Re-rev limiters. Frequently heard Toyotas, typically Land Cruisers, at full blast in a low gear hitting their rev limiters while being driven in the desert etc. in the Gulf States. It often seemed like a normal way of driving (and showing off) there! Didn't seem to hurt the vehicles at all!
No I haven't, but I have heard of others who have. I've had five Jaguars and Daimlers and I like to look after them. However there are plenty of people saying that over revving can cause the valves to bounce and touch the pistons, and that can cause severe damage. Different makes of engine have different clearances between the valves and pistons.
Almost every car I see at work. However I do work in an automobile museum :)
There seem to be a number of different faults over the years - wear, computer, cable faults. US made parts probably, so nothing to worry UK and NZ owners :)
The company said the problem is only found in accelerator assemblies manufactured by CTS Corp., a parts maker based in Elkhart, Indiana. Similar parts manufactured by Japan=92s Denso Corp., a competitor to CTS Corp., are not believed to be defective.
Some experts, including Safety Research & Strategies=92 Kane, believe the Toyota issue is indicative of a larger problem that is looming in the automotive industry. Many vehicles, including Toyota and Lexus brand cars, have given up on decades-old technology that uses a steel cable to control acceleration and have moved to computer controlled systems called drive-by-wire.
Kane said the systems are unsafe and that national regulators should not be focusing on just Toyota. He urged an industry-wide investigation into the technology.
Plenty may say that but I don't believe it. Only time valves hit pistons is when the valve drive breaks altering the timing. Such 'interference' engines are common these days - but as been said just about every car made since about '90 has a engine speed limiter built into the management. And plenty earlier ones too. On my old Rover V-8 with no speed limiter the hydraulic tappets act as one - try and go above the maximum revs and they just cease opening the valves. Of course if it's an auto this can't happen in practice. But what I'm saying is if you selected neutral on full throttle so the engine revved to max before switching off you'd be unlucky to do any damage. If you left it running like that indefinitely of course you would. But why would you?
Sounds like someone with an axe to grind. Mechanical throttle linkages are a crude way of doing things with modern engine management. Perhaps he wants to go back to carbs and points too. But I'll bet doesn't want to pay for the heavier fuel consumption of those older cars. Nor are mechanical throttle linkages perfectly safe either. I well remember flooring an E-Type Jag and the throttle sticking wide open. A 90 degree pivot on the rod linkage had gone over centre. That early example had been fitted with an aftermarket steering lock which didn't lock the steering when I switched off. After slowing the car on the brakes. It was in second gear.
OK, so maybe the engine revving at its maximum in neutral might not do any damage. But instead I will simply turn the ignition off. For 15 years I have owned two large cars that ran on CNG and petrol. When the CNG ran out after about 120 km, the engine would stop and I would switch to petrol, which took about 10 seconds. In the meantime the power brakes and power steering didn't work, but not a problem - they just needed a bit more effort to use.
Since a car engine might stop for many reasons, cars should still be able to be driven without the engine running. Therefore people should know what it's like to drive without power brakes and power steering, so they should try it if they haven't already. It might save their lives one day. I know of a lady who panicked because the brakes didn't seem to be working when she rolled her car down her driveway. All she had to do is push the pedal harder.
Ive had em fade to less than half (subjective) stopping from 115mph on an Opel Manta.
I tried the same trick from 140mph in a XKR, and they managed to do that OK.
Bigger better more vented discs.
same here.
Depends on the model. Some of us drive non servo steering anyway so its not so hard to get used to.
Which one, JOOI?
I remember a good one at Te Puke, and another at Paraparaumu, and then some chap - I think it was out west somewhere - who had amassed a ridiculous number of Morris Minors (amongst other interesting stuff). The latter one was more "lots of old stuff in a dirty barn", but then lots of museums in NZ were like that and all the better for it - it appeals to my sense of exploration :-)
cheers
Jules
a lot depends on the weakest link.
In a racing engine, mainly it is the valves. Ultimately. Which is why F1 engines use compressed air to slam the valves shut. Ought to use sleeve valves..;-)
On BMC A series engines, always the big ends. WAY before the springs started bouncing. ISTR that a racing mini would go out with special HT big end bolts, and possibly a different spec of conrod.
'rod through the block' was the standard failure mode on those.
However in road use, they were so strangled and de-timed valve wise, it was hard to get them up to that sort of limit.
I am not sure where modern engines are at.
mostly he blows it out of his arse though.
thats down to you. It DOES happen. In racing, all the time. Normally its no big deal because the piston knocks the valve upwards a bit faster. But before that happens you have already lost compression anyway, so its a zone where power rapidly tails off.
Yeah, they build some real junk over here :-(
Hmm, OK - much newer than our toy yoda, then.
That does sound more like wear in sliding parts than something like a broken spring. Perhaps even issues with the cables (I've known them to 'gum up' on much older vehicles, but I'm sure it can affect relatively-new stuff too if their quality control / testing isn't the best).
Having been in IT for years, I'm rather mistrusting of IT systems ;) I like mechanical controls...
cheers
Jules
I've had a car stick wide open too. I stamped hard on the accelerator and it flipped back. classic case is a broken carb return spring and a cable, designed to pull but not push.
the rod linkage is at least better. But a broken return spring still makes em distinctly dodgy.
A LOT of side conversions (LHD->RHD) and vice versa) use cables that have to go a long way, and often on sub optimal paths.
As a mechanic informed me in RHD S Africa 'In germany, VW it is shorter cable..here to here. This side it goes all around the engine see, and that is why it breaks' He was german of course.
Maybe. I'll gladly take increased running costs for ease of maintenance any day though, I think. I like engineering that I can "see".
Yeah, experienced exactly that problem on a Rover P6 too during a "tinkering phase" (very modified engine and therefore modified carb linkage).
cheers
Jules
There's a big difference between two identical cars one with power steering and the other not in effort when the PS dies. The PS is usually higher geared - but I'd guess has much more friction too due to the extra seals etc. I've driven an SD1 with manual steering which although heavy is manageable. Mine if the power fails simply isn't - apart from to pull into the verge.
Racing engines are somewhat different..
Depends which version. There are many, many. And of course if you fit stiffer valve springs to increase the rev limit something else will go. But the original 850 Mini could be driven flat out all day - I often did just this. And hit valve bounce in the lower gears often. ;-) Older A series weren't so robust. Nor was the later early 1100. They then increased the crank dimensions.
Of course.
They all have rev limiters built in to the engine management.
WTF has that got to do with the discussion? Racing cars don't have floor mats to jam the pedal. ;-)
Hmm. Thing is there is hardly any maintenance on modern cars. No points that need regular attention. Plugs that last 100,000 miles. 15,000 mile service intervals.
And the likes of 'us' learned how to change and set points etc because we had to - but simply didn't (wouldn't) learn about engine management. Even although most of the things that go wrong like sensors can still be tested with pretty basic equipment - if you have an idea which one has gone wrong.
The effect of engine stop on power steering (P/S) varies. Electric P/S is unaffected, Hydraulic P/S is affected to a lesser/ greater extent by the design and obviously vehicle speed. If the engine stops, firstly you must turn the wheels against tyre resistance (which increases with decreasing vehicle speed), secondly you must turn against the resistance of the P/S pump whose pulley is held by the stationary engine. P/S operate at 820-1920psi so pushing fluid past the pump seals/bypass does present some resistance if the engine stops or belt breaks, it makes steering "slow".
Steering lock. The rule is key in the ignition turned to ACC because the key is latched (can't be jolted out). Key retention in the off position is very slight (tumblers), such that a risk exists in towing if enough weight exists on the keyring and the car swerves around a corner.
As I corrected my post, I suspect most people will declutch or brake (automatic conditioning) rather than turn the engine off (unusual action). Those that panic and turn the engine off may simply not make it across sufficient lanes, the greater risk is in a town centre with pedestrians - the steering & brake impairment might create an accident.
Over rev by WOT is prevented by rev-limiter. Over rev by road wheels is not - it can be caused by miss-shift (E36 Me) or towing with drive wheels on the ground in a low gear (Miata caught plenty out in the USA). On the E36 M3 going just a little past the rev-limiter would trash the engine, on others you could run even
1250rpm past with no damage. Top-end damage depends on interference and spring poundage, lifter type. Bottom-end damage can be hidden at first (big end bearing tang movement).The Recall wording again negates the often tried "I was not speeding, the car suddenly accelerated" defence :-)
I agree cable route can be an issue - I'm sure there was one USA RHD- to-LHD car which if the firewall was pushed by the passenger could affect the controls to some extent (it had linkages from one side to the other). Things should have improved since then. Most Japanese makers do not QC inbound, the supplier must test & print results on the package which is rejected at the door if out of specification.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.