once in awhile when I start the truck for the first time in the morning for the first second or so I have get bearing noise, as if the engine is knocking. the truck is a 2008 with only 40000 miles. dealer says it is normal. But no engine should have a knock when starting. BTW I am not giving any gas at start.

 

If you have the 3.7 or 4.7, sad to say it is normal. What's happening is the engine needs to build up pressure and get oil to the rocker arms. Until then, it's going to make noise for about the first 5 seconds. I agree with you no engine should make that kind of noise, but these engines do.

 

maybe that is their way of making sure the engines will not last so you have to buy a new one every soo often....

 

Mine has piston slap at start up, Im not sure if its the same as your being noise. Its a distint tapping/knocking from the block. Everything I have researched says this is 100% normal, and even your newer low mileage cars will experience this, especially in cold temps. If this tapping doesnt go away shortly after start up, you have an issue. From what I understand, every engine will have some piston slap.

IMO, this is why it is important to let your engine idle for a minute or two (in the winter even longer) before throwing it in gear and driving. You gotta preheat the oven a little

 

Mine does out too...bugs the crap out of me. Sounds like my engine is crappy...but our does go away after a few minutes.

 

If it lasts more than a few seconds, it could be a leak at the exhaust manifold due to a busted bolt.