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#1
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85 300SD Shifting acceleration problem with video
I recently worked on my car and now it has a shifting and acceleration problem that was not there before. Basically at @ 1/4 throttle it acts pretty normal. at 3/4 throttle it stumbles a little like it's losing power half way through 1st gear. In 2nd gear, the car get's "stuck" around 40 mph, seems like it's losing power and will sometimes even slow down 1 or 2 mph, then "all the sudden" the power kicks back in and it accelerated to @ 45 and shifts.
http://www.youtube.com/watch?v=XKQ81f7ptjc This is a 3/4 or so acceleration from a stop. Work on the car started with a freeze plug leak and cracked radiator. Here's what I did: replaced accelerator pedal (old one cracked where it attaches) kickdown switch seemed operational flushed cooling system replaced all 4 belts replaced radiator replaced thermostat (spring toward engine) replaced 1 hard atf cooler line and both flexible hoses removed intake and exhaust manifold to replace freeze plugs removed exhaust flex pipe (was cracked so I welded in a new braided flex section) replaced 10 vacuum hose rubber lines (one at a time) cleaned banjo fitting on intake manifold and plastic line replaced air filter and all 3 mounts removed and tested electrical operation of heater valve Added Dexron II ATF changed oil and filter I used an unopened but old Dexron II ATF. After the first test drive I saw the fluid was over the full mark so I drained some and now it's at the same level. No change in shifting. There was a small black cap plugging a vacuum port on a silver thing that I think was what the other end of the plastic vacuum line connecting to the banjo on the intake manifold. this cap was cracked and probably should be replaced. I thought it seemed like it wasn't getting fuel, so I replaced the plastic fuel filter and put $20 of Diesel in the tank. The tank was under vacuum and made a "whoosh" when I opened the cap. I have a new metal fuel filter but have not installed it yet. Not sure how related, but it still seems to run a little hot and the interior heat doesn't heat up fast or blow really hot air. the radiator fan runs all the time. The shifting/acceleration thing baffles me and I feel like I caused it since it didn't do that before. |
#2
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I don't pretend to know everything about these cars, but intuition tells me that if an 80's Mercedes has a transmission problem, it could potentially be vacuum related. Do some tests and see where that takes you. As I have yet to experience transmission/vacuum issues, I don't know the procedures to test the vacuum pump, but it sounds like you know your way around a car, so I won't say anymore. Hell, the worst case scenario is you need some transmission work done.
Just my two cents.
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Never be ashamed to ask for help. 1985 300D 1987 300SDL 1970 Jaguar E-Type OTS 2002 Dodge Intrepid (Traded In) 2011 Ford Crown Victoria |
#3
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loosing power sounds like a clogged fuel filter to me. Replace all fuel filters
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1985 300TD Turbo Euro-wagon 1979 280CE 225,200 miles 1985 300D Turbo 264,000 miles 1976 240D 190,000 miles 1979 300TD 220,000 GONE but not forgotten 1976 300D 195,300 miles 1983 300D Turbo 175,000 miles http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg |
#4
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Thanks for the suggestions. I replaced a few vacuum lines. I'll try doing some troubleshooting. Now that I think about it i did notice that the brake pedal felt a little odd when I started it up. Granted, it was off the road for 2-3 weeks for this work and getting parts etc.
I had some issues with the door locks but that had not affected the driving of the car prior to this round of repairs. I replaced the plastic filter. The metal can type filter is next. There are only 2 filters right? Besides the tank screen. |
#5
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Seems to be fixed
I replaced the main fuel filter, blew air back into the tank to be sure it was clear and it was. I pulled off the check valve for the talk vent under back of the can and blew air though both lines and they were clear and the check valve worked fine.
Car seems to operate like normal. I did however see that the car is running a little hot. I'm not happy about this - I'm off to search for threads troubleshooting that issue. |
#6
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The vacuum and door locks on the SD are a completely different system from the engine vacuum and climate control. One cannot affect the other. If you have problems with the door locks, check the pump in the trunk and pull the lines out of floor just in front of the passenger seat and check them with a Mityvac. You may need a new door lock actuator; that was my problem and the door locks work fine again. Think I paid $20-25 each for door lock actuators.
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