Go Back   Corvette Forum > C3 Corvettes, 1968 - 1982 > C3 Tech/Performance
Sign in using an external account
Register Forgot Password?
Register Search Today's Posts Mark Forums Read FAQ Vendor Directory
Search
C3 Tech/Performance
V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette Sponsored by
VBP

Welcome to Corvetteforum.com!
Welcome to Corvetteforum.com.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join Corvetteforum.com today!


Corvette Store
 
 
C7 Parts & Accessories
C6 Parts & Accessories
C5 Parts & Accessories
C4 Parts & Accessories
C3 Parts & Accessories
C2 Parts & Accessories
C1 Parts & Accessories
Wheels & Tires
Sponsored Ads
 
 
Vendor Directory
  
Reply
 
 
 
 
Thread Tools Search this Thread
Old 11-15-2011, 09:32 PM   #1
TomAur
Junior Member
 
Member Since: Nov 2011
Default Water Pump

I have a 1968 Corvette 327/350. I have changed the water pump three times in the last 6 months. I don't believe I am tightening the belt too much. In addition, I get an engine/transmission vibration at 3000 RPMs in all four gears. It seems when the pump fails (Pump leaks), the vibration goes away and the engine runs without vibration after 3000 RPMs. Any suggestions.
TomAur is offline   Reply With Quote
Old 11-15-2011, 09:36 PM   #2
Marlin
CF Senior Member
 
Marlin's Avatar
 
Member Since: Aug 2005
Location: Springfield VA
Default

Make sure your pulleys are not bent. Could cause the pump issues and also the vibration.
What condition is the front balancer?
Marlin is offline   Reply With Quote
Old 11-15-2011, 09:53 PM   #3
TomAur
Junior Member
 
Member Since: Nov 2011
Default

I purchased the car last winter. It appears the car was restored. The pulley looks new. How can I tell the condition of the front balancer?

Last edited by TomAur; 11-15-2011 at 10:00 PM.
TomAur is offline   Reply With Quote
Old 11-16-2011, 04:27 AM   #4
joewill
CF Senior Member
 
joewill's Avatar
 
Member Since: Sep 2007
Location: Noblesville Indiana
Default

disconnect all your belts, and run your engine. according to your diagnosis, the engine should run without vibration. add 1 belt at a time until your vibration is back.. that is where your problem is.
joewill is offline   Reply With Quote
Old 11-16-2011, 07:49 AM   #5
Marlin
CF Senior Member
 
Marlin's Avatar
 
Member Since: Aug 2005
Location: Springfield VA
Default

^

Yep.

Start with no belts. If you still have a shake check the balancer, if not; 1 belt at a time.
Marlin is offline   Reply With Quote
Old 11-16-2011, 08:32 AM   #6
TomAur
Junior Member
 
Member Since: Nov 2011
Default

Thanks guys. Logical approach!! I'll keep you posted.
TomAur is offline   Reply With Quote
Old 11-16-2011, 01:32 PM   #7
Manuel Azevedo
CF Senior Member
 
Manuel Azevedo's Avatar
 
Member Since: Jan 2007
Location: Concord Calif
Default

Also check the size of the water pump shaft. There are two different size shafts maybe more. If you have the wrong size shaft as compared to your fan clutch there will be nothing to index the clutch other than the bolt holes which is not enough. I ran across this on my 68 and vibrations went away with the right combo. I believe the correct size shaft for a 68 is 3/4" and other GM cars were 5/8" Yea some pumps came with a small brass adapter the put the large clutch on the small pump but that was not always a good fix!
Manuel Azevedo is offline   Reply With Quote
Old 11-16-2011, 08:42 PM   #8
TomAur
Junior Member
 
Member Since: Nov 2011
Default

Can you explain in more detail what you mean by "there will be nothing to index the clutch other than the bolt holes which is not enough"
TomAur is offline   Reply With Quote
Old 11-16-2011, 08:46 PM   #9
RobbSalzmann
CF Senior Member
St. Jude Donor '12
Support Corvetteforum!
 
RobbSalzmann's Avatar
 
Member Since: May 2009
Location: Tucson AZ
robbsalzmann
Send a message via Skype™ to RobbSalzmann
Default

Quote:
Originally Posted by TomAur View Post
Can you explain in more detail what you mean by "there will be nothing to index the clutch other than the bolt holes which is not enough"
He means that if you're supposed to have 3/4" shaft, and the shaft you have is 5/8", then its too small and the hole in the clutch is too big so it's a sloppy fit, meaning the clutch is never perfectly centered.

If this is the case, then the imbalance of not centering the clutch (indexing it on the pilot shaft) will quickly wear your water pump.
RobbSalzmann is offline   Reply With Quote
Old 11-18-2011, 12:29 PM   #10
TomAur
Junior Member
 
Member Since: Nov 2011
Default

I checked the old water pump shaft and the hole in the fan clutch. They are both 5/8 inch. So, that appears to be ok. After doing some research, I figured out that the fan clutch is not stock. The stock fan clutch has four holes that mate to the water pump. Instead, on mine, where the fan clutch holes should be, each hole is in the shape of a U, I guess to make it more universal to other water pumps. However, since both the center hole on the clutch is 5/8 and the shaft on the water pump is 5/8 then in theory it should not wobble. Once I install the new pump, I will run the engine without any belts.
TomAur is offline   Reply With Quote
Old 11-18-2011, 03:45 PM   #11
mikep3
CF Senior Member
 
mikep3's Avatar
 
Member Since: Dec 2005
Location: Baldwinsville New York
Default

What hole size is in the Pulley for the water pump? If it is 3/4" then the 5/8" shaft will not center the pulley. If you have a water pump with 5/8" shaft. Then do you have a water pump that is too long or short for a corvette application? Most Corvette's have a water pump based on year and not all short pumps are the same.

Just my 2 cents
mikep3 is online now   Reply With Quote
Old 11-18-2011, 03:59 PM   #12
427Hotrod
CF Senior Member
 
427Hotrod's Avatar
 
Member Since: Jan 2000
Location: Houston, Tx
Default

It's possible the fan clutch itself is bad internally....or a bent fan blade. You're on the right path.

JIM
427Hotrod is offline   Reply With Quote
Old 11-20-2011, 09:45 AM   #13
mikep3
CF Senior Member
 
mikep3's Avatar
 
Member Since: Dec 2005
Location: Baldwinsville New York
Default Making any Progress ?

How is your water pump thing going?
mikep3 is online now   Reply With Quote
Old 11-20-2011, 06:41 PM   #14
TomAur
Junior Member
 
Member Since: Nov 2011
Default

Gents,

Today, I removed all of the belts checked the Harmonic Balancer; it looked fine. I installed a new water pump. I started the engine without the power steering or water pump belts. There was no vibration. I ran the engine with the water pump and belt but no fan clutch; still no vibration. When I installed the fan clutch the vibration was evident. I removed the fan clutch, and the vibration was once again gone. I have a new stock fan clutch on order.

I will keep you guys posted. Thanks for all of your advice.

Last edited by TomAur; 11-20-2011 at 06:45 PM.
TomAur is offline   Reply With Quote
Old 11-21-2011, 11:59 AM   #15
jackson
CF Senior Member
 
Member Since: Sep 2001
Location: Timmonsville SC
Default

ensure the replacement fan clutch has same size pilot hole ID as OD of forward end wp shaft.

Quote:
Originally Posted by TomAur View Post
Gents,

Today, I removed all of the belts checked the Harmonic Balancer; it looked fine. I installed a new water pump. I started the engine without the power steering or water pump belts. There was no vibration. I ran the engine with the water pump and belt but no fan clutch; still no vibration. When I installed the fan clutch the vibration was evident. I removed the fan clutch, and the vibration was once again gone. I have a new stock fan clutch on order.

I will keep you guys posted. Thanks for all of your advice.
jackson is offline   Reply With Quote
Old 11-26-2011, 09:02 PM   #16
TomAur
Junior Member
 
Member Since: Nov 2011
Default

Gents,

Just installed an OEM fan clutch. It solved the problem. I can get the RPMs up to 4000 (3000RPMs used to vibrate the drive train) with no vibration. The new fan clutch is smaller in diameter and has a shorter shaft. I threw the old clutch in the scrap metal container.

Thanks for everyone's advice!!
TomAur is offline   Reply With Quote
Old 11-26-2011, 09:25 PM   #17
7t2vette
King Of The Shyte Wolves!
Toronto Events Coordinator
Support Corvetteforum!
 
7t2vette's Avatar
 
Member Since: Oct 2000
Location: Toronto
Default

Glad you got it figured out! A relatively easy fix too!
7t2vette is offline   Reply With Quote
Old 11-26-2011, 09:25 PM
 
Go Back   Corvette Forum > C3 Corvettes, 1968 - 1982 > C3 Tech/Performance
Reload this Page Water Pump
 
 
 
Reply

Tags
34, 68, corvette, hole, pilot, pulley, pump, size, water


Thread Tools Search this Thread
Search this Thread:

Click for Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump


All times are GMT -4. The time now is 04:59 AM.


Emails & Password Backup

Search Engine Friendly URLs by vBSEO 3.5.2