Member Since: 22 Aug 2013
Location: Out in the world
Posts: 967
The concept of an engine running backwards when put into a forward gear after reverse is certainly an interesting one.
30th Nov 2013 10:02 am
SteveNorman
Member Since: 14 Oct 2005
Location: Somerset
Posts: 1145
I agree with Robbie.
The ones I have seen have freely rotating cranks & cams... (until they meet the valves), just the oil pump housing broken off, with the tensioner usually melted where the engine has still been running with it jammed into the front plastic casing, until it eats it's way through it & finally jumps the belt.
I am amazed, how can anyone believe that when engaging reverse gear the direction of rotation of the crankshaft etc.. changes.
I am inclined to ignore all future posts by boater.
NJSSAm I Gammon or Woke ? - I neither know nor care.
2016 Discovery 4 Landmark
2011 Mercedes Benz SL350 (R230)
1973 MG B GT V8 - 3.9L John Eales engine, 5 speed R380 gearbox, since 1975.
1959 MGA roadster - 1.9L Peter Burgess Engine - 5 speed gearbox
Past LRs - Multiple FFRs, Discos & a Series I - some petrol, some diesel,
none Electric or H2 fuel cell - yet.
There are 10 types of people in this world: Those who understand binary, and those who don’t.
Engine turning backwards when reverse is selected, what planet are you on, why do you think they put the rotation marks on all the belts ?.
And as for the tensioner not being under that much tension, have you ever undone one of the tensioners, they are all under quite a bit of tension, when you pull the rear pin out of the rear belt tensioner it goes with a bang.
Also the front one is under some tension as well as this does the same when you release it, its simple LR cocked up with the Oil pump casing making it to flimsy, hence thats why they changed them.
Flack
30th Nov 2013 10:28 am
boater
Member Since: 06 Dec 2012
Location: Thisted
Posts: 19
Of course i do NOT think the engine reverses when the car does under normal conditions!
I have experienced a few times, that if you reverse and put the shifter in D while the car is still rolling backwards, gear is engaged (forward), this kills the engine and forces it to turn backwards. I might be the only one that has ever experienced this, but i have.
Of course i do NOT do it purposely, and after seeing this happen i now always stop fully before shifting to forward.
If the engine is turned backwards you will have a lot more pull on the tensioner than normally, as you have to turn all the rotating (driven) parts going past the tensioner first. A tensioner is always placed just before the driving pulley, and after the driven ones. If motor is forced to turn oppostie i guess you can see what i mean... and if not i will gladly explain.
30th Nov 2013 11:17 am
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
I value everyones opinion but I just cannot see how this is possible.
To achieve this you would have to have a simultaneous failure of a whole host of components including (but not limited to) the TCM, Shift Interlock, Torque Converter, EPRS(s), speed sensors and the shaft sensors. The purist would even start to point out the shape of the turbines...
To be honest the scenario you describe should cease at the simple reverse lock-out mode hurdle (activates at 5 mph / 8 kph). Even if you tried to trick this out via 'N' the 800ms shift interlock solenoid would get you. Trying to beat that with excess revs would not help as the 2500 rpm logic would have you.
I'm trying to listen but it's not making any sense so far.Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 06 Dec 2012
Location: Thisted
Posts: 19
SteveNorman wrote:
I agree with Robbie.
The ones I have seen have freely rotating cranks & cams... (until they meet the valves), just the oil pump housing broken off, with the tensioner usually melted where the engine has still been running with it jammed into the front plastic casing, until it eats it's way through it & finally jumps the belt.
regards
Steve
So you believe the engine keeps running for a short while before the timing jumps and ruins the engine?
Cranks/bearings normally ok after this happens?'05 D3 TDV6 HSE- 156.000km - no major breakdowns, yet?
'07 RRS TDV8 HSE - 41.000km
I'm trying to listen but it's not making any sense so far.
I believe that the first law of holes should apply:-
Click image to enlarge
NJSSAm I Gammon or Woke ? - I neither know nor care.
2016 Discovery 4 Landmark
2011 Mercedes Benz SL350 (R230)
1973 MG B GT V8 - 3.9L John Eales engine, 5 speed R380 gearbox, since 1975.
1959 MGA roadster - 1.9L Peter Burgess Engine - 5 speed gearbox
Past LRs - Multiple FFRs, Discos & a Series I - some petrol, some diesel,
none Electric or H2 fuel cell - yet.
There are 10 types of people in this world: Those who understand binary, and those who don’t.
30th Nov 2013 11:53 am
SteveNorman
Member Since: 14 Oct 2005
Location: Somerset
Posts: 1145
The belt stays on the correctly timed teeth, sometimes even with the tensioner bracket broken/slack, perhaps because of the drive on the belt, but perhaps when you say, take your foot off throttle, or finally when the cover isn't holding everything roughly in place the belt hops it's teeth & the valves hit the pistons & it's game over. Perhaps not in every case but at least in some I have seen.
Damage is luck of the draw, but needless to say is extensive, & just not worth trashing a good engine for the sake of a known modified part which will prevent it.
regards
Steve
30th Nov 2013 11:56 am
boater
Member Since: 06 Dec 2012
Location: Thisted
Posts: 19
Robbie wrote:
I value everyones opinion but I just cannot see how this is possible.
To achieve this you would have to have a simultaneous failure of a whole host of components including (but not limited to) the TCM, Shift Interlock, Torque Converter, EPRS(s), speed sensors and the shaft sensors. The purist would even start to point out the shape of the turbines...
To be honest the scenario you describe should cease at the simple reverse lock-out mode hurdle (activates at 5 mph / 8 kph). Even if you tried to trick this out via 'N' the 800ms shift interlock solenoid would get you. Trying to beat that with excess revs would not help as the 2500 rpm logic would have you.
I'm trying to listen but it's not making any sense so far.
You lost me there.
What i have experienced:
Pulling a boat out of the water on a slip: Car in D, idling, slip steep enough/boat heavy enough to pull the car backwards - with the car rolling back (pretty slowly, maybe 1-2 kmh) the engine stops and is forced to rotate backwards.
OR:
Reversing on a driveway: reversing out to the road, with car rolling backwards (slow, maybe 1-3 kmh), putting thi shifter to D, engine stalling when gear engages, and forced to turn backwards (car in forward gear going backwards)'05 D3 TDV6 HSE- 156.000km - no major breakdowns, yet?
'07 RRS TDV8 HSE - 41.000km
Last edited by boater on 30th Nov 2013 12:30 pm. Edited 1 time in total
30th Nov 2013 11:57 am
Moo D3 Decade
Member Since: 13 Aug 2010
Location: Wiltshire
Posts: 14129
You must have the worlds toughest engine!
Sorry, but just don't get it. To many things would fail if this happened. Engines can't run backwards.
30th Nov 2013 12:07 pm
boater
Member Since: 06 Dec 2012
Location: Thisted
Posts: 19
SteveNorman wrote:
The belt stays on the correctly timed teeth, sometimes even with the tensioner bracket broken/slack, perhaps because of the drive on the belt, but perhaps when you say, take your foot off throttle, or finally when the cover isn't holding everything roughly in place the belt hops it's teeth & the valves hit the pistons & it's game over. Perhaps not in every case but at least in some I have seen.
Damage is luck of the draw, but needless to say is extensive, & just not worth trashing a good engine for the sake of a known modified part which will prevent it.
regards
Steve
But if you change the oil pump, when are the bearings going to spin or the crank going to break? Or other major issues?'05 D3 TDV6 HSE- 156.000km - no major breakdowns, yet?
'07 RRS TDV8 HSE - 41.000km
30th Nov 2013 12:22 pm
SteveNorman
Member Since: 14 Oct 2005
Location: Somerset
Posts: 1145
Quote:
But if you change the oil pump, when are the bearings going to spin or the crank going to break? Or other major issues?
Or it might get written off when lightening strikes the tree it's parked next to & it falls on it.
These things do happen, but are few & far between compared to the number out there.... have a look on the audi or bmw forums about engine failures, small ends etc.... it happens to all manufacturers.
They aren't connected to a tensioner bracket failure.
regards
Steve
30th Nov 2013 12:54 pm
boater
Member Since: 06 Dec 2012
Location: Thisted
Posts: 19
Moo wrote:
You must have the worlds toughest engine!
Sorry, but just don't get it. To many things would fail if this happened. Engines can't run backwards.
So you dont think i runs backwards, or how should i understand you?
Of course it does not run - it is turned over backwards. Maybe 1-2 rounds, as i of course step on the brake when it stalls.'05 D3 TDV6 HSE- 156.000km - no major breakdowns, yet?
'07 RRS TDV8 HSE - 41.000km
30th Nov 2013 1:09 pm
WillyEckerslike
Member Since: 22 Aug 2013
Location: Out in the world
Posts: 967
I can understand an engine rotating backwards, better than I can understand the engine running backwards.
One question that springs to mind though, how did you know that had happened?
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You must have the worlds toughest engine!
