duverne996

Hi Guys,
I wondered if you could help me.
When reving my 993 C4S above 4500 rpm I feel some sort of vibrations on the throttle & clutch pedals and even on the steering wheel. The engine seems to rev fine and there´s no lack of power or anything strange appart from these vibes.

My feeling is that it might be the flywheel, but I've read over here that when a flywheel is in bad state the vibrations are felt at low rpms when both starting and stopping the ride; so this has confused me because on my case is only noticeable on high rpms. ¿?

Perhaps an old engine mount?


Any idea is much apreciated!

Mike J

A bit more data please - is the car in motion or you are stopped? Clutch pedal in or out? Vibrations vary with RPM? Vary with the car moving?

Cheers,

Mike

duverne996

HI Mike,
thanks for your quick reply.

I would actually have to try it tomorrow with the car stopped since I haven´t tried recently reving it when not in motion.

In any case, I wouldn't say that the vibrations vary on intensity, they pretty much feel the same from 4500rpm and above. They feel on the clutch as I go releasing it just after chaging a gear and at the same time on the gas pedal as I hit my foot down on it. But they can also be felt on steering wheel.
but no metal noises whatsoever.
Clutch feels healthy, hard + no need to press it to the end to change gears.

At low rpms, 2,3 up to 4000 nothing of the above is felt.

I had another 993 C4 with similar milage and no evidence of these vibes at all.

Thanx!

Mike J

Given its a C4S, you can pickup vibrations in the steering if its in the driveline. If its an imbalance in the driveline/clutch etc. it should vary with RPM or Speed.

Some ideas
- drive at the same speed but try different gears to see if it changes - i.e is it speed dependant or RPM dependant -I think you sort of did that with your comment about 2,3 gear nothing untill 4000, which is RPM dependant
- if the engine remains at 4000+ rpm, what happens if the clutch is pushed in while you are rolling - does the vibration stop instantly?
- if you are rolling along at 5000 rpm and you push in the clutch and let the engine go to idle, does the vibration stop instantly?

You should play around and see if you can segment the vibration, is it engine side or transmission side? If its flywheel, the vibration may be lessened with the flywheel is not engaged in the driveline, but its should still be there.

Cheers,

Mike

duverne996

Will do as you sugest, segmenting the problem to trace its origin.

matt777

Also see if it is specific to accelerating/starting off or at constant speed.

pp000830

At times I feel there should be a twelve step program for Porsche owners. You know the line “accept the things I should not fix, have courage to fix the things I must and have the wisdom to know the difference” Be very cautious when considering repair or maintenance procedures suggested to you that involve removing the engine from the car;

Mike J

Why?

And did we say "remove the engine from the car"? The OP asked a question, we are trying to get more data to see if we can help isolated the issue, then we will worry about the fix procedure. Its totally up to OP as to pursue a fix....

I always make the assumption that any advice I give out will be interpreted and not taken as gospel by the receiver - I will try to be as factual and accurate as my limited knowledge will allow, and then its up to the owner to interpret all the responses and take it from there.

But I do agree, I think there should be a 12 step program for the slippery slope, not fixing problems. That one is wickedly hard to resist.

Cheers,

Mike

matt777

The solution is only as good as the diagnosis.

vincer77

Are you getting the proverbial coffee can rattle when you shut off the engine?

Ed Hughes

What post did I miss here?