I bought a second hand 740(91'), it runs good at first, but when I get it back from the auto repair store where I ask them to replace the engine belt, and replace the seal for engine oil system, the car start to leak gas.

but it only leaked twice, and all on the night. when the engine is completely cooled down.

it never leak at the daytime. and if it leaks at night when we drive it for several minutes or drive it at higher speed(>55) for a while or restart the engine the leaking will stop.

but I do see there is leakage around one of the fuel injector.

my question is:

is there any seal, O-ring, or pad where the fuel injector plugged into the cylinder.

I guess maybe it will be either the injector died or the seal or O-ring is out of work.

will anyone who met similar problem or knows about it, give me some direction?

thank you very much.

thanx again.happy new year.

Lux