If you can keep your hand on the exhaust manifold it's probably cool enough to rinse with a hose.

Even on a hot engine it should be okay to use a light spray and keep it moving. There won't be enough water in one spot at one time to cause a big temperatrue drop. Do this at your own risk, of course.

Can you get a hose from your house water heater to the engine bay?

Sixto
95 S420
87 300SDL