Engine braking -increased wear?

[Fillherup]

Hi, While teaching my daughter to drive a stick shift, I was telling her not to use engine braking to just slow the car down. Brakes being cheaper than the clutch and trans syn gears.

However, she noticed during mountain driving I used lower gears to slow the car down. She asked me why one was ok, but not the other. I told her it was the frequency and most of the time I did not even down shift, since I was already in lower gear. So it was ok and considered good mountain driving technique as long as you did not overrev the engine. In fact, I told her I had never heard anything negative about it.

But it did get me to thinking about the engine. Does using the engine compression as braking do any wear on the seals, rings, valves, etc? In other words, assuming I am willing to buy brakes, would just braking make the engine last longer?

BTW, I realize for long mountain passes, you might not have any choice to avoid overheating your brakes. But I did notice last weekend on Trail Ridge road in Rocky MT NP at 12K ft, most folks were using their brakes quite often as compared to my engine braking.

 

[Shannow]

Using the clutch to slow down is bad news, as you pointed out brake pads are far cheaper, and easier to replace.

Engine braking itself shoudln't worry an engine.

The rings are at a lower cylinder wall pressure, adn if anything, oil is getting back up past them. Same with guides. Cams won't know the difference, and bearings will be quite happy with the break.

If you've got an oil burner, it does give the opportunity for oil to form deposits and kill cats.

 

[mrchecker]

quote:

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Originally posted by Fillherup:
But I did notice last weekend on Trail Ridge road in Rocky MT NP at 12K ft, most folks were using their brakes quite often as compared to my engine braking.

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That's because most folks are idiots who don't know how to drive safely in the mountains.

 

[userfriendly]

I think you should teach her to do what ever is the safest in all situations.
Cars and engines can be replaced.

 

[ruking77]

As a rule it is best to let the engine/transmission do the engine/transmission work and the brakes do the brake work. Long term cumulatively, it will be less wear on the more expensive engine and transmission parts. The downshifting should really only be done if and when you are setting up for the next transition, i.e., long downhill or setting up to accelerate out of a turn. The real problem is that you have no real side by side comparison. I had a side by side comparison for example when it came to brakes tires and shock absorber wear. Same same cars but one had auto and manual. What I found was the brakes, tires, and shocks wore MASSIVELY faster. I also would guess that the alignment had to be done faster also. (I didn't really measure this for I had lifetime bal and alignment and did it EVERY 5k miles)

Another thing to keep in mind is most cars have a rev limiter on the acceleration side. They do NOT have a rev limiter on the decceleration side! Not only is there considerable room for increased wear on decceleration, but also engine and transmission DAMAGE.

Big diesel tractor trailer rigs are MASSIVELY built and engine braking is essential when needed. Most, if not all passenger cars are not built with this in mind.

[ August 17, 2003, 02:32 PM: Message edited by: ruking77 ]

 

[Ken4]

I did a lot of engine breaking the last time I drove my 2000 camry to Genting Highlands in Malaysia. Oil analysis didnt show any increase in wear metals. But what did happen is that a differential seal on the front transaxle sprung a leak. It shares the same fluid as the auto transmission. Which makes me believe that the oem ATF conventional probably overheated from the mountainous driving. Those differential seals are obviously not designed for high temperature.

 

[tom slick]

the main reason for using engine braking in the mountains is that you are doing so much braking for such long periods of time that you can overheat the brakes fairly easily.
in town you don't use your brakes as much so it is of no benefit to use engine braking.

 

[White 03]

Match the engine speed with the new gear before letting out the clutch and you should have no clutch wear.

I was taught to not slip the clutch except the take off in first gear. Any extra slipping will cause a shorter clutch life. A lot of truck drivers only use the clutch when starting from a stop; fun to try but probably not worth it with a car or PU transmission.

I would think there would be little extra wear on an engine considering it is not making any horsepower. Of course, over reving can ruin an engine.

I have never worn out a clutch or transmission and a couple of my current vehicles have over 200,000 miles and standard transmissions.

If I really need to slow down it is the brakes that I use first.

 

[Jimbo]

With modern EFI cars, there should be no extra wear because the fuel is shut off durning decel. Carbs tend to suck in extra fuel at high manfold vacuum, causing oil dilution. Badly worn intake valve guides and seal lead to oil smoke, but that would not cause extra wear.

I don't use the gears to slow down in normal city driving. I do use gears in the mountains. I can't believe the idiots that ride the brakes all the way downhill with the strong smell of burning brakes behind them. With automatics, no one is taught to use the Overdrive-Off switch!

 

[Drew99GT]

Hey, yet another Colorado Springs resident on the board!

 

[digitaldrifter91]

how much of using the gears to slow down is alot?

is it when you feel a huge jolt of decending power? i sure think so...but if ur comming onto a turn, slowing down and then downshifting thats not bad is it? i mean your doing more work with the brakes.

i appreciate the 'rev matching' where before u let off the clutch, u rev the car to match the rpm. its a little trickey at first but then u dont get that huge jolt, just a gentle deceleration like the other guy said.

 

[sprintman]

Double de clutching in a manual and using the engine for braking is good driving, least that is what my advanced instructor taught me. Must admit I practised for hours so I could go from 5th to 4/3/2 and still keep exactly the same road speed. Tried to teach my wife same but you can guess how that ended??

 

[Fillherup]

Thanks for your replies.

quote:

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I think you should teach her to do what ever is the safest in all situations.
Cars and engines can be replaced.

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Is that the truth! I have told her to always get off the road with a flat. Even if you have to ruin the tires and wheels. Some of the roads today even major highways just have no shoulders to safely stop. Also, one has to drive understanding that we all make mistakes including covering for the other drivers errors and yours, i.e. defensive driving.

[ August 19, 2003, 03:38 AM: Message edited by: Fillherup ]

 

[MolaKule]

The only thing engine braking might do is cause a high vacuum situation in the intake manifold. If you have bad valve stem seals, then you might consume some oil and make "blue smoke."

However, I feel engine braking in the mountains is a safe way to negotiate without having brake fade when you need the brakes most.

Engie wear. Little. Your engine is generating heat only as a result of some internal friction and the engine is cooling down during this time. When you need to climb that next hill, the engine will be cooler.

 

[tom slick]

the amount of engine wear is a moot point when your brakes fade away and you plunge down a cliff

 

[mrchecker]

quote:

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Originally posted by White 03:
A lot of truck drivers only use the clutch when starting from a stop; fun to try but probably not worth it with a car or PU transmission.

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Please don't try this on a car or pickup truck transmission. Heavy truck transmissions (9 to 18 speed) don't have syncronizers, the gears are coupled by dog rings instead. They won't go into gear if you float shift (no clutch) them wrong. It's also much easier to float shift a truck trans because the gear ratios are so close. The 10 speed I drive has around a 700 rpm drop between gears, imagine how close an 18 speed is. This makes it easier to match the engine speed to the road speed.

You can float-shift a synchromesh transmission, but unless you do everything just right, you will eat up the synchonizers very quickly. It will go into gear if you're a few hundred RPM off, the synchros will speed up or slow down the engine to make it work. Imagine what that load does to them!

 

[cousincletus]

Never had a problem in the mountains stopping a car by just using the brakes. Just anticipate your stop (slow down in advance) and use light, steady pressure on the pedal.

 

[MRC01]

quote:

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Originally posted by Fillherup:
Hi, While teaching my daughter to drive a stick shift, I was telling her not to use engine braking to just slow the car down. Brakes being cheaper than the clutch and trans syn gears.

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If she learns heel/toe downshift technique (and all drivers should anyway) there should be no extra wear on the drivetrain. This is a good technique to learn anyway since it keeps it all very smooth, eliminating sudden weight shift and traction issues. Furthermore, it is A GOOD THING to use engine braking because it relieves the brakes somewhat, keeping them cooler and more ready for an emergency.

Just make sure to be safe that the engine is in the lower half of its RPM range before you downshift, else don't downshift at all. Besides if the engine's not in the lower half of the range you won't need to downshift anyway.

 

[Starbreaker666]

For those of us living in the high state of Colorado engine braking is VERY smart. Especially for those of us that tow. I tow a 22 foot Camper with my 02 Dodge 1500. You try cruising down US 500 into Teluride with out engine braking. Diesel or no diesel this is a must. Trailer/truck brakes only do so much. Heh. Next purchase is Cummins! IMHO Engine braking will do little to no extra wear on a good motor.