i have been reading on here, for a few weeks , but finally signed up tonight, first off my name is jamie, and i'm a noob! also a noob to cadillac. for the last 9 years i have been a lincoln mark VIII guy but i could not pass up this 97 catera i just bought. the car has 76k on it, 1 owner car and i knew when i bought it that the coolant tank was full of milky sludge. the car runs mint and the actual oil looks perfect, so i'm leaning away from head gaskets. i have read here that the engine oil cooler/heat exchanger is the culprit most of the time. today i pulled all the hoses off and took out the fan and radiator and started flushing water through all the holes trying to get as much sludge out as i can for now. i just want to make sure that i am heading in the right direction. from what i have read i need to remove the intake plenum and unbolt the plate that covers the cooler to get the cooler out. if the cooler is in fact bad will it be obvious once i remove the plate in the valley on top of the block. will the coolant also be milky inside this hole where the cooler is? before i go ordering any parts i just want input to this dilema before i waste time and money finding out it might be something more involved or very expensive. i like the car and my wife does too and i really would like to get it up and running for her. i know i will probably have to flush the coolant out a few times after i get it back together to get all the sludge out i'm sure its going to take some time to get it clean again but thats ok. i just want to be sure i'm not wasting my time on this car. any help would be greatly appreciated as i said when it comes to this car i'm totally clueless. thanks all.