KennyTJr

I have a 91 rs with a 305. it has a single electric fan. ive replaced the water pump and t stat. I used the flush when changing the water pump. my lower coolant hose has the wire inside to prevent colapsing and when the car is hot the upper hose swells under pressure. i dont seem to be losing any coolant and my oil looks good not milky or too dirty. i removed the front grill and taped the gaps between the outer bumper and the inner bumper to insure all air that gets in the grill makes it to the radiator. which on inspection the radiator looked pretty good not alot of fins bent over. my fan is ran off the key (if the vehicle is running the fan is running) i have close to a 50 50 mixture on coolant and the darn thing still runs hot. even when the car is around 70 mph it continues to heat up like nothing will stop it from running hot. i need help and any information will be appreciated

JamesC

iTrader: (5)

Welcome to TGO, Kenny.

Is the air dam/deflector and baffle in place? If not, replace them. Pics below:

https://www.thirdgen.org/forums/body...-plastics.html

JamesC

fervernt

any chance you have tried replacing the sending unit for the gauge? that could be bad. Also, how hot do you consider "too hot"? It isn't abnormal for the temp to get up to 220-240. especially on a hot day.

KennyTJr

i looked today and i dont have an air dam. guess thats where ill start. and fervernt too hot is 265 it gets so hot that when you shut the car off the radiator makes a horrible noise like the water is boiling. but it only makes that noise if the car is over 255 when you turn it off

Dakota W.

My top hose has a nice bulge too, I took the t-stat out to save the hose.

fervernt

hmmm... well then yep I'd try that air dam first. And if that doesn't work, I honestly think it might be time to get to a mechanic. It looks like you've tried everything I can think of. And it's only gonna get hotter over the summer. Maybe try a dual fan setup?

8t2 z-chev

does it get hot at idle or speeds below 30mph?if so,
check that the fan is running the right way and that it
will hold a dollar or paper against the A/C condenser or
radiator with the fan on.One member here had a fan
wired backwards-blowing air forward and not cooling
well at all...Problem solved once fan running right
direction again

KennyTJr

im thinking that i do need to go to a dual fan set up. the single fan i have is running the correct direction. i installed a air dam. its cooling a little better but still gets hot. gonna try flushing again and gonna reinstall thermo. its drivable just limited. very limited between noon and five lol.

JimRockford

The air dam is only going to make a difference when the car is at speed.If your cars original single fan is working correctly,and you've changed the thermostat I would check the radiator,that's almost certainly where your problem is.

My car has a 305 and its factory original single fan and it never overheats even at stop lights during the summer.
One thing I would recommend is installing a low temp fan switch so the fan comes on sooner.My gauge never goes near the middle.

Damon23

You probably have a restriction in the radiator. Sometimes a flush won't work.

norcalz28

iTrader: (13)

Have you checked your timing recently? I had an 86 Z28 with a single electric fan and it had to be very hot at higher altitudes for the car to start running warmer than usual. I'd get that air dam installed, and check your timing. Also make sure the water pump you installed is the correct rotation for your setup. Are you running headers, have any other performance mods that might increase underhood temps?

StanganatorZ28

Is that also true if your gauge is accurate? Mine runs anywhere from 220 to 235, Im horrified Im gonna blow a head gasket.

KennyTJr

i have stock exhaust. installed air dam now it doesnt get any hotter while at speed but at lower speeds it heats up. it never hits the 260 mark but it rarely leaves the 3 red lines. if its at the third little line when you turn the car off you can hear the radiator release pressure. so i think the thermo is atleast close to accurate. i have my fan wired to a switch that i turn on before starting up. ive been thinking that it may be a clog in the radiator. if i took the radiator off it what would be the best way to clean it? if i put the iroc vents in the hood would that help any? havnt checked timing but the car runs great.

TreeFiddy

If the addition of the air dam improved the at-speed temps, that at least shows the system is responding to improved air flow across the core. For the low speed air flow - is the fan shroud intact - so that air is drawn from across the full area of the core, and not recirculating back around to the front?

JamesC

iTrader: (5)

With the engine off, there's no coolant passing through the radiator.

The IROC 'vents' are non-functional plastic/decorative pieces and nothing more.

JamesC

KennyTJr

it has a fan shroud across the top but its only about an inch thick. theres about 8 to 10 inches on either side of the fan that has nothing. you can see the radiator. thats why i was thinking a dual fan set up would help

TreeFiddy

That's about half the core that is not contributing fully to cooling, because the fan is only pulling air through the circle of core it immediately occupies.

Cover the full core with shrouding and/or more fans. Ideally the shroud needs to be a 'shape convertor', that changes the full rectangular shape of the core to the circular shape(s) of the fan(s).

There should be as little opportunity as possible for air to flow thru the fans from any source other than though the core.