M103 Rocker Towers - PeachParts Mercedes-Benz Forum

iwrock · #1 10-18-2009, 03:41 AM

I did some searching, but could not find any exact information...

Quick question. I am going to be removing the rocker towers, and want to know if i need to rotate the engine to get the cylinder top dead center before removing and reinstalling the rocker tower....

And the manual calls for replacing the bolts with some that are a hair longer than the ones taken out... Is it ok to reuse the ones that came out of there?

wbain5280 · #2 10-18-2009, 05:22 AM

Set the engine to no. 1 TDC and unscrew each bolt a little at a time. Don't forget that the cam is under load at a couple of cylinders. Also, place some 1"X3" wood under the head before you do this. Two sets of valves are open and you don't want to bend them. There is a half moon washer at the front of the camshaft as well.

Get new head bolts because they may be too long by now. New ones are cheap. When I removed my head, the bolts were very tight and was quite a workout to undo them. The manual recommends removing the head with intake and exhaust manifolds attached using an engine crane because the head is heavy and you will kill your back trying to lift it off.

iwrock · #3 10-18-2009, 05:39 AM

Should have been clearer, I am pulling the rocker towers with the head still attached to the block, and the engine in the car. I had the valve seals done not too long ago, but need to do the cam followers to fix the ticking that I am getting from above cylinder 1-2.

long-gone · #4 10-18-2009, 01:48 PM

I'd have to suppose that the bearing caps were removed when the seals were done and apparently had the same bolts put back in with no resulting problems. I understand that M103 heads can sometimes be prone to having the bearing cap threads strip, particularly on high milage cars. Perhaps the deeper bite is why they recommend the slightly longer bolts. They're probably not that expensive and maybe a good investment. Unless someone knows a more critical reason for it, I'd think it would be your call to replace them.
As far as TDC, I don't really see why it would be necessary. If I recall correctly, TDC will relieve pressure on 1, 4, 5, and 6. Do them one at a time. then turn the crank a little and relieve the load on 2 and 3 and do them one at a time as well. I might not have those cylinders correct but that's the idea.
Be careful not to drop the little round ball socket pads down into the oil drains in the head.

long-gone · #5 10-18-2009, 02:05 PM

I just did a little checking and the reason for the longer bolts is, as suspected, to avoid the proclivity for the stripping of threads in the older heads. The change to the longer bolts was made around 1990. If it wasn't a fairly big problem I doubt MB would have gone to the expense of the upgrade, service bulletins, and service retrofitting.

Sounds like a good idea to get them considering the PIA you'll have if you strip one or two.

iwrock · #6 10-18-2009, 02:37 PM

Quote:

Originally Posted by long-gone

I'd have to suppose that the bearing caps were removed when the seals were done and apparently had the same bolts put back in with no resulting problems. I understand that M103 heads can sometimes be prone to having the bearing cap threads strip, particularly on high milage cars. Perhaps the deeper bite is why they recommend the slightly longer bolts. They're probably not that expensive and maybe a good investment. Unless someone knows a more critical reason for it, I'd think it would be your call to replace them.
As far as TDC, I don't really see why it would be necessary. If I recall correctly, TDC will relieve pressure on 1, 4, 5, and 6. Do them one at a time. then turn the crank a little and relieve the load on 2 and 3 and do them one at a time as well. I might not have those cylinders correct but that's the idea.
Be careful not to drop the little round ball socket pads down into the oil drains in the head.

Sweet! This is the info I was looking for. I do not have the longer bolts, as I did not know there was a difference until I looked at the manual.

long-gone · #7 10-18-2009, 04:15 PM

If you're not going to use the longer bolts, make sure you untighten and tighten them a little at a time, maybe a 1/4 to 1/2 a turn and in a staggered pattern (for example, as you face them: bottom left to top right to top left to bottom right back to bottom left, etc.). You'll be relieving the load on the bolts somewhat by turning the crank to the right position as previously mentioned, but there will still be some spring pressure even when the rockers are on the flats.