Compression deviation greater than 20psi - 1998 Toyota Camry

Could be an injector problem.
20psi should not be enough to notice.

Normal compression is around 125 psi per cylinder - - the real number is what the average is for all 6 with less than 20psi difference.

If the spark plugs were fuel fouled, you could have washed the oil off the cylinder walls causing the low compression.
Or the cam timing could be off because the timing belt jumped a few teeth, or the cam gear broke.
I would pull the fuel pump fuse or relay and try to dry out the cylinders first.
And re-check the timing belt. The serpentine belt would not have any connection to the car not starting.

could be the fuel injector if it is stuck open or shorted to ground. check the compression first on that cylinder. if the compression is good check the fuel pressure bleed off time. if the pressure drops more than 20psi in 15 minutes it very well could be a faulty injector.

compression should be about 150-180 psi with maximum deviation of about 20 psi between all cylinders. A compression test is not a very reliable way to test for headgasket leaks. It should be tested for headgasket leaks by using a chemical test caled a block test or checked with a device that can check for hydrocarbons in the coolant.

well first off you need to start by checking the compression on all 8 cylinders!!!! to rule out internal engine failure as oppose to jumped timing. its very rare that timing chains will jump especially a double roller chain. get a compression gauge take the plugs out and get a reading on all the cylinders. you should be no more then 10-20psi difference from cylinder to cylinder. but on the chevy motors if there is a problem they usually show well on a compression test! good luck post back up the results then we can go from there.

You are going to have to test the compression, then test the cranks sensor. You should be getting about 130PSI on the cylinders with no more then about 20PSI difference between all the cylinders.

Bad news. You may have a head gasket leak. Do a compression check on all cylinders. If you find one or more with a different compression (by 20psi or more) you may be able to use radiator sealer. If you still see or smell fuel in the water take it to a shop before it is damaged beyond repair.

Likely the cause is the opposite of what you are thinking. Oil in the radiator (engine oil) is caused by a blown cylinder head gasket. When that gasket fails it can overpressurize the cooling system by permitting compression from the pistons to enter. (cooling system pressure rarely is above 20psi...compression pressure is more like 150psi. That will cause the radiator tank to burst)

You should start by doing a compression test on the engine. They are loaner tools from autozone. Once you do that, if your compression between cylinders varies ~20psi, there is an internal problem with your engine. Could be worn seals or rings.