnected

There's no argument. I quoted twice: <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: simplyconnected</div><div class="ubbcode-body"> Install a new (recommended) radiator cap.</div></div> It's in American English, go back and read it. Serious business; you should change radiator shops.

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Guest elmo39

Okay it seems your water flow is good , have you checked your timing, if it is not right it can cause your car to run hot

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<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: elmo39</div><div class="ubbcode-body">Okay it seems your water flow is good , have you checked your timing, if it is not right it can cause your car to run hot </div></div>

Hi, I have timed this engine, but need to check it again for peace of mind, need to borrow a timming light to do so. I really should buy a timing light, one tool I don't have.......Thanx Fred

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2nd Update,

I went for a drive tonight, outside ambient air temp was around 55 or so.

On the highway driving at at 55 mph, the temp remained at about 165 the whole time we were on the highway, when we slowed down in town, the engine temp dropped to about 156, it stayed like that in town, I was even stopped by a cab driver, who turned out to be another old Mopar nut, he has a 1950 Plymouth. The temp remained at 156 while idling for about 10 minutes.

So not sure what to make of these temp results, will see once we have warmer weather, the heat riser is still stuck, hope to fix that next week...........Fred

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Besides the heat riser (which may be the source of most of your problem), I would particularly look at ignition timing. Most cars I've run accross are timed at about 6 degrees before TDC with the vacuum advance disconnected and the engine at idle. You mentioned 2 degrees after TDC. I think you should double-check your specs and make sure you timed the car using the proper procedure. Then, with the vacuum advance still disconnected, you should gun the engine and check to see if the mechanical advance in the distributor is working. If it is, reconnect the vacuum source to the vacuum advance unit, rev up the engine and check total advance. It should be much greater than the mechanical advance alone. I have a mid-60s Buick book that lists total advance at maximum RPM in the range of 40-60 degrees.

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Well, it's porbably in the 160 neighbourhood, it was a cool evening, so no surpirse.

Today it's about 63, went for a ride, temp was holding steady at 165, it was noticeably warmer under the hood.

I know it was cool out yesterday, as my BBQ was running cool also, the cool breeze can have that effect.

I also notice after todays ride, the carb felt cool to the touch, maybe the heatriser is stuck in the warm postion, I will find out soon , as I will be taking it aprt next week.

I need a day at 75 or better, if I can keep the temp under 190, I will be happy, still need to check the timing and make sure the vaccuum advance is working, a lot of guys I know are pointing at the timimg as a cause to heat up, I am not so sure.............Fred

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Just noticed somehting, I came back about an hour ago from my ride, I just took a sample off the bottom of the rad drain to see what it looked like, the coolant was quite cool, while on the top of the rad, it was still hot to the touch, is this normal after an hour oor more of sitting, you would think they would be a uniform temp byt then, maybe this rad is partially plugged, works well in the cooler weather, then heats up in warmer weather, just an idea.............Fred

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Guest elmo39

Looking at my motors repair manual it says that the canadian 218 timing for 47-48 is , with fluid drive the second line after TDC mark on the vibration damper , without fluid drive , TDC mark

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In reference to the 2 degree ATDC timing:

My 1934 calls for that timing, but remember; the fuel at that time had about 60-70 octane, not today's 87 octane. If you use today's gasoline, you need to advance the timing. When I first got my car it too was timed to the factory setting. I could barely make it up my hill. As soon as I advanced the timing I about doubled my horsepower.

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