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Hi all. The 3.6 ran great up to Pebble and back, much fun. Even had cigars with Seinfeld.
She developed an odd shudder decelerating into corners, giving no gas. Axle/diff will clunk as if I were tapping the throttle a bit on an off rapidly. Almost like a surge problem on an MFI car. Seems like it would come from an uneven or high idle, but neither of those problems exist.
Only other concern I had was the engine running too cool. See second picture. Cruising for hours at that temp. Only got up to half way on the gauge during stop and go in Carmel. Are my oil cooler fans stuck on (except for sometimes)?
may be you discovered your lsd first time. cobalt wrote: These LSD's have a tendency to be rather noisy and IMO not the best they fail early in life. They will grind at low speeds and reverse making all sorts of noises. When they fail the noise goes away...
so you are a lucky guy, it is still alive (-:
ps: great car nd always great pictures in your posts
Haha no I’ve always known it was in there. Well this is a new behavior. I did change the gear oil from a standard with an LS additive, to Mobil LS90, and noticed the car was immediately crunchier in reverse. But this new cornering decel uneven thing appeared as a new behavior.
sure I'll comment,.... albeit I am just the peanut gallery when it comes to technical guru input
can't you just see if your oil cooler fans are running upon immediate start up (when they shouldn't be)?
... if not,... and this is probably a risky suggestion {so take it for what it's worth}. It is a brut force type test,... so I am SURE Paul, Tony or others will have a much better, safer method to test....
my first thought was maybe take it for a spin with the relay pulled for the oil cooler fans, and see if your oil temp gauge goes up higher than what you see / showed in your pic above. As soon as it does, SHUT it down & replace relay. ... like I said, probably a crappy suggestion,... but it does keep the thread alive.... hehe
In normal operation, the oil temp will rise to just above the 3rd mark before the thermostat opens. Then it settles down to just below the 3rd mark.
If the resistor for the oil cooler fan fails (they all do eventually), the fan won't come on at all. If your stuck in a traffic jam, the oil temp will continue to rise, eventually pegging the gauge.
I would have a look at the oil thermostat. The wax capsule that controls the opening and closing may have failed. Warning - it's a bitch to remove from the hard oil lines. It would also be a good time to replace all the oil hoses attached to it and the oil tank.
Much thanks Steve and Paul - no bad advice. Understood on the operation. Does running between 2nd and 3rd mark like above seem like a normal operating temp for cruising at 0 altitude and about 75 degrees? I'm used to seeing the motor warmer while driving around town. First real road trip.
if memory serves me, my oil temp usually settles right about horizontal for the needle. so yes keep chasing that one down.
back to the potential shutter on deceleration ... I have LSD in mine too,... and I have indeed experienced the behavior that Peter posted of Cobalt's comments,.. but most of that has been slow speed behavior.
I have never felt any shutter when off the throttle, on a corner entrance w/ deceleration, like you describe Wicks. Do ALL of you guys experience that? (those of you who still have a good working LSD?),... maybe that means mine is not working properly (which could easily be the case given I have 80k miles, and no idea whether it's ever been checked. Plenty of oil changes (tranny etc) over the years,... but not sure what else is required to test &/or ensure it is working.
- Started the car cold - no fans on.
- Turned on A/C - left fan turns on (engine stone cold off idle)
- Let idle and warm up until gauge hit level needle, no fans on
- Warm up a bit over level needle, right fan turned on
- That cooled the idling engine back down a bit, so I couldn't warm up enough to see if left fan would also turn on to cool engine (as well as coming on whenever the A/C is turned on)
I was running with the A/C on when the temp was super low at cruise (as pictured above). Maybe there is a switch in the A/C > left fan on process that is blown? Maybe that is supposed to work on a combo of A/C on + temp at ___ level for the left fan to be on with A/C and the temp at ____ piece isn't working.
I would consider that normal operating temps. If it gets to half way and the tstat opens it should drop to what you are seeing or you're just not driving hard enough Trying to understand the other issue. Your description isn't quite clear. It is 100% lock up on decel so it is possible your plates are going on the LSD.
You can always open the trans and have a look or test your unit. Could be the oil you used. You are using straight 90 vs a 75W-90? Porsche recommends friction modifiers to reduce the noise but it does impact how the unit works. If the plates are getting tired it could be the modifiers causing it to slip.
If it is meant to be 100% locked up on decel, then yes I'd say something must have been slipping. While in decel straight, no shudder. Soon as I enter a turn on decel, in gear, the car behaves as if I was tapping the gas a little on and off with maybe twice per second. This is at relatively low RPMs and 3rd or 2nd gear.
Recently switched to LS90, which is supposed to have the additive already in the mix yes? Previously, I hadn't noticed the problem, and had been running what the dealer put in, which was Motul 300 (which I found disappointing as it isn't for LSD), to which I had added 4oz of Delco LSD additive.
Maybe the Motul 300 plus Delco LSD additive was a better mix than the LS90 alone?
You know what they say if it ain't broke. Sorry. You might consider Swepco or Delvac and see if things improve or go back to the Motul. I gave up on the additives a few years ago. They help with the noise initially but eventually it comes back, so I just learned to live with it. Otherwise test the LSD or pull the side cover and inspect. If you remove it and there is nothing wrong and reinstall it you won't need to go through the lash adjustment.
Hah no worries, it's a good lesson to remember when you're an OCD classic car owner. I might first try adding 4 oz of the same Delco slip additive to the LS90 and see if that affects it. Then will read about how to inspect the diff.
You know what they say if it ain't broke. Sorry. You might consider Swepco or Delvac and see if things improve or go back to the Motul. I gave up on the additives a few years ago. They help with the noise initially but eventually it comes back, so I just learned to live with it. Otherwise test the LSD or pull the side cover and inspect. If you remove it and there is nothing wrong and reinstall it you won't need to go through the lash adjustment.
Let us know what you find.
The 80/100 locking factor was specifically put on the 965 to keep unskilled drivers from spinning their cars in cornering situations where the driver gets off the power mid-corner (3:56 of this video
I tried Delvac. I wouldn't recommend it unless you add slip agent so in the end you might as well use the Mobil 1 LS 90.
The previous owner of my car had to have the clutch plates replaced at approximately 60k miles.
08-20-2019, 12:45 AM
Shudder on decel entering corners
