Hello,
After numerous hours of reading forums and Google searches I'm still a bit puzzled in regards to my
987.1
2.7L 5speed issue:
After some hard driving/pulls I noticed a knocking noise when clutch is engaged at idle. However it goes away when clutch is disengaged and pushed in.
My top 3 suspects after research are A) flywheel B) throwout bearing C)clutch.
Scoring:
I Did a borescope on cylinder 4-6(driver side) and only found some carbon deposits but no scoring. So I don't believe it would be piston slap/scoring (especially since the noise goes away after clutch goes in)
Throwout bearing:
Bad bearing usually makes a rattling noise on clutch engagement and makes a difference noise then myn, so I don't think it's that.
Clutch:
My clutch doesn't slip, or seem to have any performance issues so I don't think it could be the clutch
This leads me to the flywheel which somehow is getting worn out? As IV read some
bmw
forms and they and the same symptoms where the DMF(dual mass flywheel) was causing the knocking)
Please share your leads or ideas as to what this might
I'm a tad confused about the statement:
When the clutch pedal is pushed in - the clutch is normally disengaged. Otherwise, it would be like a model-T where you had to hold down the pedal for the gear you wanted to drive in..
I'm going to assume you mean when the clutch is disengaged and leave it at that.
It sounds like gear rattle on the input gears on the gearbox. It's very common on things like BMW opposed twin motorcycles. Pull in the clutch (disengage it) with the transmission in neutral on a BMW R1200xx motorcycle and you'll hear some horrible banging and clanking, as the gears accelerate and deaccelerate.
How are the gears moving you might ask - with the clutch disengaged? There is always a bit of drag on the clutch plate from the flywheel and pressure-plate, and there is some force transferred to the input shaft on the transmission via the pilot bearing (the end of the input shaft goes into the center of the flywheel and there is a bearing there that allows the shaft to turn at a different speed than the flywheel/pressure-plate when the clutch is disengaged.)
Does that apply to cars? Yup. In the BMW world it's quite popular to installed lightened single-mass flywheels. "Because racecar." - and that's known to horrendous gear rattle at idle, clutch disengaged. And since the BMW and Porsche both use dual-mass flywheels (a two-piece flywheels) - if the dual mass damper assembly gets worn out - the same thing can happen and you have these noises.
My top of the head suggestion - if you're going into the area to explore, just replace the entire clutch assembly, including the pilot bearing (so many people don't do this, then it seizes and the transmission won't come out, things get tied to trees and pulled by tractor-trailers - and generally ugly stuff like that.) If you don't replace it - grease it carefully while it's accessible.
So this would involve a new clutch disk, a new pressure plated (these come as a kit, sometimes with the throwout bearing), a pilot bearing and if you're feeling rich - a new dual-mass flywheel. I think the test for the dual-mass assembly is when it's accessible you grab it and see if you can move the two halves in relation to each other.
Here's what Valeo - who makes these things says about testing it:
Automotive aftermarket | Valeo Service
Valeo Service, el especialista de los recambios y repuestos del automóvil, ofrece una gama completa de piezas y accesorios para tanto coches como vehículos industriales.
www.valeoservice.com
The only reason I don't suggest just replacing it - true failure is fairly rare but happens if someone abuses a clutch - and the damn things are really pretty expensive. This is a case where it'd be asking FCP_Euro about a clutch kit that includes everything you are replacing.
The bad part is the cost, the good part is - you'll be AMAZED at how much lighter in feel the clutch is, and how much smoother it engages. Clutches increase the back pressure to the clutch pedal as they wear, it has to do with the position of the pressure plate fingers on the actual pressure plate.
Anyway - that'ya go. A complete brain dump on the subject. sometimes I wonder where these things come from. Maybe AI in my head.
When you have a chance - like soon - please visit
https://www.planet-9.com/forums/new_members/
and tell us all about you, your Porsche(s), life in general, and whatever you're comfortable sharing. AND we need pictures of your Porsche. Really. We're pining away here.. waiting for new Porsche pictures to appear. I'm starting to feel weak..
Just for fun - I decided to see how it would sound if Shakespeare responded.. so I asked ChatGTP to shake it up:
I think I'm going to bed now. These new drugs (prescribed) are really a hoot... Later.
Hi
@deilenberger
thank you for responding, it is very educating.
And yes you are correct in regards to the clutch engagement/disengagement. I had to re-write the text a second time after i accidentally closed the browser, and got it mixed up when doing so 😂.
In regards to gear radle,I'm a tad confident where you said
A) what is the dual mass damper assembly?
(I'm guess it's the assembly i of the DMF?)
B) is it separate from the clutch assembly? (Or is it the same components different name/application)
And sorry for my lack of understanding/knowledge. I'll post on the new_memevers thread and you'll understand where I'm coming from
Thanks!
