I need your ears

[Foxford]

I've owned my '91 C-2 for four years now, and decided I could trust it for a quick weekend trip with my better half. The car was great fun to drive through the hills of Wisconsin, and it carried us safely out and back for almost 700 miles.

A couple hours out I stopped for gas and noted a disconcerting "clunk" when I restarted the engine. I also detected a slight shudder form the depressed clutch pedal at the same. The clutch then seemed to exhibit more vibration when pulling away, although I did actuate it tentatively due to the clunk on startup. I didn't notice any other performance problems once underway. After another hour of travel, I'd stopped worrying so much. I did detect a slight shudder from the clutch when going around a detour for a construction zone.

We stopped several times throughout the day, and each time on restart I heard a clunk as the engine caught. At one point as I lugged the engine a little in slow traffic, and I thought the engine vibrations seemed a little more "alive" than usual, maybe a higher frequency buzz accompanying the normal sounds. Of course once I hear an unusual sound, the hyper vigilance kicks in and I begin to question all kinds of normal sounds.

On some occasions the car started without any theatrics. I only heard the extra buzzy-ness when I pulled from 2500 rpm up to 3000 rpm. I also wondered if I was hearing the buzz during compression braking. For the most part, clutch actuation was normal. I may have subconsciously compensated with the pedal to avoid perceived vibrations. I didn't really try to diagnose it, as I was nervous about getting us through the trip without incident.

As I considered what was going on, I thought about the dual-mass flywheel in this model and wondered if this clunk was consistent with an impending flywheel failure. I also thought it could be as simple as a broken engine mount, although feedback I've received so far has made the engine mount theory seem less likely. Although it was built almost 18 years ago, the car only has 35,000 miles on it.

I have very little experience with the diagnosis of 911 clutches. I have made other 200 - 300 mile long trips in the car, but some road conditions were extremely bad this weekend. I wished I'd put my 16" skinny tires on just to absorb some bumps. Would anyone care to venture a guess as to the cause of the clunk at startup?

I've been doing my own basic maintenance, but I will need some greater expertise to track this problem. Until now, the noises the car makes have been all good ones. I'd appreciate any suggestions as where to go with this little mystery. Thanks!

p.s. I'm in the Chicago area, and would appreciate a recommendation for a good local repair shop

[Don Plumley]

A clunk is often associated with a suspension component that shifts during acceleration, deceleration or cornering. A broken sway bar mount for example. Could be a CV joint as well.

I don't think of clunk and DMF failure, but I could be wrong.

Suggest you post the recommendation question on the main board.

Keep us posted...

[cjoenck]

Try "Perfect Power" in Buffalo Grove - north side

http://www.perfectpowerinc.com/

They took very good care of me in the past.

Good luck

[Foxford]

Thanks for the recommendation. I hadn't thought of them.
I think they have an ad in the PCA's "Chicago Scene"

[Diverwes]

http://chicago.citysearch.com/profile/map/3432263/arlington_hts_il/arlington_performance_center.html

Chris is a great guy to work with and knows all about them.
Thats where I go when I don't want to mess with it.