Hello all,

Slight engine chatter when its first started, lasts about a minute then goes away... most of the time when it is first started there is no chatter, then 30 seconds or so later it will chatter for a minute and then stop, havent checked to see exactly where it is coming from..sounds like dry valvle chatter to me, is this common?

Oh, and its an 08 4.7 in a QC dakota.

Thanks in advance.

 

Hydraulic valve lash adjusters. Very...very common. Read below.

A hydraulic lifter, also known as a hydraulic tappet or a hydraulic lash adjuster, is a device for maintaining zero valve clearance in an internal combustion engine. The conventional means of adjusting valve actuation always requires a small clearance to be left between the valve and its rocker or cam follower to allow for thermal expansion and wear. The hydraulic lifter was designed to ensure that the valve train always operates with zero clearance, leading to quieter operation and eliminating the need for periodic adjustment of valve clearance.

The hydraulic lifter consists of a hollow expanding piston situated between the camshaft and valve. It is operated either by a rocker mechanism, or in the case of one or more overhead camshafts , directly by the camshaft. The lifter is filled with engine oil intermittently from an oil gallery via a small drilling. When the engine valve is closed, the lifter is free to fill with oil. When the valve is opening and the lifter is being operated by the camshaft, the oil feed is blocked and the lifter acts just as a solid one would, oil being incompressible.


Disadvantages
There are a number of potential problems with hydraulic lifters. Frequently, the valvetrain will rattle loudly on startup due to oil draining from the lifters when the vehicle is parked. This is not considered significant provided the noise disappears within a couple of minutes, typically it usually only lasts a second or two. A rattle that does not go away can indicate a blocked oil feed or that one or more of the lifters has collapsed due to wear and is no longer opening its valve fully. The affected lifter should be replaced in the latter situation.

In certain circumstances, a lifter can "pump up" and create negative valve clearance so that its valve cannot close. Typically this occurs in the most upper rpm range of an engine, and limits the engine's performance. Lifter pump-up is serious, as there may be interference of the valve with the piston or, burned valves may result. In all cases it is important to follow the manufacturer's recommendations for oil viscosity and quality.

 

My 3.7 V6 has the chatter you describe. I have 45,000 miles on the truck now and it still does it. The funny thing is, it does it much more on a fresh oil change, once the oil ages it doesn't seem to do it much at all. I do yearly oil changes with Mobil 1 EP.

 

Thank you very much... My truck acts exactly as described in the article... that gives me peace of mind, ABSOLUTELY love the truck, happy that what I am hearing is pretty common.

 

That is VERY helpful...I have only owned the truck a few months, and when I bought it there was about 1800 miles left till oil change..which just ran out last saturday and I had it changed.... and yes, I think it is a bit louder than before. Not sure what it calls for, but the 08 Jeep Grand Cherokee I traded in was 5w-20... id say that is pretty thin until it gets some miles on it.

Thanks for the reply, again it was very helpful

 

I think it varied by locale... look at the oil cap and it will tell you the the weight. I am pretty sure though the newer trucks are 5w-20, my 07 is this, and its 6 qts

 

Definitely check your cap, as Bolt mentioned it varies. My 2005 calls for 5w-30 and both he and I have the non-HO 4.7L.

 

I have the same issue with my truck. it seems to have gotten worse since I switched to synthetic. I've also noticed it ticks occasionally when I'm near or at idle after it's warmed up. It has me wondering if I also have an exhaust leak.

 

I occasionally hear the same thing, not often, but every once in a while if I am at idle speed like coasting through a parking lot, I hear it start and then it quits. its never as loud as when I first start the truck though.