wnycec

So I told my cousin (soon to be UTI grad) to come over and help me out with replacing my spark plugs this weekend.

He doesnt have much experience with MB's but I figured he should manage just fine. So after much hassle (damn the cable wires from the coil packs were hard to get off) we got the plugs replaced. Now the only problem is that I have a hissing sound coming from the engine as soon as I turn it on. I immediately turned it off and decided to talk to you guys here.

Could anyone help me out with this - did I not tighten the spark plugs enough? I pushed the wires back onto the spark plugs as hard as I could. The only other thing I really might have screwed up could be the metal tubing on the driver side of the engine which connects to the low side port for the AC. But I just pushed up against it when trying to maneuver the plugs into the holes.

Any advice/insight would be appreciated.

Jays_Z

Check your hoses. vacuum lines.

MarcusF

You may want to ensure the air cleaner/engine cover is securely around the MAF. If it's crooked, it may not seal properly. That vacuum noise would sound like a hiss.