Broken Cam - Why does it happen?

[pocket-rocket]

Sometimes I think GM's theme is K.I.S.S., because some of the things they do are really stupid. Ever see 3.4 DOHC intake gaskets?

[[ChaosweaveR]]

This happened to my buddy's 99 GAGT. Lack of lubrication was the suspect, but not from an LIM gasket. His dad borrowed it for awhile. Ran over the oil change interval, and thought "Hey, the motor has lots of miles, lets top it off with 20W-50!" and on top of that, he had an oil change done after that, WITH more 20W-50. Hrmmm...wonder why there was a lack of lubrication...

[60dgrzbelow0]

The autopsy results are in and the victim died of lack of lubrication. The back half of the camshaft had lightly scored journals, but the rear bearing looked very bad. I was not able to remove the section because it has a spun cam bearing floating on it between the journals and the edges of the bearing are hammered so it won't easily let me remove the cam. So, the back half of the cam goes to scrap with the block. But my conclusion is that in spite of no evidence of leakage, there must have been enough leakage to kill the oil and then the engine. If you have a decent running 3100, the best choice is probably to fill the radiator with oil. It may not cool as well, but the bearings will sure last longer.

I think my next project might have to be to design a sensor and alarm mechanism to detect the presence of either Poly-Ethylene-Glycol and/or other coolant derivatives in pressurized motor oil as an "Early Warning System" against engine component seizure from LIM and other engine gasket failures and the invasion of coolants into the oil stream..

It isn't just the lack of lubrication in modern motors that causes "Good Cams to Go Bad"... It is due to the way our lubricants are being made... or perhaps more to the point.. what is NOT being put into these oils anymore that we all use to lubricate our engines. The simple fact is that due to the California CAFE and EPA standards from the early 1980's and with the advent of Electronic Fuel Injection fuel management that is such a boon to efficiency and air quality improvement...all the additives that used to be present in abundance in the form of Zinc and other chemicals...they all had to be removed because they precipitate and coat the Oxygen Sensors along the exhaust paths and the Platinum Screens in our catalytic converters...and so as soon as these additives were deleted from the various blends of oils... All the major auto manufacturers began to see systemic engine failures because all of the original protections they had with these metal hardening and protective additives were absent from the lubrication realm. Hotter operating temperatures and new uses of Aluminum also heralded the problem of having more heat to dissipate away from pistons, rings...camshaft lobes, lifters and of course engine bearings. Automotive science has never caught up with this problem... and so when the metal friction points in our engines get stressed... catastrophic engine component failure can be expected. Here are two articles specific to camshaft failure that drives home the point:

http://www.racingheadservice.com/Information/ArticleDetails.asp?ID=-1228096506

http://www.hotrod.com/pitstop/hrdp_0702_pitstop_zinc_oil_additive/index.html

[60dgrzbelow0]

I'm new to the forum, but I'm not new to engine building. I grew up on both big and small block GM engines. All of 'em had the same cam in block with pushrods, stamped metal pans, leaking rear main seals, double row timing chains and valve covers that never really sealed. As a result, when I bought a super clean 1999 Malibu with a 3100, I knew the engine was DOA, but I was pleased to see the changes in the design of this engine family. Things like the 2 piece intakes with part of the intake serving as the valve cover surface, the cast aluminum structural pan and the fulcrum rockers are a departure from the "old ways" of GM.

But as proof that you can't teach an old dog new tricks, what's with the cut off distributor driving the oil pump? That's been a GM theme forever. What a steaming pile that is! Why not do a crank driven gear type pump like the rest of the world? How about the same old timing chain and gears with no tensioner? To take the slap out of it, they just tossed ln a couple guide rails on the inside.

This "vestigial organ" was left in place to lower the design costs for GM and to allow the same engine block to be useful when and if EFI fuel management is impossible ...or to allow the survivors of the Next and Last World War...to jam a distributor down the hole... throw a two BBL carburetor on the top and burn their home made gasoline to get out of town using a 2"X4" holding a gravity feed bottle of the stuff...

[kerno]

THe change in oil formulation occurred about 3 years ago, which is pretty close to when people started reporting the cam problem. I think you are right on the mark when you blame the loss of the Zinc and Phosphorus for the change in lubricity. It may be just enough that oil that used to be able to tolerate dilution with coolant, no longer will.

Thankfully, the oil industry has come out with oils made the old way and labeled for racing or for motorcycles. Let's hear it for a new way to lubricate out engines again! Here's to death to catastrophic converters!!!!

[robertisaar]

Thankfully, the oil industry has come out with oils made the old way and labeled for racing or for motorcycles. Let's hear it for a new way to lubricate out engines again! Here's to death to catastrophic converters!!!!

interestingly enough, i read that when the convertor is getting excercised at high temps, it burns off the zinc/phosphorus contamination due to their melting points, and they get vented to atmosphere...

[sprucegagt]

I think my next project might have to be to design a sensor and alarm mechanism to detect the presence of either Poly-Ethylene-Glycol and/or other coolant derivatives in pressurized motor oil as an "Early Warning System" against engine component seizure from LIM and other engine gasket failures and the invasion of coolants into the oil stream..

It isn't just the lack of lubrication in modern motors that causes "Good Cams to Go Bad"... It is due to the way our lubricants are being made... or perhaps more to the point.. what is NOT being put into these oils anymore that we all use to lubricate our engines. The simple fact is that due to the California CAFE and EPA standards from the early 1980's and with the advent of Electronic Fuel Injection fuel management that is such a boon to efficiency and air quality improvement...all the additives that used to be present in abundance in the form of Zinc and other chemicals...they all had to be removed because they precipitate and coat the Oxygen Sensors along the exhaust paths and the Platinum Screens in our catalytic converters...and so as soon as these additives were deleted from the various blends of oils... All the major auto manufacturers began to see systemic engine failures because all of the original protections they had with these metal hardening and protective additives were absent from the lubrication realm. Hotter operating temperatures and new uses of Aluminum also heralded the problem of having more heat to dissipate away from pistons, rings...camshaft lobes, lifters and of course engine bearings. Automotive science has never caught up with this problem... and so when the metal friction points in our engines get stressed... catastrophic engine component failure can be expected. Here are two articles specific to camshaft failure that drives home the point:

http://www.racingheadservice.com/Information/ArticleDetails.asp?ID=-1228096506

http://www.hotrod.com/pitstop/hrdp_0...ive/index.html

While it's good to know the info in the links, I also must point out that they bare no relevance to this thread. Those links are in reference to a problem with modern oils being used with flat tappet cams. Roller cams won't have that issue. The cam in question here no doubt had lubricity issues, but it wasn't due to lack of Zinc and Phosphorus in the oil.

[01GPGT]

in the High school i worked at they replaced a 3400 from a 99 monte carlo. the enigne had a hole in the side of the block. when we took it out we all thought it was a rod failure well not exactly it. the cam broke then fell jambed up the #2 rod and it broke an made a hole in the block.

the owner said when it happend he just got the car back from getting the LIM gasket done he GF called and broke up with him and when he came to the next corner he punched it and as it was turning the corner he said the oil light came on then bad noises happend.

we think the shop did not put in enough oil but hard to say. still amazed at the damage

[kerno]

While I agree that roller lifters don't require the oil to have the shear strength and high pressure lubricants that are required for flat tappet cams, the 3x00 camshaft failures don't appear to be lifter related. The broken cam I took out had perfectly fine lobes, but the journals were history. I'm new to the forum, but have read a great deal of the information posted here. One comment sticks out in my mind. It was something like "When I worked at the dealer, we never saw one, but 3 years later, I've seen several". I don't think there is any basis to presume that oil got better when they took the high pressure lubricants out.

[60dgrzbelow0]

While it's good to know the info in the links, I also must point out that they bare no relevance to this thread. Those links are in reference to a problem with modern oils being used with flat tappet cams. Roller cams won't have that issue. The cam in question here no doubt had lubricity issues, but it wasn't due to lack of Zinc and Phosphorus in the oil.

Forgive my unbridled enthusiasm for that damned tetrahedral molecule in ZDDP that I always believe is the salvation of all engines wounded by component failure due to a lack in lubrication. In spite of the OP's honest admission to having, "Dirty but Okay" Motor Oil...if there ever was such a thing...you are of course correct and instructive in getting me off of my "F-Body" centric way of thinking along the lines that all of of these motors having solid tappets. My mistake... and I stand guilty as charged. Barring any other discoveries since my last look at this thread... your clinical observations about the oil being contaminated with anti-freeze and being reactive and acidic to the Babbitt bearings holds it head up highest as the most likely culprit in this cam seizure.