A new one for me

8050 with approx. 5,000 hrs had a #6 exhaust seat fall out of the cylinder head, destroying the piston and badly damaging the head. Got the head welded up and completely refurbished and while running the valve tappets, something wasn't quite right with number six intake. Still had the oil pan off from replacing the piston and sleeve. Took a quick look at the camshaft and holy crap, the lobe to #6 intake valve is totally wiped out !! When tearing the head off of it I didn't pay any attention to the valve lash on any of the valves, but I assume the lash must have been pretty wide on that valve.  I am concerned about the newer Rotella oil that has been used in it maybe not having enough ZINC for these older flat tappet camshaft engines. Got some more investigating to do before I pass judgement on this one, but this for me is a first. My theory is with the intake only opening about half-way that particular cylinder and it's exhaust valve have been overheating (no overlap), causing the valve seat to loosen and eventually fail. Engine had just finished dragging 600+ bushels of corn on a 5 mile trip and was shut down for the day. Next morning upon start-up things went south immediately.

Please keep us updated on your findings and theories on this. I have wondered about the zinc content in rotella and wonder if we need to add zinc to the oil.

Exhaust seat is what fell out. Intake lobe is what is worn out, not damaged, just plain worn out. Not one bent pushrod anywhere. Lynn, this is a FIRST for me. Never have replaced a camshaft on any 2000 or 3000 series engines for lobe failure.

My 2 cents... we received a bulletin from our small engine mfgs years ago stating premature wear in camshaft/flat tappet due to the removal of zinc, selenium and copper from automotive oils which did not 'need them' due to roller tappets.  The small engine oils received a permit to include the "pollutants" and still have them .  We noticed the new Agco engine oil for  tier 4 engines had many less additives as it seems IV rotella  has as well (they charge more for less additives) .  I do not think the oil caused this issue as if it were the oil ALL the lobes would show wear - but I do worry long term as Al gore and his environmental minions strive to save the universe and make our old stuff suffer in the process.   

https://www.vitacost.com/dr-mercola-zinc-plus-selenium?

my dad had the same concern. I recall him trying to call some oil companies with this concern. I’ll have to ask what they ever did say.

Edited by Mikez - 24 Dec 2021 at 6:12am

My understanding is that the "Shell Rotella" With the "T4" designation meets the older spec for flat tappet cams. However the newer spec T5 & T6 oils do not. I use the T4 oil as well as The "AMSOIL" Diesel Marine oil and have not had any problem with tappet wear yet. Amsoil also has an oil for gasoline engines that has the name Z-Rod, specifically designed for flat tappet camshafts in older vehicles.  

Back when the CI-4 oils were "upgraded" to the API CJ-4 spec I did a lot of reading about the changes in the oil additives. The beneficial additives that were removed were commonly referred to as  ZDDP. At the time the oil company "experts" were claiming that while yes they removed the ZDDP there were other additives and changes made that replaced the ZDDP. My thoughts at the time was what if 5-10-15 years down the road we find out that these "experts" didn't know what they were talking about and all of sudden we had a lot of oil related failures, mostly flat tappet camshaft and lifter wear. As I have mostly older diesel engines (2006 Dodge Cummins, 8.3 Cummins in combine and tractor,  8.1L Deere and 4 diesel garden tractors) I had a real concern about this and so far I have been able to source a CI-4 Plus oil from my oil supplier.

I reached out to Amsoil and asked them if any of their products are capable of fulfilling the needs of these old tractors.  I'll get back on here when I get an answer.

I believe there's more to it than just zinc but am not schooled in that science.

Well, oil samples are back and to me are inconclusive.  The oil sample I took from the failed camshaft engine was done differently because we had already drained the oil. So, I removed one oil filter and carefully drew old oil with a siphon tube from the center of the filter, which would be clean filtered oil. I thought this would be some what representative of the oil inside the engine. If there was truly a serious failure going on even the filtered oil should be high in iron. It isn't. Iron was 9 ppm, which is fine and doesn't indicate a camshaft lobe failure to me. Zinc was 1170 ppm which I believe should be acceptable for flat tappet camshafts. New oil fresh from the barrel shows 1123 ppm on zinc. So, I guess we throw a new camshaft and lifters in it and get on with life. Things happen. I suppose the cam lobe/lifter failure could have been a long time ago, as the current owner has only put 1,000 hrs on it in the last 10 years.