Breaking an engine and clutch, because of shifting to wrong gear in downshift
Breaking an engine and clutch, because of shifting to wrong gear in downshift
(OP)
Hi,
Right now I'm getting the blame of breaking the cars engine and clutch, because an experienced mechanic was able to hear some noise in the engine, that was very alarming, and apparently indicates sudden boost to high revs, like shifting down to a wrong gear.
I'm wondering how damaging is it to a car engine, if you shift from 4th to 1st gear on a diesel car and then lifting the clutch enough so the revs suddenly hit high? Not sure, if it hit the red or not.
The car has driven 5000+ km, since I last drove it. If I really had damaged the engine and clutch 5000km back, then is it reasonable, that a damaged engine can last that long?
Best Regards,
Driver :)
Right now I'm getting the blame of breaking the cars engine and clutch, because an experienced mechanic was able to hear some noise in the engine, that was very alarming, and apparently indicates sudden boost to high revs, like shifting down to a wrong gear.
I'm wondering how damaging is it to a car engine, if you shift from 4th to 1st gear on a diesel car and then lifting the clutch enough so the revs suddenly hit high? Not sure, if it hit the red or not.
The car has driven 5000+ km, since I last drove it. If I really had damaged the engine and clutch 5000km back, then is it reasonable, that a damaged engine can last that long?
Best Regards,
Driver :)





RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
OF course it is possible. I bent a valve once and it lasted 5km before it failed.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
The number of times I would disagree with Ed is very small, but I would expect the clutch to transmit enough torque to over-rev the engine in just about any conceivable drivetrain arrangement.
The clutch is designed to handle enough torque to quickly accelerate a relatively large mass- the entire vehicle. Run the system in reverse and you have a large mass with a lot of inertia (if you're cruising around in 4th gear) driving a relatively small mass. The engine will not win. Even if the clutch slips, it is still transmitting torque, and it doesn't take that much torque to drive an engine WAY past the RPM levels it is designed to handle.
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
Dan - Owner
http://www.Hi-TecDesigns.com
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
Other than the extremely rare Buchi and the Brotherhood sleeve valve engines; and they are not car engines, I can't think off-hand of any non-interference diesels.
PJGD
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
Machines that reciprocate at thousands of RPM can do interesting and terrible things to themselves if left to their own devices or badly designed.
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
B.E.
You are judged not by what you know, but by what you can do.
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
I read somewhere that a truck maker who sold trucks in India (I think it was) fitted the gearbox with the old-fashioned sliding mesh type of gearbox when the truck maker's normal practice was to fit the more modern constant-mesh non-synchromesh gearbox type. The idea was to prevent the probably inexperienced local driver from selecting a too-low gear and damaging the engine.
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
Thank you for the replies.
I see, that it is not unreasonable, that my bad downshifting may have broken something.
The car is Honda F-RV the latest version. Tho now it has driven about 10000km without having problems, except that the current driver says that the noise is becoming more obvious.
Best Regards,
Driver :)
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
It handled well, but was slow, until I removed the thermostat to prevent the engine heat from percolating the fuel in the feed tube to the carburetor.
Then it was less slow.
The brakes, even when newly installed, were a joke, like most cars of the day.
Of course I drove it like an idiot anyway.
One day I was downshifting going into a serious chicane (stone mountain on one side, rock wall on the other), and grabbed second gear a little too soon.
Broke a rocker arm, clean in two.
Well, I thought it was a clean break, but I didn't examine it closely enough.
With the new rocker in place, oil pressure disappeared almost immediately.
The third piece of the original rocker arm was a little nugget, small enough to pass through the oil pump screen and big enough to take out a rod journal.
Luckily the crank could be reground to fit the smallest available rod bearing.
Mike Halloran
Pembroke Pines, FL, USA
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
Does the complainant explain what he's hearing is wrong?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
I have the other impression- in any modern trans with synchros, if you're trying to hustle the car around and you push hard enough on the shifter, it WILL go into the wrong gear.
There's a well-known phenomenon on 90s era BMWs where wear in the linkage and bushings of the shifter assembly lead to very easy 3-2 shifts (when you were going for 3-4) under full power.
This is common enough that it has a name in the BMW enthusiast community- the so called Money Shift.
Because it if happens to you you're about to spend a lot of it.
RE: Breaking an engine and clutch, because of shifting to wrong gear in downshift
Getting WAAY off topic, but in 1969, whilst awaiting delivery of a then-new BMW 2002 TI, I was given a Peugeot 403 as a loaner. It was a wonderful,durable, comfortable stable-handling old sedan, the likes of which the French haven't built since. Anyway, it had a 4-speed column shift. More than once, trying to complete a pass, the engine wound to valve bounce in third gear, the column shift got second gear instead of fourth. The Peugeot didn't have a tachometer, but the overspeed would have been considerable. The wonderful old car survived that abuse and was not making any untoward noise when the BMW finally arrived.
jack vines