Is this normal wear? Aluminum cam gear
 

The edges of my aluminum cam gear seem to be rolled over on to the top of the gear tooth. The bit rolled over is probably 0.002 to 0.004 inches. It easily scrapes off.
Is this normal wear and tear with 8500 miles?
If not normal, what do you think the cause is?
Thanks

Re: Is this normal wear? Aluminum cam gear
 

You have problems! Are the gears meshing deeply enough? Is the cam hard to turn? Bad crankshaft gear?

Re: Is this normal wear? Aluminum cam gear
 

Sounds like it’s worth removing the timing cover to inspect the interface with the crank gear. You’ll have to replace the timing gear anyway, it’s shredding itself into the crankcase, so I’d go ahead and take the cover off.

Re: Is this normal wear? Aluminum cam gear
 

Interesting.
Id be interested to know if you have origin of this alum gear ?
It is obviously made of inferior quality material.
Where was it purchased ?
Never have seen an alum gear deteriorate as the one pictured !
IMO, even a misfit old worn out crank gear shouldn’t cause this type damage ?
It appears to be disintegrating !!
That being said.... I’d expect to find a bad crank gear.

BTW... if shedded that much metal...you may have a BIGGER problem !

Re: Is this normal wear? Aluminum cam gear
 

No, it does not look like normal wear.

Time to pull the cover and take a look.

As someone suggested, the engagement looks inadequate, could be a couple causes.

But also, the gear looks very dry, like no oil at all on it. Obviously not a pressurized motor, but could be the valley dam is not spilling any over the front side towards the gear.

John

Re: Is this normal wear? Aluminum cam gear
 

You are looking at plastic deformation. The cause is the inherent un-damped shock wave that traverses a crankshaft with no front harmonic balancer.

It is only visible because of the great amount of plastic deformation before grain boundary failure your particular gear has. Is it a 'billet' gear or a cast gear? Billet aluminum exhibits great plastic deformation in exchange for a lower Young's modulus of elasticity. Cast aluminum gears are 'stiffer' and generally fracture (break off teeth) before reaching that must plastic movement. It does NOT mean the gear is inferior, nor the mesh.

If you had a layered fiber gear it would crush away to a point of excessive lash. If you had a short fiber compressed gear it would have broken teeth. If you had a typical 319 or 356 alloy cast gear, usually T5 heat treatment, it would be developing grain boundary faults, prior to emminent failure.

The real question is what is happening with your particular engine, or driving settings that is causing this excessive crank shock. Excessive advance? Too hot a plug causing detonation/ spark knock? The next thing to fail will be the rear crank bearing journal. Snap!!

Re: Is this normal wear? Aluminum cam gear
 

If it was getting proper lubrication (cushion) would the damage be as drastic?

Re: Is this normal wear? Aluminum cam gear
 

I am afraid that I agree with Mike K. There is something wrong. I also agree with the rest of the comments. If it was my car I would pull the engine, clean it out, and check every part. I would have the crank magnafluxed. The aluminum that has shredded from the gear has probably imbedded itself where you don't want it. Also look into adding a harmonic dampener at the front of the crankshaft.

Re: Is this normal wear? Aluminum cam gear
 

One other comment. There should be a hole inside the front of the valve tappet chamber that oils the timing gear. It was knocked out with a hammer after the block was cast so it looks rough. It could be that the hole was not hammered open when the engine was manufactured.

Re: Is this normal wear? Aluminum cam gear
 

2 guys hit the nail on the head. Lack of oil. Now you will have to have the block hot tanked to get rid of all the aluminum in every nook and cranny.

Re: Is this normal wear? Aluminum cam gear
 

I will look further into the problem and keep you posted.
Thanks for the input

Re: Is this normal wear? Aluminum cam gear
 

I thought aluminum gears were bullet proof. Now ya got me worried.

Re: Is this normal wear? Aluminum cam gear
 

I ran the engine with the timing gear cover removed for a few minutes. There was no oil from the valve chamber coming onto the cam gear.
When I bought the truck five years ago the old guy said the engine had pressurized mains. I never removed the pan because the engine ran fine. I don't know how the mains were pressurized. There is nothing visible from the outside of the engine. Maybe something internal with the pressure modification failed.
I replaced the engine today and will tear into this engine soon.

Re: Is this normal wear? Aluminum cam gear
 

If ‘bullet proof’ were used to describe ... any cam gear... it would be used for bronze gear. However, all/any gears need lubrication, eh !!
Seems the owner observed the specific (no oil) situation... prion to damage ?

Re: Is this normal wear? Aluminum cam gear
 

Chueck the cam gear lash. .003-.004 is fine.

Re: Is this normal wear? Aluminum cam gear
 

Cast alloys are only 5% "stiffer" than wrought alloys. Cast alloys are very much more brittle though; by a factor of about 1/5 th the elongation of wrought alloys. By the looks of your gear, you have wrought (billet). I think a cast gear would have lost a tooth if it was this abused.
It appears to suffer from no lube but the really weird thing is that the teeth are worn on the back side. I would guess that the gears are too tight, maybe caused by excessive heat due to poor or no oiling? The suggestion of too much advance on the timing may be causing the crank gear to knock backwards against the cam gear? Also, the suggestion that no harmonic balancer may cause this is interesting since that is a rotational phenomenon.
The other thing I see is the color of the area to the left of the cam gear. Is that rust? Is that the cam bearing getting worn? It looks too red for bronze.
I am sorry to say, you have a sick engine.

Re: Is this normal wear? Aluminum cam gear
 

Bryan, I think you may have answered the what is wrong question. My guess is whoever "pressurized" the oiling system plugged the oil hole behind the cam gear. Your engine if full of Al. particles. Rick.

Re: Is this normal wear? Aluminum cam gear
 

I have been thinking on what the picture shows. The metal on the normally loaded side of the gear transferred to the crank gear (galling). This eliminated the running clearance for the gears and caused the teeth to be too tight. This condition is what caused the wear on the back side of the teeth.
However, the cause of this series of events is probably what Richard Knight suggested.

Re: Is this normal wear? Aluminum cam gear
 

I see hack pressurization jobs.. if you race, pressurize...if not, The stock system is adequate. The timing gear sees splash oil, and at higher rpm oil flood spill over from the punched hole in the block above the gear.

Re: Is this normal wear? Aluminum cam gear
 

If this motor is pressurized I would be suspicious of the mains.
The front main should be pushing oil forward and onto the crank gear, this should be transferring oil to the cam gear.
A pressurized motor will not fill the valley and lube the cam gear through the window in the front of the block.

J