K well i was driving my car today in the 90 degree heat up here in illinois nad my car started to run really hot it was at about (235).I mean it usauly will stay at 220 or less. I have a 160 thermo, a new single 14" fan w/on/off switch inside on dash. well it has a 350 in it but it had a 305 and is still using the same radiator. i looked inside the coolant looks drity so i plan on doin a flush do u guys think this would help? WOuld a tranny cooler help? Also, one more thing is that my eexhaust is sorta rigged up. I have to deep of an oil pan and so i have a small y-pipe oon there. the pipe is almost touching the pan. do u think the oil is heating to much and is what could be causing it? what kind of symptoms would this show ifthe oil was getting to hot? it also has open headers so would this be normal? sorry for all the ? im an amatuer thanks.

 

ttt

 

Generally if the coolant actually looks bad the radiator is probably pretty well clogged up. Not always, but a neglected cooling system will usually trash the radiator first.

I notice that you say it normally runs about 220. Too high. If you have a 160 stat it should stay down around 180 or so if you are cruising on the highway, with plenty of air going through the rad. Sounds like it's marginal to begin with, the hot weather is just putting it over the top. Higher temps in traffic can be normal since the ECM doesn't usually kick the fan(s) on until temps as high as 228* under certain circumstances. That's if your ECM is still controlling the fan, which it sounds like it isn't. But making sure it's withing 20* of the stat temp on the highway is the first hurdle to clear.

One real quick thing to check is the "chin spoiler" on 3rd gens. It's a black plastic piece that sticks down about 6" below the radiator. This little piece of plastic is CRITICAL to highway cooling of a 3rd gen. Make sure it's even there, first off, and that it's in good shape- not "floppy", loose, worn down to nothing (it scrapes on everything) or held in place by a single screw and a prayer. Replacements are still available from GM.

Beyond that, I haven't found a 3rd gen with the original radiator that was still in good shape. They almost always need to be changed for a fresh stock replacement. I would do the water pump at the same time, since a bad radiator and a bad water pump can act almost exactly the same. And if you're gonna rip into the front end....

Another quickie: Make sure your lower radiator hose has the anti-collapse spring inside it. Without it your water pump can actually suck the lower hose flat and prevent coolant circuation when engine RPMs rise.

Is your radiator cap fresh? AN often overlooked part of the cooling system but probably not related to your immediate problem. It's a good idea to replace them every decade or so on general principle.

Lastly, a single 14" fan doesn't have a prayer in the world of moving enough air, even through a fresh rad, to keep a strong 350 cool. Obviously, the cooling fan only matters at low speeds- stop and go driving, but it's probably not gonna get the job done. I have used 2 of those same sized fans and still felt it was kinda "marginal" for a 350 or larger engine in a 3rd gen in hot weather. The 3rd gen has a badly placed radiator in my opinion and ANYTHING you can do to shove air through it helps A LOT. I have used both pusheer and puller fans- as many as 4 of them- to keep a really high strung motor cool in a 3rd gen with an otherwise near-stock cooling system. I doubt that kind of overkill is required here but you get the idea. More air = good.

 

Them are all great suggestions. I would like to add one more. Check inbetween the rad and the A/C condensor for bugs and a whole bunch of other UFO's that tend to impead air flow.

Auggie