Expert: Sean Halliday - 12/18/2006

Question
I have a 92 eldorado with a 4.9 ltr. engine.about a month ago it started running really hot so I took it to have the coolant system flushed.I'v replaced the thermastat and the radiator cap twice and its not really running hot now until it builds enough pressure to blow out of the cap and the coolant leval gets too low..tonight I drove it for about 5 miles and parked it and heard the cap seapping air..kinda hissing.I let it sit for about 4 hour and went to check the coolant leval...it started spraying out of the cap as soon as I loosened it.but it was cold as ice water..any ideas??

Answer
You will have to take it and have it tested for hydro carbon leak.That is the head gasket leak.It sounds like the gasket has blown and is pressurising the system.Its a major fault with caddys and if you have the aluminum block it is recommended that you remove the complete engine to have it resurfaced.So,i would make sure it is the head gasket first and its an easy way to find out as a good shop can tell you by using their sniffer ,thats the tool for smog tests, the wand that is inserted in the tail pipe for emissions tests.It is placed over the radiator bottle and will detect any carbon or exhaust fumes that are in the coolant,hence a leaking gasket.Another sure sign is water in the oil or oil in the coolant.