2-71 Detroit will not start.

Nige · Oct 6, 2015

Most marine diesels of that era will run both ways. It was always the SOP for reversing a ship until azimuth drives came in.
Even ship's steam turbines had a forward and reverse turbine built into the same housing and whether they went foreward or backward depended on which turbine you put the steam supply on. To watch all the steam valves being spun open/closed manually while a ship was manoeuvring in harbour was a sight to see...

OFF · Oct 6, 2015

kshansen said:
Well a Detroit "will run" backwards but not very good or for too long, oil pump and blower turning the wrong way is not good!

Actually wonder if the reversing gear box was a simpler design than the reversing the rotation of the engine? Bet the idea of reversing engine rotation was the brain child of someone who got their start designing steam engines!

Detroits run backwards alright.......sometimes you didn't realize it until the air filters caught on fire, it's all downhill from there. In air compressor applications you really had to watch, just a little kick back and away the Detroit would go. Good fun.

I believe some 2-stroke snowmobiles start up in reverse rotation to provide reverse gear. The idea is not dead yet!

kshansen · Oct 6, 2015

OFF said:
Detroits run backwards alright.......sometimes you didn't realize it until the air filters caught on fire, it's all downhill from there. In air compressor applications you really had to watch, just a little kick back and away the Detroit would go. Good fun.

The one time I saw it happen was back in 1968, remember because I had just started at the quarry a couple weeks before. Well driver in an old stick shift Euclid was pulling up a steep short grade in too low a gear. Truck stalled and before he could push clutch in it rolled back enough to restart the engine. Fortunately there were guys right there that new what had happened. Yelled at him to kill the engine then restarted it and back to work.

CaptainAnalyzer · Oct 6, 2015

kshansen said:
The one time I saw it happen was back in 1968, remember because I had just started at the quarry a couple weeks before. Well driver in an old stick shift Euclid was pulling up a steep short grade in too low a gear. Truck stalled and before he could push clutch in it rolled back enough to restart the engine. Fortunately there were guys right there that new what had happened. Yelled at him to kill the engine then restarted it and back to work.

I heard a story of an old R-model 6-wheeler with an E6 that was crawling a grade on a jobsite that stalled and started in reverse. Driver said all his forward gears were reverse, no oil pressure, the excavator operator jumped from the cab of the machine to shut it off. The company still has that truck.

old-iron-habit · Oct 6, 2015

I have seen them run backwards a couple times in trucks that the clutch got pushed in to late crawling out of the woods. The smokes pours out of the intake but it was always kinda white and because the exhaust valve timing was way off and opening on the compression portion of the stroke. Made the engine run slow and dirty. Shut off quickly and restart to straighten out. I need some explaination on how the ship engine Detroit's (Maybe they were not Detroits) could be reversed to run counter rotation without changing the cam. Maybe it was possible to change the cam timing enough to make it run good enough to back up?

kshansen · Oct 6, 2015

Did some Google search and no simple answers but at least one explanation mentioned a cam shaft that had two different sets of lobes on it and it was moved axially by hydraulic pressure. Say when running in "forward the cam was shifted to the front. When running in "reverse/astern" the cam would be shifted towards the rear of motor. This would address the valve and injector timing aspect. I can imagine the oil pump being designed with a set of check valves that would allow the flow to be automatically corrected for the selected rotation.

Found another page that might explain it better:

http://www.marinediesels.info/2_stroke_engine_parts/Other_info/lost_motion.htm

Former Wrench · Oct 6, 2015

40 years ago a WWII Navy Vet told me about a big Fairbanks-Morse that he was around. Compassed air shifted the double lobe cams to run the engine right or left. His comment was that unless there was all kinds of room, it was best to have a yard tug close by for mooring help.

Nige · Oct 7, 2015

Here's an explanation of how it works on various makes of 4-stroke engine.

http://www.brighthubengineering.com/marine-engines-machinery/60584-reversing-of-marine-engines/

lantraxco · Oct 7, 2015

FM's, were those twin crank, opposed piston lovelies? Always wanted to get up close and personal with one, never have.

old-iron-habit · Oct 7, 2015

Nige said:
Here's an explanation of how it works on various makes of 4-stroke engine.

http://www.brighthubengineering.com/marine-engines-machinery/60584-reversing-of-marine-engines/

Thank you for that Nige. Sliding the cam is most interesting. It would be fun to see one work to see how the pushrods move from the forward lobe to the reverse lobe. Its amazing the amount of engineering that shows up in different applications.

Oxbow · Oct 7, 2015

kshansen said:
The one time I saw it happen was back in 1968, remember because I had just started at the quarry a couple weeks before. Well driver in an old stick shift Euclid was pulling up a steep short grade in too low a gear. Truck stalled and before he could push clutch in it rolled back enough to restart the engine. Fortunately there were guys right there that new what had happened. Yelled at him to kill the engine then restarted it and back to work.

I actually had this happen on a 3406 B for just a second until I shut it of, same scenario - pulling out of a steep dock at an idle, stabbed the clutch at what must have been the perfect moment. Sounded funny with the exhaust coming out of the air filters.

spanner · Oct 9, 2015

The talk earlier about air start GM's reminded me of a time when the mine I was working at was looking at replacing the Cummins 1710's in the Euclid R 85's they ran as a way of getting a bit more speed / grunt out of them. They shoehorned a V 12 GM ( I think I am remembering silver series 92 but I could be wrong ) into that thing. They engineered mounts , pipes , brackets etc and bolted it up to the Allison tranny. It looked like it was meant to be in there. Time to fire it up. That air starter howled for two days before they realised the jimmy had decompression shafts. It did get up and boogie though when they got it on the haul road.

spanner · Oct 9, 2015

By the way , I have seen two Jap truck engines (both Hino now that I think about it ) run backwards for a few seconds . Both heavily loaded / stalled and run back down steep inclines. White smoke comes from just about everywhere it seems but I guess it's mostly intake system . Both switched off with the key and started straight up with no obvious ill effects.

OFF · Oct 9, 2015

I somehow managed to get 1 engine on a 2 engine Hitachi excavator to run backwards long enough to the destroy the air filter. Inline 6 cyl. diesel, Isuzu I think. 4 strokes can do it too I guess

ol' Grump · Oct 10, 2015

Post #62 reminded me of many years ago when I was working in a mine in NV. They had an old 315 CFM compressor that had a 3-71 for an engine and in really cold weather, you'd pop an ether capsule in, discharge it and hit the starter. The cantankerous critter would fire and go to rocking back and forth. What was happening was that it would fire on one cylinder, then kick back and fire again, kick back and fire again. Instead of making a full revolution, it was only making 1/3 of a revolution back and forth. Cure? Shut it down, repeat start sequence and watch to make sure it ran properly. Sometimes in below zero conditions, you'd have to go through the start sequence several times.

grandkobelco · Oct 13, 2015

Hey CaptianAnalizer. Don't let these old timers give you any flack, There will be a day when you are lamenting the good old days of urea injectors, catalyst, 35000 psi injection pressure, exaust filters, IR codes and pistons that go up and down! Instead of ion plasma hydrogen compressers that are always leaking the nucleus out of the center atoms of the magnetron and the operator still cant get a bucket full of dirt out of the ground. wes, class of 79, GO BULLDOGS!

kshansen · Oct 13, 2015

grandkobelco said:
Hey CaptianAnalizer. Don't let these old timers give you any flack, There will be a day when you are lamenting the good old days of urea injectors, catalyst, 35000 psi injection pressure, exaust filters, IR codes and pistons that go up and down! Instead of ion plasma hydrogen compressers that are always leaking the nucleus out of the center atoms of the magnetron and the operator still cant get a bucket full of dirt out of the ground. wes, class of 79, GO BULLDOGS!

Grandkobelco,

Who you calling an oldtimer? The real oldtimers were like my dad. Here's a old picture of him running the pit loader when I was but a wee one!

If you think the emissions were a problem with the old two-smoke Detroits, think about running one of these on a hot day in July!

CaptainAnalyzer · Oct 13, 2015

grandkobelco said:
Hey CaptianAnalizer. Don't let these old timers give you any flack, There will be a day when you are lamenting the good old days of urea injectors, catalyst, 35000 psi injection pressure, exaust filters, IR codes and pistons that go up and down! Instead of ion plasma hydrogen compressers that are always leaking the nucleus out of the center atoms of the magnetron and the operator still cant get a bucket full of dirt out of the ground. wes, class of 79, GO BULLDOGS!

Thank you very much Grandkobelco for your support. Are you still in the area? Where did you go after graduating?

2-71 Detroit will not start.

Nige

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OFF

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kshansen

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old-iron-habit

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kshansen

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Former Wrench

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Nige

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old-iron-habit

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spanner

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spanner

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OFF

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ol' Grump

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