[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.