Aussie 964C2 Maintenance Diary (pic heavy!)
10-21-2011, 02:19 AM
#76
Burning Brakes
Thread Starter
When I first got the 964, it never had a problem with cold starts. But in the past couple of months, it's developed a strange habit. First, it'll take quite a bit of cranking to fire up, and when it does, it'll immediately stall again. But on the second try, it'll fire up and settle down to a steady idle like a champ.
This seems to be a reasonably common complaint, and we had a recent thread on it. I first suspected that maybe lack of use has left some of the injectors a bit gummed up. There is even a Porsche TSB that recommends using Caltex Techron to clean them out: http://members.rennlist.com/jandreas...10-TECHRON.pdf
I tried it, but it didn't seem to make any difference.
The next port of call is to check out the famous Idle Stabilization Valve, or ISV , and there's zillions of threads on RL about cleaning it out, usually when your car starts to stall for no reason (but not necessarily have any issues while starting).
Luckily I have a spare inlet manifold, and it's easier to see what it does out of the car. It's the cylindrical thing on top, and you can see that it allows intake air to go up, and bypass the closed throttle. After going through the ISV, the intake air is routed into the hotside of the inlet manifold.
It's basically a rotary valve, which is electrically controlled by the ecu. That cylinder you can see inside rotates to regulate the opening to allow more or less air to go through.
Now the spare ISV is pretty clean inside, so the engine it was attached to, can't have done many miles before the car it was in came to a sticky end and got parted out. I blasted it with some brake cleaner and what came out was pretty clean.
The spare ISV is in great shape, but while it looks the same, it's a different part number than the one from the car. So I'm going to clean out the one on the 964.
And I don't think you can see it too clearly, but everything inside is covered in black crap. You can even see that the barrel has a bit of a scratch in it, so the gunk must be gritty enough to catch the barrel when it tries to move.
Which took about a half can of blasting with the brake cleaner to remove, and what came out was er...surprising
This was a pretty easy, the ISV is easily removed from the car, and it was equally easy to put back. If you're going to do this DIY, make sure you have two hose clamps of the right diameter to reattach the rubber hoses to the ISV. The stock hose clamps are crimped on permanently, and in order to remove them I prised them off, which rendered them useless. But overall it's an easy DIY, and if your engine is less than enthusiastic about starting in the mornings, then maybe cleaning out the ISV will improve things.
...and the result
I suppose the ISV must have been gummed up, so that on cold start it was sticky to move into the right position. But now that it's clean, not only does it start more easily, but it idles more smoothly (and drives on small throttle openings more smoothly too.)
This seems to be a reasonably common complaint, and we had a recent thread on it. I first suspected that maybe lack of use has left some of the injectors a bit gummed up. There is even a Porsche TSB that recommends using Caltex Techron to clean them out: http://members.rennlist.com/jandreas...10-TECHRON.pdf
I tried it, but it didn't seem to make any difference.
The next port of call is to check out the famous Idle Stabilization Valve, or ISV , and there's zillions of threads on RL about cleaning it out, usually when your car starts to stall for no reason (but not necessarily have any issues while starting).
Luckily I have a spare inlet manifold, and it's easier to see what it does out of the car. It's the cylindrical thing on top, and you can see that it allows intake air to go up, and bypass the closed throttle. After going through the ISV, the intake air is routed into the hotside of the inlet manifold.
It's basically a rotary valve, which is electrically controlled by the ecu. That cylinder you can see inside rotates to regulate the opening to allow more or less air to go through.
Now the spare ISV is pretty clean inside, so the engine it was attached to, can't have done many miles before the car it was in came to a sticky end and got parted out. I blasted it with some brake cleaner and what came out was pretty clean.
The spare ISV is in great shape, but while it looks the same, it's a different part number than the one from the car. So I'm going to clean out the one on the 964.
And I don't think you can see it too clearly, but everything inside is covered in black crap. You can even see that the barrel has a bit of a scratch in it, so the gunk must be gritty enough to catch the barrel when it tries to move.
Which took about a half can of blasting with the brake cleaner to remove, and what came out was er...surprising
This was a pretty easy, the ISV is easily removed from the car, and it was equally easy to put back. If you're going to do this DIY, make sure you have two hose clamps of the right diameter to reattach the rubber hoses to the ISV. The stock hose clamps are crimped on permanently, and in order to remove them I prised them off, which rendered them useless. But overall it's an easy DIY, and if your engine is less than enthusiastic about starting in the mornings, then maybe cleaning out the ISV will improve things.
...and the result
I suppose the ISV must have been gummed up, so that on cold start it was sticky to move into the right position. But now that it's clean, not only does it start more easily, but it idles more smoothly (and drives on small throttle openings more smoothly too.)
Last edited by Babalouie; 11-05-2011 at 04:41 AM.
10-22-2011, 04:46 AM
#79
in the past few days I've been trying different thing in the pursuit of the "ideal" solution.
It looks like the only way to fool the system and avoid to get fault codes is this, but it generates too much heat, so I think it's too risky....!
The CCU knows if the blower is there through pin 87 of the original relay (thin yellow/green wire). The resistors you need to simulate the motor get dangerousely HOT
So, I chose to forget about fault-codes and get the system work fine and safe, and I ended up with this:
you can leave the original wiring as it is (so it is reversible) and simply rout the switched positive from the coil (thank you
) into pin 87. I also added a 7.5 fuse to protect this line. The original 30 amp fuse can be completely removed.No need to use a relay, no need to modify the original wireness.
Very simple and it works
Thank you for the great inspiration
Last edited by anto1150; 10-22-2011 at 05:41 AM.
10-26-2011, 04:48 AM
#82
Burning Brakes
Thread Starter
If you've been following the thread, you'll notice that one constant is that I'm always chasing a gearshift issue. The PPI identified a leaky slave cylinder hose, and replacing that made it better. But a few days later it would get worse again. So I'd replace the slave, and then the master...and then the pedal rollpin, and then some of the linkage bushes. And every one of those repairs did make it better, but the cycle always repeated, in that later it would go back to its old ways again.
What were the symptoms? The main one was that the gearshift was stiff going *out* of gear on deceleration. So you're cruising to a halt, and as the car rolls to a stop, you try to knock the gearlever into neutral, but it's stuck in gear....once the car stops, it frees up and becomes normal. Changing up is pretty ok, though, and if you changed down under acceleration, like say for an overtake, then it would be fine.
The penny dropped when I was parking the car one day, and with the clutch pedal to the floor, the car still creeped forward. Then I started to notice that the clutch would bite inconsistently: sometimes high, sometimes low. Do a search for any of these symptoms, and you pretty much get a rusty gearbox input shaft. And this, is what I got.
Sadly fixing it means removing the trans to get access to the gearbox input shaft, polishing and lubing it with a special spline grease, and then refitting everything. Oh yes, that's right....just to scrape off some rust, we have to remove the engine and trans
Now, a man's gotta know his limitations, so this was a job I entrusted to my favourite P-Car specialist, Autohaus Hamilton, and the engine and trans were dropped.
First thing to note...aha...rusty gearbox shaft (and no sign of the special spline grease, either)
And...team that up with rusty splines on the clutch disc itself, and the disc was very stiff on the shaft. When you depress the clutch, the pressure plate is meant to draw back, and the disc is meant to naturally slide back from the flywheel. But the rust means that the disc "sticks" on the shaft and drags on the spinning flywheel. This has the effect a little bit like changing gear without pressing the pedal down all the way.
So how come it always seemed to get better with a master/slave repair, but then get worse again? I think the explanation is due to something called galling. You would think that regular use might "free up" the clutch disc and maybe make a clean spot on the shaft, but the opposite is true. As the disc slides back from the flywheel, little particles of rust get trapped in the splines, and as the disc moves back and forth the little particles of rust snowball and get bigger, and the disc in fact gets more and more stuck. it's a little bit like trying to tighten a rusty nut onto a rusty bolt...the more you tighten, the more it gets stuck.
So I think what was happening in my case was that the rusty disc was getting more and more stuck over time, but I was merely compensating for it by repairing other things, until one day I ran out of things to replace...and now we (hopefully) fix it for good
Another casualty of the sticking clutch was the pressure plate, which is badly heat-spotted.
And while the engine is out...(oh gosh, the ground suddenly became so slippery...
) the Hamilton techs pointed out that the front gasket on the gearbox is leaking, so that will have to be sorted.
And, as we discovered a few weeks ago, the frotn trans mount is actually in good shape. But since the nose of the gearbox is coming off for a gasket replacement anyway, they'll press on the new RS mount for me
Another thing noted (whoops...nearly slipped down the slope there) was a leaky oil pressure sender, but that's just an o-ring replacement and is easy-peasy with the engine out.
And finally...oh joy of joys...the dual mass flywheel isn't heatspotted or ruined by the sticking clutch. If it looked like the pressure plate does, possibly I might be up for a new one, and they're quite er...rather pricey.
So that's what happened today. I dropped off a new Sachs clutch kit, so we should have a new pressure plate, clutch disc and throwout bearing...oh, and a new RS trans mount too. Fingers crossed that tomorrow, we have a shift that's silky and smooth like a supermodel's inner thigh
And oh yes, my original plan to sign the credit card statement with my eyes closed still stands.
What were the symptoms? The main one was that the gearshift was stiff going *out* of gear on deceleration. So you're cruising to a halt, and as the car rolls to a stop, you try to knock the gearlever into neutral, but it's stuck in gear....once the car stops, it frees up and becomes normal. Changing up is pretty ok, though, and if you changed down under acceleration, like say for an overtake, then it would be fine.
The penny dropped when I was parking the car one day, and with the clutch pedal to the floor, the car still creeped forward. Then I started to notice that the clutch would bite inconsistently: sometimes high, sometimes low. Do a search for any of these symptoms, and you pretty much get a rusty gearbox input shaft. And this, is what I got.
Sadly fixing it means removing the trans to get access to the gearbox input shaft, polishing and lubing it with a special spline grease, and then refitting everything. Oh yes, that's right....just to scrape off some rust, we have to remove the engine and trans
Now, a man's gotta know his limitations, so this was a job I entrusted to my favourite P-Car specialist, Autohaus Hamilton, and the engine and trans were dropped.
First thing to note...aha...rusty gearbox shaft (and no sign of the special spline grease, either)
And...team that up with rusty splines on the clutch disc itself, and the disc was very stiff on the shaft. When you depress the clutch, the pressure plate is meant to draw back, and the disc is meant to naturally slide back from the flywheel. But the rust means that the disc "sticks" on the shaft and drags on the spinning flywheel. This has the effect a little bit like changing gear without pressing the pedal down all the way.
So how come it always seemed to get better with a master/slave repair, but then get worse again? I think the explanation is due to something called galling. You would think that regular use might "free up" the clutch disc and maybe make a clean spot on the shaft, but the opposite is true. As the disc slides back from the flywheel, little particles of rust get trapped in the splines, and as the disc moves back and forth the little particles of rust snowball and get bigger, and the disc in fact gets more and more stuck. it's a little bit like trying to tighten a rusty nut onto a rusty bolt...the more you tighten, the more it gets stuck.
So I think what was happening in my case was that the rusty disc was getting more and more stuck over time, but I was merely compensating for it by repairing other things, until one day I ran out of things to replace...and now we (hopefully) fix it for good
Another casualty of the sticking clutch was the pressure plate, which is badly heat-spotted.
And while the engine is out...(oh gosh, the ground suddenly became so slippery...
) the Hamilton techs pointed out that the front gasket on the gearbox is leaking, so that will have to be sorted.And, as we discovered a few weeks ago, the frotn trans mount is actually in good shape. But since the nose of the gearbox is coming off for a gasket replacement anyway, they'll press on the new RS mount for me
Another thing noted (whoops...nearly slipped down the slope there) was a leaky oil pressure sender, but that's just an o-ring replacement and is easy-peasy with the engine out.
And finally...oh joy of joys...the dual mass flywheel isn't heatspotted or ruined by the sticking clutch. If it looked like the pressure plate does, possibly I might be up for a new one, and they're quite er...rather pricey.
So that's what happened today. I dropped off a new Sachs clutch kit, so we should have a new pressure plate, clutch disc and throwout bearing...oh, and a new RS trans mount too. Fingers crossed that tomorrow, we have a shift that's silky and smooth like a supermodel's inner thigh
And oh yes, my original plan to sign the credit card statement with my eyes closed still stands.
10-27-2011, 09:53 AM
#86
Burning Brakes
Thread Starter
I didn't ask, but I'd imagine that you'd use something like a brass wire brush on a drill to remove the rust, and then polish the shaft (oo-er) with a scotchbrite pad until shiny. Then apply the special factory lube called Optimoly (the Sachs clutch kit also came with a sachet of spline lube too).
But I picked up the car today and it's greeeeat! Finally, we have a nice, silky shift, and the lever flies around the gate like chopsticks at a noodle restaurant The pressure plate, clutch disc and throwout bearing are renewed too, so the pedal is lighter, and the biting point lower, more like in the middle of the pedal rather than the top. The 1-2 shift, is especially fast now compared to before, and no more sticking in gear on decel
..not entirely sure if I can feel any difference from the RS trans mount though
But I picked up the car today and it's greeeeat! Finally, we have a nice, silky shift, and the lever flies around the gate like chopsticks at a noodle restaurant
The pressure plate, clutch disc and throwout bearing are renewed too, so the pedal is lighter, and the biting point lower, more like in the middle of the pedal rather than the top. The 1-2 shift, is especially fast now compared to before, and no more sticking in gear on decel ..not entirely sure if I can feel any difference from the RS trans mount though
10-27-2011, 01:53 PM
#87
Intermediate
How does rust get onto the gearbox shaft? I assume it must not be from the shaft itself as it should be in oil 100% of the time.. but the rust seems confined to where it interacts with the clutch plate splines.
Did they do any maintenance on the pressure plate?
Great pics and commentary as usual, thanks.
Did they do any maintenance on the pressure plate?
Great pics and commentary as usual, thanks.
10-27-2011, 07:48 PM
#88
Burning Brakes
Thread Starter
http://www.pelicanparts.com/cgi-bin/...TIMOLY%20PASTE
The grease will protect the parts from corrosion. But in my case there are 2 theories: one is that the clutch was changed (possibly because of DMF recall) and the techs were lazy and installed the new clutch without any grease. The second theory is that my car just grew more rust than usual in that spot, because it was sitting idle in a collection and not driven for a few years.
But it's a surprisingly common issue, maybe not so much on the 964 forum, but if you search for rusty shaft on the 993 forum, you get quite a lot.
Sure. The old pressure plate is in the trash, there is a new Sachs one in there now
10-29-2011, 09:06 AM
#89
Burning Brakes
Thread Starter
Well tomorrow is the Porsche Club concours and so most of today and yesterday evening has been spent cleaning, in full-blown OCD Mode (facial twitch, frothing at the mouth, the whole thing)
Went nuts with a toothbrush and cotton buds
Even cleaned the front door jamb..
Clayed, polished and waxed the inside of the roof gutter LOL
First I did a wash (Meguiars NXT), then clayed, then a polish with Meguiars Deep Crystal Paint Cleaner, then sealed it with two coats of Zymol wax.
Came out pretty good.
Took ages to clean the dirt out from between the lettering
Probably the deepest point of OCD was when I noticed that the screws in the fuel filler hole were corroded, so I wire brushed them smooth and resprayed them black again Oh, and polished the underside of the fuel flap too 
Well, I figure that's as clean as she's ever gonna get, so wish me luck tomorrow!
Oh, and I hope to see some Sydney Rennlisters there, details here: http://cms.porsche-clubs.com/Porsche...2578CC001D4FA5
Went nuts with a toothbrush and cotton buds
Even cleaned the front door jamb..
Clayed, polished and waxed the inside of the roof gutter LOL
First I did a wash (Meguiars NXT), then clayed, then a polish with Meguiars Deep Crystal Paint Cleaner, then sealed it with two coats of Zymol wax.
Came out pretty good.
Took ages to clean the dirt out from between the lettering
Probably the deepest point of OCD was when I noticed that the screws in the fuel filler hole were corroded, so I wire brushed them smooth and resprayed them black again
Oh, and polished the underside of the fuel flap too Well, I figure that's as clean as she's ever gonna get, so wish me luck tomorrow!
Oh, and I hope to see some Sydney Rennlisters there, details here: http://cms.porsche-clubs.com/Porsche...2578CC001D4FA5