On my battered 1984 300CD Diesel Sports Coupe .
There are HUGE fires in Southern California right now , the sky is dark and ash is (was) falling like snow all over the San Gabriel Valley....
I was at a car show early Saturday morning when the sky got so opaque the sun was no longer visible and the heat eased off a bit so I bailed out and drove home because my engine still lopes at idle and I wanted to do a hot valve adjustment just to see.......
I found three slightly snug (not tight) valves and loosened them .001" each (NOTE : a loose valve is a happy valve! tight valves cause missing and burn ) .
Raising the hood I noticed the air cleaner was crooked , I'd recently replaced all three rubber mounts , it turns out the forward end of the 'T' bracket had broken right at the 8MM bolt hole , this was a used Junk Yard bracket I got a while ago , it had been broken on the rear end and welded up , for $6 I didn't care it's now in the rubbish bin (blue recycle)
As long as I had it off I looked closely at the engine and noticed some speckled spots on the right side of the valve cover , grabbed a deep 15MM socket and discovered all the manifold to cylinder heads nuts were loose to varying degrees , I wonder how long that's been going on , I had this engine ' rebuilt ' a while ago and keep finding mistakes and having failures caused by poor workmanship 
.
Loose intake gasketing means lower boost pressure ~ a bad thing for a Turbocharge engine as it reduces power and makes it run too rich , this one has been consistently smoking and having ' soft ' throttle response .
As long as I was getting filthy I decided to remove the EGR valve , I'd already heat sealed it's vacuum pipe to disable it but I was concerned the valve proper might not be sealing closed due to carbon buildup and sure enough ~ I could blow through it .
Cleaning it is fairly straight forward if amazingly filthy , my Harbor Freight vacuum pump doesn't hold vacuum so I had to continually stop cleaning and pump it up again to hold the valve open so I could clean the seat...
As it turns out the EGR valve was replaced (date code 1987) and isn't the nicer (IMO) adjustable one , in time and with 1/3 can of brake cleaner , some rags a small wire brush and a tiny flat bladed screwdriver to scrape the heavier deposits away, I was able to clean it up to like new again . it now seals firmly , NO bleed off of pressurized air from the inlet to the exhaust or vice-versa .
I fiddled with a bunch of small things like this then decided to run to my favorite local Pick-A-Part Junk Yard , left a note for Tom and off I went .
He arrived just as I was parking , the sun came out and it began to bake .
I found _one_ slightly damaged 'T' bracket and a shorted out and fried block plug heater cable , I'll see if I can splice in some new wires , maybe The Classic Center will still be able to order me a new one , one never knows ~ these cold (80° F!) Southern California nights , maybe I'll need it some day 
.
I only worked a while before nearly passing out and getting over exposure in spite of my floppy sun hat and long sleeve shirt , loaded up and headed home , hydrating all the way , installed my new (used) 'T' bracket then installed a good used overboost protection valve on Tom's '87 300SDL , the rubber boots were badly rotted and the plastic piping was all clogged plus the special tiny clamps were gone missing so it took some time to make work .
I still need to find one for my '84 plus a 1984 W123 air cleaner assy , I bought a nice one from an '84 W126 and it's ever so slightly different , I'm using it but will discard it as soon as I find the correct one . I'm pleased to announce that snugging up the manifold nuts instantly raised the intake manifold pressure at all RPM's including idle .
less smoke in my rear view mirror as I drove to SWMBO' place at sunset ~ I've been diligently tinkering and tweaking this car and the smoke is vastly less than it used to be but *any* visible smoke isn't acceptable to me .
It also takes off from a dead stop better than it has for a long time so maybe the reduced boost pressure due to leaks was effectively making it run richer ? . I don't know but I'm learning as I go like always , not sure why the weirdest problems always wind up ay my door step but it's mostly fun and always challenging to learn .
-Nate
Posted by: vwnate1@yahoo.com
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