Chrysler Hemi 5.7 6.4 class action re lifter failure.

[bjm]

Originally Posted by Jeeper6

The ole "Hemi ticK' as a lifter or two fails.

My previous WH Overland had the 5.7 Hemi engine, it had 194,000 kms on it when I sold it, that Hemi just purred.

I only sold it and moved to the diesel as the standard 75 litre tank meant cruising from servo to servo much of the time, and when going away with the camper I always had to carry additional 40 litres of petrol so as to be able get back from where I went! Petrol ain't the best to be carrying a round in jerry cans!

I always used Nulon 5w 20 in that engine as recommended. It just ran better on the Nulon stuff than any of the other oils I tried. If I used higher spec such as 5w 30 the MDS wouldn't operate properly and the OBD read would come up with an "incorrect oil viscosity" fault code. The MDS needed a thinner oil to operate effectively...a thicker oil and the MDS wouldn't kick in reliably.

The MDS could have had some effect on the failures, but I read an article some time back by an engineer who reckoned the MDS really made no difference to the roller cam follower failing.

The rollers would starve for oil and could in some cases seize and begin to wear the cam lobe down. Hence the tick as that cam follower got it's turn to open a valve. usually the tick would disappear at revs....but ultimately the engine would develop a miss.

He maintained that the main reason the followers failed, was due to the engine design by Chrysler to shorten the valve train push rods so as to achieve better valve opening with less push rod bend...all assisting fuel economy allegedly.

To do this they set the camshaft higher in the block which was further away from the crankshaft. The cam followers largely rely on oil spray from the crank for lubrication. They also had a new oil gallery running under the camshaft. On top of that due to the higher camshaft the flatter angle of the lifters in the block needed to work with the shorter push rods also hindered oil running down the lifters to oil the rollers.

These modifications to the original Hemi motor layout he claimed contributed to much less oil spray reaching the cam lobes and followers...especially at low revs such as crawling in traffic where oil spray was virtually non existent....and at idle.

His answer was to ensure the engine doesn't lug too long at low revs, to use a lower gear to keep engine revs up, or make sure to run the engine up to at least 1000rpm from time to time in traffic to get the oil spray lubrication up to the camshaft roller followers. Never idle that engine longer than absolutely necessary.

I followed that advice and wouldn't idle the engine if I could avoid it, and would make sure especially at start up when things were a bit dry, once oil pressure was up to warm it up at around 1000rpm...not a 500rpm idle.

The same problem is occuring with the performance GM V8 s with roller bearing
cam lifters. Various non genuine manufacturers of replacement lifters are
also having failures. There are guys in US who have done a huge amount
of research on the failures. The only consensus is that the needle bearings are
failing ,then the rollers turn into solid lifters ,bingo to camshaft wear where lobes
worn down to virtually nothing.My view is it could be a combination of a number factors not with standing roller lifters may not be capable of handling the power output in the Chrysler and GM motors.

[jeepsgofaster]

I've researched this extensively and my conclusion is that like crd's it's emissions compliance that has created this flaw in eagle head engines.

The previous gen III hemi never had this issue this is proof that the engines inherent design is not flawed as many will try to convince you. IMO it's not the cylinder head either. When it comes to pushrod, rocker lay out and valve placing ect. All the things the lifters and cam care about are carried over from the previous engine, so no changes there.

My conclusion is that this issue is purely a lubrication issue caused nearly entirely by 3 factors.

Number 1 being that manufacturers are constantly trying to reduce oil pump volumes because pumping oil is considered a paracidic loss. When your focus is emissions paracidic loss is your enemy. In this case it wasn't a case of reducing oil pump volume. It was a case of not increasing it enough to accommodate other new emissions equipment, being the vvt, mds and crazy oil recommendations.

Number 2 is the way the mds shuts down cylinders is by collapsing some lifters, it does this by sending oil pressure to the body of the lifter. But when you idle mds is not active so oil to the body of the lifter is reduced to keep it engaged. Couple that with the recommended stupidity thin oil that is by this time hot and even thinner even an adequate oil pump would struggle to keep sufficient oil supplied to the restricted lifter bodies. Oil especially thin oil is like water it'll take the easiest path and that will be through bearing clearances ect.

Number 3 is the rediculous oil recommendation for this engine. No engine you care about should be running anything less than a 30w oil imo. If you're towing or driving spiritedly 40w and the final nail for the oil recommendation is that it's an enviro spec oil meaning no zinc or any other elements that maybe able to assist the lifters in a low lubrication situation.

2 more contributing factors are that these engines run so smooth the std idle is only 500rpm which means the oil pump is turning slower at idle than a lot of other engines and the running temp on these engines is so high for emissions reasons thining out an already crazy thin oil.

Sent from my CPH1921 using Tapatalk

Sent from my CPH1921 using Tapatalk

[jeepsgofaster]

Just to dispell a couple of myths the high cam position and flatter push rod angle are actually not to do with emissions directly but has a side effect of slight efficiency increase.

The Achilles heel of the original old school hemi was the huge exhaust rocker arm that had to reach right across cylinder head. Back in the day this used to limit it's rpm capability because of the spring pressure required to overcome the inertia of such heavy rocker design.

Fast forward to modern hemi this problem was engineered out with the new cam position and pushrod layout now only requiring rockers of smaller dimensions than ordinary push rod v8s. Also the rockers are shaft mounted. Much better design than the 426.

Another myth is that pushrod motors rely on crank splash oiling at low rpm. This has never been true even back in the day. At low rpm there's not enough crank through to oil much of anything. This was an issue with aggressive camshafts in engines that spent a long time idling in traffic back then but oils had zinc in them to combat this. That's why failures were nearly unheard of.

Oiling for the lifters at low rpm comes from the lifter bores. Not crank splash so all the hooplar about about oil galleries in the road and high camshaft mounting position affecting lifter oiling at low rpm is unfounded.

Another myth, thicker oil upsets the MDS operation. Also bogas considering the srt 6.4lt and the normal 5.7 have completely interchangeable MDS components and lifters with one another yet the factory recommendation for the srt is a 40w oil.

Sent from my CPH1921 using Tapatalk

[Jeeper6]

5.7 HEMI Lifter Failure Could this FIX the lifter issue FOREVER? - YouTube

[bjm]

Another theory.The problem is nonMDS lifters failing as well in the JGC SRTs 6.4s

[downunderdave]

I have very recently bought a late 2014 Overland with the 5.7. The car has only travelled 22,000klms. Not used for the last 5 years and prior to that, only driven in Sydney, no highway. This means heaps of idling. I have ordered the Melling 10452HV oil pump from Summit in the US. Will use Penrite 10 Tenths 5w-30. I also want to get headers/extractors and a less restrictive exhaust fitted. This will avoid the other Hemi tick, being broken exhaust manifold bolts. Researching now re these bits, may just get an exhaust shop to modify.