Advance over-Heating Tech

I felt like I've gone threw the usual fixes with no postive results so maybe some unusual or advance advice could help. I don't think LT1 Tech can answer this


I bought my car in January of 2000 and I've had overheating probelms since i bought it. It seems to come and go, but I at least have a issue with it once a year

The problem is at a slow to zero speed the car wants to warm up. It often is unable to cool itself after it gets hot.

Heres a List of what I've done
New heads
new GM radiator
new thermostat (quite a few in fact)
Drilled holes in the thermostat
tried a stock and electric water pump
swaped radiator caps around
pressure checked the system
run straight water
new heater core

As you can see the coolant system itself has been replaced at one time or the other. in the past 3 years

Its not pushing air into the system that I can tell

Its not over flowing

I have both fans coming on at like 150 degrees for daignostic purposes

It got warm the other day and I got it home and sprayed water threw the radiator while it was idling and it took a good 10-15 minutes too cool down.

I just put a blower on the car, but it was overheating on the trip home to put the blower on, so while I think it might have contributed I don't think its the cause.

I bought ANOTHER electric water pump yesterday and i'll try that just as soon as it comes in the mail

HONESTLY, WHAT THE HECK IS GOING ON? ANY IDEAS PLEASE?

Forgot to mention that there is no hint of water in my oil or oil in my water.

The coolant looks clean and good

the car doesn't puff smoke, not even when i first crank it in the morning

Also nothing blocking the radiator


What am I missing? What haven't I checked yet?

Oh,

Both coolant temperature sensors read consistant and both have been replaced

Do you have any actual temperatures? "Overheating" and "warm" mean different things to different people.

What "diagnostic purposes" are served by turning on the fans at 150degF?

well, if you set in traffic long enough you would see 240 degrees. Who knows when it will level off, I don't like to see it pass 220 . With a 160 thermostat it shouldn't be anywhere pass 180 degrees.

I just wanted to make sure those fans are on, while i'm diagnosing this thing and to buy a little more time between drives before it over heats too badly.

I'm completely stumpped on this thing

BTW,

I've got a stock oil cooler on my car, It takes the lower 5/8's hose from the bottom of the waterpump runs it threw some sort of cooler above the oil filter then returns it to the radadiator.

Does anyone know how those things actually work? I'm thinking about trying to bypass it tomarrow and see what happens

Is the car running lean? IF everything else checks out that seems to be your last resort. Do you have any missfire codes?

nope, car is PERFECTly tuned.

128 all around.

I told you guys this would be advance, what the hell? what will fix this thing

welp, the first thing I would check is if your
water pump is running backwards, some won't function
correctly if the belt is on them wrong..

secondly, i'd replace all hoses to make sure they're not clogged
with anything.


does it overheat while driving on the highway? no? how about
your air dam, is it feeding air properly to the radiator at slow
speeds?

the only thing I can really think of if it's absolutely
taking forever to cool down is that you have a passage that's
partially clogged in the block somewhere.

it'd take a high pressure cleaning, but I don't know how you
could do it, or even if it could be done.

Originally posted by scuzzy
welp, the first thing I would check is if your
water pump is running backwards, some won't function
correctly if the belt is on them wrong..

Seeing as how the stock LT1's WP is cam driven, and he has said he has an electric WP, I don't see that being the problem. :)

Are you running non-coated headers? Could be extra heat soaking through the primaries if not.

There should be a small crossover pipe behind the engine from head to head, may be clogged.

If that checks out ok, i'd pull the radiator and have someone pull the endtanks off. On my old '93 i had the radiator pulled apart and cleaned out (he took a rod throuch every single row of the radiator). Within a few months it was doing it again. So even though you have a new radiator, it could be clogged.

Check the "suction" hose from the radiator to the engine and make sure it isn't collapsing.

Have you checked the tranny for any sign of severe overheating... to the extent it is pouring excessive heat into the bottom of the radiator?

Still not convinced this is "Advanced"..... but its an interesting diversion... :D.

I got a new crossover pipe on the car so it can't be clogged.. You can see its flow when you take off the cap... it looks fine to me

The transmission has its own seperate cooler, I'm not using the stock cooler anymore

It over heats at any time of course getting hotter while accelerating or in gear in traffic.. It will not cool back down on the highway which kinda makes me think its a flow issue because the radiator should be cool by then.

I should take a picture of the water that comes out, You could probally drink from it. Still I guess it could be getting clogged again.

Yesterday I took the coolant lines off the aux oil cooler and it made no difference. Today I'm going to buy some of that cleaner and let the car run for quite a while.. see if it will break anything loose.

Oh I don't know about the collapseing hose idea because its a electric water pump (remeber I swaped that out last year to no avail) and it would be collapseing all the time... Also the hoses are less than 1 year old.

I heard you could pick up a exhaust gas tester from autoparts stores.. Is this true? Never seen it before

I think you can get a kit at The Eastwood Company (online, do a search) to check for combustion products in the coolant.

When the car is hot stick your hand behind the radiator and see how hot it feels. When my radiator was bad it felt warm but not hot like it should.

My car overheats all the time also. The fan switch helped but I think I broke that when I put my headers on. I was out last weekend (cold weather) and it was still overheating unless I was going 45+ for a long streach.

Well i took it to a radiator shop and they where pretty confident it wasn't a cracked block/bad head/gasket

They are convenced its a flow problem too.

Today I flushed the system for about 30 minutes and refilled it with a good antifreeze/water mix. Also added a quart of that cooling additive that helps lower boiling point..

Something similar to water wetter

Originally posted by GreenZ28in503
Seeing as how the stock LT1's WP is cam driven, and he has said he has an electric WP, I don't see that being the problem. :)



:o Ugh, excuse me while I locate my BRAIN. :(

welp.. Still overheating

I guess I'm going to tear it down and start all over again

Any ideas?

I dont know about you but before I pull my heads to check the headgaskets I am going to run without a thermostat for a while and see if that helps. Its summer time now so it wont hurt anything.

put a CSI pump on the car today and its overheating still from what i can tell its still overheating..

It did have a small leak... its probally still gonig to oveheat though

really does sound like a flow problem man..

the heads on that block wouldn't happen to be stock, would
they?

if they're not, well this is just a shot in the dark, the coolant
passages may not be drilled properly in the heads, causing
bad flow..

it would only happen if someone puts heads on that block
that wern't really designed for that revision block..

like on big blocks, Gen 4 heads won't work on Gen 5 or 6 blocks
because of different coolant passages...

good luck, man.

I had very similar problems as you did last year.

If it was 30 degrees outside My coolant temps were like 175, then when it got upto 80 degrees outside, My temps would have raised up to 195. And would continously climp as the weather got hotter and while driving on the highway. I tried the manual fans switch, running 80% water and 20% Coolant, a new thermostat and water wetter with NO Luck. My Radiator had about 110K on it as of last summer and was pretty filthy when we pulled it out of the car.

Over the winter, We (me and My friend) swapped out my old motor for a new 383 motor. We accidentaly broke my old radiator in the process. Fred (Injuneer) came thru with his old radiator that had about 60K mile on it and he had cleaned the fins prior with a compressed air. My Friend and I also clean out the AC condensor (trying to removed all the debris from the fins of the AC condensor). Now, with Freds cleaner radiator and My cleaned AC condensor with a blown 383 motor, On a 30 degree day, I would see 173 coolant temps and on a 80 degree day my temps only rise to 178 on the highway and stay there. Mabee you should clean out the fins on your radiator or if your radiator has too many miles, or you can buy a newer one in the forsale section. I know it worked wonders for my car.

Hope that helps,
Claude

Actually the radiator was replaced with a brand new GM delco unit last summer. It seemed to fix it for a while but came back.

I plan on having it flowed/rodded out if it still overheats.

my car has been getting hotter than usual as well but today i just found out that the STUPID black plastic thing that sits in front of the radiator, actually i believe it sits infront of the condensor but since my a/c is removed that stupid black thing made its way to sit dead flat on the radiator and that was causing air not to get to the radiator :mad: i swear the STUPIDEST things sometimes :rolleyes:

sounds like you have got everything replaced though! ONE thing i would definately suggest is i know on my CSI pump there is a BLACK wire (GROUND) and a BLUE wire (POSITIVE) make sure those are correct cause if you install them backwards the pump will spin backwards and cause the water to go the wrong way! also maybe you should pull the pump off and verify that the fins are turning the correct way neways! just a thought

Since you said it wasd getting hot on the interstate, have you made sure that all of the factory air ducting is still in place and working right? Make sure the air dam isn't damaged or just flapping back...or completely gone. Also the duct work behind the facsia that directs the air into the radiator, still there and working right?

I would think after replacing the water pump, radiator and stat. that the only thing left to give any kinda of blockage would be the heads or block. If they have been cleaned right and it still does it, and you think its a blockage problem to me the only way to fix it would be to tear it all apart and hot tank the parts. Before I did that I would triple make sure the gages are working right, pull the stat completely and pressure test the system and the cap. Along with everything else one last time since it would take a little while to do it.

One other thing....what about the head gaskets themselves? Might be the wrong part or some of the holes might be getting blocked.

You said you tried a new GM water pump as well, not using the electric motor? Just wondering if the electric pump can't flow enough for the motor.

Check your air dam if it has seen a few driveways in it's day and is now deformed it will not direct air properly. Also check to make sure both Black plastic pieces(air-Guides) and properly in place. Make sure that the three black plastic clips that hold your bumper cover to the rebar underneath are in place. When they are together with the air dam and the air guides. It will make more air flow to the radiator. It will cause cold air from the ground to be directed to the radiator, kinda like the top side of a wing on an airplane. I know that these are essential to froper air flow.
Chris

This may sound stupid, but make sure you blead the living hell out of the system. When you think you're done, blead it again.

My car would continually run hot or over heat & no amount of flushing or turning the fans on early would help. There was maybe an ounce of air or so in the system & that's what caused it.

Also, make sure all of the stupid plasic things around the radiator are on. They do help.

I finally figured it out.

I had put a brand new Delco radiator in the car last year so i figured it must be good. Turns out it had clogged. THe guy at the radiator shop said it was not unusual some brand new radiators are clogged.

I put yet anthor delco radiator in it and it has never stayed colder. I mean with the ac on it will hardly hit the first tick mark in 100 degree weather