: Changing That Water Pump Belt

08-12-04, 01:05 PM
I pose this question to the Northstar engine experts. I am working on my sister's 98 STS tomorrow, and I want to change all the belts...including the water pump belt. How complicated is it to change? As one of the previous posters said, that water pump belt doesn't owe us a thing after it has been in place for a long while. This car has 83,000 miles, but is running very rough.

So all the tune up parts will be changed first, and then the DEX-Cool will be done. Then clean the throttle body and run injector cleaner through the system, and change the fuel filter.

I would attempt the water pump belt if I knew it wasn't going to take all day, or I would mess up something.

I appreciate any help anyone could give me.


08-12-04, 03:23 PM
The water pump drive belt is very very easy to replace. Just remove the little guard that is covering it, release the tensioner that is on the belt and slip the belt off the cam pulley. Twist the belt between your fingers and it will slid out between the water pump pulley and the adjacent casting if it is on edge. Slip the new one in the same way and away you go. Lube the tensioner pivot to make sure it is working freely and exercise it a little before installing the belt to make sure it is free and not binding on rust or something.

If you are doing the major serpentine accessory belt (desireable if the miles are high) then make yourself a tool out of a piece of 3/8 tubing about 2 feet long. Bend a 2 inch "L" on one end to use as a third hand to manipulate the belt into position down in the recess where your hands can't fit. Makes all the difference in the world. You can also work thru the right front wheel well as the crank damper is readily visible behind the wheel well splash shields behind the tire/wheel.

08-12-04, 05:41 PM
You are a veritable wealth of Cadillac knowledge, and I salute you, sir. It is nice to talk to folks who have experience on things. I have been tinkering with all sorts of mechanical, electrical, hydraulic and air conditioning since my Marine Corps days. Did 22 years in there, and now make a living as a Technical Representative for the same equipment for the Navy here in San Diego.

This will be my first experience working on the Northstar, but I am UP for the job. Just being careful to get good parts..(factory wires, plugs, filters ect). I am suprised that the transmission doesn't have synthetic fluid in it. I will go back with either Dexron III or Mercon. 83,000 miles on the same fluid is unheard of, even in the other cars I have..(2000 VW beetle, 1997 Ford Explorer, 2003 Hyundai Elantra GT, and 1999 Lexus GS-400.) All of these fluids have already been changed. Is the transmission pan gasket reuseable like many cars are, or should I get a new gasket from Cadillac?

Thanks again for your prompt help, and look forward to talking to you again on these pages. I take all suggestions in stride, so go ahead and share your vast knowledge. I definitely appreciate it.



08-12-04, 09:48 PM
I would grab a new trans pan gasket.

The Dex 3 / Dex 4 fluid can easily go 100K or further. The newer Dextron fluids have a high synthetic content anyway so no substitutes are needed.

Look for Texaco Dextron fluid as Texaco is the OEM supplier of trans fluid for most of GM.

About the only enemy of trans fluid is heat and modern automatic transmissions are adequately designed with adequate cooling to avoid overtemping the fluid in all but the most strenuous situations.....such as towing heavy trailers or livery service.

Transmission fluid is not exposed to the by products of combustion in blowby as engine oil is so contamination and dilution of the trans fluid just doesn't happen. Engine oil needs to be changed due to contamination primarily but this is not the case with automatic trans fluid.

If you are changing the fluid in a 4T80E remember to remove the "hidden" drain plug that is underneath the bottom pan that will drain the oil stored in the side cover to effect a complete oil replacement.

09-12-04, 04:11 PM
It appears to be an easy job to replace the water pump belt, but I am stumped on one thing. I have been able to get the belt off of the pulleys, but how do I remove the belt, specifically, how do I get the belt around the idler pulley assembly? A valve cover bolt appears to be so close to the idler assembly that there is no room for it to fit between there.

Should I remove the idler pulley to make this easier? Thanks for any assistance. I do all of my own maintentance on all of my cars (I have 5 different GM's), so I hope to one day be able to be a contributor rather than an "asker" on this forum.

BTW, my new ride is a 98 STS. It is the most awesome car that I have ever owned and I am spoiled now. Having moved up the GM progression from Pontiac to Oldsmobile to Cadillac, I am afraid that I am now spoiled. I will never drive anything but Cadillacs from now on.

Thanks again for any help that you can provide!!!!

John E. Dawson
98 STS
93 Pontiac Trans Am
93 Olds Cutlass Supreme SL
87 Pontiac Fiero GT (dead, but for sale)

09-12-04, 09:57 PM
I did end up taking off the idler pulley. That was a much smaller task than I had thought it would be. Now I have a new Serpentine and water pump belt. All I need to do now is the coolant change.

Everybody have a great day!

John E. Dawson

09-12-04, 10:26 PM
Make sure you lube the pivot of the small water pump belt tensioner so that it moves freely and doesn't seize up eventually due to corrosion...