WHY? Engine temp runs cool in traffic, but overheats on highways?

[Malibu795]

#1 is fan clutch thermal or non thermal?
Thermal doesn't care about RPM speed unlike non-thermal..
#2 is fan fix blade or flex blade?
#3 if fix blade OEM or aftermarket... Aftermarket general move more air than OEM of same size..
Like so.. yes 19" fan will fit in stock cowl personally running an older version of this in mine
https://www.jegs.com/i/Flex-A-Lite/400/1119/10002/-1
#4 is air side of radiator clean? Moving create more load on engine vs idling

 

[jlcustomz]

I think I hinted at your most likely problem on 1 st page & a low cost solution. An original radiator is not likely to handle highway speed in Arizona. The replacement type plastic /aluminum radiators aren't the best for long life, but one of these from a parts store (possibly with lifetime warranty) could well solve your problem. Get the largest version made for g-body. Get new lower rad hose with spring at same time.
Even if you have other contributing issues, I don't see an old radiator cutting it.

 

[Malibu795]

Also 200-210ect isn't not over heating 250+ is over heating

 

[69hurstolds]

Here is a cluster from an 84 Monte Carlo. The temperature gauge is 220 at the top of the gauge which means that is the normal operating temperature and designed for your eye to easily pick that up with the needle pointing straight up. Operating tempatres of the 80's 305 is 210 to 230. Corvettes of the 80's had an electric fan that came on at 228. Your problem is overcooling and not overheating

I do not agree, kind sir. I think you're overestimating the accuracy of factory gages in ANY year G-body. The gages aren't linear, and if it's reading 220 on the gage, what is the real temperature of the coolant? That's right, you have no idea. 190-220 max is a generally accepted "normal operating range" for most car engines. While you don't want to go too cold, the hotter temps in the 80s likely was for emissions BS. Hence the 195 T-stats. But no factory gage of the 70s or 80s is going to tell you that.

With your theory, you should also drive this car about 45 mph at 3K RPM with 30 psi with a 1/2 of a tank of gas at the top of each hour. 🙂

To me, everything is acting like crud build up in the radiator. JMO.

 

[azmusclecar]

I am considering all alternatives...from lower radiator hose to timing to clogged radiator to fan clutch to water pump belt slippage to faulty gauge to overcautios driver.

I'm sure the answer lies somewhere within.

Meanwhile, I am enjoying a peaceful holiday remembering why we have so much to be grateful and thankful for. It's a great day for all of us. Enjoy it.

 

[pontiacgp]

I do not agree, kind sir. I think you're overestimating the accuracy of factory gages in ANY year G-body. The gages aren't linear, and if it's reading 220 on the gage, what is the real temperature of the coolant? That's right, you have no idea. 190-220 max is a generally accepted "normal operating range" for most car engines. While you don't want to go too cold, the hotter temps in the 80s likely was for emissions BS. Hence the 195 T-stats. But no factory gage of the 70s or 80s is going to tell you that.

With your theory, you should also drive this car about 45 mph at 3K RPM with 30 psi with a 1/2 of a tank of gas at the top of each hour. 🙂

To me, everything is acting like crud build up in the radiator. JMO.

that was not my theory or an opinion but you guys carry on solving the overheating problem. I have better things to do with my time

 

[69hurstolds]

that was not my theory or an opinion but you guys carry on solving the overheating problem. I have better things to do with my time

No you don't. 🙂 C'mon, we know you better than that.

 

[DRIVEN]

that was not my theory or an opinion but you guys carry on solving the overheating problem. I have better things to do with my time

You sure you aren't just getting confused by all that Farenheit stuff?

 

[64nailhead]

Not sure how long your radiator has sat, but corrosion of the solder joint and copper alloy corrosion will occur no matter what you do if a system sits for years. Corrosion in the block can and will migrate.

The radiator which I had out of the car looks to be original. I have NOT found any leaks bowever there is natural build up of corrosion on the
inside. I made sure when I had it out that there were minimal fins bent on the cooling surface.

There's your sign^^^^^^^in bold

I'm somewhat late to this thread, but the corrosion on the ends of the tubes internally is the tip of the corrosion iceberg lol. Someone, Driven I believe, mentioned checking the radiator with a heat gun. I'll just about guarantee that you have cold spots and hot spots.

Don't work around a known issue - the rad is plugged internally and if it's not the entire issue, then it's a big share of it. Find a budget Rock Auto or parts store unit, then drive and be happy. But also it is some excellent advice to check the tune, i.e. vacuum reading, base timing, all in timing and vacuum advance - there is no need to not check the free stuff 🙂

Good luck - Jim

 

[Ribbedroof]

There's your sign^^^^^^^in bold

there is no need to not check the free stuff 🙂

Good luck - Jim

But if you ever want to get to 100 pages, you HAVE to ignore the free stuff! 😆