Worn cam lobe symptoms

[NICAT]

Hi.
Can worn cam lobe affect performance at certioun conditions (may be during acceleration or high rpm) in naturally aspirated engines without causing rough idle or any noise ?
Mechanic told that "cam lobe is slightly worn. But there is no need to replace it until it causes any noise or rough idle."
Regards

 

[Omahaug]

The profile and curves of the lobes affect the timing of the cam components like when valves open and return, I'd think if they were worn bad enough you'd notice it.

You really can't get any better answers without specifies as to how bad it's worn. Is it some minor marring? Is it scored or is a deep groove cut into them enough to cause lips on either side of the groove?

 

[OneEyeJack]

If your car is a daily driver and you are not up to an expensive repair right now then his advice is good. You might just have a good, honest mechanic.

 

[FCD]

My Ford Escort's engine has certainly a worn cam and lifters as most high mileage Ford CVH engines and the top end in noticeable rattly, but it runs perfectly and the power delivery is good.

 

[Chris142]

My Chevies that ate cams would backfire out the carburetor if it was a worn exhaust lobe.

 

[riklyn]

I had a worn lobe in my 04 TJ. it had a bad miss going down the road, had no choice but to change it out. I'd take your mechanics advice if it's not missing or causing other issues.

 

[NICAT]

Thanks guys, for great answers

 

[Ducked]

Thicker oil?

Not a symptom, obviously, nor a cure.

More a bit of "band aid" to buy you some time.

 

[BrocLuno]

What engine and what cam/lifter system? Some react more than others ...

 

[oldhp]

Or the bad news. Bad cam lobe + bad cam lifter = lots of metal in the oil going everywhere in the engine. I would fix it.

 

[Lubener]

Compression test would verify a worn cam. I don't know what engine you have but weak valve springs can act up at high RPM.

 

[RoadRaceJosh]

Originally Posted By: Lubener
Compression test would verify a worn cam.


Probably not. The opening and closing ramps are usually fine in all but the most severe wear cases so at cranking speed plenty of air gets into the cylinder.

 

[mattd]

A dynamic compression test would diagnose a valve train issue.

 

[Ducked]

Originally Posted By: oldhp
Or the bad news. Bad cam lobe + bad cam lifter = lots of metal in the oil going everywhere in the engine. I would fix it.


Maybe thicker oil, magnets, and more frequent oil changes meantime then.

Or fix it of course. Which'll depend on relative cost and projected lifespan of the car.

 

[PeterPolyol]

Originally Posted By: NICAT
Hi.
"cam lobe is slightly worn.

This is an ultra vague diagnosis from your mechanic. The cams in all our cars are 'slightly worn' TBH. Is it scored/galled? Is the max lift noticeably out of spec??

 

[Lubener]

Originally Posted By: Joshua_Skinner
Originally Posted By: Lubener
Compression test would verify a worn cam.


Probably not. The opening and closing ramps are usually fine in all but the most severe wear cases so at cranking speed plenty of air gets into the cylinder.

I would think if the symptoms are noticable, there should be more than a 10 percent difference between the cylinders or the readings are lower than they should be.I would do some further test before changing out a cam which may not be bad. Problems elsewhere can give the same symptoms.It sounds like the mechanic is winging it w/o testing.