0

I went to a mountain range the other day with my Seat Toledo from 2001. Going downhill, with 12% inclination, I downshifted to 2nd gear to avoid braking all the way. The car still picks up speed, maybe 60km/h, reaching 4500 RPM (redline is 6000).

I wasn't sure if this was harmful for the engine, and whether I should tap the brakes occasionally (not because of the speed being dangerous, but because the RPM were too high). Father-in-law says it's bad, forum says it's fine.

As for harm to the engine... there is none.

So, is it harmful for the car to reach high RPM when going downhill in a low gear (a.k.a, when braking with your engine)?

Improve this question
0

2 Answers 2

Reset to default
1

I've been taught to do exactly that (4wd). Use the engine over brakes to avoid brake overheat and maintain control.

Not a mechanic but I'd assume that 4,500 RPM under no power is just as ok as 4,500 under power, if not more ok due to less combustion.

In my diesel 4wd I put it in low range 1 or 2 and keep it under control with occasional dabs on the brake (redline is 4,500, so dab around 3,750).

Regarding comments in your link - for 4wd at least, under no circumstances coast downhill in neutral. You lose control (no drive to correct direction if you lose traction on the front) and demand more of the brakes (no engine).

Improve this answer
1

This is not any more harmful to your engine than driving it as long as you use care to avoid two things:

  1. Over-revving your engine, which you mention you kept track of and saw that the maximum rpm was 4500 with a 6000 redline. So this is safe. Over-revving should be avoided and you should apply the brakes if the engine speed approaches the redline to avoid engine damage.

  2. Overheating your engine. The energy being dissipated during engine braking ends up in your cooling system and goes out the radiator. Under some conditions this can cause overheating. So you should keep an eye on your temperature gauge or temperature light and use the brakes if the temperature gets too high.

Improve this answer

Not the answer you're looking for? Browse other questions tagged .