[EMAIL PROTECTED] wrote: > Since the engine was smoking black smoke I know the fuel is getting into > cylinders but it appears not enough oxygen is getting into cylinders, either > due to plugged exhaust or plugged intake. I was thinking intake since I know > theTDI's have problems with intake plugging.
Okay, I forgot to mention the EGR. If it has not been disabled, then probably it is plugged up. I am 'cribbing' a response from another list, below, as the Web page that dealt with this (from the Ritter/Easley list) isn't responding tonight. (Or maybe my link is out of date?) The TDi problem is pretty much unique to that engine, and IIRC has something to do with the EGR setup (some valve or other) and the driving patterns of the owner. There's precious little to clog up on an OM617, it's just a gaping hole and a set of intake runners. Mac Previous response to an SD owner with similar symptoms to yours: 1. ALDA pressure line clogged: Hollow bolt / banjo fitting on intake manifold, and / or switchover (boost safety) valve need to be cleaned. If ALDA pressure line circuit is plugged, you get no power increase from the turbo. Slightly plugged, less power. The switchover valve is a safety device in the event of an over boost condition. Not good to bypass it but OK for a quick test to see if the valve is plugged up. Note: cap on top of switchover valve is a vented dust cap. Don't replace it with a solid rubber cap. Don't over torque hollow bolt when re-installing. Don't lose the two washers (one on each side of banjo fitting). Don't pull the plastic hose off the fitting. 2. EGR: Plug its vacuum line with a BB gun BB. Although this will keep the EGR from working, the valve may leak. Any leaking will reduce turbo boost. Fix is replace EGR (dumb since you want it disabled) or fabricate a solid metal plate (holes only for bolts) and install it between EGR and intake manifold. Maybe need a sealing gasket on each side of the plate. I haven't done this yet to my SD. 3. Air Recirculating Valve: If your '84 is a "California emissions" '84, it has a vacuum actuated Air Recirculating Valve on the output of the turbo, at the intake manifold, just to the left of the EGR. This valve cuts the turbo boost from 1000rpm to 2500rpm by 30 to 50%. Worse yet, if the vacuum system's return line vent filter is plugged up, the Air Recirculating Valve will be operating throughout the RPM range and your turbo boost will be reduced by 30 to 50% throughout the RPM range. If your 300SD has this valve, pull the vacuum hose from it and test drive the car. If you get more power off the line and all the way to ~ 5000 rpm, find and replace the vacuum return line vent filter, re-attach the hose to the Air Valve and test drive again. And then, trace the Air Valve vacuum line to the other end. It should be connected to the front port on the other switchover valve that's located near the front (passenger side) wheel well. Pull the rubber coupling hose from the port on the switchover valve and insert a BB gun BB in it. Re-attach coupling hose. 4. ALDA might be set too lean: Opening it up 1/2 to 1 turn (CCW) will increase power regardless of Items 2, 3, 5, and 6. 5. Waste gate spring may be fatigued. May need to tighten it up. Requires a boost gauge, several hours' time, and lots of patience. However, turbo manufacturers and repair outfits have told some list members that waste gate springs do not fatigue. I've tightened mine up almost as far as it will go. Since my boost is not at full ( 0.9bar + / - 0.1bar) spec., I will soon be checking my SD for manifold and EGR "leaks". You should inspect, clean, plug, everything else before fiddling with the waste gate. When / if you fiddle with the waste gate, you must first adjust (open) the ALDA. 6. Other vacuum or pressure leaks: If shifts from gear to gear are harsh, you have vacuum leaks and your ALDA pressure line circuit is probably plugged up. Your brake booster could be going out. You should inspect / replace all rubber (vacuum) hose couplings. Especially any that are dry, cracked looking, or feel spongy. Do them one at a time so as not to re-attach any to the wrong ports.
