how to tell a lobe is wiped?

[tsaltario]

I don't think mine is, but I have a flat tappet style cam in my car, and i hear lots of problems about wiping lobes off. When this happens, what are the characteristics when this happens? Is it noticable?

Thanks

TJ

 

[TT/Ameasap]

Shavings in the oil, Tapping sound (off and on ) inside the motor just to name a couple.

I always run a magnetic drain plug and change my oil often. You also need to use ZDDP additive or VR1 racing oil with a flat tappet cam.

HTH
Bo

 

[Topjimmy]

My car ran surprisingly well with my less than 5,000 mile club cam (#3 cam lobe whipped), I just happend to see it while I was replacing the crank (long story but that block is long gone).

I saw this check in another post;

Quick check: Disconnect ECM (orange wire at battery), Remove valve covers, have someone crank the engine while you look for a rocker arm with little or no action. Double-check #3 cylinder, that's the most common culprit. - Jimmy

 

[Donniejr81]

You can definitely tell a wiped lobe. The "peak" will be noticeably shorter than the other lobes. Also, the wiped lobed will usually have a rougher finish than the other lobes. Another way to tell is to see if you have any badly cupped lifters...that usually points to a bad lobe. If a lobe is wiped bad enough, it can even cause a dead miss, and backfiring....I speak from experience.

 

[A2000RICH]

I don't think mine is, but I have a flat tappet style cam in my car, and i hear lots of problems about wiping lobes off. When this happens, what are the characteristics when this happens? Is it noticable?

Thanks

TJ

obviously a bad cam lobe/lobes will present different behaviour depending on the degree of wear---------lots of metal in the pan and filter are a sure sign that things are bad, really bad--------by the time its that bad its more than likely that other parts of the engine are damaged due to secondary causes------things like rings/walls and crank/cam bearings etc.--------naturally it would be best to determine this long before it caused damage requiring more than cam and lifter replacement---------typically the surface hardening on a cam is in the .020" range and as long as the wear is below this amount things are not going to be severe-------a gradual lack of performance can be expected but unless you constantly operate your car in conditions that can resolve minute differences (track/dyno) it might be hard to sense by "seat of the pants"---------if you have been operating your car for the last year with much mileage with off the shelf SM oil I believe it is certain that you have not done your cam a favor-------if it is too late to prevent catastrophic failure with the use of fortified oil or additives is in direct porportion to the amount of wear already caused----------- my recent study of automotive and lubrication industry papers is clearly showing that Nick Michale is right about the synthetic vs dino issue------for flat tappet cams there is a lot of evidence that dino is best ESPECIALLY if you are using API SM oil------there are very clear scientific reasons for the things Nick has stated that he has observed in his years of building engines---------i was somewhat skeptical when he first stated his beliefs but there is solid evidence that he is right-------I am in the process of preparing an informative tech paper on this subject that will deal directly with this subject based totally on published reports from lubrication industry tests and reports-------since the subject has expanded into such a complex study it will actually be published in two tech papers-------when they are done they will be published on the ZDDPlus site as tech paper #11 Oil base stock characteristics------ the second paper number and title will be announced later ---------at any rate we know if a cam is bad it is pretty obvious that performance is going to suffer-------by the time things have progressed from gradual to "severe" you can certainly expect missing, popping etc. and other strange symptoms--------a compression check that shows definite cylinder to cylinder differences with no other explanation is a good indication of trouble---------problem is that you must do several compression checks in a row on the same cylinder--------my best guess is that it could take as many as three or four--------i am in the middle of replacing a cam on a car with a couple bad lobes-------it was diagnosed as running bad and had lots of metal in the oil--------first compression check every cylinder looked fine--------160 PSI +/- 5----------since i already knew it had a bad cam i was puzzled------i decided to do another check cause i couldn't beleive that a compression check would show nothing especially with such a bad cam as this engine had----------second time same as the first---------third time one cylinder compression dropped nearly 40 PSI----------next time it went back up to normal----------a study of the lifter will show why---------only one side of the lifter and cam wore severly----------obviously the lifter was still spinning and if the high side of the lifter and the high side of the cam happened to line up things appeared normal------------check out the pic of cam and lifter....................RC

 

[Blown&Injected]

You can look at the cam or the rockers - but the first thing I would look at is the vacuum gauge - is it bouncing rapidly? I do not mean a large movement.

There is a wear pattern on the cam lobes just either side of the nose - a lobe going down will not show the same pattern as the others.