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jamal posted:I definitely didn't spill a bunch of oil on my parents' driveway doing an oil change for my mom yesterday after just talking about that. Did this once at my parents' house while changing my oil (was living in an apartment with a "no vehicle maintenance" clause at the time), decided using an impact wrench set to low torque to remove the pan drain plug was a good idea. It wasn't. The plug flew out and I dumped about 2 quarts of oil on their concrete patio (they have a gravel driveway, it was the only way to properly support the car) I was working on.
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Mar 14, 2018 18:00
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I didn't spend half a day draining radiator fluid from the petcock at dripping speed when I could have just pulled the lower hose and drained it all in seconds.
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Mar 14, 2018 18:42
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Elmnt80 posted:I certainly have never forgotten to set the parking brake before changing a tire. And I certainly never did this on uneven ground. And obviously since I've never done those things, the lovely scissor jack won't have pretzeled itself as I was putting the spare on, causing my '91 acura legend to fall directly on my best friends foot. I've never forgotten to check that the car wasn't pulled back from the wheel chocks (rather than the jack rolling) after jacking of the rear of a car to change springs (live axle), then had the car roll and the jack stands slip down the curve of the frame just enough to trap my hand between the rear axle and the frame, before the front tires stopped against the chocks. Not crushing it, but still hurting like the dickens, while leaving just enough space to (painfully) pull my hand back out. Had this happened, it would have certainly left my hand almost useless for several days thanks to the bruising across the back of it. It also would have scared the living poo poo out of me as the car started to move. What has happened is the Toyota scissor jack for my girlfriend's (now wife) Celica stripping out the screw as I was attempting to change a tire. Scared the bejesus out of me. Thankfully, no part of me was under the car. I was so ticked off I hurled that jack across the parking lot into an empty field. FogHelmut posted:I didn't spend half a day draining radiator fluid from the petcock at dripping speed when I could have just pulled the lower hose and drained it all in seconds. petcock.
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Mar 14, 2018 18:44
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FogHelmut posted:I didn't spend half a day draining radiator fluid from the petcock at dripping speed when I could have just pulled the lower hose and drained it all in seconds. I have not recently stripped the plastic phillips pattern on my miata's new petcock. Nor have I resorted to 'gently caress it, pull the rad hose' and splashed myself in the face with a quart of bitter, rusty coolant that I didn't taste for the rest of the day. I guess they didn't have bitterant in that premix 
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Mar 14, 2018 18:46
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I don't recall ever doing an engine swap, throwing a few grand in parts at and subsequently scrapping a car that would never quite run right and sorta had lovely brakes in such a way that very much suggested a torn booster diaphragm, even though the engine coming out was fully rebuilt by a reputable shop c/o the PO and the engine going in was a known good runner. No recollection whatsoever. I also do not recall removing the rad cap on an overheating Chevy Malibu, those scars on my face are birthmarks that didn't show up until I was 18 and that brand new e46 was covered in coolant when I got there. I've got better ones but I don't remember those either. Turbo Fondant fucked around with this message at 19:30 on Mar 14, 2018 |
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Mar 14, 2018 19:26
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I also did not mistake the quote button for the edit button.
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Mar 14, 2018 19:28
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Not me but i worked on a 90 Integra some guy had bought for $500 with a b16 swap. Po never got it to run. New owner came to us, we were shop number 3 to take a crack at it. Hooked the ECU ground to the thermostat housing and had it idling a few minutes later. My foreman at my current job bought a b16 swapped 90 civic for $500. The guy who did the swap gave up on it ever running right. Handed him cash, pulled out his pen knife, and trimmed the cracked bit of vacuum line going to the map sensor. Dude was pissed.
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Mar 14, 2018 19:36
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I too did not forget that I had placed foldable wheel chocks behind the rear wheels, and I definitely did not just give it a little more gas to get moving out of the driveway and only realized it after pulling out onto the street and seeing the remains of the pancaked wheel chocks. Nope. (They still kinda work, just have a decorative twist to them)
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Mar 14, 2018 20:51
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Never replaced the 22RE long block in my old Celica GT just find out that the new block ran worse with bad fuel injectors than the old block did.
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Mar 14, 2018 21:36
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The Door Frame posted:I've certainly never tried to start my car for 10 minutes, checking grounds and fuses, only to realized that I hadn't actually pushed the clutch all the way in I've definitely never forgotten to adjust the clutch interlock switch after replacing the pedal. Fun part: you can't see the switch once the steering column is back in place on this car. You gotta do it by feel, and good loving luck if you have sausage hands like I do. Farmdizzle posted:e: I definitely could pull the key out anytime on my '98 Villager. More than once, I left it in reverse instead of park overnight. I use my parking brake religiously, and I did turn the ignition and lights off. I was just so dog-rear end tired getting home from work that I failed to notice that I hadn't put the column shifter all the way up. My stepdad's F-150 has so much slop in the shifter that you have to slam it as hard as you can into park to actually get it in park. Otherwise it's left in reverse. He never uses the parking brake either. Good thing they live on a flat road, but I got bit by that once when I hopped in to borrow it, started it, and it took off backwards.  HandlingByJebus posted:I was certainly never party to using a pair of suicide jacks to lift the front end of an '86 Accord during an aborted attempt to change the clutch. 88 Accord. I definitely didn't get under it while on the lovely little scissor jack it came with, while trying to break a caliper bolt loose. I also didn't hear a creaking sound, and didn't roll over out of the way just as the car fell. Still have nightmares about that too. Goddamn, I was loving STUPID when I was 19. I'm still stupid at 39, I just know I'm stupid now.
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Mar 14, 2018 21:56
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Dave Inc. posted:I've always remembered to get the distributor back in properly and not out of phase 180, so of course it wouldn't take me several days of troubleshooting, parts replacement and backfires to figure it out. Pop the plug you time on and stuff a glove in the hole. Crank it and when it shoots out that was the compression stroke.
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Mar 15, 2018 05:32
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Slim Pickens posted:Definitely never hosed this up, either, especially on someone else's car. Oh my god that was such a revelation when I figured that out. Camshaft spins at half the speed of the crank to allow for two movements of the piston for one of the valves. “Timing is off 180” made no sense before I understood, I thought each time the distributor went was one revolution, not two, and if the timing mark was at zero that was spark time where I wanted it to be! Caps should have been clear.
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Mar 15, 2018 06:00
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I did not forget to torque my caliper bolts before doing a highway run to a shop to get the car aligned. It did not take me several hours after I limped home to figure out what the problem was.
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Mar 15, 2018 06:04
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I definitely didn't let intake gasket fall into the valley on my Blazer, probably causing the loss of oil pressure the next morning, killing it instantly.
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Mar 15, 2018 06:56
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I certainly did not lift the rear left of my MX-5 up on uneven ground. I also did not then release the handbrake and put it out of gear to check if the wheel spins freely without putting a chock on the front wheels...Good news though, it spun freely...both wheels, then it spun freely off of my jack and continued to freely spin into the bushes. On a lighter note: I'm not the guy who sat in his brand new rental A4 trying to figure out how to turn off the loving engine! Pull the weird stubby key? No. turn it? No. Push it in? No. Either do a proper button or a key you can turn not some weird halfway thing with a key without a blade you can't turn.
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Mar 15, 2018 09:53
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You guys loving terrify me, then I remember this is an automotive subforum where everyone has probably 10 times the average car knowledge.
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Mar 15, 2018 11:41
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I've seen people on Jalopnik post about how they literally didn't know how a turbocharger worked.
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Mar 15, 2018 12:29
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StormDrain posted:Pop the plug you time on and stuff a glove in the hole. Crank it and when it shoots out that was the compression stroke. But you see I had done it so well and with so much thought that the distributor couldn't have been out of phase. It had to be something else, it wasn't even worth checking the distributor.
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Mar 15, 2018 13:52
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um excuse me posted:I've seen people on Jalopnik post about how they literally didn't know how a turbocharger worked. The fun part is blowing peoples minds when you explain that turbochargers are powered by heat.
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Mar 15, 2018 14:00
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CommieGIR posted:The fun part is blowing peoples minds when you explain that turbochargers are powered by heat. Nah, the fun part is explaining that an ICE is just an air pump and they're less than 60% efficient. As for dumb poo poo? I've never drained all my oil, took the filter off, let it drain, then refilled it without ever putting a new filter on. Nope not me. Or used stacks of cinder blocks and wood to get a 4th gen f-body lifted to where the glfog lights were at eyeball height, with the front end resting on two stacks of wheels/tires, to help do a header install.
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Mar 15, 2018 14:03
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I've never filled the front differential on my wife's Subaru with ATF. And I definitely did not attempt to drive it down the street after having drained the tranny.
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Mar 15, 2018 14:10
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iwentdoodie posted:Nah, the fun part is explaining that an ICE is just an air pump and they're less than 60% efficient. Yup. I love explaining to people how the average gas ICE is less than 30% efficient, so only 30% of their purchased fuel gets turned into actual mechanical work, the rest is just heat and exhaust.
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Mar 15, 2018 14:32
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And only a few percent actually go into moving you in said vehicle!
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Mar 15, 2018 14:45
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um excuse me posted:And only a few percent actually go into moving you in said vehicle! Yeah, for Automatics its like a 10% loss, for Manuals its like a 5% loss So 30% thermodynamic efficiency - 5/10% mechanical losses = Road Wheel energy given
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Mar 15, 2018 14:47
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No I mean the remaining power to said wheels gets evenly distributed into total mass. Meaning if you weigh 180 lbs and your car is 2900 lbs, on 6% of the remaining power to the wheels actually drives you forward.
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Mar 15, 2018 15:02
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CommieGIR posted:The fun part is blowing peoples minds when you explain that turbochargers are powered by heat.
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Mar 15, 2018 15:07
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Fifty Three posted:Care to elaborate on this? It sounds like a textbook "um, actually" but I'm curious. Heat from expansion of hot exhaust gases rushing past turns the turbine. Basically: Heat itself can transfer energy, but heat's goal is to get from the hot place to the cold so it can reach an energy equilibrium, and while the piston itself exerts some force upon the exhaust gases, the actual energy derived is from the heat expanding to cool down as it rushes past the turbine to the cooler portions of the exhaust. https://van.physics.illinois.edu/qa/listing.php?id=1754
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Mar 15, 2018 15:09
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CommieGIR posted:Heat from expansion of hot exhaust gases rushing past turns the turbine.
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Mar 15, 2018 15:10
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Fifty Three posted:Gotcha. I gotta admit I'm a bit surprised that the exhaust stroke doesn't do much work compared to the expansion of the exhaust gases. It certainly has an impact, but overall the rapid expansion of gas is the larger portion of the energy.
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Mar 15, 2018 15:12
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CommieGIR posted:It certainly has an impact, but overall the rapid expansion of gas is the larger portion of the energy. It's also what makes the Atkinson cycle more efficient than the typical Otto cycle. The greater cylinder volume during the power stroke compared to the intake stroke (facilitated by closing the intake valve during the compression stroke instead of BDC) means that the ignited fuel/air mixture can expand more than the volume of air that was compressed and thus exert more work than if it was only allowed to expand to as much as was compressed.
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Mar 15, 2018 15:57
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Edward IV posted:It's also what makes the Atkinson cycle more efficient than the typical Otto cycle. The greater cylinder volume during the power stroke compared to the intake stroke (facilitated by closing the intake valve during the compression stroke instead of BDC) means that the ignited fuel/air mixture can expand more than the volume of air that was compressed and thus exert more work than if it was only allowed to expand to as much as was compressed. Time for some more Napier Deltic engine porn.
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Mar 15, 2018 16:08
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um excuse me posted:I've seen people on Jalopnik post about how they literally didn't know how a turbocharger worked. Please don't doxx.
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Mar 15, 2018 19:07
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I recently got in an argument on a subaru forum with a guy who insisted that a turbocharger was just a "fan" and could not compress air.
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Mar 15, 2018 19:12
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jamal posted:I recently got in an argument on a subaru forum with a guy who insisted that a turbocharger was just a "fan" and could not compress air. So how do rocket engines work then?
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Mar 15, 2018 19:12
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jamal posted:I recently got in an argument on a subaru forum with a guy who insisted that a turbocharger was just a "fan" and could not compress air. Technically, fans compress air as well. That's why the air moves. It's just not very much.
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Mar 15, 2018 19:14
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CommieGIR posted:Yeah, for Automatics its like a 10% loss, for Manuals its like a 5% loss
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Mar 15, 2018 19:16
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Fermented Tinal posted:So how do rocket engines work then? Out in space they work by throwing the mass of the fuel backwards
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Mar 15, 2018 19:17
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slidebite posted:It's actually worse than that. Helical/Spur/Hypoid gears have an efficiency of around ~95% per stage of gears (varies of course depending on ratio/size and cut ...95% is probably generous to be honest). So if you're at 95% after the first gear set, you're taking 5% off of that at the second, 5% off of that at the third. Assuming your transmission is going through 2 stages and 1 stage at your differential, you're at 85% (.95x.95x.95) just on mechanical alone. Uh. Stop for a second and think about what that implies about heat dissipation in automotive transmissions. Or doing some quick math, at full power the oil in my WRX trans would go from operating temperature to flash point in about 15 seconds of full throttle. jamal posted:I recently got in an argument on a subaru forum with a guy who insisted that a turbocharger was just a "fan" and could not compress air. I don't doubt there was someone that insisted that, but why bother arguing? 
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Mar 15, 2018 20:00
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Are you assuming 100% of that heat is going into just grease and that it's a closed system or something?
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Mar 15, 2018 20:07
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mekilljoydammit posted:Uh. Stop for a second and think about what that implies about heat dissipation in automotive transmissions. Or doing some quick math, at full power the oil in my WRX trans would go from operating temperature to flash point in about 15 seconds of full throttle. Let's throw some Fermi Estimation into the mix: 200 horsepower is around 150kW. At 85%, that's around 22kW lost. The total capacity of a Crown Vic's transmission is 14 quarts. Motor oil weighs around 3kg/gal, or .76kg/quart, making a total weight of 10.64kg of oil in the transmission. The heat capacity of water is higher than oil, but not by too much. All the formula examples I've found say that, to raise 1kg of water from 10 degrees C to 110 degrees C, it would take 2700000 joules of energy. Spread over one minute (assuming closed system), that's 44kW required to raise only one kg. Spitball and take that and multiply it by another .85, assuming engine oil has 15% lower specific heat capacity, you get only 37kW to do the same to the oil. Multiply that by the total system volume (make it an even 10, ) that's 370kW required to raise the oil from 10 to 110 C in one minute. At the estimated 22kW lost at full throttle by the figures given by sidebite, at full throttle with a completely closed system, without any heat-sinking or cooling being done by the transmission casing to the air or the (actively cooled) engine, or by the transmission cooler all automatic transmissions have, it would take 16 minutes at full throttle in a 200 HP car with an 85% efficient gear train to raise the oil 100 degrees celsius. The figures are just fine, and transmissions have multiple coolers: radiated and air-cooled by the casing, and oil-water-air coolers in the front radiator on automatic and (many) manual transmissions.
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Mar 15, 2018 20:25
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