curacaoz28

94 z28 auto, overheating

replaced radiator, removed thermostat,hoses are fine, fans are working ok, check waterpump seems okk. bleed system for about 15 minutes.

As soon as we started the car in less then 10 minutes it went in red.(placing my hand on the waterpump it was steaming hot) all the water from the radiator dissapeared BUT the reservoir was still full (read somewhere that the pipe under the battery may cause that). Tomorrow i will replace the cap and check it.

What else may be the problem??

PS: how is the waterpump shaft suppose to feel like to be okk??

KW Baraka

iTrader: (7)

Check your oil.

KW

curacaoz28

oil is ok, no water in it, level is ok

z28jimmy

iTrader: (1)

When this happened to me it was a blown head gasket and there wasn't any coolant in my oil. But it sounds like you were doing a bunch of work on the cooling system. What was the original problem?

CFLFORMULA93

same here but hate to say it. i changed the radiator,hoses,wp, tstat, etc bled air and bled air some more but didnt fix it. mine ended up being a hg and i tend to think that if it gets that hot that fast. my oil was ok i supposes these hg can only leake on the exhaust side ?

curacaoz28

it was overheating

BALLSS

so how exactly did you "check WP"?
is it actually circulating water (sometimes the impeller shears off shaft)

if you are asking about the WP drive coupler...confirm the splines on the inside are not stripped or the drive spline on the wp drive gear in timing cover

curacaoz28

the waterpump was removed and the owner turned the shaft with his hand but the front cover was not opened

BALLSS

is this your car with EWP in sig...or another car with a mechanical WP?

if the "owner" removed a mechanical WP and spun the spline shaft by hand and it spun freely without making any noise than that WP is likely OK . If the impeller did shear off I would think you would hear something

There should be no play in the WP spline shaft

curacaoz28

correct, its another car,...what i found weird is that the although it was over heating and the radiator became empty, the reservoir (the one next to the battery) was STILL FULL.

CFLFORMULA93

if the rad is being drawn down with no signs of leaks isnt that even more reason to suspect hg? if you are losing water it has to be going somewhere ...whether that be leaking/intake being burned off or mixing with oil? any chance you have checked plugs for signs of a pressure washing? lol any symptoms of a hard start? mine gave out very slowly thought it was fine for a day or two....thought i might have an air pocket trapped but once the combustion chambers and/cylinders fill with water they will let you know. you could keep chasing parts bc most of them are cheap but a leakdown/comp test might be in order to prevent any further damage....ask me how i know....

z28jimmy

iTrader: (1)

Yes that is my understanding.. I had sweet smell coming out of my exhaust and over time a very little bit of white smoke. I also had one spark plug that was white-ish I believe.

CFLFORMULA93

for whatever reason it seems to be a common problem with our motors. reverse cooling or not they dont like to get hot and running @220+ for any kind of extended time will easily pop ....

curacaoz28

wauw okk, the car still starts okk, i read somewhere that if the 2 pipes just below the radiator cap are crossed this may happen.. i will check into that later

Heatmaker

If your missing coolant like that and you've checked everything it's probably the headgasket. You can still start and run the car depending on how severe the issue is but it going into the red so quickly is a giveaway that either something is wrong with your coolant flow or your engine is taking on water like the Titanic.

Seems like every GM car from the mid 90's is prone to coolant/gasket failure issues. The 3100 and the LT1 really like blowing gaskets but the LT1 F-bodies and C4's really had some idiotic cooling designs as in the air flow to the engine sucks... but now these damn things come with all kinds of vents and coolers for the motor. The guy that did the Opti probably designed the air flow system as well.