As in if you are adjusting your valves, and you are turning the engine with a wrench. Would it throw off the timing or something. I'm not dumb enough to do this, but I am curious about this one. Thanks.

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1989 300E 144K

Hmmm, Timing Chain jumping and IP damage come to mind...

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Excuse my ignorance, but how so?

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1989 300E 144K

not sure about the IP part, but the timing chain is only held one one side by tension, the other side is tight because of the crankshaft pulling on it. when you rotate the engine the wrong way (CCW) you put slack in the side that usually is being pulled, then the chain has a chance to skip teeth.

the tensioner will compress without oil pressure if enough force is applied. this will let the slack through to the other side while turning CCW.

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-Trevor

OBK #12
1980 300SD 333,XXX miles - Totaled
1986 Mazda RX-7 212,XXX miles - impounded and auctioned off
2005 Jeep Liberty CRD Limited 33,000- SEGR, Provent, Fumoto

I think the timing chain would have to be really stretched to actually skip a tooth. I have rotated the engine backwards (on my old 300D's) before I knew it was bad but nothing happened. I'm sure I would have noticed if the chain had skipped a tooth (which is like 18 degrees of timing). But today now that I know what I know I wouldn't take the chance again.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

Not sure about the effect on a diesel. But I have actually seen a gasoline engine run backwards. It doesn't run well and it doesn't run for long, but it can run.

Cheers, John

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'98 E300TD (W210) | Sold 6/09 with 205k and counting
'04 VW Touareg V10TDI

diesels can run backwards, it will melt the intake and suck crap up through the exhaust.

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Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.

Yeah, all my Hondas ran backwards.

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tgingrich
'83 300TD 282k
'83 300D 239k
'82 300SD 204k
DFW

Actually this was common problem with primitive bathtub Benz diesels of 1950's. Its even mentioned in the owners manual - what to do if diesel runs backwards. They'd start up running backwards, sputtering and spitting, depending on position of pistons when previously shut down. No permanent damage resulted.

I've heard of people driving diesels with the engine running backwards. Four speeds in reverse and one forward.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

There's a WWII vintage tug which is a National Monument of some kind, based in Oswego NY. The only way to back it up is to stop the engine and start it in reverse. Don't want to have to do that on the lip of Niagara Falls.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

reversiing the engine to back up was pretty common on some large marine diesels years ago and Mercury even built AND sold a 6 cyl inline out board with that fine feature some years back,Harley Davidson golf carts were that way not too long ago,and the funny little Messerschmit car also worked that way when it worked!Two stoke engines dont really care which way they go.Honda had one that they had to modify the ignition system on to prevent it as it was a little kids bike and kids were getting hurt. My $.02 Don

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Red Green "This is only temporary,Unless it works!"

97 E300D 157000 miles
87 300TD ?141k? miles

Personally, I don't think you can cause any harm by rotating the engine in reverse. My only concern would be the very trailing edge of the tensioning rail. The chain might abrade this edge slightly, however, you'd need to make hundreds of revolutions in reverse to do any serious damage to it.

I've reversed direction on the 617 several times during the head installation. It really didn't care.

The first mercedes diesel that I adjusted the valves on some years ago, I rotated it backwards to get the cam set for adjusting the valves. Did all 4 cylinders that way. When we started it up, It made ALOT of chain slap noise but went away when the tensioner pumped up. NO damage BUT I didn't do that again!

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My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.

BUT, those engines used gears instead of a chain to drive the cam and injection pump. The last model to use gears was the 180D.