• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

383 running hot

ChiCy

Member
Local time
8:33 PM
Joined
May 28, 2019
Messages
16
Reaction score
1
Location
Chicago, IL
I acquired my 66 Coronet station wagon last fall and am still getting a feel for it. It is running hot and my local radiator shop and I am working on troubleshooting it. The guy at the radiator shop says for an engine like this running at 220 is not a big deal but from everything I have read that seems pretty hot. Seems like closer to 190 is ideal. The car has an electric fan (installed by the previous owner) and we realized it wasn't working so we fixed that but that didn't seem to be help much. We have also changed the thermostat (the previous one was in upside down) and flushed the radiator. I have yet to take it on a long drive but in the short trips I have taken, even on the open road, it seems to be running way warmer than it should. Has headers now but I have exhaust manifolds that I am looking to put back on once I get the chance. Thanks in advance for your suggestions.
IMG_5734.jpg
 
Last edited:
Nice wagon! If you didn't get it to run cooler after your next test drive, I would check the impeller on the water pump. I have seen them rust off . Which causes insufficient water flow.
 
Years ago I removed my original fan and replaced it with a flex blade fan. Big mistake. Its been running a little hot ever since. I think these engines generally require a big fan (and shroud) to run at the right temperature. I have read that for some owners, the electronic fans were a step backward as well.
 
Get a regular factory type fan on there and a fan shroud to match.

The electric fan on there now is only covering about 1/3 of the radiator surface.
 
The factory shroud covers the whole core sort of like a funnel. The factory belt driven fan ends up pulling air though the entire core as opposed to the tiny surface area that your electric fan is doing.
 
Agree with what's been posted so far. Also, what is your initial timing? Have the block cooling jackets ever been cleaned out? Is the lower hose soft? Does it have a spring? Just some random thoughts.
 
Hope this helps. Rule of thumb for me.
If the car holds around 190 - 200 on the open road no matter how you drive it = OK
If it gets hot idling in traffic or low speed = not enough fan air flow
If it gets hot driving it = radiator or mechanical problem.
Note : from that pic that electric fan is not installed correctly. It needs a sealed shroud to pull air across the whole radiator. Electric fans get a bad reputation but they are almost always badly installed from what I see. Try and find a mechanical fan installed on a modern car.
We drive cars equipped with electric fans every day to work and rarely to you have a cooling problem.
 
All good suggestions - thanks...what would be a reasonable operating temp? And would you agree 220 is too hot?
 
I wouldn't balk at 200-210 on hot days with a 195 thermostat. Bad install on electric fan, no shroud, radiator flow could be low due to restricted core.
 
No more than 210. If you can find oem fan blade and fan shroud is a step in right direction.
Making sure block is clean, I've removed the pipe plugs on the sides of the block before only to have them either plugged solid with muck or very slow draining, if this seen chances are you clean clean block out, your temps will fall into a safe zone. I would pull those and make sure there is no sediment. make sure lower hose has the internal spring in it. reason being is at speed, the hose can get sucked shut...spring prevents this. If your block is mucky, good chances are impeller on pump is toast. A pump from an AC car has 8 blades I believe. Sometimes over the years people monkey with fan pulleys, which if wrong ones are in place cause H20 pump to either over rev or not move enough water. Make sure your timing is in the ballpark to retarded and it can run hot. Run decent gas in it.
 
Steve340 above has great suggestions n facts. I am currently having custom shroud made for my 383/496 with dual electric fans.
1. Shroud should cover entire core area so at idle, fans pull air through entire area.
2. Rubber flappers in empty space on shroud so during highway driving, air can flow freely through core and not be bottlenecked. But at idle, suction of electric fans pulls them closed and sucks air from in front of radiator.
3. I only use Robert Shaw style thermostat. Actually got a new one last week from Mr Gasket. I was afraid of it being Chinese n tin, but nowhere does it say made in China or Anyplace else and it was completely brass. Flows much more volume than any other style.
4. Thermostat regulates "Minimum" operating temperature of an engine. A. Engine is going to run where it's going to run based on 1. Flow 2. Radiator efficiency 3. Shroud 4. Fans. New cars don't even turn on fans until 220-230°.

Too many people think a 180 thermostat means the engine will run at 180. That is when the thermostat will start opening once the engine is up to minimum temp. My '87 K5 Blazer w 350 in 120° desert temps runs about 220° normal and climbs sometimes. This is w a laser temp gun not the gauges. No pinging, no knocking, no overheating.

Get a proper shroud sealed to core, fans sealed to shroud, air flow through shroud while moving.

Just saw the lower hose spring thing in post above. Have never run one once original was removed. "Fact" lower hose spring was so when pulling vacuum on radiator system at factory to remove air it didn't collapse the lower hose. Have never seen one collapse without the spring.
 
Just saw the lower hose spring thing in post above. Have never run one once original was removed. "Fact" lower hose spring was so when pulling vacuum on radiator system at factory to remove air it didn't collapse the lower hose. Have never seen one collapse without the spring.
Agreed!
 
Steve340 above has great suggestions n facts. I am currently having custom shroud made for my 383/496 with dual electric fans.
1. Shroud should cover entire core area so at idle, fans pull air through entire area.
2. Rubber flappers in empty space on shroud so during highway driving, air can flow freely through core and not be bottlenecked. But at idle, suction of electric fans pulls them closed and sucks air from in front of radiator.
3. I only use Robert Shaw style thermostat. Actually got a new one last week from Mr Gasket. I was afraid of it being Chinese n tin, but nowhere does it say made in China or Anyplace else and it was completely brass. Flows much more volume than any other style.
4. Thermostat regulates "Minimum" operating temperature of an engine. A. Engine is going to run where it's going to run based on 1. Flow 2. Radiator efficiency 3. Shroud 4. Fans. New cars don't even turn on fans until 220-230°.

Too many people think a 180 thermostat means the engine will run at 180. That is when the thermostat will start opening once the engine is up to minimum temp. My '87 K5 Blazer w 350 in 120° desert temps runs about 220° normal and climbs sometimes. This is w a laser temp gun not the gauges. No pinging, no knocking, no overheating.

Get a proper shroud sealed to core, fans sealed to shroud, air flow through shroud while moving.

Just saw the lower hose spring thing in post above. Have never run one once original was removed. "Fact" lower hose spring was so when pulling vacuum on radiator system at factory to remove air it didn't collapse the lower hose. Have never seen one collapse without the spring.
2 years ago while walking through the showfield at Carlisle I stopped to check out one of many perfectly restored cars. Looking under the hood, one of the first things I noticed that looked out of place was a nearly completely collapsed lower hose. The owner wasn't around to ask if he was aware of it or not but I'm glad mine didn't have that issue, especially how hot it gets out there.
 
Unless you can put thermocouples with a remote display or a temperature meter on the radiator inlet and outlet, it can be difficult to determine if the radiator is fouled or restricted. Evaporust has a radiator flush called Thermocure. You leave it in for 3-4 days while you drive. Pull the block plugs every time you drain it. Try a high flow thermostat with an opening around 1 7/16" The 1' opening on standard 'stats is too much restriction.

https://www.summitracing.com/parts/...dBbNAtZrb5YhuCm_hmZQFYw0T4LfRkeBoCQIkQAvD_BwE
 
Unless you can put thermocouples with a remote display or a temperature meter on the radiator inlet and outlet, it can be difficult to determine if the radiator is fouled or restricted. Evaporust has a radiator flush called Thermocure. You leave it in for 3-4 days while you drive. Pull the block plugs every time you drain it. Try a high flow thermostat with an opening around 1 7/16" The 1' opening on standard 'stats is too much restriction.

https://www.summitracing.com/parts/...dBbNAtZrb5YhuCm_hmZQFYw0T4LfRkeBoCQIkQAvD_BwE
That thermostat is the same as the Mr Gasket but the Mr Gasket is all brass. Available from O'Reilly's for $17ish.
 
That thermostat is the same as the Mr Gasket but the Mr Gasket is all brass. Available from O'Reilly's for $17ish.

Not the same, and brass in a bellows seal or similar moment has a tendency to crack. The Mr Gasket models have a rep for failing closed I have found. Sometimes you get what you pay for in this life.
 
Not the same, and brass in a bellows seal or similar moment has a tendency to crack. The Mr Gasket models have a rep for failing closed I have found. Sometimes you get what you pay for in this life.
I don't pay much mind to "reps" as I do documented facts. A couple people on forums saying something is bad is a drop in the bucket compared to the millions without a problem. I'll find out I guess. The original Robert Shaw were all brass and had a great "reputation".
 
Just think about this... you can go read anywhere that a properly working clutch fan will eat 5-7 horsepower. Ever see a 5-7 hp electric motor? Does the motor on your electric fan look like that? Takes a lot of radiator to compensate for an electric fan’s airflow.
 
A clutch fan on the Engine Masters channel robbed 14 horse power from the engine - and the loses only went up from there to around 28 horse power.
Sorry Nate S your thinking has one big flaw - it is not about the power of the electric motor it is about the CFM of air the fan can move.
If your theory was even close to right every cooling system in every passenger car produced in the last 30 years would be in big trouble.
 
Forgot in my original post.. if you dont already have one... get an IR temp gun. HF has them pretty cheap. measure temp at thermostat housing, then measure temp at bottom hose see how much temp difference you have. IR temp guns are invaluable in diagnosing things.
Also as a kid I worked at a machine shop / parts store. I honestly can say I sold hundreds of lower rad hoses with springs inside. It did not matter if it was a Gates, or Goodyear hose, I vividly remember the hoses having springs when I restocked them.
 
Last edited:
Auto Transport Service
Back
Top