380SL HUGE smoke going downhill only - Mercedes-Benz Forum

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post #1 of 4 (permalink) Old 01-11-2011, 10:15 AM Thread Starter
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Date registered: Jan 2011
Vehicle: 1985 380SL
Location: Los Angeles
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380SL HUGE smoke going downhill only

I purchased an '85 380 SL 4 years ago. It drove pretty well and passed SMOG here in CA. All was well until I drove DOWN the hill from my home the next morning. The smoke cloud was bigger than anything James Bond had in his Aston. The trans shift was also sluggish, so I put an additive in and that cured the shift problem. The additive had a unique odor. From time to time, I smell the additive in the passenger compartment. O.K., that is the background info..
I have had the valve covers off and there is no oil pooling along the valve train. I did notice indication of worn valve guides. I have run the car (gently) with only 3.5 quarts of oil to see if crank splash from oil getting deep at the front of the pan, while going down hill, was the problem. No change. Hill angle needs to exceed 25 degrees down to have the problem. GOING DOWNHILL (steep) IS THE ONLY TIME THERE IS A SMOKE PROBLEM. It seems it's time overhaul the heads, but wonder if there is more wrong before going to that time & expense. I'd hate for the problem to be bottom end too, or that be the real problem. The car has 172K. It has the X2 timing chains, not sure if that indicates previous head overhaul. The car virtually sat for 5 years prior to my starting it in the previous owner's garage. It is gorgeous and I want to get it running right.
I live in Los Angeles and would like to get the opinion of an expert, someone who will take the time to diagnose this problem correctly, then proceed with the repair. I have not found that shop yet.
I hope the right person reads this.
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post #2 of 4 (permalink) Old 01-11-2011, 04:31 PM
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post #3 of 4 (permalink) Old 01-13-2011, 11:20 AM
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Definitely sounds (looks!) like valve guides/seals. If it sat for 5 years, the valve seals have probably deterioated (sp) due to NO oil for so long (the neoprene or whatever is used is probably in little, crumbly, pieces in the bottom of your oil pan (let's HOPE that's where they wound up..............).
Pull off the valve covers and have a lookey.

Last edited by larrypayne; 01-13-2011 at 11:22 AM.
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post #4 of 4 (permalink) Old 01-14-2011, 12:13 AM Thread Starter
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Thank you, Larry. I've had the valve covers off and the seals are still there. No chunks missing, but they may very well have shrunk and hardened. Guess if I replace the seals on #1 and #8, I'd stand a shot of knowing if the problem is top end, or not. I finally have a bit of time to give that a shot.
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