Camshaft wear on my 560SL

[Jerry Hudson]

Help! I need some advice.

I bought my 560SL last November and have been poured about $2K into it already.
I have replaced both fuel pumps, fuel filter, spark plugs, wires, distributor cap and roter, the front flex disk and front sub frame and motor mounts. basicaly the car runs strong but I don't know when the timing chain was last replaced (the car has 120K mi). So I took it into an independent shop this morning to have the chain, upper guides-rails and tensioner replaced just to be safe.
Well.... The mechanic just called and told me my cam are showing wear and that I will need to get them replaced soon at the sum of about $1500. My question is if the engine run's fairly smooth and I don't hear alot of clatter from the lifters, how long do I have before I have to replace the cams. I only plan to drive it 3000 to 5000 miles a year and will change the oil about every 2K. Also how much of a job is it if I do it myself?

[Mark Herzig]

I thought pre-mature camshaft wear was common for the 450SL's - not the 560's. I'd get a second opinion so I could sleep at night .

[Jerry Hudson]

I was able to get to the shop before the valve covers were put back on and I could see the cam wear. It doesn't look too bad, (no flat spots) but several lobes have small grooves on them where they make contact with the rocker arms.

Right now I am not too worried because the engine runs strong and smooth with a faint ticking above 4000 RPM. My real question is now that the cam's have begun to show wear how long will it be before it gets worse to the point that it affects performance and drivability? In other words if I change the oil frequently do I have 5,000 mi, 10,000 mi or 20,000 mi, before I need to replace the cam's and is that a job that someone like myself with average mechanical ability can do on my own. I have the 107 CD Rom and all the necessary tools.

[michael rybikowsky]

I would use mobil 1 in it and not worry It could go for years.If it does get to the point that it needs replacement You still only have to replace the same amount of parts.A cam Change is not a difficult job.While you are at it replace all of the followers and valve seals.Good luck Michael.

[Jerry Hudson]

Thanks for the replies and advice. your suggestion to drive it and not worry is what I was hoping to hear. I just don't know how fast the cams will wear now that the hardened outer surface has been damaged. The mechanic that replaced my timing chain said that once the outer surface has been removed that continued wear will accelerate and that there will be metal particles in the oil. While that may be true, I think frequent oil changes will minimize any further damage. Michael: your suggestion to use Mobile 1 sounds like a good idea, but I have heard that switching to synthetic on a high mileage engine (120K) may cause an increase in oil consumption due to worn seals. I guess I can try Mobile 1 and if I start to use too much oil I can switch back.
By the way after the timing chain was replaced the engine runs stronger than ever and it's good to have the peace of mind that I don't have to worry about it breaking. Thanks

[michael rybikowsky]

forget about it if anything you will use less oil.

[Jerry Hudson]

Thanks I'll try it..

[73MB280SEL]

Jerry,

A worn camshaft will cause idle problems once it gets pronounced. I've got a 4.5 M117 with the typical worn right side cam. On mine, one lobe has worn through the hardening. What you see is a distinct ridge on the trailing edge of the lobe where the softer metal is exposed.

The hardened surface is thicker than you'd think. You can have some pretty deep grooves without punching through.

Once the cam is worn, you won't be able to set the valve clearance properly (N/A on a 560) so you will hear ticking. It really should affect idle at that point. Mine runs fantastic at higher RPM, but not so hot at idle. I'm going to replace mine in a couple of months.

You should probably turn the engine over by hand and carefully examine all lobes. You can take the valve covers off, unhook and ground the coil wire so it won't start, and crank it over a little at a time. I've done this, but you can cause oil to splash. A helper is beneficial for this. Just crank it over in short bursts. And make sure nothing is caught on the exposed cam when you crank it.

Sholin

[Jerry Hudson]

Right now its hard to tell if the idle is affected because I have a high idle problem that I have traced to my idle air valve. It idles between 800 and 1000 RPM's when in neutral but idles 600 RPM in gear and seems pretty smooth so far. I hear a slight ticking under hard acceleration but not when driving normal or crusing.
I plan to replace the air valve within the next few weeks and will probably pull the valve covers off in month or so and do a close inspection of the cam then. I am hoping that I can hold off until next year before I need to replace the cam's, and I may be lucky and only have to do the one on the right side where the ticking seems to be comming from. ...Oh well it took 120,000 miles of poor maintenance to get in the condition it was in when I bought it and if it takes a year of two to put it back in top shape I will have a great car for not a lot of bucks that will last another 150K miles.

Thanks