shouldahadav8

I just swapped out the stock 305 for a 350 4bbl, brand new radiator, hoses, water pump, dual electric fan hooked to a toggle switch, and a 180 thermostat.

The car ever-so-slowly heats up, starting at the normal center run temp of 220 and working it's way up to 240 and on.

I have the fans on ALL THE TIME, and I went so far as to swap the 180 thermostat with a 160, but it actually seems to overheat faster with that.

While driving, while idling - doesn't matter. The car will overheat.

The air dam is custom, but works.

I simply cannot find the cause, and any and all help will be appreciated.


Just out of curiosity, the electric fan is supposed to pull the hot air to the back of the radiator, not blow towards the engine right?

l_dis_travlr

Where are the fans mounted?

"Puller" fans mount between rad. & engine, and "pull" air
through the rad. back toward firewall.
"Pusher" fans mount between rad. & bumper, and "push"
air through rad. back toward firewall.

Also, as DC motors, reversing the polarity connection
(easy to do, since these are not case grounded units)
will cause them to reverse spin. All this should be
easy to observe.

I hope you have a relay driving the power circuit. Kevin
McClelland's Tech Column in this mo's Chevy Hi-Perf tells
a horror story of direct switching power.

Now a more subtlety, if you have an aftermarket radiator,
that LOOKS like it fits. At a recent NTTGA meeting, one of
the members was relating about overheating, with ALL new
hi-perf components, including custom radiator.
To get the rad to fit, it was angled into the core support.
(Hold-down is a separate issue...) In this configuration, there
was an angle gap between the side of the rad, & core support,
through which hot air was circulating BACK to the front of the rad.
Plug the gap, problem solved.

Hope this helps.

transam85dudeman

airlock, engine sits lower than the radiator's input hose. try take off the top radiator hose to radiator input, lift it straight up (hose sitll connected to engine) and fill it up, youll hear glopping sounds or air bubbles, then reattach fast.. oh and drill a couple of small holes on the mech tstat itself around the opening to help with airlock. I had airlock once, same problem youre having. the radiator sits too high in the cars, which is fine but sometimes while reinstalling there always air locked up. run the engine with cap off next and constantly keep topping the radiator off until the input hose gets hot(mech tstat opening), try to bleed as much air out. then cap it once the t stat opens. oh and defiantly use the fans to pull air(more efficient)

shouldahadav8

yeah, i already ran through the bay and made sure there wansn't an airlock, that was one of my first thoughts

Turns out my fans were wired to blow towards the engine, so the hot air was just being recirculated and not run through the radiator

But what's this about direct wiring the fan?

naf

iTrader: (7)

Not sure what you mean by that. The fans should blow air through the radiator towards the motor. This is the route the air would normally take while the vehicle is in motion and you won't want the fan to fight this while driving. Did you mean something different?

transam85dudeman

i bet you need to water pump

shouldahadav8

i dunno what the hell to do with this fan.

When i got the car, the old single fan wasn't cutting it, so i bought a double blade fan.

The fan mounts to the back of the radiator (the side facing the engine) but i don't know whether to mount it as a pusher or a puller. If it blows air, how will it cool the air around the engine? And if it pulls air, how does that cool air get back to the engine?

Will someone just tell me exactly what needs to be done so my car will stop over heating? Is the fan supposed to push or pull air?

BadaPwned

lol what?

Quit making it so complicated lol...

If the fans are between the rad and engine, it needs to pull air through the rad and blow it on the engine.....

If the fans are mounted between the bumper and rad, they need to pull the air from the front of your car and push the air through your rad.....

This is as simple as it gets lol


In your case, the fans should be pulling air from the rad.....

BadaPwned

This is very interesting, that all it took huh?

Hot air is recirculating around the rad....going to have to check that out next time.....very good tip...big props....

l_dis_travlr

Were there instructions with the fan when you bought it.

If you've mounted it behind the radiator, to function properly,
it must "pull" air through the rad (as indicated above). Blowing
air over the engine is largely irrelevant to cooling capacity.
If you're fan is "pushing" air through the rad out to the bumber,
you probably have it wired backward. Try switching the connections,
and test to see that its moving air through the engine comp, instead
of out to the bumper.

naf

iTrader: (7)

Don't worry so much. Your engine is water cooled. Worry about cooling down the water-the cool water will then cool the engine. It's not a VW beetle.

shouldahadav8

alright dudes, sorry i was freaking

i've tried to everything to get my engine to stop overheating.

it's not a quick thing, it's more of a really slow crawl up to a hot temp, like over the span of an hour or so

i've replaced everything to do with cooling and sunk a lotta money into it and nothing has changed... which got me to thinking:

is there any way my temp gauge could be off?

transam85dudeman

is you transmission lines connected to the radiator. you say after an hour it get hot, i was think if your transmission get too hot..then it could heat up the radiator's water and heats up your engine, maybe external oil cooler with fan for the engine, and external oilcooler for the transmission might help, whats your timing? just a thought.

naf

iTrader: (7)

The guages are notorious for inaccuracy. You'll know for sure it's overheating (or in need of a new radiator cap) when it actually boils over.

You can take it by Autozone or one of the others and they should have a scan tool that can tell you what the ECM temp sensor is reading. This sensor is in the water neck and will likely run a few degrees cooler than the one in the head that's for the dash guage but they shouldn't be too far off from each other.

shouldahadav8

i'll take it by autozone and get a reading, i hope it's not off too bad

but whats this sbout my transmission overheating? that sounds like a legitimate cause. how would i fix that?

shouldahadav8

what's this about a spring in my radiator hose? although i replaced all my colling parts, i didn't mess with any of the hoses, which i think are still stock from 1986.

naf

iTrader: (7)

Some return hoses from the water pump will have a coil spring inside to prevent them from collapsing from suction. I do not know if any 3rd gens came from factory with springs in the lower hose. I've replaced a few that did not, but it's much harder to prove something does not exist vs. the other way around.

If you replace your hose check the hose you pull off for a spring if the replacement hose does not have one, simply swap over.

zaxanllc

What is the condition of the air-dam? If the airdam is damaged this will cause overheating even when parked.