Little tapping when start up

[Bru]

You could take the heat shields off and look for black carbon tracks around the exhaust manifold. FelPro makes a nice thick beefy exhaust gasket. The exhaust nuts are notorious for rusting to the stud and then you end up stripping the stud in the head instead of tightening the nut. If you want to, apply a small amount of penetrating fluid to the nuts and let it soak awhile. Try loosening a quarter of a turn and see if they move together or separately. If they are frozen together try backing out the stud and nut together then soak in penetrating oil. Break them loose by grabbing the middle of the stud where there are no threads with a pair of vice grips. You may have to alternate using a torch and a cleaning with a wire brush then adding more penetrating oil it comes loose. When they separate clean the stud threads with a wire brush. Keep track of which end was in the head. Use a jam nut to reinstall the stud. This is easier done with the exhaust manifold off. Then you can tighten 2 exhaust manifold nuts facing each other temporarily to drive the stud in. Again, its aluminum so don't overtighten. Worst-case scenario is you have a rotten stud hole or threads are pulled. A repair consists of drilling out the hole and tapping new threads and using a "Heli coil" repair. Apply small amount of anti-sieze compound and torque than nuts gradually using the pattern in the repair manual and torque to spec.

Is your oil old or thined out? Use the proper viscosity for the temperature range are going to be in encountering. I also replace a quart of my oil with Lucas oil additive which is quite thick and a lot like STP but not that thick. The oil pressure with 20% lucas oil is a little bit higher than otherwise. Another thing that can make a ticking sound is a loose spark plug. Make sure they are torqued down to 13 - 16 ft. lbs. Another thing you can check is the valve lash. Since Supras do not have hydraulic valves, they are adjusted using a wafer shim that rides under the camshaft for each valve. It's best to have a manual to follow the procedure to get the measurement correct. Valve lash clearance measurement is accomplished using flat feeler gauges on a cold engine. Excessive clearance here can cause a ticking sound. If you're going to replace a shim, it's helpful to have the S shaped specialty tool to hold the valve opened when removing the wafer shim and a mechanic's magnet. You don't want to scratch the camshaft face with screwdriver or get your finger pinched. You also need either micrometer or vernier caliper (and know how to use one) to get a measurement of the thickness of the wafer in the cases where there is excessive clearance and want to calculate the replacement shim to order. If your cheap, like me, you can play musical chairs with the shims. Find one that's tight on the spec. and see if you can swap the loose one to bring them both in spec (or at least closer than they were). The thickness of the shim and the valve lash is the total distance. I have even sanded the backside of shims with worn emery paper on a flat surface to shave off one or two thousandths. Just be sure the sanded side stays down and not riding against the camshaft. Hopefully it's not a connecting rod bearing or wrist pin. Thicker oil could buy you a little time. Carbon buildup can cause preignition taping but that's more likely on a hot engine. I use redline SI-1 gas additive (Amazon.com). Try one bottle full in a tank of gas for a quick cleanup and then to 2.5 oz. per tank there after. It comes in a 15 ounce bottle.

Good luck