Stress on Engine When Engine Grade Braking

[CarlB]

I've never heard of engine damage caused by in gear deceleration.

 

[KrisZ]

It's a little different for automatics. With automatics, you'll have to contend with transmissionmission heat and clutch pack wear. This can be minimized with rev matched downshifts. Some modern automatics designed to be "sporty" can and will do that, while there's still plenty of brain dead electronically controlled automatics out there that don't, and slowly wait for RPMs to drop to a certain threshold before slipping into the lower gear. On older toyotas that are pretty slow and dumb at that, if I'm going down hill at any significant speed, I always just blip the throttle like I do with a manual to bump up the RPMs quickly and closer to what the engine speed will be to get it to downshift quickly. Not only that, it's my belief that wear is minimized this way.

but with manuals, you still have to worry about clutch wear if you don't rev match... most people don't know how to do this and just slip the clutch for downshifting... the motor lurches when that happens too and that also wears out the motor/transmission mounts

You don’t need to rev match a traditional automatic that is coupled to a torque converter. Not sure where you got the idea from that it helps with anything. It doesn’t and may actually put more wear on the plates as you have no control how they engage/disengage.

 

[KrisZ]

I've never heard of engine damage caused by in gear deceleration.

It’s typical bitog drivel. We have countless pages of people discussing this kind of silliness, or how to torque the oil drain plug, or how quickly one should put the car in D after a cold start. Pages and pages of people theorizing this silly stuff.

 

[DCDG]

unless hauling some load or pulling a weighted trailer the vehicle will take care of itself. modern vehicles have overbuilt cooling and oiling systems i can be in bumper to bumper traffic 110 heat index my oil temp sits around 190-194 putting a load on the vehicle what I may see 210-212. My biggest concern would be overheating the brakes as long as one is diligent on vehicle maintenance when it comes to oil changes GDI and turbo engines could benefit from a little spirited drives.

 

[melk]

Are we talking about downshifting an Automatic transmission into 3 or 2 from D ?

Wouldn’t that put entirely too much stress on the trans?

 

[Delta]

Maybe it's vehicle dependent, but on the one mountain pass I occasionally drive going up the mountain the oil temps rise as expected, but engine braking going down it goes down a good bit. This is on the WRX, 6MT.

We had the CVT in an Outback and it was really weird "downshifting" it going down the mountain. It more or less just made a bunch of noise and didn't engine brake much.