I just had valves adjusted and my 84 300 D still has rough idle. While at the shop for valves, my mechanic informed me that I need a new rear muffler. Could the muffler cause the rough idle??

Thanks,
Harry

You sure it's not just change of muffler fluid needed, instead of whole new muffler?

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Cheers!
Scott McPhee

1987 300D

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1987 300DT
2002 Ford F-250 7.3 Crew Cab Short Bed

Well I don't think your muffler is causing the rough idle. It could be an injector or it could be compression. What I think you should do is a compression test. You need a compression test kit to do that. Maybe your mechanic could do it for you. But if it runs good, just a little shabby on the idle, maybe just live with it. Does the idle improve when you pull it out of gear? If it does maybe the idle speed is to low, and it can be difficult to increase as there is no adjustment screw.

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Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

I would start with an injector cut-out test. Just crack the line at each injector one at a time with the engine at idle. If you get to one that doesn't change the running of the engine when you crack the line, you've found your problem cylinder. After that, swap the injector with an adjacent cylinder to see if they problem follows the injector or stays with the same cylinder. If the problem goes with the injector, you know the injector is bad. If not, then you know it is something else.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

Try adjusting the rack damper. It is easy to do and doesn't cost anything. A 12 and 14MM wrench are all you need.

If you have only just done the valves, give it a couple of 100 miles. best do a good Italian tune as well.

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I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving