Scared to EOC / EOC vs coasting in gear

[Eddie25]

first question -

what damage does prolonged EOC do to your car? i am taking a new route to work an i now have the opportunity to EOC for quite a distance, about 10km or 6mi, at an average speed of 80kph to 100kph (60mph) taking about 7 min. im just wondering with my Hyundai Tucson 2.0 manual, what sort of prepwork does the car need. im worried about things like gearbox oil circulation, power steering loss, and brake loss. are any of these components now going to get damaged or broken with continuous EOC?

second question -

part of the hill im freewheeling down gets very steap and even if i am freewheeling in gear i still have to slow the car down using the brakes to keep within the speed limit (90% of the time not done). How much fuel will be saved EOC this portion of the hill vs coasting in gear?

i am not going to go into details like power steering delete and using a switch to kill ignition for now i just want to use the car as it is

[MkVer]

I'll let the veterans dive into answering your second question, but as for your first.

No damage. None. Zero. Your brakes are designed to be fail safe, yes some cars do have a pump to make braking a bit easier but you will still have full use of the brakes. Power steering will turn off but once you're moving you don't need it, the new fuel sippers coming off the line use an electric assist set up that completely turns off at highway speeds and again, it's a fail-safe system. Gearbox oil, if you're in Neutral your gearbox isn't turning, therefore no need for fluid to circulate.

[LitterBug]

Originally Posted by MkVer

Gearbox oil, if you're in Neutral your gearbox isn't turning, therefore no need for fluid to circulate.

Not completely true. The output shaft is spinning inside the gearbox. No synchros are engaged so the gears are not spinning. Most manual transmissions should have enough passive lubrication circulation to be fine with this though.

Cheers!
LitterBug

[UFO]

Originally Posted by LitterBug

Not completely true. The output shaft is spinning inside the gearbox. No synchros are engaged so the gears are not spinning. Most manual transmissions should have enough passive lubrication circulation to be fine with this though.

Cheers!
LitterBug

You are not only right, but engine on/off the gearbox gets the same lubrication. It's designed to lubricate itself, whether the input shaft is turning or not, the lubrication is the same.

With my Toyota truck I use engine braking to control speed and also keep up the braking vacuum. On steeper downhill slopes, you need to keep up the brake vacuum, so I engage the engine (ignition off) and it controls speed and maintains brake ability. Otherwise it can be very dangerous to coast downhill out of gear.

I was recently up in the foothills, and I coasted home for more than 6 miles with the engine off the entire time by simply coasting and engine braking.

[spacemanspif]

Brake booster holds vacuum for a few pumps before the pedal gets hard and the system essentially goes into old school manual brake mode. Test out how much you get buy shutting the car off in your driveway and pumping the pedal and that will give you an idea of how much braking you can do with the engine off before you lose power assist. If the Hyundai shuts off the injectors when you are not on the gas, coasting in gear down the hill is just as efficient since no gas is being burned in either situation. Using DFCO is better than EOC in your case since it will help to keep you slow and not gain excessive speed. If you have an MPG gauge it should read 99999 when the engine activates DFCO and stops using fuel. The best compromise between safety and MPG would probably be to DFCO the first 2/3 of the hill and then near the bottom throw the trans in neutral and EOC the last bit, allowing yourself to increase speed some to extend your coast a little farther before you bump start and carry on with your commute.

[JRMichler]

Before I started using EOC, I ran a test. I found a hill with no traffic and a safe runout area at the bottom. Then got it rolling, shut the engine off, lightly pumped the brakes until the vacuum reservoir was empty, then stopped on the downhill portion without the power assist.

I was not going to do EOC until I was satisfied that I could stop the truck using the brakes without any power assist.

[UFO]

That's why I periodically use engine braking with engine-off. It is virtually impossible to stop my truck without vacuum assist. I have to put all my weight on the pedal, and the stopping force is still less than moderate pressure with vacuum assist.

[oil pan 4]

The manual transmissions have historically not had any issues with being flat towed.
I have seen Hyundai Tucson being towed behind RVs. I originally thought they were all autos, so I would bet those being towed were manual transmission.

[Eddie25]

thanks guys! ive done a test before i get about 5 pushes. im not too stressed about the braking performance though was more concerned about gearbox. but it is true it is self lubricating. im not sure if the car cuts off the injectors on coasting in gear. its a 2007 model. the car does have a trip meter. i will reset it at the start of the coast and see what figure it says at the end of the in gear coast. averaged my best with the car this month with a figure of 6.9 L / 100km on the on board trip meter. Trip meter has an error of about 0.2 so 7.1L / 100km is not bad for this car.

[Ecky]

I'd be surprised if it didn't cut off fuel when coasting in gear. This has been in most vehicles since the late 80's.

Generally speaking, you want to coast in gear when you need to lose speed, and coast with the engine off, in neutral, when you can afford to maintain momentum.