79' Water Temp

[jvmagic]

Hi,

I flushed the original radiator a couple of times using ionized water throughout the process but even after flushing twice and using a cleaning additive, the antifreeze/water color was dark colored.  The radiator gave a few months thereafter and I ended up purchasing a 3-row radiator (standard not aluminum). Even then the antifreeze/water color is almost mud like. 
If the outside temps are below 85 F the needle reads on the marking between 100 and 220 which seems to be the norm.  When I drive the car in 90 F weather the temp goes to 220 after 30 minutes of driving.  Is this normal?  I don't have a/c, the compressor went out. 

Thanks in advance

[81Blackbird]

Have you checked the water pump plate clearance?

http://www.wallaceracing.com/water-pump-mods.php

I think you meant Antifreeze and not Freon...)

[firebirdparts]

I don't get the mud/color, all that.  It sounds like you need to keep cleaning on it.  I think 220 after 30 minutes driving in hot weather with a new radiator sounds a little hot.  You can probably improve on it.  The gauge is not super accurate, but just by looking at where it tends to hang, you should be able to tell where the thermostat is opening.

[b_hill_86]

I don't get the mud/color, all that.  It sounds like you need to keep cleaning on it.  I think 220 after 30 minutes driving in hot weather with a new radiator sounds a little hot.  You can probably improve on it.  The gauge is not super accurate, but just by looking at where it tends to hang, you should be able to tell where the thermostat is opening.

To add on to that, unless you’re positive the sender is an original one, I’d install a mechanical gauge, even temporarily, and compare it to water crossover temps using an infrared thermometer just to have an idea of the mechanical gauges accuracy. Plus a mechanical is easier to read.

Not only are the factory gauges not spot on, if the sender was replaced it may not have been replaced with an accurate one. Parts store senders are often a one size fits all. For example, my 77 had a “new” sender installed when I bought the car. Turns out it wasn’t the right one. After I changed out my 160° thermostat to a 180°, when my mechanical temp gauge read 180°-ish the factory one rear a touch over 220°. I installed a sender from lectric limited, who advertises as having the correct ohm senders for various applications, and my factory gauge is much closer but still probably not spot on with the mechanical.

[jvmagic]

I'll try the infrared thermometer since it's the easiest and we have one already. I'll post the results.

**I'm pretty sure that when I replaced the lower rad hose it did not come with a spring inside.  Is this an issue? If so, what now?  TIA

[5th T/A]

The lower radiator hose should have a spring. In the olden days new hoses usually came with a new spring. Today it is not unusual to see a replacement hose without a spring. Without a spring the lower hose might collapse.

[BlueBaron762x39]

I don't get the mud/color, all that.  It sounds like you need to keep cleaning on it.  I think 220 after 30 minutes driving in hot weather with a new radiator sounds a little hot.  You can probably improve on it.  The gauge is not super accurate, but just by looking at where it tends to hang, you should be able to tell where the thermostat is opening.

To add on to that, unless you’re positive the sender is an original one, I’d install a mechanical gauge, even temporarily, and compare it to water crossover temps using an infrared thermometer just to have an idea of the mechanical gauges accuracy. Plus a mechanical is easier to read.

Not only are the factory gauges not spot on, if the sender was replaced it may not have been replaced with an accurate one. Parts store senders are often a one size fits all. For example, my 77 had a “new” sender installed when I bought the car. Turns out it wasn’t the right one. After I changed out my 160° thermostat to a 180°, when my mechanical temp gauge read 180°-ish the factory one rear a touch over 220°. I installed a sender from lectric limited, who advertises as having the correct ohm senders for various applications, and my factory gauge is much closer but still probably not spot on with the mechanical.

I had never heard of Lectric Limited until I saw this post.  I ordered a new temperature sending unit just now from them.  I don't know if the parts store temperature sending unit that's currently in my car is accurate or not but might as well replace it with one of Lectric Limited's better quality parts and see how it reads.

[nUcLeArEnVoY]

I have a Lectric Limited sender in my '79 and it seems to be accurate. I have a 160 thermostat and as the car is warming up, I can see the temp start to drop down to 160 once it heats up to 175-180 degrees on the gauge.

OP, you said your AC is out?  Most cars equipped with AC also had mandatory RPO code V02 HD cooling, which was a 4-core radiator, if I recall.

Might want to step up your new rad, see if that helps. Try a 4-core, or a fat 2-row with the oversized 1" to 1.25" rows like Griffin, Cold Case, etc. Those usually outperform any other radiator. When you get your AC working again, the three core you got may not be good enough to shed the condenser heat.

And as suggested, check water pump divider plate clearance. That usually ends up being the number one issue with hot-running Pontiacs. Over the decades, vendors used crappy impellers prone to cavitation, they didn't press them on at the right height, or they shaved the vanes at the top; and so when adding the divider plate, there is a huge gap, often reported exceeding .250". Because of all this inconsistency, the original specs got lost in translation. Most owners with factory/NOS pumps and divider plates report no larger than .100" clearance with OEM parts, so that is the generally-accepted maximum spec, so most try to shoot for under that. I'm getting pretty hot at idle after 30 mins of driving lately too, so I took a look at my water pump and after some searching, I was able to identify it's an 11-Bolt A-1 Cardone unit that was installed by a PO in 2018, and given Cardone's reputation, odds are good when I pull it to replace it with the new Flowkooler I got, it'll probably have a crappy stamped impeller and a huge clearance. I'm almost expecting it.