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.

 

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... .

 

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.