Camshaft Lobes / How to prevent wear?

[300SDog]

Adjusted the valves on the 240D today and was shocked to see signs of wear on #1 cyl. exhaust valve camshaft lobe..... am guessing previous owner was slack on oil changes and maintaining valve adjustment.

What are preventive measures to sustain healthy camshafts...... replacement of acorn nuts that rub against the lobe?

If it crunches down to replacing the camshaft and its stantions in another 50k miles - I'm also wondering if different cams are available - knowing that MB provides superior performance camshaft grind on Euro spec gasoline engines.

-Sorry no pic showing camshaft wear.... i tried but crummy camera could not pick up scuffs on camshaft lobe.

[P.E.Haiges]

240DieselDog,

About the only thing you can do is to use a top rated synthetic engine oil and keep the valve clearancesto spec.

P E H

[Kestas]

The valvetrain is often last to get oil during startup. Is the #1 lobe last of the lobes to get oil? If you do a lot of short trips, make sure you use the thinnest oil specified for your engine to get the oil up there quickly.

[Stevo]

DieselDog

Cams after "80" were hardened as were the rockers. We replaced the cam on my daughters "78" 240d that the PO had neglected to adjust the valves for who knows how long, on. A couple of the lobes were "dished" WAY out. If you get one at the pick and pull, get a post "80"s. Cost me $100.00 for cam, rockers and towers. I got the older style as thats what he had. I figured that I will keep the valves adjusted so it really wont matter.

[mr. Goodwrench]

Starting in '82 Mercedes used cam followers with a tungsten carbide overlay on the wear surface. This was mentioned in an article in "The Star" magazine in '81. Anyone with these cam followers on an earlier engine had them retrofitted.

[samiam4]

Yep,

They improved the cams. Make sure the oil tube holes are not plugged with crude. That and frequent oil changes. I'd guess if the wear is noticable, the cam is probably woofed (ie through the heattreatment and into soft metal). Rockers and camshafts are matched in hardness. Make sure you get the right parts- a used engine would be cheapest for parts. Lemforder camshafts are garbage-buy a factory camshaft if you go new.


Michael

[300SDog]

As usual outstanding advice from everybody - thanks for providing info i need regarding camshaft upgrades from '79 - '82.

I should have thought about pulling the oil tube and giving it kerosene bath and toothbrush scrub when in there for valve adj. Gotta go back and do this. Meanwhile I'll bide my time for junkyard cam, stantions and tungsten acorns from '82 model.

Have experienced camshaft wear before - on my twincam 280/8 - so can calculate I've probably got 20,000 miles left (i hope) on camshaft lobe that shows minor wear.

Bit of vintage lore the forum might enjoy - primitive finbody diesels of early '60s had hollow camshaft that shot oil through holes on the back surface of lobes instead of external oil tube. Oil was channelled through one stantion to another and down the last stantion directly through the camshaft that also shot oil directly on camshaft followers.

[samiam4]

In junk yarding,

Get everything from the upper end. You mentioned tungsten acorn nuts. I think he was talking the wear pads on the rocker arms of the later camshaft are tungsten carbide. Camshafts are different too.
Later style camshafts have more lift- so make sure you've got the camshaft tower. You'll need late style valve seals.

Problem I've seen with hollow camshafts has been clogging in engines with mild overheating.

Michael

[Stevo]

240DieselDog

You can tell the difference because the towers are constructed slightly different. The new (Hard) style is SLOPED on one side below the round part that holds the cam and with the old style the tower is VIRTUAL below the bearing. The acorns are LESS tapered in the new version (tapered from hex to round on top) and you can see the "layers" in the rocker face of the new style. The place I go to for used parts just has a bunch of engines sitting around in a dark room (bring your own light) and it can be hard to tell the differance.

Steve