I am wondering if anyone can help diagnose this. the past couple of days my truck has made a very unusual sound at startup. The sound occurs on the passenger side of the engine. it sounds like exhaust would with headers, but it doesn't have headers. I've only used Mobil-1 10W30 in Texas since the truck was new (20,000 miles). any help?

 

Blown donut gasket.

 

thats seems really unlikely to me, especially since it only occurs at start up.

 

Greg is right. Check the exhaust first. It does'nt take long at all for things to heat up and swell shut that close to the engine. Look for black streaks on the heads and flanges of the manifolds.

Mike

 

fortunately, the truck is still under warranty.

 

piston slap?

 

no, it's not the piston slap sound. its airy sounding, not the knocking of piston slap.

 

took it to the dealer since its under warranty, we'll see what they say in the morning.