BlackZ28

the story...

car has been running fine. went to pay my cell phone bill today and as i came out, saw this stream of coolant coming from the underside of my car. im like o sh*t it better not be my car. so i get in the car, pull it bak a little bit and look under the right side fender where it was coming from. sure enough it was from my car but it was just dripping not coming out like i thought it was. so im like lemme take it home so i can take a better look at it. i got home and took out the flashlight and check under my hood. the only parts with coolant on them is the bottom panel. i tried to check for leaks around the overflow and radiator but didnt see anything. so i decided to take it to my friend at tires plus so they can pressure test it for leaks. they tested it, topped it off with coolant and the car started to over heat. i was like wtf, the car has had that problem before but it was a blown fan fuse. but that wasnt it, the fans turned on fine (they turn on kinda late from the factory as it is). so they said it could be a couple of things. the thermostat is malfunctioning, the heads are warped (i hope not, they are aluminum heads!), or a blown headgasket. they couldnt do any further testing cuz they were about to close so i waited for the car to cool down and took it home. i got home and left it on to see if it would overheat again. i checked the fuses again and waited. it got really close to redline on the temp guage but stopped just short of it and went bak down as the fans cooled it down. wtf. wut could it be? a half-open thermostat? could the head gasket really have blown? the car runs fine and strong still, but i dunno wut to do from here. im thinking i should change the thermostat and put in a 160 one in there. wut else could i do to have my car run cooler? i know there is a way to have my fans come on earlier but i forgot how/wut it is that does that. my car is completely stock cept for a cold air kit. i havent done any of the free mods cuz the car is a 96 and it would set off codes. thanx for any help

HybridSS

Hmm...start with the basics. You say they already pressure checked it...so that eliminates alot of things. Should eliminate a head gasket too, but you could do a cylinder leak down test too and maybe change you oil looking for signs of coolant in oil. But unless you have really overheated it prior or are hitting some serious power..i doubt the heads are warped.

Change the T stat...its cheap.

Dont the LT1s need to be bled after servicing coolant??
Could it be posssible you just let it get too low and it overheated....now that its serviced it needs to be correctly bled?

Take off the belt driving the water pump and spin it by hand...see if you hear funny things or if its hard to turn.

Make sure your fans are coming on.

Look at the front area of your radiator up in the nose from underneath to make sure you havent sucked a bag or something in front of the radiator.

Did they drain and flush the system or just top it off. You may want to drain and flush...see what come out.

BlackZ28

changing the oil this week before sat cuz i want to get my car dynoed. ill check the oil for any signs of coolant. ill be changing the t stat as well, cuz ur right, it is cheap and it uses a 180 so im gonna throw in a 160 in there. not sure wut they did cuz i was hungry and went to steak n shake, but they had coolant all over the place and filled it bak up so i think they did do a complete coolant service on it. it couldnt of been to low cuz it overflowed and also cuz i had it serviced a little over a year ago. wut would spinning the water pump by hand do? ill try it out anyways tho. hard to tell when the fans are on but i hear them come on way late in the temp guage, i think they r set at something like 270 i remember reading one time which is kiinda high. good idea about checking the radiator to see if something is blocking it, i should of thought of that before and wil check first thing tomorrow. when they flushed it it was nothing but coolant. thanx a lot for your help. right now im leaning towards the T stat not working properly or something blocking the radiator. THANX!!!

HybridSS

Spinning the water pump should be fairly easy with some feeling of resistance. If you cant spin it by hand or hear grinding noise or other weird things the pump could be shot.

Serviced it a year ago??? Just because it over flowed doesnt mean it had enough water. If there isnt enough coolant in the system the engine will get hot and the water will eventually reach boiling point and overflow. So low coolant can cause overflow.

Uncle Ben

The LT1 water pump is driven off the timing set not a belt.

Check the weep hole on the water pump. If it's damp that's your problem, change it and hope it didn't screw up the opticrap.

The LT1 cooling system has 2 bleeders. One is right by the thermostat housing and the other is by the throttle body. Air in the system will cause hot spots and surging coolant. Changing to a 160 thermostat will have no effect without also adjusting the fan on temps in the programming.

I'd bet it's a water pump going bad and weeping coolant when it's hot.

Matts50

I'm def no GM pro, but my first guess is water pump also. Good luck! Let us know what happens.


Matt

HybridSS

Yeah yeah...damn crazy reverse cooled LT1s

ZDriver96

Yeah the pump is driving by the cam. Even if coolant is coming out of the weep hole it should still not over heat... unless it is really really bad or clogged..

having an air bubble in the system can cause over heating but ive never heard of an air bubble developing without changing the coolant. You have to expose the cooling system to air when changing or draining the fluid.

A 160 thermostat will only keep your car at the 170 temp range on the highway.
Low fans should be on at 226, off at 221... high fans kick on at 235 and off at 230.

Change the thermostat first.. U can take it out and check it by hand to see if its sticking, then bleed the system.
If you have a blown head gasket or cracked head you can pull a spark plug and check for coolant in the plug hole.

BlackZ28

local shop has determined that its just the fans not turning on at all. they only turn on if i turn on the air. they said they traced it to the computer not turning the fans on. they wanted to charge me $289 for the part and $100+ to install it. are they talking about the pcm? if so i could get a modified pcm at www.pcmforless.com for cheap and comes with tuning capabilities for mods. if thats the case, cant i do the egr and tb free mods and program those codes out of the pcm i order as well?

ZDriver96

tb bypass needs no computer adjustment, egr needs reprogrammed to eliminate the ses light on an OBDII but shouldnt show on a OBDI, fans can be reprogrammed from pcmforless with the obdI, and if they want 100 bucks to install a computer then they are smoking crack. Just hope that it is the pcm that is your problem..