How do engines deteriorate?

"Jake - Has Bad Luck So You Don't Have To" (murdersofa) 07/24/2014 at 17:13 • Filed to: None

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Seems like an odd question, but here's context:

My car's engine, a 14-year-old Buick 3800 Series II N/A has gone through 220,000 miles. 90% of this has been us, and we've always changed oil regularly, used synthetic, etc.

The car hasn't been thrashed on, been used for commuting and road trips, and parts are replaced as they wear out (or before).

As of stock the car is supposed to do 0-60 in about 8.2 seconds.

Now it takes 10.1.

The engine is still getting similar fuel efficiency numbers to when it was new (have a logbook as old as the car is), compression is good, it burns no oil, makes no strange noises, and has given me no cause to think that any hard parts are very worn out.

So what could explain the drop in power? I'd be surprised if I'm making even 190 of the 205 that it had originally, which is a big difference in a 3,567 pound car.

Vince-The Roadside Mechanic > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:15

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Well petrol is getting crapier every year so that might be it.

Jcarr > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:18

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What about the transmission? I'm guessing it's a bit looser and lazier than it was fresh from the factory.

Nighthawkwill7, Hoon Depot Manager > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:18

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0-60 times are done by professional drivers in ideal conditions so if you can't match the time then that doesn't necessarily mean your car has suffered a loss in power.

Twingo Tamer - About to descend into project car hell. > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:19

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Transmission wear could account for poorer 0-60 times too.

Jake - Has Bad Luck So You Don't Have To > Jcarr 07/24/2014 at 17:22

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If you're referring to changes, yeah they're a bit slower but between 0-60 at WOT I only go from 1st to 2nd, so that shouldn't be a two second discrepancy right there. Then again, it could be.

bob and john > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:22

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I'm with everyone else. it might not just be the engine. trans fluid, diff fluid, and bearings all have to be services at SOME point in their lives.

and again, tht time was set by a pro drive on a track. ur not going to get that time

deekster_caddy > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:22

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a couple things - these are quick off the top of my head thoughts, there could be more.

1) the fuel itself - the factory ratings were probably on "plain" gasoline. Now you can only buy e10, which has fewer BTU.

2) the engine, although seeming to run right, may have something like dirty, clogged or leaking fuel injectors. Hard to tell.

3) the cat - with over 200K it may be getting more restrictive.

Fuel filter been changed recently?

Jake - Has Bad Luck So You Don't Have To > Nighthawkwill7, Hoon Depot Manager 07/24/2014 at 17:23

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Well, my dad's butt-dyno says the car is a bit more lethargic than it used to be, for what that's worth. Though the more I think about it the more 2 seconds doesn't seem like very much for how far this car has gone.

Arch Duke Maxyenko, Shit Talk Extraordinaire > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:24

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Parts wear out. Even after regular fluid changes and looking after things, they still wear due to all of the forces put on them, thermal expansion and contraction, friction, corrosion, etcetera... All parts have a designed life span.

norskracer98-ExploringTheOutback > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:24

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Engines lose power over time anyway. I'm sure even with the best oil every time there's still some wear inside the cylinders and elsewhere within the engine and drivetrain.

Zipppy, Mazdurp builder, Probeski owner and former ricerboy > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:25

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I feel it could be a variety of things, it could be either one:

More slippage on the torque converter, or worn-out transmission, this could make the power losses after the engine greater.

It could also be the current tune, it maybe hasn't factored in the lack of a catalytic converter. I've had this happen on a friend's car once.

Grindintosecond > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:32

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Fuel filter. change that...injectors are dirty, get those cleaned out and put back in (factory fresh injectors all sprayed a nice fine mist and had a balanced volume each so each cylinder was perfectly identical). could easily be build up of carbon all around the cylinder head, pistons, backside of valves. Not necessarily caked on but enough to disrupt airflow over time reducing the pumping ability. The CAT converter could be clogged up ljust a little bit affecting the backpressure of the exhaust....Various vaccuum leaks here and there.

Just age related.

CAR_IS_MI > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:40

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For starters, there is no way that there is not some form of mechanical wear / loss on an engine with 220,000 miles. Lets just say your average lifetime RPM is 1,800 and your average lifetime speed is 23 mph (this is actually a pretty common mixed use average speed number). This means your engine has run for at minimum 9,565.22 hours, or roughly 573,914 minutes. At 1,800 average RPMs that means that your motor has turned over, at minimum, one billion thirty three million forty five thousand two hundred times (1,033,045,200). Tolerances will loosen, gaps will widen, even though they will stay within acceptable parameters, these wears will cause different reactions (even if they are minimal, 100 minimal things can be a moderate thing).

JGrabowMSt > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:40

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valve tolerance, piston rings, sloppy bearings, they all affect the power output and ability to make the full compression and therefore power. With fuel injection, youre not necessarily going to consume more fuel over time, but compression wont be the same.

Jake - Has Bad Luck So You Don't Have To > JGrabowMSt 07/24/2014 at 17:46

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But if the compression was lessened, then there'd be slop around the pistons which would make the engine burn oil, correct?

Arch Duke Maxyenko, Shit Talk Extraordinaire > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:50

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No. Compression is more to do with the heads and valves.

Jake - Has Bad Luck So You Don't Have To > CAR_IS_MI 07/24/2014 at 17:51

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That is a fascinating response. The scale of "1,033,045,200 rotations" is mind-boggling in itself. I am impressed and a bit awed at how a machine can last that long at all.

Jake - Has Bad Luck So You Don't Have To > Grindintosecond 07/24/2014 at 17:53

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Hmm. Rats. I wish I had more money, or I could get slightly larger injectors and have my tune changed accordingly, since I'm sending my PCM to ZZP today.

CAR_IS_MI > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 17:57

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a machine powered by tiny explosions created by combining dead dinosaurs with breathable air, kept lubricated by forcing more dead, liquefied dinosaurs through pressurized channels, and cooled by passing near boiling liquid through an oscillating, semi permeable barrier as air passes through the permeable areas at an intersecting angle.

Magic!

GhostZ > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 18:03

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Power is lost when air and fuel enter the engine at sub-optimum ratios and timing, or when the engine has greater levels of friction. If any of these tight values go out of balance, small power loss (and in some cases, rather large power loss) can happen.

1. Friction. As parts deform and oil stops lubricating as effectively (and becomes more viscous), the engine has more internal friction, which can greatly reduce power. This is also why engine temperature is important in making power, since it affects oil viscosity, and thus, friction. In extreme cases, there isn't enough oil and parts start rubbing, produce further heat and friction compounding the issue. This can mostly be avoided by simply using the right oil, driving at the right temperatures, and If you use the wrong oil, run the car at a bad temperature, it affects oil temperature (which affects the pressure of the oil) and that can cause great friction.

2. Valve timing (Cams, valve springs). The shape of the camshaft, and the stiffness of the valve springs all effect when valves open or close. Since most camshafts are driven by belts, as the belt changes shape (it's rubber, so it will deform eventually, or get dry and crack) it affects the timing also. For timing chains, they can sometimes get bent, but rarely. If this moves forward or backward off optimum timing, then air and fuel doesn't mix as well. While timing belts can be replaced easily, valve springs and cams, when they wear out late into a car's life, are often costly and difficult replacements.

3. Cleanliness of the Intake (air filter, intake, mass O2 sensor, or carb tuning). This can affect the level of air and fuel ratio, which can sometimes cause small drops in power. Likewise, a dirty air filter means less air can get into the engine and so it can't breathe properly, or that foreign dust and dirt gets inside the engine, which affects the ability for the fuel to burn.

4. Cleanliness of the exhaust (exhaust line, catalytic converter) Exhaust pressure affects how quickly air and fuel exits a cylinder, which in turn affects how quickly the next charge of air and fuel gets back in. A clogged cat will prevent exhaust for exiting as easily. Likewise, exhaust leaks might make pressure too reduced, so air tries to push out of the closing exhaust valves, which both wears down the valve springs AND reduces the amount of incoming air (resulting in less power).

5. Transmission and differential fluid. Adds more friction after the engine.

6. Radiator effectiveness. Bent vanes, clogged circulation, etc. all reduce the ability of the radiator, which means that the engine may not run at an ideal temperature, affecting power and aggravating other issues like oil viscosity.

7. Sealing (piston rings, head gaskets, crankcase). As these age, they can stop sealing the engine compartment as well, letting oil into the cylinder. This both affects how the fuel burns and increases friction, as well as reducing oil pressure.

ly2v8-Brian > Arch Duke Maxyenko, Shit Talk Extraordinaire 07/24/2014 at 18:26

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Bad rings don't help that either.

Arch Duke Maxyenko, Shit Talk Extraordinaire > ly2v8-Brian 07/24/2014 at 18:31

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He would be burning oil then.

ly2v8-Brian > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 18:35

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Things stretch out over time. Tolerances widen and so on. In the construction/ag equipment side of things engine rebuilds are part of scheduled maintenance. It is something that I feel should be done on cars. But that is cost prohibitive for most.

ly2v8-Brian > Arch Duke Maxyenko, Shit Talk Extraordinaire 07/24/2014 at 18:36

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True

ilostmypants > Jake - Has Bad Luck So You Don't Have To 07/24/2014 at 22:21

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Lots of long answers didn't read them all but in short wear,

the cross hatching on your cylinder walls wears out, bearings and seals wear and open up become loose, deteriorate, the big one is cylinder wall cross hatching not bringing oil up to the piston rings as a engine ages with use, that's why things like slick 50 and dura lube dont work, they smooth out all the cross hatching reducing friction in your engine, and then a month later your engine takes a shit because there's no oil left where it's supposed to be!

thebigbossyboss > CAR_IS_MI 07/25/2014 at 08:22

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WOW!!! Man, my car only has about half as many miles (117,000 or something) but to think it's turned over half a BILLION times, it an amazing feat of engineering!

thebigbossyboss > CAR_IS_MI 07/25/2014 at 12:29

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Ok mr the engineer I have mathed mine using your parameters but metric'd.

188,000 kms at 37 km/h (23 mph) = 5,081.08 hours running. x 60 = 304,864.8 minutes by 1,800 RPMS is 548,756,640 turn overs.

WOW. My engine has work properly half a billion times in a row.