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Rough idle after new water pump?

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Rough idle after new water pump?

Posted: 7/17/07 9:49amMessage 1 of 13
f
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Toledo, OH - USA
Joined: 2/22/2007
Posts: 175
Vette(s): 1977 auto.L48 383 stroker
I just replaced the water pump on my 77.  For some weird unknown reason, it is idling rough now.  I never touched the carb, wires, etc. and do not understand this.  Is there something about changing the water pump that would create this problem that I don't know about?  Thanks for any suggestions and input!Smile
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Rough idle after new water pump?

Posted: 7/17/07 9:50amMessage 2 of 13
f
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Toledo, OH - USA
Joined: 2/22/2007
Posts: 175
Vette(s): 1977 auto.L48 383 stroker
Forgot to ask.....would it have anything to do with the tension on the alternator or power steering belt when I put it back together?  Tension on both appears to be fine/normal.
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Rough idle after new water pump?

Posted: 7/17/07 10:30amMessage 3 of 13
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 22720
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
Is this a vibration? If it is, then it may be the fan is not centered on the pump shaft, or the pump shaft may be bent...
If you loosen the belts, does it idle smoother?

Joel Adams
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Rough idle after new water pump?

Posted: 7/17/07 10:52amMessage 4 of 13
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SHELBYVILLE, TN - USA
Joined: 7/5/2002
Posts: 3944
Vette(s): 1976 L48 auto

1978 L82 4speed

1994 LT1 6speed
might check to see if you accidently knocked off/broke a vaccuum line....

StingrayJim
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Rough idle after new water pump?

Posted: 7/17/07 2:41pmMessage 5 of 13
r
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North Charleston, SC - USA
Joined: 3/20/2004
Posts: 4208
Vette(s): 1975 L48 AT AC T-top
Did the car overheat before changing the water pump?

Scott
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Rough idle after new water pump?

Posted: 7/17/07 4:13pmMessage 6 of 13
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visalia, CA - USA
Joined: 10/27/2006
Posts: 641
Vette(s): 1981 red with silver interior,350(L-81), 350TH, glass t-tops, aluminium rims, 1980 Black/ Black int., 350 GM crate engine/350TH, 1976 black/ saddle int., L-82 w/headers, holly carb, Hypertech ignition
my guess would also  be  a vaccume line .  On mine in the past, I've just bumped  vac. lines  doing repairs w/o even knowing it ,that later caused problems.
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Rough idle after new water pump?

Posted: 7/17/07 5:31pmMessage 7 of 13
E
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Mansfield, TX - USA
Joined: 12/4/2001
Posts: 110
Scott:
 
I recently experienced the same thing and the car did overheat. What does that have to do with the rough idle???
 
Jim
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Rough idle after new water pump?

Posted: 7/17/07 6:38pmMessage 8 of 13
r
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North Charleston, SC - USA
Joined: 3/20/2004
Posts: 4208
Vette(s): 1975 L48 AT AC T-top
If the engine got hot enough it could have breached a head gasket. The introduction of water in the combustion chamber can at a minimum foul a spark plug or worse, warp a valve. This of couse is only one of several possiblities.
Scott
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Rough idle after new water pump?

Posted: 7/17/07 9:06pmMessage 9 of 13
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Apache Junction, AZ - USA
Joined: 10/15/2006
Posts: 285
Vette(s): 1982,150K,Renegade CFI,Hooker Side Pipes,85 fuel pump,Bilsteins,HD suspension, Aluminum radiator, SharkBar/w 5-Point Restraints. 3:73 gears coming soon.
Does your 77 have a Coolant Temperature Sensor? On my 82 it is just above the water pump and if it is unplugged or malfunctioning, similar problem arise.   
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Rough idle after new water pump?

Posted: 7/18/07 4:56amMessage 10 of 13
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Toledo, OH - USA
Joined: 2/22/2007
Posts: 175
Vette(s): 1977 auto.L48 383 stroker
No, my car did not overheat before changing the water pump.  It does not have a coolant temperature sensor on it.  I am not experiencing a vibration from the fan but rather a small "miss" when idling.  With acceleration when parked it smooths right out fine.  I'll have to double check the vacuum hoses but I am sure nothing was moved.  I am going to loosen the belts a bit and see if this might take care of it but like I said the tension on them now is fine.  I'll keep you guys updated.  
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