273 overheating after new timing chain set and waterpump

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Wally-T

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Hi again guys. I had a problem last fall with overheating so I installed a new thermostat and it ran nice and cool again, under half on the temp gauge even in hot weather in heavy traffic.
A couple of weeks ago I installed a new timing chain set, new manifold gaskets and a new water pump. Now it runs nice and cool on the highway and about half on the temp gauge in town but when I'm in traffic it moves 3/4 way up the gauge and would keep going if I didn't pop it into neutral and raise the rpm. I noticed that the old pump had a plastic impeller and the new one has a steel one. Does anyone know if the plastic impellers flow more water than the steel ones.
Thanks again for all your help folks, I'm gaining much knowledge here. Wally
 
Do you still have your old water pump and can you post some pictures of it if you do?
 
It depends on how many impeller veins there are. The plastic one I have has more veins than the stamped steel one I have. Cooling is about flow, typically more flow more cooling if everything else is functioning properly. 65'
 
Sounds like your radiator maybe stopping up !! Is there a fan clutch on your motor ? Is there a fan shroud on your radiator ?
 
My 273 did the same thing in traffic or waiting for a train even with a factory shroud. I replaced my original radiator with a champion aluminum one with no shroud and 0 over heating issues. A re-core I’m sure would’ve fixed my problem but was twice price.
 
It depends on how many impeller veins there are. The plastic one I have has more veins than the stamped steel one I have. Cooling is about flow, typically more flow more cooling if everything else is functioning properly. 65'
If memory serves me correctly, I do believe the plastic impeller had more veins. Bummer
 
My 273 did the same thing in traffic or waiting for a train even with a factory shroud. I replaced my original radiator with a champion aluminum one with no shroud and 0 over heating issues. A re-core I’m sure would’ve fixed my problem but was twice price.
I've been thinking of getting a new rad anyway and it's easier than doing the water pump again. Thanks
 
Theres 2 types of impellers. 6 blade and 8 blade.

The 8 blade impellers are for non A/C cars because of a larger diameter water pump pulley that turns the pump slower. The 2 more blades is to increase the coolent volume because of the larger and slower turning pulley..

The 6 blade impeller pump is for cars with A/C as the water pump pulley is a smaller diameter and turns the pump faster at the same given engine RPM.

Metal or plastic bladed pump does not matter. What matters is you have a pump with the right number of blades or fins for the given pulley diameter and its subsequent pulley RPM.

Putting a non A/C water pump (8 blade) on an A/C pulley equipped car helps increase coolent flow. Putting an A/C water pump (6 blade) on a non A/C pulley equipped car does the complete opposite and slows the coolent flow down further.

Hope this helps.
Matt
 
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My 69 Dart has the original 273 radiator in it with a 360 in it now with factory A/C. My car would do the same thing, cool great as long as I was moving, but slowly climb in temperature when I was at a red light. The radiator looked very clean but I pulled it out and took it to a old school radiator shop that removed the tanks and Rodded it out. Man what a difference, it cools in traffic even with the A/C on. The guy at the radiator shop did tell me it was pretty clogged up.
 
I forgot to mention that since my Dart was a factory A/C car, it did come with a three core radiator.
 
Years ago, I replaced a broke slant 6 with a rebuilt 318 in our 1st 67 fish. On the interstate daily to work and back. Someone would screw up, I would get caught in slow traffic and over heat. Somwhat puzzled because the slant had never over heated. New radiator cured it.
 
Theres 2 types of impellers. 6 blade and 8 blade.

The 8 blade impellers are for non A/C cars because of a larger diameter water pump pulley that turns the pump slower. The 2 more blades is to increase the coolent volume because of the larger and slower turning pulley..

The 6 blade impeller pump is for cars with A/C as the water pump pulley is a smaller diameter and turns the pump faster at the same given engine RPM.

Metal or plastic bladed pump does not matter. What matters is you have a pump with the right number of blades or fins for the given pulley diameter and its subsequent pulley RPM.

Putting a non A/C water pump (8 blade) on an A/C pulley equipped car helps increase coolent flow. Putting an A/C water pump (6 blade) on a non A/C pulley equipped car does the complete opposite and slows the coolent flow down further.

Hope this helps.
Matt
I wish I'd been thinking more critically when I was putting it together. My car is non A/C and I'm pretty sure the new pump had fewer blades. If that's the case then it looks like I'm looking for the correct water pump or a smaller pulley. I bet you can guess which one I'd rather change lol.
 
Pictures would be a great start.
What does 1/2 or 3/4 equate to in Fahrenheit?
Is it actually over heating to the point of releasing pressure from the cap?
Have you temped it with a temp gun?
Have you looked into the radiator to see if there is circulation?(dont remove a hot cap please)

You live in Canada and you really think the pump is going to make that much of a difference.
 
Pictures would be a great start.
What does 1/2 or 3/4 equate to in Fahrenheit?
Is it actually over heating to the point of releasing pressure from the cap?
Have you temped it with a temp gun?
Have you looked into the radiator to see if there is circulation?(dont remove a hot cap please)

You live in Canada and you really think the pump is going to make that much of a difference.
Exactly! It doesn't sound like it's overheating. That doesn't happen until the coolant boils out onto the street. Did you replace the thermostat? Sounds like it could be a bad cap not holding pressure.
 
Sounds like your radiator maybe stopping up !! Is there a fan clutch on your motor ? Is there a fan shroud on your radiator ?

He stated engine was fine after a T stat change last year, and did not start getting real hot until "right after" he replaced the water pump. I am betting they sold him an A/C type 6 bladed pump. Y'all are shooting down the wrong snake hole. If it was a plugged radiator issue it would have gotten hot before and after the water pump change. It's getting hot only after the pump change. That is the only thing coolent related he changed right before this started to happen. Car is non A/C with the larger slower turning pulley, and probably has the wrong 6 bladed A/C pump on it. It's not flowing enough coolant for the impeller speed.

What year valiant?
 
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Still curious what "real hot" equals in degrees? I run a $9 amazon reman here in Florida and during the summer 95+ degrees, headers, stopped at a light pavement is proly 120 and with a 195 thermo my sun gauge cycles between 190-200, you could set you watch by it!

Last fall? what 60 degrees? and your comparing that to the summer heat?

"I had a problem last fall with overheating so I installed a new thermostat and it ran nice and cool again, under half on the temp gauge even in hot weather in heavy traffic."
 
Unless the new pump was made defective such as wrong impeller it doesn't matter if it's an AC or non AC pump. EITHER should cool that engine especially a 273. The same pump cools a 340!!!

Are you CERTAIN the problem started with a pump change only?
 
Something else I'm sure happened to me:

Oldmanmopar has claimed that over time, the tubes can crack loose from the fins and lose heat transfer. The rad can flow lots of water and not radiate very much heat!!

My original 273 rad would not cool a 318 or 360. Rad shop claimed it would "cool anything." It is the factory 2 core. I finally swapped in a later 73-74 2 core slant six rad I had and the temp instantly dropped a LONG ways. I'm convinced the old rad suffered this fate
 
dd your new timing set advance your cam timing> Did the new set slide right on when you took the old set off or did you have to turn the cam to line it up? Id run a jug of rad cleaner through and see what comes out. You'd be suprised what that can break up and flush out.
 
Hi again guys. I had a problem last fall with overheating so I installed a new thermostat and it ran nice and cool again, under half on the temp gauge even in hot weather in heavy traffic.
A couple of weeks ago I installed a new timing chain set, new manifold gaskets and a new water pump. Now it runs nice and cool on the highway and about half on the temp gauge in town but when I'm in traffic it moves 3/4 way up the gauge and would keep going if I didn't pop it into neutral and raise the rpm. I noticed that the old pump had a plastic impeller and the new one has a steel one. Does anyone know if the plastic impellers flow more water than the steel ones.
Thanks again for all your help folks, I'm gaining much knowledge here. Wally
There must be 2 threads on this... or the other I answered last nite at 11 pm and it was deleted.

I said you may have swapped a 8 blade for a 6 blade....that explains the traffic overheating. Typically a cooling system that is adequately sized will not boil over at idle with the radiator cap off...so you might gather that the cap is not responsible for the overheating in traffic....the cap issue would show up at speed, higher heat and pressure from the pump and growing temps its fighting along with the radiator.

Is or was it an 6 blade and ...what is the new pump 8 or 6?
 
"There must be 2 threads on this... or the other I answered last nite at 11 pm and it was deleted."

Was that before or after the 12 pack..........Just kidding
 
He stated engine was fine after a T stat change last year, and did not start getting real hot until "right after" he replaced the water pump. I am betting they sold him an A/C type 6 bladed pump. Y'all are shooting down the wrong snake hole. If it was a plugged radiator issue it would have gotten hot before and after the water pump change. It's getting hot only after the pump change. That is the only thing coolent related he changed right before this started to happen. Car is non A/C with the larger slower turning pulley, and probably has the wrong 6 bladed A/C pump on it. It's not flowing enough coolant for the impeller speed.

What year valiant?

could be brother !! When I it comes to automobiles anything is possible !! I’ll play the devil’s advocate here !! He has the right pump on there now !! New pump really works well ! Maybe to good to push the water thru the plugged up radiator lol !!
 
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