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General Category => General Discussion => Topic started by: John A on May 31, 2020, 11:41:58 AM
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Uncle Tony on Hemi cam failures.
https://youtu.be/dI93-Zdx_nY
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You should see the issues some BMW R1200 LC (liquid cooled) owners are having with soft cams!
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Interesting story...I remember the first few years of the Pinto with the cam failures on the 2000 cc ohc engine . And the wide spread Chevy V8 cam failures in the 70's. Once the cam lobes wear down the metal gets imbedded in the bearings and piston skirts...So even with new cam and so on the engine life is usually compromised.
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I am a big fan of Uncle Tony. I watched that one with great interest as my wife's Durango is Hemi powered. Chrysler tried to design a better valve train and got bit by something unexpected. Idling and low speed operation seems to be the main culprit. Cop cars are especially prone to the problem due to hours of idling.
kk
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I meant to add that Uncle Tony looks and kind of comes across as the ultimate hayseed but he is very smart and knowledgeable. I have learned a lot from him even after all the years of wrenching myself. Uncle Kathy also does a great job with the camera and microphone.
kk
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I did some searching and found the cam failures weren't due to soft cams but due to the roller lifter not rolling on the cam due to lack if a fiction between the cam face and the lifter.
What caused this?
Oils that don't have proper anti wear ingredients. Chrysler changed the oil requirements.
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According to Tony it is due to a lack of oil. In a nutshell, Chrysler dedigned the block in a way to get better geometry for the valve train. By doing it the way they did, it doesn't get a lot of oil dropping down from the rockers on to the cam at low engine speeds. It has been suggested to add some squirters to the oil gallery but there isn't much space to do so. The engine is actually a very good design but this was an unforseen circumstance. This kind of thing has happened to every manufacturer on the planet, I am sure. Failure has been somewhat common but I don't think it has been widespread. I think the Hemi is a short timer in the overall picture of things due to Corporate Average Fuel Ecomomy ratings.
They are working on a couple of new engines. There is a lot of talk about a turbo straight six in the works. Also possible putting a turbo on the Pentastar V6, an excellent award winning engine for several years now. Fiat Chrysler is in the process of finalizing a merger with Peugot who builds some excellent platforms that we may see here in the near distant future with Mopar badges.
kk
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I know hemi owners and never heard of cam failures. Maybe they never idle or drive slowly? The first couple years supposedly dropped valves due to broken valve springs.
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Sounds like another theory in search of a problem. More likely to be poor lifter bore machining and alignment to the cam axis.
Ciao
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Sounds like another theory in search of a problem. More likely to be poor lifter bore machining and alignment to the cam axis.
Ciao
There is trouble with them, I thought UT had the best theory. https://youtu.be/inPUz3pCHa0
https://youtu.be/7OsxOd4x8LU
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Worn BMW 1200 LC cam:
(https://i.ibb.co/LdbP9jy/r1200gs-cam-at-3200-miles.jpg) (https://ibb.co/LdbP9jy)
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The most numerous OHV roller tappet by far is the LS Chevy V8 found in their trucks since 1999, vettes,and some cars a bit earlier. Outright cam failures are rare. But lifter failures ,especially with the cylinder cut out on some is more common. LS is not fussy about motor oil so long as it's changed on schedule .
With the cam spinning at 3000 rpm, I always wonder if those little wheels are spinning as they were designed. I do know if the little wheels get a bit cocked it all goes to shit pretty quickly.
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The most numerous OHV roller tappet by far is the LS Chevy V8 found in their trucks since 1999, vettes,and some cars a bit earlier. Outright cam failures are rare. But lifter failures ,especially with the cylinder cut out on some is more common. LS is not fussy about motor oil so long as it's changed on schedule .
With the cam spinning at 3000 rpm, I always wonder if those little wheels are spinning as they were designed. I do know if the little wheels get a bit cocked it all goes to shit pretty quickly.
I think those little wheels are done for if they skid, even just a little.
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And that looks to be the problem on some MoPar hemis.
https://www.chargerforums.com/threads/answers-5-7l-hemi-camshaft-professional-failure-assay.382357/
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And that looks to be the problem on some MoPar hemis.
https://www.chargerforums.com/threads/answers-5-7l-hemi-camshaft-professional-failure-assay.382357/
So that's why you mentioned the oil that gives "traction" so the wheels keep spinning.?
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Basically, yes. If there isn't any stiction the roller won't roll. And with oils of today with less anti wear additives the cams and rollers fail.
Notice the guy said it didn't fail due to lack of lubrication but failure of the oil.
So the THEORY of lack of lubrication was disproved. And Chrysler admits it by changing lube spec.
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Did the oil spec change fix it?
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Seen or heard of any problems? :boozing:
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There is trouble with them, I thought UT had the best theory. https://youtu.be/inPUz3pCHa0
https://youtu.be/7OsxOd4x8LU
Interesting, thanks. So its simply failed lifter bearings. Maybe just substandard quality.
Ciao
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I know hemi owners and never heard of cam failures. Maybe they never idle or drive slowly? The first couple years supposedly dropped valves due to broken valve springs.
The last couple of years at work before I retired, I had to trade in my Crown Vic for a Charger with the 5.7 Hemi engine. I think it was at around 80,000 miles that the Charger started running like crap. I took it to our garage and one of the mechanics popped the hood and listened for a few seconds and then closed the hood. He told me it was the cam and lifters. I was told to drive the car until it died because the parts from Chrysler were back ordered because of some many failures. They finally did get the parts and fixed the engine. By that time, it seemed reluctant to start immediately and had a weird idle, sort of bouncing like a Harley.
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If I recall correctly Yamaha had a starter slipping issue caused by using oil other than Yamalube..if you upgraded to synthetic the bike would not start on the button.
Best,
Peter