I have an '84 Camaro with a LT1 in it.

a 4-core radiator and 2 cooling fans (pusher, puller) the car still overheats!!

I've tried different thermostats and it still overheats WTF!!!

any advice?

 

Radiator Cap! Even if it's brand new, if it's the wrong pressure it'll throw a wrench in the works. I run a 13psi cap, single row rad, stock thermostat and a single electric fan on a toggle switch and my car barely hits 180* in the summer.

 

Good thinking!

BTW what does a radaior cap have to do with anything?

I thought if it kept a lid on things it was good

 

It maintains a certain pressure in the cooling system. The thermostat opening point is a certain pressure also. So if the system is always too high of a pressure, the thermostat stays open and the coolant doesn't spend suffiicient time in the radiator to be cooled, instead it gets hotter and hotter while it swirls straight through the system. I only know this because I slapped a 16 pound cap on mine thinking bigger was better. 13 pound works good on my stock 305 tbi.

 

What kind of water pump do you have? Do you have a lower radiator air dam?

 

Was the cap the problem? Also keep in mind that water pump rotation changes if you go to a serpentine belt

 

I don't think the belt will change the direction of his water pump as he has an LT1....

 

sounds more like a stuck thermostat..

 

wrong. The faster you circulate the coolant, the more it will cool the engine down. Plain and simple. It will travel just as fast through the radiator as it will through the engine, bringing the temp differential between the two down.

The idea that you aren't spending enough time in the radiator with a higher flow rate to cool the engine down is an old myth. Sort of like how synthetic oil is thinner than conventional, only even more wrong.

You want the coolant to go as fast as possible when you are cooling, the thing is, the engine needs to be run at a given temp range, thus we have valves to allow the flow to be restricted or open to reach that range. Too much flow would cool the engine down too much, too little, and it would overheat. The radiator cap being too high of a pressure will cause steam to not be able to escape, leaving it inside the coolant passages and reducing heat transfer. It also causes the fluid to not make that phase change to steam, causing it's temperature to rise as well. Basically, the rad cap needs to be the pressure it's supposed to be to match the pressures the rest of the system is designed to run at or steam and valves may not function correctly due to the increased pressure of the system.


edit: You tried different thermostats, but what were their temps, and what temp do you consider overheating? Some people think 220 is overheating, and some people dont consider themselves to be overheating until they hit 260. I have no idea what your LT1 engine is supposed to operate at, but i'm guessing it's gonna be in the general range of a normal SBC. So i would assume you were using around 180 degree thermostats as a replacement, and are operating in the opposite direction (i think lt1's coolant flows the opposite direction anyway, maybe that's ls# engines...). I would also assume you are installing the thermostats in the correct direction. Assuming all that, the only other idea i have is that your have a lower radiator hose or some other hose that is collapsed or clogged, causing a major restriction in coolant flow.

Have you tried running the engine with the rad cap off and watching what the coolant does inside the radiator? Are you flowing in to the top of the radiator, and out from the bottom? This is to remove air pockets. If you go in the opposite direction, you'll trap air pockets and this will seriously cripple cooling.

edit2: Oh one more idea i have. Since it's an engine swap. I would wonder if you've checked if you have sufficient oil flow. Low oil flow would also cause an increase in heat, an increase that could be low enough to not burn the oil outright, but too much for the cooling system to sustain.

 

That makes alot more sense. I gotta say thanks, I knew a cap with too high of a pressure could cause overheating (personal experience) and thought I had the theory to explain it. Thanks for clearing that up.

 

Here's a link that helps explain the benefits of an aluminum radiator vs the copper/brass ones:
http://www.carolinarodshop.com/Store...in/griffin.htm

 

Are you sure you have an air damn under the radiator? My 92' Rs with my fresh 358 ran at 210 even with jegs dual fans, jegs aluminum dual core radiator and a stewart stage 2 water pump. I installed the air damn and it runs at 160 all day. If its really hot and i'm in traffic it might touch 180, but its better to have an over efficient cooling system than to be worried about being stuck in traffic

 

LT1's do have the reverse flow water system (flows to the head first). They also are a bugger for air in the system, which is a major overheating cause in them. Also, they are not a self bleeding system, so you have to manually bleed all the air out.
On my LT1 Formy, there are two bleed screws, the best technique is to get the front of the car elevated so the bleed screws are the highest point in the system. One other point, the LT1 uses a different thermostat than regular SBC motors, and won't work properly with the wrong one.

Sara Lou