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84 300D; 85 380SE
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75 Posts
Discussion Starter · #1 ·
85 380 SE 188,000 miles, new chain, etc., at
133,000.

well, we've developed a top-end ticking noise on the
left side and i'm wondering if anyone can give me some
insight.

it is constant in conjunction with motor speed, just started about a week ago when the temperature dropped; haven't taken the valve cover off yet (waiting for the weekend and hopefully 50 degree weather).

when i started hunting it down, it sounded more in the middle of the left valve cover area, so i'm thinking (hoping) away from the chain and guides. on further listening with my shadetree stethoscope (large, long screwdriver affixed to the large right ear) it sounds like it's coming from the area around the injector valves and beyond the air distributor hose. of course i know sound transfer can be tricky and/or questionable, but anybody want to take a shot in the dark?

i'm in the light mechanical ability range but have strong supporting cast (in other words, they tell and i do what i can) and i will pull the valve cover this weekend. i know one cam lobe near the fire wall is pretty banged up, but this sounds closer to the fuel
distributor and air regulator to me. do the injector valves tick like that when going south?

thanks in advance.
 

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1991 300 SE
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18,534 Posts
As a shot in the dark I’ll say it’s not the injectors as they’re always spraying, hence CIS. It could still be the chain. When you pull the covers inspect he cam lobes and rockers for wear.
 

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-85 380 SEL
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56 Posts
Check the free-play in the area where you suspect the noise is coming from. And remember that wear on the cam flanks can be nearly invisible, but still the cam can be bad. When you go through the hardened surface on the flanks the cam normally is worn-out.
 

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84 300D; 85 380SE
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75 Posts
Discussion Starter · #5 ·
Stjernegrisen --

when you say free-play, i take it you're referring to
free-play at the cam towers? (sorry, this is a new
repair level to me. i'm used to water pumps and belts
and starter motors and low-tech repairs.)
 

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-85 380 SEL
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56 Posts
I mean the freeplay between the cam flanks and the rocker arms (where the cam push on the rocker arm, the freeplay is specified in the shop manual). If you are lucky it is just a question about adjustment. But if you can see even minor signs of wear or can feel an edge on the cam flanks you´ll have to replace the whole camshaft. Good luck!
 

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84 300D; 85 380SE
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75 Posts
Discussion Starter · #7 ·
thanks. i got you. after thinking about it, i
realized that's where you were talking about.
 

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1991 300 SE
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18,534 Posts
The noise you’ve been hearing COULD be caused by excessive ‘play’ between the cams and rocker arms. Let’s hope that’s all it is.
 

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84 300D; 85 380SE
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75 Posts
Discussion Starter · #9 ·
if that's the case, are we then talking about thrust
washer/shim adjustment? don't i need that tool that
fits over the ball stud to measure the gap?
 

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'98 C43 Kombi daily. '94 C280 factory manual track/drift slag.
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1,030 Posts
It's a common fault on the 116 3.8 engine - the cams / followers wear out at anytime after 100k miles.

I didn't bother with measuring tools, as when it starts to tick, you will probably be able to tell which one is ticking just by feel. All the followers will be tight, with a little free-play on the culprit. The cam wear may not be immediately apparent as someone said above, but you will be able to see it quite clearly on the strike face of the followers. I replaced all my followers and cams + chain, followers and tensioner, and it was immediately apparent just how worn the cams were as the car was way smoother and had so much more power.

Here is a photo of the wear on one of my followers:



This is extreme wear, cause by bad maintenance of the previous owner. You can see bits of it have even broken off. I hope these bits got trapped by the filter before doing any serious damage to the rest of the engine.

Good luck if your car has the same problem. It's not a fun job, but is only a day's work.
 

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84 300D; 85 380SE
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75 Posts
Discussion Starter · #11 ·
thanks for the direction. i've seen the photo of the
follower damage in an earlier post. i'm starting to get the picture (sorry, couldn't pass that one up).

i'll post a follow-up when i get that cover open on
saturday. thanks for all the responses. i'm sure i'll
have more questions and i really appreciate the support!
 

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Registered
1991 560 SEL
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260 Posts
Rockers are pretty easy to change, but you will need the valve spring compressor. I think the rockers are $15 at BAP/GEON. Valve spring compressor cost me about $160 from Performance Parts. Check the oiling tube above the camshaft for blockage. Even if you have to do a cam, its not that tough. $300 in parts and an afternoon.
 

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84 300D; 85 380SE
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75 Posts
Discussion Starter · #13 ·
that was my next question -- valve spring compressor.
that's a good price compared to a shop doing it, but i suppose it needs to be that one. (more concerned about timing the repair.) i have a BAP GEON local, so that
part's easy.
 
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