Ug so a new issue popped up on the wife's G35 sedan.

she parked it in the drive on Thursday, we moved it once on Saturday to blow off leaves, then on Sunday afternoon (heading to car wash) heard the most god awful lifter/valve clatter that I have ever heard.

Had her turn off the motor to check the drive belts, as at the time it sounded like a belt was ripping apart and strands of the belt were slapping against components under the hood.

With the hood open, I had her restart the motor and the motor got quieter, took out my stethoscope poked around the top end. The sound reminded me of the old hydraulic lifters on the old 60s engines where the lifters were not pumped up with oil and the rocker arms et al would clatter.

So I have to do the valve cover seals soon, so then would be a good time to inspect valve geometry.

Without delving into the engine manual....can someone describe whether this motor has lifters too and are they hydraulic and whether what I heard is a symptom of lifters going bad? can they go bad? What to check?

NOTE: this AM the motor sounded normal when she left for work.

 

Looked at the manual and some videos of the valve train....ugh...it appears to me that these lifters are not what I am used to ....without taking the motor apart and seeing for myself, I'm not sure how they work.

They appear to be an inverted bucket, not sure where oil would fill them up like the old hydraulic lifters.

My guess at this point that one or more lifters got stuck in their bore (carbon build up on lifter's edge?) and took a while to get loose and rise up and down.

any teachers out there who want to school me on this motor's valve train....please do so.

 

https://en.wikipedia.org/wiki/Hydraulic_tappet

 

@iideadeyeii

I know how a hydraulic tappet works in a rocker armed engine. What I don't know is how the lifters in THIS engine work.

do the lifters in this engine work the same way in that the have two pieces that spread apart with a spring in the middle....I've never seen one of these bucket style lifters before



Wikipedia's article is not the greatest...could stand to add some pic

But this statement seems to describe my symptom

""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 a significant issue provided the noise disappears within a couple of minutes; typically it usually lasts only 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."

 

These "lifters" do not appear to be hydraulic at all, but rather a solid piece of metal...they appear to come in varying thickness.

I assume that one would have to use a feeler gauge between the top of the 'lifter" and the cam lobe...then swap out the lifter with thicker or thinner height depending on gap.


I'll assume the gap measure measurement is done with no cam lobe pressure ....right? I'll check the EM.pdf

 

There is no gap. The link explains overhead camshafts. I wouldn't worry about lifter noise anyways. You can seafoam the engine/swap the oil with synthetic and call it a day.