4.3 Milky Oil

[tylerdale101]

I bought a 4.3 it has milky oil. I can’t see a crack on the exterior of the engine block. The exhaust manifold is cracked though. Could water get in to oil from exhaust manifold. Is there a way to test engine if the block is internally cracked? Thanks for your help am a high schooler and trying to fix it up.

 

[Scott Danforth]

Drain and pressure test the system. You may have freeze damage inside the motor or from the bottom side of the intake manifolt.

Could be from exhaust too

Pressure test the cooling jacket
Perform a compression test
Perform an acetone test on the manifolds

 

[Rick Stephens]

Most common location for a 4.3L to crack is in the lifter galley just above the lifters. So yeah, before disassembling the motor, block off the lines going to the manifolds and pressure test the block. I blew it once with a water damaged engine by disassembling it before pressure testing.... you never REALLY know until you reassemble and run it or pressure test it whether there are any internal cracks.

 

[Scott06]

Likely if the exhaust is cracked that the block wasn’t winterized and is cracked where rick suggested, would add that also check water cross over under thermostat block tests ok

I think there is a plug in this crossover that could easily be forgotten