Worn Cams

[supercity]

This is a picture from a Fiat/Lancia 2L 4cyl 16V engine. As you can see the lobe is worn away a lot compared to the adjacent one. This seems to be a common but random problem. It can be any lobe and more than 1 per engine. Some high mileage engines can be fine. These engines are now 15-23 years old now. Can it be the oil? If so why aren't all the lobes affected? Maybe it is just the materials or hardning.

The original oil for these engines is Selenia 10w40 semi syn. I very much doubt any would have seen a 30 grade or lower in this part of the world. They most likley get 40 or 50 grade.

In more recent years other engines from this marque including Alfa Romeo are having trouble too. The Alfa 2.0L JTS (direct injection) engine is bad for it. That engine also has heavy oil consumption and uses a 10w60 full synthetic. This is a 150hp motor.

Edit: maybe this should go in the european section.

 

[abycat]

Maybe thicker isnt better.

 

[Chris142]

probly not properly hardened when made

 

[Phishin]

Junk material: made by inferior material....made to inferior standards.

 

[tig1]

Originally Posted By: Phishin
Junk material: made by inferior material....made to inferior standards.


Yeras ago( 70s and 80s) GM had some very poor quality cams. Soft cams as they were called.

 

[SS1970chrysler]

I had a couple '85 Caprices do that same thing on 305 V8's. No 2 looked the same, but the results were.

 

[supercity]

Yeah a friend of mine had a 305 Caprice when living in California. One lobe had worn off completely and it ended up only running on 7.

If it is a problem with the metal, what did they do wrong? Hardning? It seems odd as the rest of the engine is well over engineered. These are the engines used in the Group A Lancia Integrale rally cars.

 

[Garak]

Perhaps it was the metallurgy. At the time, we had Caprices/Impalas on fleet duty, and they all ate cams. It's not like there were excessive valve spring pressures or anything like that.

We replaced the cam at least once on almost every Chevy small block we had in fleet usage. And, as you mentioned over engineering, the cams were the only consist, repeating flaw we observed. One example went to 1,000,000 km and was running fine the day we parked it, driving to its retirement home.

 

[A_Harman]

I recall hearing that GM had introduced a laser-hardening process for cam lobes at the time, and the process was not fully developed.

Was this a fleet where the engines were subject to long periods of idling? It is an under-appreciated fact that idling and low-rpm operation is very hard on cam followers. Cam contact stress at idle is actually higher than at 5000 rpm for most engines.

 

[Garak]

In my application, there was plenty of idling, and yes, that is not easy on cams. Anecdotally, other vehicles with the same engine under different operating patterns did have cam issues, too. However, the amount of time at idle in the fleet usage was most certainly did not help matters.

 

[INDYMAC]

How often were the valves adjusted and retainers checked on this engine?

 

[oggb]

Poor materials. Honda has had this problem with fairly recent Civic models.

 

[addyguy]

My dad had a 1978 Malibu 305 that ran like dung in it's later years; I'm guessing it had this problem.

The 305 was a garbage engine...just junk.

 

[mechtech2]

Since only one is affected,and it does not have an exclusive oil supply, it is the cam itself that is bad .
Maybe the bucket.

 

[chevman4life]

Originally Posted By: addyguy
My dad had a 1978 Malibu 305 that ran like dung in it's later years; I'm guessing it had this problem.

The 305 was a garbage engine...just junk.


Really, got one in the 82 Chevy with 209k, never rebuilt and actually took it for a highway run at 80mph. Runs like a champ after 30 years in service for my family.

 

[Robenstein]

I replaced a lot of cams in 80's Chevy and GMC trucks with the 305. They were just soft because the cams and spring pressures were pretty mild. And back then the zinc in the oil was pretty darn good. I also had a cam snap in two on a 99 Monte Carlo of mine at 100k out of the blue. Sometimes cams just go bad.

 

[tightwad]

My '83 El Camino is about to roll over to 150k. Still runs good and doesn't burn much oil. Made on a Wednesday?

 

[Kestas]

There are a lot of reasons why cams go bad. Many reasons were mentioned above. A few more:

- clogged oil passage that lubricates the lobe
- short trips (many startups). Overhead cams are the last to get oil during startup.
- poor break-in, leading to scuffing and wear
- poorly finished surface of lobe and/or follower