Horror, scored cam - PeachParts Mercedes-Benz Forum

erubin · #1 03-31-2004, 08:54 PM

1972 450SL
4.5 engine: 117.982
220,000 miles

I took off the valve covers today and to my horror here is what the right bank camshaft, lobe #3 exhaust looks like (right most lobe in photo). The scoring is only 3mm wide and 16mm long. My finger nail grabs a bit as I slide across it so it's not a really deep but appears to have gone through the hardened (polished) surface. I Really hate to buy a new camshaft and rockers because of the expense. What do you think? All the other lobes have no scoring except a slight scratch on intake lobe # 4. You can maybe see that on the left most lobe in the photo and the scratch is on the right side of the lobe. What will happen if I don't replace the cam?

BTW, my cams are numbered 52 left and 53 right. That's kind of weird since the FSM shows that number going into other 3.5 and 4.5 engines but not for the 1972 450SL!

Thanks,
Elliot

erubin · #2 03-31-2004, 08:59 PM

Here is a blurry photo but shows the scoring a little better.

stevebfl · #3 03-31-2004, 09:32 PM

If you can feel it, it is in failure. You can get some more life with a new rocker arm. If the original shape is intact it may go a while. If there is a dip where the loading is greatest it won't last long.

I looked at the cam numbers and I see no motors but 3.5 motors using the 52 and 53 cams. What is your chassis number.

erubin · #4 03-31-2004, 10:12 PM

Chassis# 107-044-12-002644
Engine# 117-98212-002659

The lobe does not have a dip. The scoring is as described (3mm x 16mm and catches nail when slid across). What if i don't replace the cam or rocker, can this lead to other damage? Can this cam last another 100K?

Attached is the page from the FSM showing engine and cams used.

Thanks,
Elliot

I cant post a PDF page from the FSM CD so i can only refer you to camshaft document 05-215 on the 107 CD. Here you will see all the camshaft numbers and the cooresponding engine.

erubin · #5 04-01-2004, 01:18 AM

camshaft document 05-215

stevebfl · #6 04-01-2004, 08:08 AM

I looked this morning on a US information and the 52 and 53 cams are listed for 117.981,2,3, and 4 motors. Interesting that the european cars had 56 and 57 cams in them in 117 motors.

The cam won't last long at all, if you don't replace the rocker arm which is simple to do and CHEAP. The rocker failed first. Also check out the oil feed pipe. Be sure it isn't plugged (watch oil flow when cranking with valve cover off - catch the oil with rags - disable ignition) and besure it is firmly mounted to the cam bearings.

The problem with leaving it the way it is, depends on whether you have oil and how soon you wish to dump the problem onto someone else. MB would say replace it all. I would say replace the rocker and re- evaluate the situation in a year. Leaving it will continue to grind metal into the oil system BTW.

erubin · #7 04-01-2004, 01:35 PM

Steve,

Your suggestion will be followed. I will replace rockers on the 2 scored lobes. I know you prefer replacing the cam and all the rockers but I guess you can empathise with my budget.

I've read that the right cam on some MB V8s generally fail first. Is this because it does not get oiled as well as the other cam?

GermanStar · #8 04-01-2004, 01:41 PM

While you're in there, replace the oiler line nipples as well. Part No. 1161800084 -- 1 kit does 1 cam. It's a little nickel-dime part and may add some longevity to your cams.

erubin · #9 04-01-2004, 02:27 PM

Thanks Germanstar,

I already broke one so they will be ordered.

I want to replace several rockers off the right cam Two lobes are scored so this is just a bandaid until funds improve. Can i also emery cloth the scored cams to take away the "tooth".

Can the rockers be removed without a valve compressor with the cam in place?

autozen · #10 04-02-2004, 10:59 AM

Plan on cxhanging that cam out someday. You are right about the right bank failing on the 4.5s. I think they had an mfg problem in those early years. I wish I had a dollar for everyone of those I have changed. The replacement cam doesn't give any trouble. They had they had the same problem with the early 300D cams. You had install upgraded cam, rockers, and valve springs.

Peter