I HAVE A 99 CADILLAC STS WHICH JUST BEEN IDENTIFIED AS HAVING A HEADGASKET PROBLEM, MANY SHOPS WONT EVEN DO THE REPAIR. THE CAR DOESN’T RUN HOT ALL THE TIME, BUT IF IT IDOLES FOR A FEW MINUTES THE TEMP GOES SLIGHTLY UP. I BEEN TOLD TO TRY TO USE HEADGASKET SEALANT. ARE THERE ANY SUGGESTONS
Mind you I did not do any of the work myself but I worked for Cadillac around 1998/2000 and we had several heavy line mechanics that were daily working only on Northstar engines, but for oil leaks. They have what I saw a complicated multi piece engine case design.
General Motors used something called engine coolant tablets in the coolant of those engines, as well as a number of other Cadillac engines in the past. Many shops will flush the cooling system and forget or neglect to add some tablets to the system. This will sometimes cause problems like what you are having. These can be had at any auto parts store. Ten dollars will get you more of them than you will ever need. Try adding some of those to your system, following the instructions on the package exactly and not using too many of them. This is the only thing I would add to your cooling system, outside of the usual coolant and water.
“ARE THERE ANY SUGGESTONS” Stop using CAPS…Did a professional mechanic diagnose the problem as a head gasket or what? How many miles on the car? Has it EVER been severely overheated? Is coolant being forced out of the recovery tank?
The Northstar engine was designed by Lotus to be a racing engine… Keeping with Lotus tradition, it has a two-piece crankcase. GM bought Lotus and used the engine in the Cadillac car line for 10 years or so… It has been fairly reliable if properly maintained…Because of the chain-driven overhead cams, few mechanics will risk doing major repairs on these engines because the probability of a satisfied customer is not very good and costs are very high…To do your head gaskets, the engine and transmission must be removed from the car…