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#1 |
Registered User
![]() Join Date: Jan 2013
Location: Roanoke, TX
Posts: 39
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Here's a problem I have been working on for several months now. I found the culprit this past weekend, but thought some of you might like to take a stab at it.
Background: '82 C20, 350 SBC, NV4500 5spd trans. Several months ago I installed new GM Performance L31 with serpentine belt setup. I used the 91 TBI setup that was on the old engine but on a new vortec TBI manifold. I also replaced the mechanical clutch setup with a hydraulic clutch setup from a 85-87. The new engine required a new flywheel but I used the same pilot bearing, pressure plate, and clutch disk that was in the 82 because they only had about 5K miles on them. I did replace throw-out bearing. OK, to the problem... After everything was installed again it was out for a test spin. The new clutch setup worked very well. Engine ran well and I was very pleased for the first 15 minutes or so. Then a loud squeal began from under the truck. It was localized to the bell housing area. I used a probe to try and isolate the noise... it was definitely in the bell housing. ![]() Since the pilot bearing was real sloppy in the crankshaft, I removed the trans and clutch assembly and replaced the pilot bearing. After reassembly and 15 minutes into the test drive the noise reappeared. ![]() Now it is your turn... what you think? Ask any questions you have... let's see if you come up with the same culprit I did. Mike |
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#2 |
Registered User
Join Date: Sep 2007
Location: N.E. Florida
Posts: 500
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Re: For those who like to troubleshoot...
What style/type hydraulic clutch set up did you use ? Was it a Hydraulic throw out bearing style ? Similar to what Jeep use for so many years ?
__________________
1985 IROC Z28 190HP TPI 305,700r4,T-tops,rear trac lock, Black on lite gray, 16in Z28 wheels 2007 Lexus ES350 (wifes) 1984 CJ7 with 1995 HO4.0L MPI, 2 1/2 OME YJ Lift “There is no limit to the amount of good you can do if you don't care who gets the credit.” ― Ronald Reagan |
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#3 |
Registered User
![]() Join Date: Jan 2013
Location: Roanoke, TX
Posts: 39
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Re: For those who like to troubleshoot...
It is the original Chevy/GMC master/slave cylinders activating a release arm on the driver side.
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#4 |
Registered User
Join Date: Feb 2011
Location: Cold Canada
Posts: 310
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Re: For those who like to troubleshoot...
oe or advance adapter bell housing, is the noise when pressing the clutch or all the time?
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1981 c30 dually, 350 sm465 ex tow truck now yard mule 1985 k35 dually, 454 th400 np205 1985 D30 cucv M1008, 6.2 th400 np208 1999 toyota tacoma, lifted 6'' 31'' tires 2003 toyota echo, reliable and damn cheap on gaz |
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#5 |
Registered User
Join Date: Sep 2007
Location: N.E. Florida
Posts: 500
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Re: For those who like to troubleshoot...
Have you checked the throw out bearing operation? How where the clips that hold the bearing on the arm? Is one possibly weak or bent allowing the bearing to settle down and get hung up?
What about the input shaft bearing ? Input shaft collar? If you could get it on a lift, and run it up to road speed when the condition occurs. Then have the throw out arm grommet off so you can maybe see something. Get a spray bottle and use some soapy water to see if you an pin point the noise. Ken
__________________
1985 IROC Z28 190HP TPI 305,700r4,T-tops,rear trac lock, Black on lite gray, 16in Z28 wheels 2007 Lexus ES350 (wifes) 1984 CJ7 with 1995 HO4.0L MPI, 2 1/2 OME YJ Lift “There is no limit to the amount of good you can do if you don't care who gets the credit.” ― Ronald Reagan |
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#6 | |
Registered User
![]() Join Date: Jan 2013
Location: Roanoke, TX
Posts: 39
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Re: For those who like to troubleshoot...
Quote:
The noise starts after about 5 minutes of driving and then remains constant and doesn't vary in tone or pitch much no matter if clutch pedal is in or out. It does hesitate or lighten up while accelerating. |
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#7 | |
Registered User
![]() Join Date: Jan 2013
Location: Roanoke, TX
Posts: 39
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Re: For those who like to troubleshoot...
Quote:
We checked the release arm and the throw out bearing when we changed the pilot bearing and everything looked normal. As far as input shaft bearing or collar, we did not disassemble but did the yank check to verify there was no excessive play. Trans has less than 5K miles since major overhaul. |
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#8 |
Registered User
Join Date: Sep 2007
Location: N.E. Florida
Posts: 500
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Re: For those who like to troubleshoot...
I would pull the tranny as a very last resort. After exhausting all diagnostic options. Sometimes it helps to get somebody who doesn't know the truck to take a look and listen. It could be a very minor thing. If it was a imput shaft bearing/bushing issue, I would think you would be hearing the noise more as a grinding.
Do you know someone with a Chassis Ear. http://www.steelmantools.com/chassis...-ii-combo.html great tool for such noises.
__________________
1985 IROC Z28 190HP TPI 305,700r4,T-tops,rear trac lock, Black on lite gray, 16in Z28 wheels 2007 Lexus ES350 (wifes) 1984 CJ7 with 1995 HO4.0L MPI, 2 1/2 OME YJ Lift “There is no limit to the amount of good you can do if you don't care who gets the credit.” ― Ronald Reagan |
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#9 |
Registered User
Join Date: Feb 2015
Location: Lester West Virginia
Posts: 244
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Re: For those who like to troubleshoot...
Input shaft to long bottoming out on the crank causing a clearance issue
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#10 |
Registered User
Join Date: Jul 2011
Location: WV
Posts: 946
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Re: For those who like to troubleshoot...
Does the noise change or go away with the clutch pushed in and you are at a stop? Or when it is engaged and you are driving?
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72 GMC C2500 402/Th400 first truck (still have) 77 GMC C3500 CC dually Sold ![]() 70 C50 dump truck "Rusty" 87 K10 Suburban Sold 93 K2500 xcab 6.5TD 96 GMC K2500 Suburban 6.5 TD |
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#11 |
Registered User
Join Date: Feb 2007
Location: Memphis MI
Posts: 1,851
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Re: For those who like to troubleshoot...
OK, I'll play.
So, noise is there with clutch in or out. So my first reaction is that it's not directly related to the clutch system. It does lighten up when you accelerate? So its sensitive to engine torque. Think about what happens when you torque the engine - the engine rolls to one side, and the trans tries to twist in toque reaction. Based on your description once it happens it stays, whether moving or not. If you shut the truck off, wait 20 seconds, then restart, does it happen immediately? If so, I'd yank the serp belt and check. I've seen some weird noise paths.... Does the frequency change with engine RPM, ie more RMP higher pitched noise? If so, then flywheel rubbing when then engine block expands with heat, rear main seal out of position and binding hot, or a really tight rear main bearing would come to mind.
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1987 2 ton ![]() 1982 ![]() Dad's 1981 ![]() Plus a mess o' tractors |
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#12 |
Registered User
![]() Join Date: Jan 2013
Location: Roanoke, TX
Posts: 39
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Re: For those who like to troubleshoot...
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#13 |
Registered User
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Location: Roanoke, TX
Posts: 39
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Re: For those who like to troubleshoot...
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#14 | |
Registered User
![]() Join Date: Jan 2013
Location: Roanoke, TX
Posts: 39
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Re: For those who like to troubleshoot...
Quote:
We did yank the serpentine belt and still had the noise. I like the way great minds think the same! We checked flywheel clearances. I like the way you think outside the box (bell housing)... |
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#15 |
Proprietor of Dale's Corner
![]() Join Date: Nov 2012
Location: Vacaville , CA
Posts: 16,087
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Re: For those who like to troubleshoot...
Is the harmonic balancer rubbing on something ie..timing cover or timing mark and resonating the noise to the bell housing?
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"Some Days Chickens And Some Days Feathers" Dale XNGH ECV Sam Brannan 1004 R.I.P. 67ChevyRedneck R.I.P. Grumpy Old Man |
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#16 |
Registered User
![]() Join Date: Oct 2015
Location: Allen, TX
Posts: 63
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Re: For those who like to troubleshoot...
Did you put the throwout bearing spring retainer thingy on backwards?
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#17 |
Registered User
![]() Join Date: Jan 2013
Location: Roanoke, TX
Posts: 39
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Re: For those who like to troubleshoot...
So far you guys have asked all the same questions that we asked; but, everything appeared to be installed properly with no clearance problems seen. The noise was definitely coming from inside the bell housing.
However, I am a hot rodder/guy and as soon as we hot rodders get to a point that we can test drive a project... we do! I did! Maybe everything was not installed. Everything ran well and shifted well and when the noise came I concentrated on it and not a few lingering items that had not been put back on the new motor. ![]() ![]() This help any? |
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#18 |
Registered User
Join Date: Mar 2015
Location: Manchester, CT
Posts: 433
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Re: For those who like to troubleshoot...
Did you put the clutch disc on backwards ?
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#19 |
Registered User
![]() Join Date: Jan 2013
Location: Roanoke, TX
Posts: 39
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Re: For those who like to troubleshoot...
Nope... I did check that, though.
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#20 |
Registered User
Join Date: Dec 2011
Location: Regina, SK, Canada
Posts: 622
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Re: For those who like to troubleshoot...
Long shot, but I had a similar issue a few years back. It was the starter drive not disengaging .
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1979 Chevy Dually Crew 4X4 454, D60 Tru-trac, D70 Detroit Locker, 3.73, 4L80E/NP205 1971 GMC 3/4 Ton 4X4 |
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#21 |
Registered User
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Location: Roanoke, TX
Posts: 39
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Re: For those who like to troubleshoot...
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#22 |
Registered User
![]() Join Date: Jan 2013
Location: Roanoke, TX
Posts: 39
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Re: For those who like to troubleshoot...
Well it looks like you guys have run out of ideas... I did too. I went and purchased new pressure plate, clutch disk, and throw out bearing and was about to yank the trans AGAIN when a friend of mine ( a 40 year veteran of a dealership shop) called and said he had these same symptoms back in 1990 and told me to try something before taking the trans out. Here was his instructions:
Drive until the noise returned, stop and remove the oil filler cap and see if the noise stops.... What? ![]() Well I'll be damn!! The noise stopped! I put the cap back on and after a minute the noise was back! The cap off... noise gone! The thing I had not reinstalled was the breather tube to the valve cover. This one whipped me for sure... thanks for all the feedback. This was fun. Mike |
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#23 |
Registered User
Join Date: Jul 2011
Location: WV
Posts: 946
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Re: For those who like to troubleshoot...
Sorry for missing post 6. LOL.
__________________
72 GMC C2500 402/Th400 first truck (still have) 77 GMC C3500 CC dually Sold ![]() 70 C50 dump truck "Rusty" 87 K10 Suburban Sold 93 K2500 xcab 6.5TD 96 GMC K2500 Suburban 6.5 TD |
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#24 |
Registered User
Join Date: May 2010
Location: Mountain House, CA
Posts: 555
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Re: For those who like to troubleshoot...
That was fun. I love odd ball problems like that. So in short the crank case pressure was "whistling" past a seal in the back? No oil leak?
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My Chevy habit is paid for by Ford diesels... Here is my SLOW LS install: http://67-72chevytrucks.com/vboard/s...55#post6456355 Caliper Rebuild: http://67-72chevytrucks.com/vboard/s...d.php?t=613748 Upper Control Arm Bushings: http://67-72chevytrucks.com/vboard/s...d.php?t=616974 IG mattcrp1 |
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#25 |
Post Whore
![]() Join Date: Aug 2014
Location: Sacramento, CA
Posts: 10,827
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Re: For those who like to troubleshoot...
WOW, thank you for sharing goes to show the importance of the Positive Crankcase Ventilation system, oh and by the way I would have totally guessed this one right if I saw it in time... NOT!
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