Asking for help with noise (clutch) diagnosis - ZR-1 Net Registry Forums

Duff · 06-09-2010

I have developed a mechanical (clanking) sound that seams to be coming from the clutch area. It has gotten gradually worse over the past few weeks and is now fairly loud at idle. It sounds like the something doesn't completely disengage when the clutch is in, It's kind-of a metalic rattling/tapping sound.

It only happens when the clutch is depressed at idle and gets louder and more consistent after the car is driven and heats up. (barely noticable at start-up). The clutch engages and shifts fine and there is no sound while in gear.

When detailing the car over the winter, I noticed fluid aroung the slave and the reservior was slightly low. I never noticed the sound until I topped off the fluid.

Based on what I've read, I believe the slave is going bad, so I am going to replace it anyway, but my question really is, would a bad slave cause the sound I'm describing by not completely disengaging the clutch? I don't feel any pull when stopped.

Any help is greatly appreciated

QB93Z · 06-09-2010

How many miles on the Z and how often is it driven.

Without hearing the noise it is hard to troubleshoot. If the clutch disengages and engages properly, it is probably not the clutch or slave cylinder causing the noise.

The noise may be coming from the Dual Mass Flywheel. Usually the noise is caused by an engine miss that causes the engine rotation to be uneven and the flywheel noise results.

Since your ZR-1 is a 1990, if the injectors have never been replaced, that is most likely the cause of an engine miss. Original 1990 injectors eventually go bad when they are exposed to ethonol mixed fuels.

I replaced the injectors in four 1990 LT5's in the last year, and all 4 cars had three or more failed injectors.

Also, Check for good plugs, plug wires, and coils.

If you need someone to help investigate and repair your ZR-1, Rick (Rickyrj1) is about 1.5 hours from you and there is a lot of help available here in the Baltimore area (2-2,5 hours away).

Jim

Duff · 06-09-2010

Jim, thanks for the response.

The car has just under 12,000 miles and not driven a lot (1,000/year and stored in winter).

I've been doing some more research since I posted and came across the DMF issue as you suggest. Sounds like the problem to me, although I know I need and to replace the slave and bleed the clutch hydraulic system. From reading some info on the ZFDoc site, the system needs maintenance.

I wouldn't say I have a bad mis or real rough idle but I'm going to listen more closely tonight. As I said, the noise has been getting worse over the last few weeks and definately gets worse after warm up (which correlates to the injectors failing more as they heat up) and I kind of noticed a drop in performance last night. I also know I have a vacuum leak under the plenum so I was going to do a pull as next winter's project but it looks like that may have to be moved up. From what I've read, I'm sure the injectors are, or are going bad.

I mainly wanted to get a direction of where to start.

Again thanks for your suggestions and It's nice to know there is help near by if I need it.

GOLDCYLON · 06-09-2010

Hi there Duff welcome aboard. I Suggest replacing the Slave ASAP. The sound you may be hearing could be coming from a couple of places. The Dual mass flywheel for one and the fork and bearing if the slave is failing. Speaking to the ZFDOC in the past most chose to replace both the clutch master and the slave master at the same time. As the ZFDOC has indicated a poor funtioning Slave in the beginning of the end of most ZF transmissions. Knowing Bill for about 5 years now what he tells me is (IS).

As to the injectors most of us have either gone to RC injectors, Accels or FICs. The RCs are the most expensive and you need 16 of the little buggers to get the job done. Your car if its not driven much is prone to injectors failure as the injectors tend to rust and pit over time. The OEM injector also can not tolerate modern fuel additives that we put into our fuels today for EPA reasons so they tend to fail. The RC injectors are stainless steel sleeved hence no rust. I beleive the accels are as well and I have no idea on the FIC injectors. I give you these three names as brandname options as folks have reported success with them but your mileage may vary. GC
GC

secondchance · 06-09-2010

Quote:

Originally Posted by QB93Z

How many miles on the Z and how often is it driven.

Without hearing the noise it is hard to troubleshoot. If the clutch disengages and engages properly, it is probably not the clutch or slave cylinder causing the noise.

The noise may be coming from the Dual Mass Flywheel. Usually the noise is caused by an engine miss that causes the engine rotation to be uneven and the flywheel noise results.

Since your ZR-1 is a 1990, if the injectors have never been replaced, that is most likely the cause of an engine miss. Original 1990 injectors eventually go bad when they are exposed to ethonol mixed fuels.

I replaced the injectors in four 1990 LT5's in the last year, and all 4 cars had three or more failed injectors.

Also, Check for good plugs, plug wires, and coils.

If you need someone to help investigate and repair your ZR-1, Rick (Rickyrj1) is about 1.5 hours from you and there is a lot of help available here in the Baltimore area (2-2,5 hours away).

Jim

I know it sounds strange but my 94 for years had similar noise. This noise would go away when the clutch was depressed. Motor seemed to run fine but had a faint pining I could hear at medium throttle around 1900 - 2200 rpm.
Eventually, as a last resort, I replaced all 16 injectors. Pinging was cured and hardly any noise from throw out bearing at idle.

Duff · 06-09-2010

Thanks again for the replies

After reading as much as I can on the subject, I'm pretty convinced it's the flywheel caused by the injectors, but the slave needs to be replaced anyway so I'm going to start there. I ordered a replacement today.

Tonight I'm going to run the car and really pay attention to when the noise first appears and if it's present when in neutral with clutch out or only when clutch is depressed. I'm also going to listen closely for a miss although, as I said, I really didn't notice a bad miss or major decline in performance (secondaries fire and no warnings).

I was hoping to wait until next winter for the plenum pull but if I can't, I can't.

rkreigh · 06-09-2010

the dual mass will get clunky if the car doesn't idle well, and it's common at shutdown as well

I messed up and got the spark plug well wet (yea don't ask) a long time ago and the car knocked so bad I thought I threw a rod

didn't like not running on all 8

the dual mass could be bad too, but it will bang around quite a bit if it's gone bad.

have a brutha give a listen! my bet is that the injectors are past their prime and you're hearing either the dual mass or some gear clatter from the ZF

gbmidyear66 · 06-10-2010

My 90 did the same thing when I got it. No noise on cold start, but after it warmed up, at idle - it sounded like my turbo-diesel.

Yup, it was the injectors. What happens to the injectors is that the original design had the internal coils exposes to the fuel (I believe intended as a cooling mechanism). The ethanol in current fuels eats the coil winding coatings, causing parts of the coil windings to short, thus lowering the coil resistance. As the resitance degrades below about 9 ohms, the injector fails to function. When the engine (and injectors) heat up - this further reduces the coil resistance (Vs cold injector resistance) - this is why you notice the problem after warm up. You likely have one or more injectors "on the edge" the reduction in resistance after warm up is enough to push them into failure.

Get a handheld DVM and you can confirm the above diagnosis (you only need to check the primaries given it is an idle issue). There is a post on this board that explains the procedure

Talk to Jerry and get some plenum gaskets and Jon at FIC (he has about 3 products for you to choose from)

Glenn

Oh yeah - you might also want to call Haibek Automotive and get the plunum pull video.

Duff · 06-10-2010

Quote:

Originally Posted by gbmidyear66

My 90 did the same thing when I got it. No noise on cold start, but after it warmed up, at idle - it sounded like my turbo-diesel.

Yup, it was the injectors. What happens to the injectors is that the original design had the internal coils exposes to the fuel (I believe intended as a cooling mechanism). The ethanol in current fuels eats the coil winding coatings, causing parts of the coil windings to short, thus lowering the coil resistance. As the resitance degrades below about 9 ohms, the injector fails to function. When the engine (and injectors) heat up - this further reduces the coil resistance (Vs cold injector resistance) - this is why you notice the problem after warm up. You likely have one or more injectors "on the edge" the reduction in resistance after warm up is enough to push them into failure.

Get a handheld DVM and you can confirm the above diagnosis (you only need to check the primaries given it is an idle issue). There is a post on this board that explains the procedure

Talk to Jerry and get some plenum gaskets and Jon at FIC (he has about 3 products for you to choose from)

Glenn

Oh yeah - you might also want to call Haibek Automotive and get the plunum pull video.

I replicated my trip from the night before. Went for a 10 mile ride, as the car warmed up the noise got louder and more consistent. Also noticed a slight miss. Shutdown for a half hour and when I restarted the sound was very apparent.

I have the procedure for checking the injectors with plenum on. But, I probably won't get to it until the weekend. I have no doubt it's the injectors at this point. I'm still going to change the slave and bleed new fluid into the system as I know there is a slight leak.

I looked on the FIC website yesterday and plan on calling today. Is there any performance difference between the FIC rebuilt Bosch and the OEM replicas? I would like to stay as original looking as possible but if the Bosch perform better I may go with them and save $200. I'm probably going to go with headers and porting in the future (may now be my winter project) anyway as the longer I have the car the less I care about originality. In the end, the only thing that won't be reversible is the porting but you can't see that.

I have read a lot about the plenum pull and have the service manual as I planned on doing that anyway so I'm going to order the gaskets and have at it. I also bought a Haibek chip so I'll call Mark and get the video. Part of the reason I bought the car was to maintain and service it as a hobby and learn more about the mechanics so I'm kind of looking forward to it.

The information available hear is outstanding.

Hammer · 06-10-2010

Welcome aboard Duff.

I have the regular FIC's in my car, I think around $360 a set.

I just got back from BG and on that trip I averaged around 24-26 MPG at, oh, probably 75 to 80 MPH or so. I too had the knocking you are talking of before the injectors and it of course went away after installation.

GL

06-09-2010	#1
Duff Join Date: Jan 2010 Location: West Deptford, NJ Posts: 14	Asking for help with noise (clutch) diagnosis I have developed a mechanical (clanking) sound that seams to be coming from the clutch area. It has gotten gradually worse over the past few weeks and is now fairly loud at idle. It sounds like the something doesn't completely disengage when the clutch is in, It's kind-of a metalic rattling/tapping sound. It only happens when the clutch is depressed at idle and gets louder and more consistent after the car is driven and heats up. (barely noticable at start-up). The clutch engages and shifts fine and there is no sound while in gear. When detailing the car over the winter, I noticed fluid aroung the slave and the reservior was slightly low. I never noticed the sound until I topped off the fluid. Based on what I've read, I believe the slave is going bad, so I am going to replace it anyway, but my question really is, would a bad slave cause the sound I'm describing by not completely disengaging the clutch? I don't feel any pull when stopped. Any help is greatly appreciated

06-09-2010	#2
QB93Z Join Date: May 2007 Location: Westminster, Maryland Posts: 3,689	Re: Asking for help with noise (clutch) diagnosis How many miles on the Z and how often is it driven. Without hearing the noise it is hard to troubleshoot. If the clutch disengages and engages properly, it is probably not the clutch or slave cylinder causing the noise. The noise may be coming from the Dual Mass Flywheel. Usually the noise is caused by an engine miss that causes the engine rotation to be uneven and the flywheel noise results. Since your ZR-1 is a 1990, if the injectors have never been replaced, that is most likely the cause of an engine miss. Original 1990 injectors eventually go bad when they are exposed to ethonol mixed fuels. I replaced the injectors in four 1990 LT5's in the last year, and all 4 cars had three or more failed injectors. Also, Check for good plugs, plug wires, and coils. If you need someone to help investigate and repair your ZR-1, Rick (Rickyrj1) is about 1.5 hours from you and there is a lot of help available here in the Baltimore area (2-2,5 hours away). Jim __________________ If it isn't fun, you aren't doing it right! 1990 Black ZR-1 - sold 1993 Quasar Blue ZR-1 1994 Competition Yellow ZR-1 1995 Dark Purple ZR-1 Maryland State Coordinator WAZOO Member

06-09-2010	#3
Duff Join Date: Jan 2010 Location: West Deptford, NJ Posts: 14	Re: Asking for help with noise (clutch) diagnosis Jim, thanks for the response. The car has just under 12,000 miles and not driven a lot (1,000/year and stored in winter). I've been doing some more research since I posted and came across the DMF issue as you suggest. Sounds like the problem to me, although I know I need and to replace the slave and bleed the clutch hydraulic system. From reading some info on the ZFDoc site, the system needs maintenance. I wouldn't say I have a bad mis or real rough idle but I'm going to listen more closely tonight. As I said, the noise has been getting worse over the last few weeks and definately gets worse after warm up (which correlates to the injectors failing more as they heat up) and I kind of noticed a drop in performance last night. I also know I have a vacuum leak under the plenum so I was going to do a pull as next winter's project but it looks like that may have to be moved up. From what I've read, I'm sure the injectors are, or are going bad. I mainly wanted to get a direction of where to start. Again thanks for your suggestions and It's nice to know there is help near by if I need it.

06-09-2010	#4
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,155	Re: Asking for help with noise (clutch) diagnosis Hi there Duff welcome aboard. I Suggest replacing the Slave ASAP. The sound you may be hearing could be coming from a couple of places. The Dual mass flywheel for one and the fork and bearing if the slave is failing. Speaking to the ZFDOC in the past most chose to replace both the clutch master and the slave master at the same time. As the ZFDOC has indicated a poor funtioning Slave in the beginning of the end of most ZF transmissions. Knowing Bill for about 5 years now what he tells me is (IS). As to the injectors most of us have either gone to RC injectors, Accels or FICs. The RCs are the most expensive and you need 16 of the little buggers to get the job done. Your car if its not driven much is prone to injectors failure as the injectors tend to rust and pit over time. The OEM injector also can not tolerate modern fuel additives that we put into our fuels today for EPA reasons so they tend to fail. The RC injectors are stainless steel sleeved hence no rust. I beleive the accels are as well and I have no idea on the FIC injectors. I give you these three names as brandname options as folks have reported success with them but your mileage may vary. GC GC __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V Last edited by GOLDCYLON; 06-09-2010 at 10:17 AM.

06-09-2010	#6
Duff Join Date: Jan 2010 Location: West Deptford, NJ Posts: 14	Re: Asking for help with noise (clutch) diagnosis Thanks again for the replies After reading as much as I can on the subject, I'm pretty convinced it's the flywheel caused by the injectors, but the slave needs to be replaced anyway so I'm going to start there. I ordered a replacement today. Tonight I'm going to run the car and really pay attention to when the noise first appears and if it's present when in neutral with clutch out or only when clutch is depressed. I'm also going to listen closely for a miss although, as I said, I really didn't notice a bad miss or major decline in performance (secondaries fire and no warnings). I was hoping to wait until next winter for the plenum pull but if I can't, I can't.

06-09-2010	#7
rkreigh Join Date: Jan 2004 Location: Alex VA Posts: 1,087	Re: Asking for help with noise (clutch) diagnosis the dual mass will get clunky if the car doesn't idle well, and it's common at shutdown as well I messed up and got the spark plug well wet (yea don't ask) a long time ago and the car knocked so bad I thought I threw a rod didn't like not running on all 8 the dual mass could be bad too, but it will bang around quite a bit if it's gone bad. have a brutha give a listen! my bet is that the injectors are past their prime and you're hearing either the dual mass or some gear clatter from the ZF __________________ 95 390 LPE ZR1 (505 rwhp) LSV = Lingenfelter Super Vette Twin Turbo 2003 Z06 (800 RWHP)

06-10-2010	#8
gbmidyear66 Join Date: Feb 2008 Location: Vancouver, BC Posts: 252	Re: Asking for help with noise (clutch) diagnosis My 90 did the same thing when I got it. No noise on cold start, but after it warmed up, at idle - it sounded like my turbo-diesel. Yup, it was the injectors. What happens to the injectors is that the original design had the internal coils exposes to the fuel (I believe intended as a cooling mechanism). The ethanol in current fuels eats the coil winding coatings, causing parts of the coil windings to short, thus lowering the coil resistance. As the resitance degrades below about 9 ohms, the injector fails to function. When the engine (and injectors) heat up - this further reduces the coil resistance (Vs cold injector resistance) - this is why you notice the problem after warm up. You likely have one or more injectors "on the edge" the reduction in resistance after warm up is enough to push them into failure. Get a handheld DVM and you can confirm the above diagnosis (you only need to check the primaries given it is an idle issue). There is a post on this board that explains the procedure Talk to Jerry and get some plenum gaskets and Jon at FIC (he has about 3 products for you to choose from) Glenn Oh yeah - you might also want to call Haibek Automotive and get the plunum pull video. __________________ [SIGPIC][/SIGPIC] __________________ 1990 Corvette ZR-1 #2824 4.10's, Custom PROM, Flowmaster, Top End Port NCRS BC Chapter

06-10-2010	#10
Hammer Join Date: Apr 2006 Location: Ideho Posts: 2,653	Re: Asking for help with noise (clutch) diagnosis Welcome aboard Duff. I have the regular FIC's in my car, I think around $360 a set. I just got back from BG and on that trip I averaged around 24-26 MPG at, oh, probably 75 to 80 MPH or so. I too had the knocking you are talking of before the injectors and it of course went away after installation. GL __________________ [I][FONT=Comic Sans MS]John Boyd[/FONT][/I] [I][FONT=Comic Sans MS][SIZE=1]Ideho[/SIZE][/FONT][/I] [FONT=Comic Sans MS][SIZE=1][I]2015 ZL1 [/I][I]Camaro #1121 BLACK/BLACK 6 SPD (540 RWHP)[/I][/SIZE][/FONT] [I][FONT=Comic Sans MS][SIZE=1]1991 ZR-1 #458 [COLOR=red]RED/[/COLOR][COLOR=black]BLACK 72[/COLOR]k miles ([B][COLOR=red]SOLD[/COLOR][/B]) 1991 ZR-1 #473 [COLOR=red]RED/[/COLOR][COLOR=black]BLACK [/COLOR]37k miles ([B][COLOR=red]SOLD[/COLOR][/B])[/SIZE][/FONT][/I]

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