Sorted out surging idle, now this.....

mhinch · 09-07-2007, 01:10 PM

I fixed my idle problems (thanks to the Pelicans and the search button) now she's ticking over at 850 rpm, no problem sooooo I went for a celebratory drive and now I've got a loud clicking noise in third gear (no unusual noise from 1st,2nd,4th or 5th) I think it'll be a gearbox overhaul but could it be the shifter adjustment? Anyone experienced the same clicking noise.

All input appreciated

Mark

Paulporsche · 09-07-2007, 01:29 PM

Can you try to pin down where the noise is coming from and get back to us? Does it vary with engine speed? Road speed?

mhinch · 09-07-2007, 01:33 PM

I can "feel" the sound/clicks coming from the shift tunnel and through the lever, I didn't leave it in 3rd gear too long in case I caused further damage, 3rd gear was selected from 4 th at about 30 mph.

jester911 · jester911's Garage

Quote:

Originally Posted by mhinch

I can "feel" the sound/clicks coming from the shift tunnel and through the lever, I didn't leave it in 3rd gear too long in case I caused further damage, 3rd gear was selected from 4 th at about 30 mph.

Going that slow in 3rd or 4th you probably are lugging the engine. I am not saying that is the cause of the noise but...

DonMo · DonMo's Garage

Did you hold the gear shift to see if you were getting a vibration or a harmonic?

mhinch · 09-07-2007, 10:35 PM

DonMo, definetely a vibration, sounds like the teeth on the gears are not engaging fully.

spuggy · 09-08-2007, 02:49 AM

Mike Bainbridge (MBEngineering) in Cumbria rebuilt and modified a used '86 915 for me. The clicking noise in 1st turned out to be a gear that was cracked and opening up as it went around, then snapping shut again. Makes a good paperweight...

If the clicking noise was in all gears, odds are good it's the speedo drive, but if it's only in one gear, that's not it. Making sure the shift mechanism is adjusted correctly can't hurt, but it doesn't sound like that's the problem. I'd talk to someone about a rebuild - and Mike's a lot closer to you than he is to me...

The 930 is a torque monster and I'm never in 3rd @ 30 MPH, so that seems pretty odd unless you were just checking that it went into all the gears correctly?

81SCRosewood · 81SCRosewood's Garage

Please share what you did to correct your surging idle.

Thanks!

mhinch · 09-08-2007, 10:44 AM

A further investigation tonight has revealed some more symptoms/details. Perhaps the 30 mph issue was a bit shy, I was down changing from a quick blat on a 70 mph road, for a roundabout, I don't labour the engine and do use the car as intended. Driving this evening and the noise unfortunately hasn't been fixed overnight by the Porsche pixies...its still there.
Basically 1st is ok, shift to 2nd still ok, clutch in, shift to 3rd and when I lift the clutch its like something on third gear is touching the clutch arm in the box, I can feel the clancking (a better description than clicking) through the clutch pedal and gear lever. Push in the clutch and the noise dissapears, I can then select 4th gear and drive as normal, 5th gear and reverse are ok no clancking. I've checked the shift coupler and tried a few permutations but I think its going to be a engine and box drop...........

Rosewood, the surging idle was a number of things, but to sumarise the engine ran well apart from idle was a little low at 600 rpm. When the emmisions were checked however the ppm's were around 3000 indicating a vacuum leak and mixture problems. Using the search function on this site led me investigate the inlet manifold gaskets, these had sucked and that I thought was the problem........I replaced the gaskets, built the engine back up ( this can be done with the engine in situ) started her up and the surging idle started, all electrical connections were checked, ICV was replaced as the car had the original one fitted, idle switch was checked and adjusted, vacuum pipes double checked and then replaced, but all to no avail. I checked the Co and it was off the scale (which stops at 9.99 %) but interestingly when I tried to adjust it via the srew underneath the AFM no adjustment was happening no matter where the adjuster was, even fully closed or open. The spring loaded flap on the AFM seemed to be a bit slack after 96,000 miles so the spring was clicked around 7 more notches. Fitted the AFM started the engine and 1200 rpm for a few seconds and then settled down to 850 rpm, a quick adjust of the Co had my emissions back to an acceptable level, and the car starts, drives and runs so much better.

Mark