Driving Around With A Leaking Exhaust Manifold Cause Any Damage Apart From Sounding Horrible

[reeceo21]

Gday,

I have a leaking manifold due to one of the holes were the studs screw in being threaded and not having a stud in there. It never was a problem for about 9 months but now i believe it has warped the manifold from the heat unfortunately and in turn completely ruined the gasket for the last cylinder. At first it was just a tick tick tick when cold now everytime i downshift or let off the throttle you can hear loud backfires from the motor escaping the manifold and a bit of a sucking noise under boost. I know this isnt ideal to drive with due to it sounding like a tractor but the manifold gasket and studs have been purchased and im just waiting to buy a new front pipe and decat to do all my exhaust gear at once.

So as the topic states does driving around like this cause any problems e.g bad for valves. I know it takes longer for turbo to spool up, cant hold boost for as long, sounds terrible etc but more worried about the motor as this is my daily driver. I would of thought it would ruin economy but it has probably been better as i have been rarely hitting boost. Its a rb25det btw with a stock turbo and internals. Within a week or two it will be fixed but i rely alot on my car and time is always short. ANy input will be greatly appreciated

[Traah221]

Without having heard it myself, I would be on the cautious side and say nurse it as much as possible. Aside from the carbon monoxide rolling into your cabin, the leaky manifold increases bay heat much quicker, and can eventually cause some valve damage. Best avoided if possible. Also, rarely hitting boost doesn't necessarily equate to better economy, since, if it's struggling to hit the higher RPM range, it offsets the lack of air with a bit more fuel. Just a thought.

[mad082]

rarely hitting boost will generally mean better economy, but not in the case of a leaking exhaust. in normal cases, using lighter amounts of throttle means less boost, which means better economy for 2 reasons. 1: less air going into the system, so less fuel is required, and 2: lower throttle percentages means the ecu is reading in lower load cells, so it will generally stay in closed loop (using o2 sensor feedback) and be running on leaner AFRs.

but in the case of an exhaust leak, you will have less efficient exhaust flow, and you will be using more throttle (so higher load values) to go anywhere, so while the boost levels may be lower, you would be using more fuel than if you were to have no leaks and be driving around at the same boost levels (which would mean less throttle than you currently are).