Putting the cart before the horse:

Hot Day Outside and/or A/C on + Highway Speeds = Hot to Overheating Motor.

I had my Olds 260 replaced in my 1979 blue Calais back in 1992 with another rebuilt Olds 260. Ever since then, whenever it's a hot day outside and I'm on the highway, I just watch the temp rise and rise until it will over heat. Quite frankly I can't even use this car in the summer due to this issue.

I've installed a Flowkooler water pump, and a heavy duty radiator, no luck. The Flowkooler really helps to bring the temp right back down as soon as I get off the highway. I can sit the car for hours in the hot summer at an idle and I have no temp issues, it's just on hot days or when there's a really heavy load on the motor like climbing steep upgrade.

Other than pulling it & replacing it with a 350, does anyone have any ideas what if anything can be done? I don't want to replace the motor, it runs just too good other than this issue. It has about 65,000 miles on it since the rebuild & this problem gets worse every year.

thx

 

Fan clutch? thermostat? heater control valve? Tiny leaks in hoses(bad clamps, maybe?)

 

Does the lower radiator hose have a "spring" (actually a coiled wire) in it? If not, it can suck closed when the engine is at higher rpms (as in cruising down the highway) and you get no water flow. It also could be a timing issue. If it is advancing too far it can overheat. Both of these problems would not show up when idling.
Just a couple of thoughts. Unfortunately it could be a number of other things too, but the lower hose came instantly to mind because it happenend to me after an engine R&R when I put on a nice new one with no spring.

 

If it's getting worse every year it could also be that the radiator is getting more and more clogged.

 

Have you taken it to a shop to have it checked out? It's going to be a process of elimination and may take some time to figure it out.

Look at it this way, if worst comes to worst, you'll have a nice car for cruising around town in the spring and fall.

 

Couple of things come to mind, I agree with the lower hose as stated above, thermostat, I would double check my fan and make sure it's not backwards. Also as stated above I would check timing.

 

If the shop had chevy on the brain it would make sense. For some reason they
(chevy mechanics) can't seem to get 20° of initial around their brains. Check the initial at 1100 RPM with the vacuum advance disconnected and make sure it's at 20° BTDC. If it is move on to the thermostat and lower radiator hose.

 

You are a very funny guy, don't make me come down there! (Especially in the summer cuz I won't get out of CT). I know where you live!

 

Too Funny. You're welcome here any time but you better leave the Stanley Steamer at home if it's a summer visit and you want to get here. Better bring the Hurst Olds instead because we both know that one will make the trip.

 

Sounds like a real headache, I could take the car off your hands for ya

 

Nah, thanks but as my buddy 69442C can attest, I've got a nice 79 Hurst Olds that can run all day with the A/C on, anytime. I've owned this 79 Blue Calais since 1984, it was my first nice car out of college.

I plan on it being the last car I ever own.

 

It's been doing this since '92 and now you ask about it? That was 19 years ago! I'd check the radiator first. Any radiator or cooling component could go bad in 2 decades.

 

That is a good looking car!

 

Thanks, it has a heavy duty radiator about 8 years old, but I'm first going to try a new lower hose with a spring & check that timing 1st. If that doesn't work, replacing the rad will be the next step.