I finally had to replace the muffler on the 300D yesterday. It was rusting away after 22 years and finally dropped the tail pipe off about a week ago. Bought a muffler from Fastlane with the help and expertise from Phil. After picking it up from the muffler shop I pulled out with the usual heavy diesel foot and BAMM the car took off like a jack rabbit ! I looked down at the boost guage and it showed 11 psi of boost. Now I have suspected that the wastegate on the turbo was stuck part way open or I had a weak turbocharger for a long time. The most boost I could ever get was about 8 or 9 psi at 3000 RPM going up hill on a 7% grade in the mountains of PA. Now I can feel the turbo KICK in where as before It was pretty slow to build up boost pressure and then usually not more than about 6 psi. The turbo kicks in hard at about 2200 rpm and the pressure jumps up to 10 PSI with just a little pressure on the accelerator. It's like driving a different car. Also I don't have any visible exhaust smoke even when romping down on the fuel pedal. So it looks like the whole problem was a plugged and worn out center muffler. When the shop replaced the muffler I had them use a straight exhaust pipe off it and out to the back and left the rear muffler out of the picture. The PO had removed the rear muffler when it rusted out and replaced it with a section of exhaust pipe. The car is not loud and the turbo can be heard winding up. A plugged muffler was not high on my list of usual suspects for why I had low boost pressure. I had cleaned the banjo bolt and ALDA lines and did all the other things recommended here on the web site. So it looks like time to tweek the ALDA.. Russ

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1978 300 D 258,000 + miles sold 1995
1983 300 D Turbo 152,000 miles
Thank God for the man who put the white lines on the highway