Bad cam lobes on a new 1979 300SD purchase - PeachParts Mercedes-Benz Forum

CasqueHead · #1 12-20-2010, 04:36 PM

I recently purchased a very nice looking 1979 300SD. I won't go into the details right now, but let's say the purchase was a bit impulsive.

I had managed to overlook a good deal of oil seeping from the valve cover, but it wasn't enough to leave more than a few drops on the ground. I figured I would take care of it when I adjusted the valves the next day and that would be that.

As I adjusted the valves, I noticed considerable wear on several of the cams and it dawned on me that the reason the valve cover was leaking was because the VC gasket had not been changed because the valves had not been adjusted for some time. The cams with the most wear were also the tightest.

Compared to my old 1984 300D Turbo, the car seems to have really good power and only a slight amount of white smoke when I floor it from a stop (if those are any kind of good indicators), so I am hoping the engine hasn't sustained any damage that can't be resolved. I haven't had a chance to do a compression test yet.

From what I have read here, the most prudent thing seems to be to replace the camshaft and rocker arms. I spotted a set over the weekend (shown below) and went ahead and made the purchase.

Now that I have committed to these parts, I really don’t have a clear idea of what it takes to swap these out. I’ve browsed around the forum quite a bit, found many good tips, but don’t really have a full grasp of where to start, what to look out for, etc. I am guessing I would want to swap out the timing chain at the same time. Do I need to remove the head (and am I in over my own)? Any specific tools, other than sockets and wrenches, etc?

If anyone would be kind enough to point me in the right direction, I would truly appreciate it. I’ll continue to browse the forums as well, as I plan to prepare very thoroughly before I even crack the valve cover. In the mean time, I’ve got a leaking turbo drain, complete set of engine mounts and shocks, as well as a bunch of suspension work to keep me busy. I’ll do my best to document whatever I do with pictures, etc., and hopefully be able to give back in some way.

Thanks very much,
- Chris

vstech · #2 12-20-2010, 05:29 PM

not sure, but there is a really nice 80SD in the PNP in charlotte. perfect saddle interior.

panZZer · #3 12-20-2010, 07:13 PM

Dont feel bad the sd you have had the 107 hp cam--you needed to swap to the 125hp one anyway.

vstech · #4 12-20-2010, 09:54 PM

the pnp also has some 123's and 126's and a 107, and some 124's.
the valve cover was still in place on the 123, 83 300D I don't think I'll have time tomorrow to pull a cam, but it is there.

rs899 · #5 12-21-2010, 06:40 AM

You really need to consult the service manual for what you are going to do. As luck would have it, there is one for your car over at www.116.org. They hardened the cams in 1980( the service manual will tell you the markings on the later one) so I hope youe bought one of those.

kerry · #6 12-21-2010, 08:31 AM

If I'm not mistaken, there was a recall or a TSB on those cams. There were problems with the early cams.

CasqueHead · #7 12-21-2010, 01:56 PM

Quote:

Originally Posted by rs899

You really need to consult the service manual for what you are going to do. As luck would have it, there is one for your car over at www.116.org. They hardened the cams in 1980( the service manual will tell you the markings on the later one) so I hope youe bought one of those.

Coincidentally, I came upon that very site this morning before checking back here. I had been planning to buy the CD version (and will probably still), but the information I found is just what I was looking for. Not sure about which cam I bought yet, but it's on its way, just the same. I'll post more here as I dive into this thing (which may not be for a while, want to stabilize the patient with mounts first). In the meantime, any additional advice/gotchas would be most appreciated.

Thanks again,
- Chris

rs899 · #8 12-21-2010, 07:43 PM

The CD version is identical to what's on that site. I would save your money and look for some paper manuals- they are worth it.

CasqueHead · #9 12-23-2010, 02:58 PM

Quote:

Originally Posted by rs899

The CD version is identical to what's on that site. I would save your money and look for some paper manuals- they are worth it.

I will do that. Thanks for the tip.

- Chris

Zacharias · #10 12-23-2010, 03:34 PM

Quote:

Originally Posted by panZZer

Dont feel bad the sd you have had the 107 hp cam--you needed to swap to the 125hp one anyway.

What years had the 125 horses camshaft?

rs899 · #11 12-24-2010, 08:17 AM

I thought the numbers I read were:
pre-1980 110 hp
1980- 120 hp

and somehow they squeezed another 3 hp out of the OM 617 around 1982

strelnik · #12 12-24-2010, 08:49 AM

Quote:

Originally Posted by vstech

the pnp also has some 123's and 126's and a 107, and some 124's.
the valve cover was still in place on the 123, 83 300D I don't think I'll have time tomorrow to pull a cam, but it is there.

Wow I need to establish a beachhead in NC and just buy a couple 123 bodies for reuse, as well as a 126 interior, if it is really nice. The 126 I got from benhogan is great, has no rips but does show some wear, which is expected. If the interiors in the cars in NCD are nice enough, I wouldn't need to make a new one.

strelnik · #13 12-24-2010, 08:55 AM

Quote:

Originally Posted by CasqueHead

Coincidentally, I came upon that very site this morning before checking back here. I had been planning to buy the CD version (and will probably still), but the information I found is just what I was looking for. Not sure about which cam I bought yet, but it's on its way, just the same. I'll post more here as I dive into this thing (which may not be for a while, want to stabilize the patient with mounts first). In the meantime, any additional advice/gotchas would be most appreciated.

Thanks again,
- Chris

There must be more than one 116 site, the one I went to was a site for teachers in Ukraine

Doktor Bert · #14 12-24-2010, 01:51 PM

Quote:

Originally Posted by CasqueHead

I recently purchased a very nice looking 1979 300SD. I won't go into the details right now, but let's say the purchase was a bit impulsive.

I had managed to overlook a good deal of oil seeping from the valve cover, but it wasn't enough to leave more than a few drops on the ground. I figured I would take care of it when I adjusted the valves the next day and that would be that.

As I adjusted the valves, I noticed considerable wear on several of the cams and it dawned on me that the reason the valve cover was leaking was because the VC gasket had not been changed because the valves had not been adjusted for some time. The cams with the most wear were also the tightest.

Compared to my old 1984 300D Turbo, the car seems to have really good power and only a slight amount of white smoke when I floor it from a stop (if those are any kind of good indicators), so I am hoping the engine hasn't sustained any damage that can't be resolved. I haven't had a chance to do a compression test yet.

From what I have read here, the most prudent thing seems to be to replace the camshaft and rocker arms. I spotted a set over the weekend (shown below) and went ahead and made the purchase.

Now that I have committed to these parts, I really don’t have a clear idea of what it takes to swap these out. I’ve browsed around the forum quite a bit, found many good tips, but don’t really have a full grasp of where to start, what to look out for, etc. I am guessing I would want to swap out the timing chain at the same time. Do I need to remove the head (and am I in over my own)? Any specific tools, other than sockets and wrenches, etc?

If anyone would be kind enough to point me in the right direction, I would truly appreciate it. I’ll continue to browse the forums as well, as I plan to prepare very thoroughly before I even crack the valve cover. In the mean time, I’ve got a leaking turbo drain, complete set of engine mounts and shocks, as well as a bunch of suspension work to keep me busy. I’ll do my best to document whatever I do with pictures, etc., and hopefully be able to give back in some way.

Thanks very much,
- Chris

What do you need?????

bgiovan · #15 01-01-2011, 11:25 AM

The definitive W116 website (run by Australians): http://www.w116.org

Just picked up a 79 300SD in similar condition and am going thru a head issue due to overheat at present. Luckily have an '80SD parts car in the garage. Need to R&R the heads this weekend.