tree95zlancca

95 Z28 LT1 w/ A4. Thought my water pump was shot because when I would try to start the engine cold and cap off the radiator, anti-freeze would blow out the cap. So I swapped the water pump and lo and behold, same problem. My guess being a tree trimmer with a part time job as a mechanic working on my wife's Z28, is a blown head gasket. Yes there was water in the oil. What is the best solution? Rebuild or head gasket change, or new engine. Any help will be greatly appreciated.

grabbem88

you can rebuild..or atleast get the heads leak tested and check for flatness,and put some new head gaskets on it and put it back together and hope for the best,but everytime i seen water get in my oil i was rebuilding it,cause a couple bearings thought it would be nice to tear the crank up..

if you caught it and didn't drive it a lot and don't have internal havoc going on i'd drain the milkshake out of the pan and put fresh in it,and pull the heads off and get them checked out..

bw_hunter

Do a compression test before you do any disassembly.....there are more ways to water in the oil than head gaskets.

cthomson21

It would make since that it is a head gasket though.......Aluminum heads and cast iron expand at different rates which is hard on gaskets.......But a compression check could be the best way to see....

ACE1252

Last time I had that kind of problem was on a 3.1 V6('90 Z24). The engine would blow coolant out the overflow tube and onto the ground. The problem was a crack in one of the cylinders. That being said, the Chevy dealership said, for some reason, it was common on those V6 blocks. That car had a closed cooling system.

First....lets make sure we are not talking about normal operation of the cooling system. As the engine heats up, coolant will flow from the radiator and to the coolant overflow tank via a tube in the neck of the radiator. It is what is known as an open atmosphere cooling system. The level in the overflow tank should go to the hot level when hot and then as the system cools down, the coolant will be drawn back into the radiator.

If you have a head gasket blown, the overflow tank may be filling itself up to a very abnormally high level....and then can't pull it all back into the radiator after cool down. I know you said coolant/water was in the oil...certainly not a good sign.

grabbem88

i had to reread your post...so you are saying engine cold radiator cap you start car and coolant instantly blows coolant out? did you change thermostat while changing wp?
there is a restriction somewhere for that to happen unless you got alot of air in the system and didn't burp or bleed out the coolant system..

now in saying this..and not discrediting your mechanical skills..did you ever change the oil after water pump swap?..

no matter what i always change oil after intake,head and water pumps<on fords because coolant always finds there way in the oil pan no matter how well you drain the coolant system...

tree95zlancca

I did change the oil, but because autozone gave me the wrong thermostat, I left the old one out. I left the radiator cap off when i went to start it for the first time. It would not start and blew coolant out the top immediately.