M110 camshaft
 

Yesterday we were adjusting the valves on my son's 280SL and found the exhaust cam on the # 3 cylinder is starting to wipe. Can the cam be replaced without removing head? My son has limited funds(in high school). Where to find camshaft?

TIA

Try your wrecking yards. Remember that the new used individual rockers on a unit should be installed in the positions they were operating on with the used cam. So you want the used cam and it;'s rockers plus them numbered.

I cannot see having to remove the head to change the cam. Although I have never worked on a m110 engine. If for any reason you cannot locate a cam. I can recommend a place that builds up lobes and regrinds the whole cam. In my experience they do a good job. Make sure the hard wear surface of the rockers has not worn through. When it does it is quite visual it has done so.

Do I need to be concerned that is euro m110 or will a US cam work?

The answer is a conditional Yes; although the cylinder head itself can remain on the engine, the cam carrier (cam box) will have to be removed. Some of the cylinder head bolts do double duty; they secure the cam box as well as the head, however five head bolts (and two smaller ones) remain untouched to hold the head.

The cam code #s are stamped on the back end of each camshaft. Most codes have appeared in both the the US and the rest of the world.

Are the codes#'s accessible with cam installed?

The short answer is, have a look.

With good fortune, good lighting, and a small mirror like a dental mirror, you may be able to see the numbers on the back of the cams. But most important, you will have to hold your mouth just right!

If there is sufficient room in the chassis, the rear covers of the cam box can be removed for a better view.

I have 4 used engines I could look at for a cam. 801 706 6871. Short term temp fix put in new or used rocker.

Replacing a cam is not very hard.

1. Remove the rockers.
2. Turn the engine to align the marks on the cam (or gear)
3. Remove the small cover in front of the cam.
4. Loosen the bold holding the gear.
5. Remove the chain tensioner (put it in a plastic bag, otherwise you can lose parts).
6. Remove the bold holding the gear.
7. Slide the cam to the back and remove the gear.
8. If you have enough room in front of the engine you can now slide the cam out, otherwise you have to remove the cam tower.

The tensioner is spring loaded, you have to slide the inner part out and reinstall if from the back. It is a bit tricky, I put it in a plastic bag when working on it.

The camshaft bearing journals of the M110 engine become progressively larger in diameter from front to rear. As a consequence, obviously, the camshafts cannot be removed through the front of the cam box. As I noted above, the cam box will have to be removed from the engine to remove the cams, when the engine is installed in the chassis.
In the case of the engine being out of the chassis, the cams may be withdrawn rearward without removing the cam box from the engine.

I removed the exhoust cam of a M110 engine through the front without removing the cam tower. There are at least 3 different types of cams for the m110, it is possible that some euro versions are different.

Aftermarket tuning specialists may very well have modified cam boxes in such a way (all cam bearings the same size) that the shaft could be withdrawn in a forward direction, but not as delivered by Mother Benz.

Taken from page 01.2-471/1 FSM dated 11/1983:
The production bearing sizes front to rear for the exhaust cam in mm:
37.95, 49.95, 49.95, 51.44, 51.44, 52.94, 52.94, 53.94

when in doubt, read the book
 

Having the service manual helps some times, as I've long forgotten the details, not having done this myself for like 20 years.

The M110 service manual starts the procedure with a note... Camshafts can be removed from an installed engine only together with the camshaft housing.

The second note says that if a new camshaft has to be installed, the rocker arms must also be replaced.

Lastly, there's a note regarding replacement camshafts being available with wider journals so finding a used cam shaft may be easy, but double check the journal sizes to ensure its going to fit correctly in your cam housing.

Having said all that, I recall there being early and late versions of the housing and that early versions had a habit of starving cams of oil. Given the relative age of these cars, it would be interesting to decide which ones are originals and which have been replaced.

Once you have the cam housing off the motor, you'll need to have it checked for warping and possibly milled flat as you would a cylinder head.

Removal is pretty simple says the book...
1. Remove the camshaft housing (see procedure 01-470).
2. Unscrew both rear covers.
3. Unscrew necked-down screw of lefthand camshaft while applying counter hold pressure with holding wrench (soft-metal wrench that can hold the cam w/o marring it surface).
4. Press back the camshafts and remove the sprockets.
5. Remove both camshafts toward the rear.

Watch that first step...

-CTH

Oh, and I have a suggestion for your son being able to do this on his limited budget. First off head to a pick-n-pull and practice doing the job on a car there. Given the wealth of yards north of DC, there has to be something with an M110 motor in it.

Treat the dead car like your own, as it might well be the donor of cams, rockers and that cam box. If the two of you can master the job, then you're ready to work on your own car.

I am up in NY and rarely get the pleasure of spending a day in a yard. I managed the Jessup Crazy-Ray's once last year and it cost me a vacation day and lots of making up to my wife and my boss (thankfully one of them likes flowers).

-CTH

CTH350 I sent pm

Wish we had time to scrounge salvage yards.

Would EPC Mercedes site give me correct cam number or do I need to get it from the cam itself?

Gd:

Exhaust cam codes 24, 57, & 71 will all be suitable.