Yo guys, I live in the mountains, and on long downgrades, I usually shift into a lower gear and let the engine keep the car's speed down, instead of burning off my brake pads. In this mode, I don't let the engine rev over 3000 or so. Is this bad for the engine? I've been doing it for some time and the engine has not objected (so far). TIA.

 

I never hurt any of my cars by using engine braking, be it diesel turbos, 4 cyl petrol or V8s. However, you may get a blue cloud out of the exhausts when you go back on the power if the valve guide oil seals aren't up to the job

Mark.

 

every car I owned I do engine braking with from my I4 honda or celica, to my automatic v8 camaro even did engine braking up to my rotary mazda

not one has complained yet and the only car that really has a problem with it is my mazda gets a little smoke sometimes if I'm goosing it then go into engine braking but what can i say the car has over 200k miles on the clock

 

Well, I do it all the time, and she don't smoke, so I guess it's not hurting anything, as long as you keep the RPMs reasonable.

The reason I ask is I read a thread on another forum that suggested that the very high vacuum you get when doing this was hard on pistons, rods and valves. One poster even went to far as to suggest that it may cause a rod to fail in tension, or pop the cap off.

Did the IROC engines use the PM rods?

 

No, regular old forged I-beams.

 

Engine braking never does any harm.
As long as you dont drop it from 5th to 1st at 90mph.