I recently just purchased a 1996 sc400 with 155k miles as it’s been a car I’ve wanted for 5 years now. It has a stack of maintenance records from the previous owner and I was very pleased to find that along with the timing belt being replaced. However I have noticed white smoke from the exhaust and I smelled the smell of a burnt head gasket. The oil looks good and the filler cap has no residue, however my coolant was low so I added water and ran it for 30 minutes and let it cool, after opening the radiator cap it looks like how oil usually does in water. The car doesn’t over heat. How difficult would it be to do a head gasket at home? Is there a chance the block is warped as it’s aluminum? Would a headgasket stop leak have any chances? I haven’t even registered the car and I’ve just found this out?

 

Don't use any stop leak product. Head gasket replacement is a major project and to do it properly the block and heads will need to be checked for flatness and ideally the surfaces machined. Have you torn down an engine before?

 

UZ engines are not notorious for blown head gaskets and at that relatively low mileage it is even more odd just the gasket failed. I'd say confirm the gasket is blown with a compression test and/or coolant system test where you expose the test fluid to air in the overflow tank to see if exhaust gas is detected. If the engine got super hot it will likely be much more than just the gasket that is damaged. The heads could be cracked or warped and the internal parts of the engine like the cylinder rings and bearings could be damaged. If you plan to just daily drive or weekend cruise it you are better off doing major maintenance (timing belt, tune up, water pump, belts/hoses, etc..) on a good known used engine and swapping it out. Unless you have your own machine shop and DIY, the cost to fix it the right way will not make economic sense.

Try and use as many OEM Toyota parts as possible with an engine swap since they have kept these cars going 20+ years in many cases. Parts support is drying up from Toyota for these cars so get what you can while you still can.