engine braking / down shifting

[andrew]

i have been poking around the internet and this seamed to be a mixed opinion. is it safe to engine brake or down shift in an automatic or stick? I hared that it is bad and can mess up the car/ truck and ive also heard that it is fine. I have done it a few times in my truck with both with the gas peddle and with out the peddle. I know it make little to no difference in a stick shift.

Topic

[Mike]

I have been driving very aggressively for 15 years, mostly with stick shift but recently had to get my first automatic. I’ve been engine braking as a normal part of driving the whole time, and I’ve never EVER had any problem due to engine braking. I’ve had a car on the road with the original engine for 15 years (244k on it), which I’ve flat towed numerous times using engine braking to keep tension on the tow rope instead of riding the brakes. That’s in a case where the engine will not run on it’s own and is spinning only because it’s being towed at speed while in gear. I’ve been daily driving a automatic Accord for almost a year now, and I drive it in D3 most of the time because of the engine braking it provides. 206k on that engine and beat the piss out of it and it’s great.

I really can’t put into words how alright it is to engine brake. If there is a problem related to engine braking then there is a failed part of some kind. It’s like how washing a engine can cause a problem, but only if there is already a failed part that works fine as long as you don’t get it wet. If everything is in good working order, it’s totally fine.

[Alex]

I’m likewise of the opinion that engine braking will not cause harm to the engine or transmission. The user manual for my car even explicitly recommends it, especially for going down steep slopes with a trailer or heavy load. Take a look in your user manual to see if there’s any mention of it.

As long as you don’t downshift too low while moving fast or overrev the engine, the drivetrain will handle it just fine.

Only other caution I can think of is understeer in a FWD vehicle or oversteer in a RWD vehicle under heavy engine braking and/or poor road conditions. Open differentials could make this worse because of potentially uneven distribution of braking force to the wheels. This would only happen in an extreme case, but it is something to be aware of.

Small diesel engines won’t have nearly as much engine braking effect because they don’t have a throttle to restrict intake air flow like a gasoline (petrol) engine. Large diesel vehicles use a special compression release engine brake (Jacobs Brake / Jake Brake) or an exhaust brake (controllable backpressure) to achieve the same effect.

[EricTheCarGuy]

I don’t know about a video on it, but I’ve done it for years without issue. I don’t believe it does any damage to the engine unless it gets over revved.

Thanks for the suggestion.

[James O’Hara]

If you downshift to engine break you cause more wear to your clutch. If you rpm match really well there is little to none of this. I have a diesel so with my high compression i just let up off the gas and it engine breaks hard due to the compression. If i downshift too i drop 10 mphs normally in the matter of less then a second and it will literally throw me a 270 lb man forward fast.

In my opinion unless you can rpm match well using brakes is better because it prolongs the life of your clutch. If you can rpm match it doesn’t matter.

[Ken]

I modified the warmup valve in the exhaust of my 7.3 F350 to provide some compression braking while towing. I then learned that that particular transmision (4R100) can suffer premature wear to one of the clutch bands by doing this, so I don’t do it anymore. That was only while towing 10000-20000#.

I still do it regularly with other vehicles and have for almost 20 years without any trouble. I mainly use it to control speed while descending, not as a replacement for braking.

[Author]

Replies