backwards engine running

[ben hall]

my engine was running the correct way for 3 - 4 mins then during running started going the wrong way . anyone had that happen?

pre detination from wrong plug was my thoughts causing engine reversal . what i really wanted to know was  if anyone know much about this glow plug tuning and such like . i go to model shop they just give me any one . i havent really had a clue about hot cold normal plugs untill reading in to it . in this huge forum some one must have the answers and experience of matching glow plugs to fuel and such like . i heard that the incorrec t plug for fuel can make a engine run at 2000rpm less then its capable of . along with predetination it gives bad preformance . just want to hear what people have found out over the years and am sure there will be people in here that know .

Edited By Timbo - Administrator on 23/03/2010 12:20:48

[mal brewer]

 

Posted by John Privett on 22/03/2010 19:14:40:

2 strokes - no problem.  we've all "been there, done that, got the T-shirt." 

 

But I'm struggling to work out how a 4-stroke manages to run backwards.  Surely it is then sucking air in through the exhaust and exhausting out through the carb?  Maybe if there was some unburnt fuel in the exhaust it may run very briefly, and probably very badly.  Is that what people are seeing, or are they seeing more prolonged reverse running of 4-strokes?

 It's not only model 4-strokes that will run in reverse.When I was a hgv driver,it was fairly common for a well-known make of engine to fire up and run in reverse.This engine was was built by Gardner,of Patricroft,Manchester,and was a boss'es favourite,on account of it's economy.It was common in those days to have the air filter inside the driver's cab,and when the engine started backwards, the exhaust fumes and smoke would come out of the filter and fill the cab with fumes- very nice !...........Mal.

[ben hall]

this is interesting stuff never thought a 4 stroke could run backwards. where does it take its fuel from or is it just burning unburnt suff or is it sucking vapor and fuel from tank via the exhaust presure pipework

[Peter Beeney]

   It is with a great sense of trepidation that I send this post! I’m wondering what next will go wrong.

   I, too, have boggled about the reverse running four-stokes. The fuel tank must be full, so that fuel can be drawn up through the vent tube in the tank. It’s a pressure system, so how does any air get into the tank when fuel is drawn out? The nipple in the silencer must act like a very crude jet. They certainly do run backwards, though, the exhaust fumes exit through the carburettor. Is the pressure increase in the carb the method by which air gets back into the tank? It’s amazing how, when you don’t want something, it happens, and then when you want it to happen………
   Long ago, in the past, I’ve watched a man decoke small two-stokes and then run them, minus the carb and silencer, simply by filling an oilcan, the lever operated type with a spout, with petroil, and just squirting it in the open inlet port. He was quite good at it. Very impressive! And so was the noise. PB

Edited By Peter Beeney on 22/03/2010 22:31:58

[Martin Harris - Moderator]

Interesting one - may be related to the valve overlap if it happens in practice. 

 

Checking an old 40 Surpass rotating backwards, there's almost 90 degrees of movement after TDC which will admit a small amount of gas from the inlet tract.  The exhaust valve then opens, sucking burnt charge back in which may contain some unburnt mixture closing at less than 270 degrees so some of this will be pushed back out again. The remaining movement to TDC and almost to BDC occurs with the valves closed allowing a reduced power "power" stroke if there's enough combustible mixture.

 

The fly in the ointment is that the final up stroke occurs with the inlet valve open which would push exhaust gas back into the inlet tract and it's pretty unlikely that the short induction period mentioned earlier would suck in anything very combustible but with more different valve timing maybe there would be enough for weak running?

 

Can anyone confirm observing this happening and on what engine(s)?

[Martin Harris - Moderator]

Posted by mal brewer on 22/03/2010 22:09:27:

 It's not only model 4-strokes that will run in reverse.When I was a hgv driver,it was fairly common for a well-known make of engine to fire up and run in reverse.This engine was was built by Gardner,of Patricroft,Manchester,and was a boss'es favourite,on account of it's economy.It was common in those days to have the air filter inside the driver's cab,and when the engine started backwards, the exhaust fumes and smoke would come out of the filter and fill the cab with fumes- very nice !...........Mal.

 Some Gardner commercial diesels were 2 strokes - perhaps this was one of them?

Edited By Martin Harris on 22/03/2010 23:23:24

[mal brewer]

Posted by Martin Harris on 22/03/2010 23:05:41:

Posted by mal brewer on 22/03/2010 22:09:27:

 It's not only model 4-strokes that will run in reverse.When I was a hgv driver,it was fairly common for a well-known make of engine to fire up and run in reverse.This engine was was built by Gardner,of Patricroft,Manchester,and was a boss'es favourite,on account of it's economy.It was common in those days to have the air filter inside the driver's cab,and when the engine started backwards, the exhaust fumes and smoke would come out of the filter and fill the cab with fumes- very nice !...........Mal.

 Some Gardner commercial diesels were 2 strokes - perhaps this was one of them?

Edited By Martin Harris on 22/03/2010 23:23:24

  No Martin, the Gardner diesel was never a 2-stroke, the main builders of 2-stroke commercial engines were Commer,with their TS3 engine, and Foden,with a supercharged 2-stroke. The Commer engine was unusual,possibly unique,in having three cylinders and six pistons.The Commer engine was also supercharged,via a Rootes blower.Going back to the bubble cars with the Dynastart reversing gear referred to earlier,a curious side-effect was that all gears were available in reverse,and the vehicle could be driven as fast in reverse as forwards...........if you had the nerve !...Mal.

[Martin Harris - Moderator]

Well it was only a suggestion and I'm certainly no commercial diesel expert.  It does appear that Gardner built some 2 strokes many years ago but perhaps they were only used in stationary/marine applications?

[mal brewer]

Posted by Martin Harris on 23/03/2010 00:53:47:

Well it was only a suggestion and I'm certainly no commercial diesel expert.  It does appear that Gardner built some 2 strokes many years ago but perhaps they were only used in stationary/marine applications?

 Hello Martin,you could be right,although I have never heard of a 2-stroke Gardner engine.Every Gardner engine I know about,from 4 ,5 ,6 and 8 cylinder,have all been 4-strokes.Incidentally,Gardners were originally marine engines,and were adopted for road vehicles.They ceased production about 20 years ago...........Mal

[Stephen Grigg]

Weve a Galaxy diesel that only runs by spraying brake cleaner into the air inlet,think the Turbo has gone

[Brian Parker]

As posted above, I also fail to see how a 4 stroke glow engine is able to maintain reverse running.
I have heard several stories over the years of Diesel engines, automotive, marine and stationary, running backwards. Also of stationary engines installed in engine/generator sheds where the air vents became blocked and the running engine caused the shed to implode.

The problem I have with automotive/marine engines, perhaps I'm missing something, if the injection timing was advanced enough to 'back-rock' the engine then surly the timing in the reverse direction would be so retarded that the compression temperature would be insufficient to combust the fuel.

 Perhaps the long stroke of a Gardiner engine and its relative piston speed could maintain revolutions for a period.

The two stroke diesel, (certainly the TS3 (as mentioned above) and also the Napier Deltic) that utilised a blower(supercharger) for scavenging could only run in the 'forward' direction.

[Martin Harris - Moderator]

Posted by Brian Parker on 23/03/2010 10:23:04:

I have heard several stories over the years of Diesel engines, automotive, marine and stationary, running backwards. Also of stationary engines installed in engine/generator sheds where the air vents became blocked and the running engine caused the shed to implode.

 

Surely an urban myth - by the time there was so little air in the incredibly well sealed shed there wouldn't have been anywhere near enough oxygen to support combustion!

[Peter Beeney]

 

   Timbo, Sorry, I’ve just caught up……    

   Regarding the posts that distorted this thread. On page one it was my post that was responsible. There were no links in the post and it was pasted from TextEdit, as Plain Text. I think it’s just the volume of the post that overcame the site. However, page two was very unfortunately stuffed by Ben’s post, 21:12:25, this was the unsuspecting culprit. There were no links here either, but he did have one emboldened, underlined sentence to illustrate his point. Could this have had a bearing here? His post was certainly not overly long. Rather unfortunately, it was part of my post that he used, so I unwittingly became embroiled in this, too!

  

   So, it would seem as though it’s not only links that cause a problem, but also large posts and possibly long underlined sentences. The underlining is common to both long links and the long sentence. Maybe the technical division could corroborate this? I shall make a careful note of exactly the size of post that will be accepted.

   

   I do apologise for ruining this thread, actually quite a good one, I thought, but as I explained before, the Mac computer expert’s view, and I stress only a view, was that Pages, and Word, were not very complicated and any problems would be down to the site. We’ve been here before, in ‘How do we get rid of the adverts that cover the posts,’ by Lazygit, 21:03:2010.

  

    Again, sorry!                                  PB

 

 

[Brian Parker]

Martin,
 Fully agree.  

An urban/rural myth.

Gardner even specified a range of optional fuel pump governor springs to compensate for altitude running to maintain output power.

[Tim Mackey]

As you suggested Peter, the page two error was young Bens post after yours that caused the issue, not yours - so apologies.  However simply removing the underlined/bold text from his post had no effect - I suspect he copied and pasted incorrectly from another doc?

Ive cleaned things up, and have re-posted your page one contribution so it should all make sense again now.

You thought it was your overly long text that caused the issue - but not so.

I copied it in its entirety into Word, and used the forum paste facility to convert it to a useable format ......and its fine.

Edited By Timbo - Administrator on 23/03/2010 12:35:39

[Ultymate]

Posted by Stephen Grigg on 23/03/2010 02:11:14:

Weve a Galaxy diesel that only runs by spraying brake cleaner into the air inlet,think the Turbo has gone

 You're brake cleaner's working like "Easystart" /Ether sounds like no fuel being injected not your turbo !

[ben hall]

Posted by Timbo - Administrator on 23/03/2010 12:28:08:

As you suggested Peter, the page two error was young Bens post after yours that caused the issue, not yours - so apologies.  However simply removing the underlined/bold text from his post had no effect - I suspect he copied and pasted incorrectly from another doc?

Ive cleaned things up, and have re-posted your page one contribution so it should all make sense again now.

You thought it was your overly long text that caused the issue - but not so.

I copied it in its entirety into Word, and used the forum paste facility to convert it to a useable format ......and its fine.

Edited By Timbo - Administrator on 23/03/2010 12:35:39

 I USED THE FORUMS BUILT IN QUOTE THINGY

[Tim Mackey]

Its not the quote facility Ben, its the "paste from word" button ( third from the right on the toolbar )

 

Perhaps the combination of pasting, and capitals, underlines /bold etc screwed it up?

[ben hall]

[Tim Mackey]

wrong

[Martin Harris - Moderator]

Not wrong for quoting though - or is it?

[Tim Mackey]

Of course not - but its the whole copy and paste thing Im trying to sort.

[Stephen Grigg]

Is the quote button what you use when your quoting somone elses post then and if so how does it work?

[ben hall]

Posted by Stephen Grigg on 23/03/2010 18:35:08:

Is the quote button what you use when your quoting somone elses post then and if so how does it work?

 cvlick the quote button under the post and it puts the post ur quoting in the dialogue box SIMPLES even the meerkat can do it

[mal brewer]

 How do you use the system to quote part of a previous post ? I've tried to do this, and always end up with the complete post being quoted .I don't think me and computers were meant to meet !.......Mal.