Quote:
Originally Posted by bjm
Actually the 5.7 Hemi with MDS came out in 2005 in US.Its not actually variable valve timing but deactivation of a number of cylinders when cruising etc to give better fuel economy. For whatever the reason there seems to be little info re cam lifter failure of this early motor even though nearly identical in all respects to the present day engine.In the last 3 weeks I have seen at least 3 late model WK 2 SRT8 s on Gumtree advertising new cams etc fitted. Oils ,service intervals ,etc probably have a bearing on the cam lifter failures in these motors. The hemi engine rebuilders here and in US I contacted all said in their opinion the block has two basic problems. ,low oil splash on cam and cam lifter angles .Suffice to say the problem is still happening on rebuilt motors with aftermarket cams ,lifters etc
|
Yep the Gen 3 hemi got MDS in 2005, but then got VVT in 2009.
It sounds like there were quite a lot of changes in the VVT engines, largely around oil supply to the valvetrain.
See
https://www.knowyourparts.com/techni...-hemi-anatomy/
Just a random article I found via Google'ing, but the info in it seems to be repeated in many other articles/discussions.
A particularly interesting line is;
Quote:
|
Chrysler included provisions for a “multiple displacement system” (MDS) in the original design, so the main oil galleries were used to supply oil directly to the solenoids that disabled the lifters and the oil for the lifters came down through the pushrods from the rockers up topside. |
I wonder if that means the lifters in the VVT engines are
not lubricated directly through the pushrods, which I've seen a couple of builders claim.
That could be a significant difference between the non-VVT and VVT engines and explain the apparent lack of lifter failures/cam wear on non-VVT engines.
At-least that's what I'm hoping for, since I have an '06
.