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1976 450SL 153,000 miles lifter tick, camshaft lobe has flat spot and rocker badly worn

352 Views 9 Replies 3 Participants Last post by  nobby
My car runs great. But ... it sounds like a "sewing machine" with passenger side valve train ticking. I finally got my hands on a valve spring compressor and examined my rockers and cam today. I think I definitely found the source of the ticking. The #2 exhaust and #3 exhaust rockers are badly worn (obvious finger feel diagnosis). However, further finger feel diagnosis revealed that the #3 exhaust cam lobe also has a bad flat spot after the peak. Big bummer ... so I also need to replace the cam.
I'm a pretty good mechanic and I'm up for doing this work. Can anybody on the forums point me to a thread for cam replacement? Also, what are the best sources to get my new cam and other parts?
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My car runs great. But ... it sounds like a "sewing machine" with passenger side valve train ticking. I finally got my hands on a valve spring compressor and examined my rockers and cam today. I think I definitely found the source of the ticking. The #2 exhaust and #3 exhaust rockers are badly worn (obvious finger feel diagnosis). However, further finger feel diagnosis revealed that the #3 exhaust cam lobe also has a bad flat spot after the peak. Big bummer ... so I also need to replace...
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My car runs great. But ... it sounds like a "sewing machine" with passenger side valve train ticking. I finally got my hands on a valve spring compressor and examined my rockers and cam today. I think I definitely found the source of the ticking. The #2 exhaust and #3 exhaust rockers are badly worn (obvious finger feel diagnosis). However, further finger feel diagnosis revealed that the #3 exhaust cam lobe also has a bad flat spot after the peak. Big bummer ... so I also need to replace the cam.
I'm a pretty good mechanic and I'm up for doing this work. Can anybody on the forums point me to a thread for cam replacement? Also, what are the best sources to get my new cam and other parts?
I’m in the middle of that myself. Most important thing: read manual about camshaft R&R. Twice. Then watch a couple of videos. Mine is the left (drivers side) which means I couldn’t remove the back cam tower completely. Pull all rockers. Pull gear Ang KEEP TENSION ON IT SO YOU DONT LOSE CHAIN TIMING. Remove camshaft tower bolts from outside to inside (one row doubled as head bolts). I stressed over the possibilities of these bolts being seized but they came out smoothly. Camshaft slid out easily. I sent my camshaft to Delta Camshaft in Washington - $180 including shipping (one lobe was chipped from a thrown rocker). Came back like new. Reverse for install. Use assembly lube. Might consider replacing upper guides at this point as well.
 

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1976 450SL: 153,000 miles
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Discussion Starter · #3 ·
I’m in the middle of that myself. Most important thing: read manual about camshaft R&R. Twice. Then watch a couple of videos. Mine is the left (drivers side) which means I couldn’t remove the back cam tower completely. Pull all rockers. Pull gear Ang KEEP TENSION ON IT SO YOU DONT LOSE CHAIN TIMING. Remove camshaft tower bolts from outside to inside (one row doubled as head bolts). I stressed over the possibilities of these bolts being seized but they came out smoothly. Camshaft slid out easily. I sent my camshaft to Delta Camshaft in Washington - $180 including shipping (one lobe was chipped from a thrown rocker). Came back like new. Reverse for install. Use assembly lube. Might consider replacing upper guides at this point as well.
Thanks, Reef, for the quick reply and the great tips!
 

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Thanks, Reef, for the quick reply and the great tips!
Sure. Let me know if I can be of any further help. It wasn't as bad as I imagined it could be, but the engine had a top-end dealer overhaul in 2007 (broken chain guide, bent valves, etc) and only about 1K miles since, so the bolts came out easily. The compensators (which you don't have) are another story.... :). It's still in pieces.
 

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Discussion Starter · #5 ·
Sorry you're having such a battle. My car really runs great. I just really hate that valve train tapping. Drives me crazy.
And, by the way, mine's a '76 which is the first year of the "hydraulic compensators", so our cars are alike in that detail.
I am trying to convince myself that the cam isn't so bad ... so ... I might just put it back together with the other new parts I now have and see how it runs ... maybe the tapping will be gone.
 

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Sorry you're having such a battle. My car really runs great. I just really hate that valve train tapping. Drives me crazy.
And, by the way, mine's a '76 which is the first year of the "hydraulic compensators", so our cars are alike in that detail.
I am trying to convince myself that the cam isn't so bad ... so ... I might just put it back together with the other new parts I now have and see how it runs ... maybe the tapping will be gone.
My fuel distributor is likely gummed up. Sat for 15 years in the CA sun…. That’s my biggest worry.
and my dash is cracked in about 15 places….
 

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83 280 SL- 5 speed-The PIG
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· Outstanding Contributor , Bob's Your Uncle!
83 280 SL- 5 speed-The PIG
Joined
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35,607 Posts
Thanks Nobby. I think I must have stumbled on one of the better companies. My dash cover fits imperceptibly. Pretty amazing.
And good to know.
 
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