Hot answers tagged

71

Engine oil does much more for an engine than lubricate. It provides cooling, cleaning, and a bunch of other chores. You already know engine function is degraded when you run out of oil. Let's see if we can run it down to make more sense for you how it happens. Let's say, for lack of argument, your engine is running with very little to no oil. The engine ...


57

One of your questions as stated and not answered is: What is the recommended thing to do if you need to pass through an area that's been flooded? The answer to this has nothing to do with Mechanics.SE, but I'll answer it anyway ... Bottom line: DON'T DO IT. It has nothing to do with whether your car can run through the water and survive. It has ...


56

There's probably no damage at all, the engine just ran at low revs for a long time. One issue you may have is if it ran out of fuel the line may have sucked sediment from the bottom of the fuel tank and drawn it into the fuel filter, which can clog the filter up. If you notice it's lagging a bit in the future what's what I'd look at. Fortunately fuel filter ...


52

It signifies that the car is running absolutely correct. Here is the reason why: A gasoline (petrol) molecule is made up as such: C8H18 (or 8 Carbon atoms and 18 Hydrogen atoms) Energy is obtained from the combustion of it by the conversion of a hydrocarbon to carbon dioxide and water. The combustion of octane follows this reaction: 2 C8H18 + 25 O2 → ...


47

I wouldn't touch the odometer. The rule I always subscribe to is that the odometer measures how far the chassis has rolled. Otherwise a person could go mad trying to figure out which repairs/replacements should reset the clock. (Obviously not tires or wheels, but wheel bearings? Axles/driveshaft? Transmission/differential? etc...) It also makes sense when ...


46

There are regional taxation and tariff issues associated with displacement Manufacturers will intentionally keep their displacement just under a limit that may increase their local/regional taxation as well import/export tariff regulations in accordance with trade agreements, etc. It's easy enough to make an engine exactly 3 Liters. Math is exact if you ...


44

That sounds very risky to me. The portions of the plugs that reside in the combustion chamber are designed to tolerate the heat and pressure there. I don't think they will melt. So what will happen is that those parts are likely to remain in the cylinder and may get caught between the top of the piston and the head and/or valves. That is likely to do more ...


42

For those who don't know, SOHC and DOHC refer to the following: SOHC - Single Over Head Cam DOHC - Double Over Head Cam A cam refers to a "cam shaft" or the thing which goes bump in the night. The cam has a "bump" or "hump" in it which actuates the valves which allows air into and exhaust out of the cylinder of the engine at the correct time so the engine ...


41

Stop trying to crank it and start beginning to disassemble it. Something is seriously wrong with it and forcing it will only break more stuff that might not already be broken. Especially if you have no idea what caused it to seize in the first place. The only thing more annoying than a seized engine is a seized engine with a sheared off bolt in the nose of ...


40

A seized engine due to not being used is usually due to the pistons / rings sticking in the bore, which with some freeing fluid may be easily solved, but this will not help the future life of the engine. An engine seized due to lack of lubrication, such as you describe, means that the crankshaft bearings, main bearings and camshaft bearings have all ...


39

The term you're looking for is Wading Depth which is specified by the manufacturer. They may surprise you, and its info you should know about your vehicle. Its in your manual, or search it online. Examples Jeeps say 500mm, and some models go to 700mm Mercedes GLC SUV has a wading depth of just 300mm Landrover Discovery (not the more compact Discovery ...


38

I'd be tempted to restate the question as "How do vehicle manufacturers decide what to tune for?" For the question as asked, there are a lot of possible reasons, and probably no way to know in a specific case unless somebody involved speaks up, but in general: To match the engine to a specific use case (as you suggested here). To find a balance between ...


36

It's not practical to attempt a repair on that engine; it's toast. It also doesn't sound like you're in a position to do an engine replacement yourself, so you're now looking at a math problem rather than an engineering one; a. How much is the car worth in a working condition? b. How much is the car worth in it's current condition? c. How much does a ...


35

tl;dr To combat detonation (in SI engines) To increase power/efficiency Details There are a few important factors at play here. Engine detonation is a real concern for SI engines A spark-ignition engine is more likely to experience premature ignition (aka knocking or detonation) with hotter air. In fact, the calculations in the example below can show ...


34

Simple reason: volume. @ 14.7:1 stoich, your input into the cylinder would need to be 14.7x bigger (or push that much more) through a nozzle than you would the fluid which is fuel. You state it would have fewer mechanical parts, but is that true? You'd have to furnish a mechanical method to create the high pressure air as well as introduce it into the ...


32

Do NOT drive a car with a piece of sparkplug inside the engine. It can (and likely will) lead to serious damage (up to a catastrophic engine failure). Get your car towed to a service and have the pieces of the broken plug removed. Additionally, get the oil changed (probably with a flush too, to remove all the debris). You will have to spend some money on ...


32

Engines have an "engine stamp." Find it, write down the numbers on it and call the Mazda Head Office for your region (delearship can't always help for this). They will tell you which car the engine was previously installed in, if any. Also, licensed mechanics don't buy parts off eBay, they buy parts from reputable distributors, both for warranty purposes ...


31

It isn't something restricted to old vehicles; my Lumina has fans like this, though not as irregular as the picture shown in the question. As far as I can recall, the chief reason cited for this by the manufacturer is noise reduction. You'll notice the additional weight on some of the blades to ensure that rotational balance is maintained despite the ...


30

What is a 5 stroke engine? They tend to consist of only three cylinders rather than the more traditional 4 stroke, 4 cylinder engines that many people are using today. There are two small small high-pressure cylinders and one larger low-pressure cylinder. This video has some good information and animations. Why aren't they using them in vehicles right ...


28

Per @Eric Urban's suggestion, I found the Technical Manual for the M4A3 tank published in 1942. That tank did use the aluminum Ford GAA 18L V8 engine which produces 500 hp at 2600 RPM! It says: Capacity: 32 Quarts Above 32°: SAE 30 32° to 10°: SAE 30 or 10 10° to -10°: SAE 10 Below -10° : Not Listed Replace the oil every 50 ...


27

It is totally possible. Combustion chambers are quite small and it doesn't take much fluid to fill one up. As the piston goes down during the intake cycle, a vacuum is created and anything in the intake will be sucked in. During the compression cycle, if fluid has been injected it has to go somewhere since it can't be compressed. A little bit of it will ...


27

If your friend is moving your vehicle without your consent and does so deliberately your friend is committing a crime. Vehicle theft. If you are asleep when this happens then consent was not given. I would suggest that you have a police officer have a long discussion with this individual about this. If this individual when moving your vehicle hits another ...


27

As others have noted, the O/D button is used to disable and enable the overdrive gear. What hasn't been discussed is why you might want to use this button, and in what circumstances. The vehicle you have shown is a 9th generation Toyota Corolla. From the user's manual (which should always be your first source of information for your vehicle, specifically) ...


26

You have almost but not quite described the operation of either a Turbocharger or Supercharger. The idea of the air under pressure being injected from a common fuel rail would likely not work as it would be difficult to guarantee decent atomization.


26

If the intent is strictly to rebuild, here is a list of items which should always be replaced: Rings Compression rings Oil control rings Bearings Main bearings Rod bearings Cam bearings (not always needed, but good choice if equipped) Freeze plugs in block Head bolts (if torque to yield type) Gaskets Seals Absolutely needs done Block Clean all ...


26

I'll make it very simple for you, Dave. Just remove the relay highlighted, in yellow, from the diagram above. This goes to the starter.


26

Generally the car shouldn't be driven through water! On your Yaris, where you had high revs, what would happen if your air intake was submerged would be that your engine would fill some cylinder(s) with water and since water doesn't compress it would bend a piston. This is called hydro locking and is often a catastrophic failure. So don't do that if you want ...


25

tl dr: Cylinder heads (commonly just called "heads") are the big piece of metal which caps and seals the end of the cylinder bore. Types of Cylinder Heads: There are three basic types of cylinder heads: Flathead Cylinder Head - These cylinder heads were used on older engines such as the flat-head Ford engines (like seen below). The oval protrusion at the ...


25

I've never replaced an odometer when replacing an engine. What I will do, however, is make a note in the cars documentation that the engine was replaced at xxx,000 miles with a new/refurbished engine with xx,000 miles. I also keep all the receipts of any ancillary parts replaced at the same time (tensioners, water pumps, etc), so that a new buyer can see ...


24

What does the power at different rpm mean? Does it mean Car 1 has better power than Car 2 because it is at lower rpm? It depends. Or does the rpm not affect the power comparison? tl;dr: The rpm of the power peak affects the engine's usability for different applications. The "peak power" number is just one point on the power band of the engine. ...


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