My grandpa has a 91 Deville. Here is the problem the coolant is overflowing out the recovery tank. It is also low on oil. He thinks its a blown head gasket. There is no sing of burning oil. Or any coolant in the oil pan its self. still has all its power dosn't even run rough. I think its a matter of checking the oil and a bad radiator cap that is the problem. Any ideas would help thanks

First check for coolant in the oil and/or oil in the coolant. If that's OK then try proceedfrom there as you outlined.

First check for coolant in the oil and/or oil in the coolant. If that's OK then try proceedfrom there as you outlined.

i found out that there is oil going into the coolant. im thinking head gasket or the seal where the liner meets the block.

I would check for a bad intake gasket first.

i found out that there is oil going into the coolant. im thinking head gasket or the seal where the liner meets the block.


A failed intake manifold gasket is not an uncommon issue on the 4.9.