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Discussion Starter #1 (Edited)
My 265 runs pretty warm all of the time, and at the top of the dial (but not boiling) when outside temps are 100 plus. And this is highway stuff, not stop/start.

Radiator has been flushed and repaired and I have just replaced 4x block plugs and had the block cleaned at the same time. Looking forward to taking it for a test run now to see what it does!

It has a shroud, but that makes no difference at highway speeds,
of course. Similarly, a booster fan would not be helping.

If it is still running hot after all this, it is a sign the engine needs a rebuild?
 

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If not puking coolant check coolant temp with a digital pyrometer your temp gauge may not be reading corectly.
Rule of thumb:
Hot on the highway not enough radiator.
Hot in traffic not enough fan.

If using a flex fan they flatten out @ highway rpm & block air flow through the radiator.
If turning 3K+ rpm on the highway you cooking the oil an oil cooler is an option
or less gear or overdrive.

Good luck
 

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Here's a few things that may help in troubleshooting.
1.Fan belt slipping.
2.Carb mixture screws set too lean.
3.Late ign. timing.
4.Centrifugal advance fails to advance spark as spd. increases due to weights sticking.
5.Water circulation slowed down by rust,scale,or dirt in water jackets.
6. Thermostat fails to open fully or sticks closed,or opens at too high a temp.
7. Leaky head cyl. gasket permits exh. gas to enter water.
Hope this helps. Bob :anim_25:
 

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Discussion Starter #4
Excellent rule of thumb and checklist – thanks to you both!

Btw – the car has standard fan and runs a 700R4 ... so pretty low rev and speed.
 

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Discussion Starter #6
What type of fan blade and shroud set up do you have.
Standard 4-blade fan.

Plastic shroud – looks common. Fan positioned half-way in.
 

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If you are running hot at highway speeds your cooling system is not working properly. You either have a blocked radiator or your block is full of sludge or possibly both. The fan is not part of the cooling equation while on the road at speed.
 

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Good point Bruce :tu
 

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Not sure if it pertains to tri-five cars but I know with Pontiac cars they seem to have an issue with running hot and a majority of Pontiac owners swear by using the stock water pump with the cast impeller vanes and a proper backing plate.

I know it isn't the same with these cars, but could it be an issue?
 

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265 runs hot

When I restored my car I put ac in it. Before restore and ac my stock 265 would get to almost half mark on hot day in traffic. I put 5 blade fan and shroud and added 1 can of water wetter With same driving condition it never gets past 1/4.
 

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Discussion Starter #12 (Edited)
Good test drive yesterday – it was about 82˚F.

Started from the city and the gauge got to about 7 on the dial. But the time we were on the coast road we were at 9. That's not unusual. Then as we got back to the city traffic it was hitting 9.5 and eventually 10.

The coolant was not boiling, but I could feel the motor was labouring so I was super gentle.

In the past I have put a gun to the motor and read that 10 on the temp gauge reads an about 218˚F.

So, it would appear that regular driving (flow-through) can still get the car pretty hot ... but it is the stop/start that takes it to the limit.

Remember, the welsh plugs have been replaced and the block flushes, and the radiator cleaned and repaired.

Maybe it needs a radiator core replacement or a bigger fan? I can get hold of a 6-blade that a friend has sitting on a 283 he has just removed ;) ... but that may be a flex.

And I'll get the thermostat out and test/check it.
 

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Spend $20 on an actual temp gauge install sender, just leave gauge in glove box so you can see it and read what its actually doing in real time and get actually numbers. Cheaper than shotgunning parts and guessing.
 

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Discussion Starter #14

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seriously look at ignition timing, retarded timing will cause a serious temp rise. and since your rpm are real low at speed it probably doesn't have enough timing.
 

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Start with some basic radiator troubleshooting basics. When the engine is hot the air coming off the fan should also feel hot. If the air is cool or just warm the radiator isn't working. If the heater is blowing air hotter than the radiator it's another indication of a bad radiator.

With the engine hot and running carefully place your hands on both the upper and lower radiator hoses. If the radiator is working properly the upper hose will be considerably hotter than the lower hose. If the hoses are the same temperature the radiator isn't doing it's job.
 

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Discussion Starter #19
seriously look at ignition timing, retarded timing will cause a serious temp rise. and since your rpm are real low at speed it probably doesn't have enough timing.
Ja. Will do tomorrow. That's a simple one.

I learned from my '57 (with similar issues) to work through the system and just change one thing at a time. In that instance, when everything looked right and it was still overheating, it was the wrong fan (too small) that was the issue.
 
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