Cadillac Repair: 94 caddy deville, head gasket problem, coolant temp

Question
QUESTION: I have a 94 caddy deville 4.9 engine. the symptoms are as follows. runs rough like its missing on multiply cylinders only at idle. also if the radiator is left with the cap off the coolant will start coming out of the opening. any ideas please help

ANSWER: IS or HAS the CHECK ENGINE light ever illuminated while driving the vehicle and or has any other lights illuminated or any messages from the message display center ?.

What work or diagnostics of ANYKIND WHAT-SO-EVER have been performed on the vehicle trying to fix this problem ?.


What happens if you keep the radiator cap ON all the time ?. Does the engine over heat ?.

---------- FOLLOW-UP ----------

QUESTION: no check engine light , only message is service ride control. fuel pump, fuel filter, ECM, plugs, wires, cap, rotor, distributor no luck so far.  as far as overheating I don't have a coolant temp gauge and i haven't seen any messages about over heating.

Answer
Since this engine has a long history of head gaskets leaking due to loose head bolts which cause combustion chamber pressure to get into the coolant system, I would recommend performing a radiator and cooling system pressure test and a cylinder leakage test on all the cylinders to determine if it is a head gasket problem.


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