Tachometer revs


#1

Hey all,

I have a 2003 Mazda 6, 5-speed. Whenever I’m driving in higher gear (4th or 5th), the tachometer seems to jump. For instance, if I’m driving at 50mph at 3,000rpm in 5th gear and I want to accelerate to ~65mph, the tachometer seems to jump to 3,5000-4,000rpm, then drop down to 3,000rpm and then slowly increase as I accelerate.

What’s the reason for this random jumping/revving? I don’t think the clutch is going bad or slipping. It only seems to happen in higher gears, even without me shifting–only when I want to accelerate.


#2

What you describe is a classic sign of a slipping clutch. How many miles on your Mazda 6?


#3

That’s a classic case of a clutch slipping.

It doesn’t do it in lower gears because the quicker acceleration prevents the steady application of engine torque, and the engine doesn’t spend much time at the speed of maximum torque.

How many miles on the clutch?

(I opened my reply in a tab before mcparadise made his reply)


#4

Currently there are 90,000 miles on the clutch.

So, does this mean I will have to replace the clutch soon?

Ugh, I can’t afford to pay more money on this car. I just had the engine replaced last year at 80,000 miles! Apparently, there was issues with oil leaking and what-not. I subscribed to an Edmund’s Auto forum thread, and apparently, many other Mazda6 owners have had engine failures at relatively low mileage (<80,000).


#5

The only cure for a slipping clutch is a new clutch.

You’re not going to like the price.


#6

The ratio of speed to RPMs should be constant for any given gear in a manual transmission. If that’s not the case, then the clutch is slipping.


#7

Only other possibility is a bad tach/connection (doubtful). Does the noise from the engine match the tach in the odd behavior? If so, then it’s the clutch.


#8

If they replaced the engine and did not replace the clutch, that was pretty foolish. Especially at 80K miles. That not withstanding, I have seen times where a clutch master cylinder had failed and would cause the clutch to slip by not releasing pressure quickly enough.
It does not cost that much to check the $25 part first.