Napoleon1991

I have a 403 and i recently replaced the radiator and after that i noticed it running much hotter. Previously it always ran between 175-195 but after the rad swap it runs around 210. The strange thing is that it only gets that hot on the interstate. I only replaced the rad becuase it leaked. I squeezed the upper hose and it is definately pressureized so im pretty sure i got all the air bled out. The fan clutch seems to never engage so i replaced it, and the new one acts the same way. If i shut the engine off when its hot, the fan still spins 5 or 6 times around. Is that normal? The thermostat seems to work but im not totally sure. Thanks in advance for any help. Im getting so frustrated that im about ready to put the old leaky radiator back in.

Oldsmaniac

Maybe the new radiator was smaller or less rows of cooling tubes?

Napoleon1991

They are both 4 core radiators. Im actually surprised the old one cooled as well as it since it had about a quarter of the fins missing.

MDchanic

You've just described what happens when you replace an adequate radiator with an inadequate radiator.

Unless you changed something else, you need to find a radiator that is adequate to the job (4-core or not), or, as you mentioned, patch the old one and put it back in.

- Eric

coppercutlass

There is a radiator shop in downers grove il. A-len radiator they can fix it. They fixed a gas tank for a friend of mine and a radiator some years back.


BTW a 2 core radiator is sufficient . that's whats on my dads car right now and it will not go over 185 . It might be air flow. Try to run a solid spacer instead of a clutch to see if that helps if so then your clutch might be bad. Im not saying to use the spacer as a crutch but to diagnose. Are you running a shroud ?

MDchanic

Clutch and shroud won't matter in this case - it gets hot on the highway, when airflow is best.

- Eric

coppercutlass

That's true but even my running temps improved by adding a full shroud vs the cut up one I had but in my case it was shrouding.

Fun71

I agree that your new radiator likely doesn't have the cooling capacity that your old one had.

classicmuscle442

Did you re-install the strips of rubber that force the to go through the radiator and not bypass it, even on highway.

Beob

What percentage of coolant to water are you running

Octania

Did you replace the lower radiator hose?

I have seen them collapse due to suction and the Bernoulli effect. This typically happens at elevated engine speed, you will not see it in a non-running or idling scenario. I noticed some movement when I revved the engine during an underhood inspection, it was the lower hose sucking shut. I had removed the "spring" from inside it, not knowing what it was there for. Hint, if you do not understand the function of a part, that is not license to discard it.

We can more or less rule out your FAN as the culprit if your issue occurs at hiway speeds. The fan is there to provide airflow as needed. At hiway speeds, you have airflow aplenty.

This isn't one of those reverse-pitched fans that blows air forward, right?
You may laugh, but it happened right here at CO.com not too long ago.

dc2x4drvr

Check to make sure you installed the fan correctly, they don't help much if installed backwards..

Octania

Agreed. To clarify:
The pitch of a fan blade does not change if installed backwards.

However, due to the shape of the blades, efficiency suffers.
They generally do not even fit into place if reversed.

There are fans with reversed pitch, for serpentine drive systems.

Napoleon1991

Thanks for all the replies. I double checked the fan to be sure it is installed correctly and i do have a shroud. I have replaced the fan clutch and thermostat so i have pretty much ruled them out. Im starting to think the new rad just isnt up to the job. I may try that rad repair that copper suggested. Any idea how much that might cost?

coppercutlass

If A len radiator wont fix it . My friend has a shop he uses sublet big rig radiator jobs to but they are near Melrose park il. Last I asked him he said it cost about 100 to fix a leaky radiator on a big rig so it probably cost less on a car unit.

jaunty75

These statements have no bearing on each other. Do you know how a fan clutch is supposed to work? The fan clutch doesn't engage the fan in the traditional sense of a gear engaging when you change gears. It operates to disengage the fan when the car is moving at highway speeds as the fan is not needed then. When your car is zipping along at 60 or 70 mph, there is so much air rushing through the radiator due to the car's speed that the fan is superfluous and might as well not even be there. The car would also roar like a freight train if the fan ever turned at the speeds the engine turns at when at highway speed. (In fact, a loud roar when the car gets up to maybe 20 or 30 mph is one indication of a fan clutch that is seized and needs to be replaced.) So the fan clutch would have nothing to do with the engine getting hot at interstate highway speeds.

If your car were overheating when idling at a stoplight or when parked and running in your driveway, then you might suspect a bad fan clutch. The fan clutch IS temperature-controlled, and it's usually when you're sitting in traffic with no air moving that the temperature of the engine rises enough to engage the clutch and turn the fan to draw more air through the radiator. But your car is apparently not overheating under these conditions.

Like everyone else, I suspect your problem is due to a too-small radiator.

BlackGold

It bears repeating:
I once purchased a brand new 4-row radiator from a reputable Olds vendor. More than half the tubes were mistakenly soldered shut and would flow no coolant. Worthless. Luckily I noticed this before installing. Inspect all parts before installing!!!!

ziff396

If it doesn't matter, I am running a cheap epay aluminum in mine. 2 core. 455 and it doesn't go over 180. However I do have aluminum heads. I don't know if that makes a difference or not. And yes it has a shroud and rubber baffles installed on the top. 180 thermostat. This is at cruise of course.

Octania

I can say that my high compression 403 is very happy and cool with the '85 442's original and seemingly small radiator. However, before the timing was set up right it overheated badly. It was running quite rich then also.

Correcting the timing curves made all the difference.

Sampson

X2 Chris! Correct Timing is crucial in more ways than one.