: Could it be the Water Pump Knocking



RICOMRD
01-23-08, 04:19 PM
Well, at last I found a nice diamond white STS a 1997 model, which I must confess, I am totally fascinated with the car. I purchased the car with 80K miles from the first owner. Lately I have noticed a light knock, but this light knock is only perceptible when the engine has reached operating temperature and is at idle speed. Once the engine is accelerated, the light knock is no longer audible. The engine performs flawlessly except for the light knock at idle speed when warm. I have tried to locate the source with a stethoscope and established that the noise is stronger around the water pump area. Before I tear into the engine, I wanted to read about your experiences and recommendations in reference to this subject. Is it possible that a water pump in its beginning stages of failure manifest itself by a light knock? Is there a way I can test and confirm the noise originates from the water pump?

The engine does not experience overheating temperatures, I have searched for codes, and there is none present in the system. Any suggestions?

JimD
01-23-08, 04:40 PM
.... Is there a way I can test and confirm the noise originates from the water pump?
You could remove the tensioner pressure on the water pump drive belt and see if the noise level changes.

Or completely remove the water pump drive belt and see if the noise goes away.

Ranger
01-23-08, 05:34 PM
Then spin the water pump tensioner pulley by hand to check for any roughness. Might be a bad tensioner bearing.

tateos
01-23-08, 07:56 PM
Carbon knock maybe?

Ranger
01-23-08, 09:47 PM
I don't think so Tateos. He says "It is only perceptible when the engine has reached operating temperature". Cold carbon rap usually goes away after about a minute.

RICOMRD
01-23-08, 11:23 PM
The situation with this knock is puzzling me. But I will follow the lead in reference to isolating the water pump by dismounting the water pump drive belt. This will definitely be a hot affair, for this will have to be done after the engine has reached operating temperature, but I guess will be the logical path to clarifying if the knock is originating from the water pump. I will keep you posted. Maybe we are on to something that might help fellow Cadillac owners. Whish me luck!!!

Ranger
01-24-08, 12:03 PM
Keep in mind that you do not have to "dismount" the belt. Just use a 1/4" drive breaker bar in the square hole in the tensioner as a lever and move it just enough so that the belt starts to slip. If the noise goes away, you have located the source of the noise. Most likely the tensioner bearing.

Chasespeed
06-30-08, 12:17 AM
Okay, I just did this test. Noise goes away when tension is removed.

Problems. I drove from Corpus Christi, TX, to Western Massachusetts......

I did bring tools with me....and, if I can just replace the pulley, great....

NOW, I did search, and look, etc,

Can I just get the pulley and bearing? If so, where? and how much.

I am hoping to deal with this before it becomes a major issue...

Thanks for the help.....

Chase

AJxtcman
06-30-08, 09:33 AM
I have seem a few W-pumps making strange knocking noises. Even on an 06 DTS. Hmmmmmmm you don't want to change a W-pump on an 06+

jeffrsmith
06-30-08, 05:50 PM
I just bought the pulley from my local parts store - it was ~$30.00.

Gates part # 38025

tateos
06-30-08, 07:30 PM
Chase - Western MA is nice this time of year, huh? I am originally from the Boston area - live in Phoenix now.

So is the noise coming from the tensioner pulley bearing? It sounds like that is what you think, but couldn't it be the water pump? In any event, it seems like you can live with it until you get back to TX, no? I mean, it's just a light knock, and only at idle, and only when hot, right?

Chasespeed
06-30-08, 09:25 PM
Cool. I will probably replace the pulley, and, since I can smell coolant now....and, I am getting a puddle, no leaks at hoses, radiator, or tank....

I dont need the whole housing right? Just the pump?

Chase

jeffrsmith
06-30-08, 09:32 PM
You should be able to get by with just the pump - but while you got it apart you may want to replace the t-stat as well. Don't forget you will need a waterpump socket to get the old one out and the new one in.

Chasespeed
07-01-08, 12:47 AM
Someone care to enlighten me on this "water pump socket"?

I AM losing coolant, left a puddle at the funeral home this evening. I am going to top off the coolant res, and hope for the best tomorrow(funeral procession is about 3 miles).

I brought a good amount of my tools, but, I dont know anything about this socket....

Probably gonna replace that tensioner pulley while I am in there for good measure.

And yes Tateos, Mass is great this time of year.... better than sweating my arse off 9 months out of the year like in Corpus.... just hope I can get this handled in time to get back to work...


Chase

Submariner409
07-01-08, 10:34 AM
The water pump is a capsule held in by tangs. It takes a special socket and a big breaker bar to rotate the capsule clockwise just over 1/4 turn to remove it. A cheap socket is available for around $25 from some of the big parts houses, the preferred GM unit is around $80. Replace the entire tensioner and belt.....www.rockauto.com, or Lindsay Cadillac, over there ---->, Parts, Luke.

Chasespeed
07-01-08, 03:39 PM
Well, the stuff was available locally. Except the socket, which will be here tomorrow. I am not gonna do the tensioner right now, I need to get it fixed to drive the 2100 miles home in a couple days. I have a new pump(not reman), new pulley and bearing, new belt, and a belt.

I dont suppose anyone has a diagram of how this pump and or housing comes out, or, at least torque specs...

Thanks,
Chase

Submariner409
07-01-08, 05:41 PM
You drain the cooling system and remove enough interference to get the socket on the pump capsule and, forcefully holding the socket against the pump, turn the pump clockwise toward the firewall about 1/8 turn or so. The pump capsule and O-ring will loosen and may be pulled out. Clean the cavity and O-ring seat, lube the new O-ring with a dab of oil or petroleum jelly and reverse the removal procedure. Install the tensioner and belt the same as before removal but leave the belt guard off.

Refill as much coolant as possible, to about halfway up the tank, and start the car with the cap off. The purge (3/8" upper line) line should spit coolant and bubbles while the coolant level drops. Maintain the level at halfway. When the bubbling stops and there's a fairly solid stream of coolant from the purge line, install the cap, watch the belt to make sure that looks OK, and go for a 20 minute drive. Shut down, let the system cool to below warm, and check the coolant level; refill to halfway up the tank. Look around the new pump for leaks. OK? Install the belt guard. Good to go. (Insurance/peace of mind: Mix any coolant left into the 1 or 2 jugs and put it in the trunk for the trip home; you won't need it.......:thumbsup:.)

tateos
07-01-08, 06:18 PM
The leak in that area could be coming from:

1. where the housing cover meets the housing, which is part of the coolant crossover

2. from the pump itself,

3.from where the pump meets the housing,

4. from where the thermostat meets the housing,

5. from where the coolant crossover meets the block or heads.

Troubleshoot before you start replacing parts. Lot's of places to look. Make sure the leak is coming from the weep hole on the pump before you condemn it. I have had leaks from ALL of the above at different times on my Northstar over the last 11+ years

Turn the water pump tool clockwise just until the water pump releases - I don't think it is more than a 12th of a turn. You will need a long breaker bar to break the water pump loose - maybe with a pipe on it for extra leverage. I can't remember the install torque - tighten to maybe around 70 ft pounds - somebody correct me here please?


Cool. I will probably replace the pulley, and, since I can smell coolant now....and, I am getting a puddle, no leaks at hoses, radiator, or tank....

I dont need the whole housing right? Just the pump?

Chase

Ranger
07-01-08, 06:38 PM
I dont suppose anyone has a diagram of how this pump and or housing comes out, or, at least torque specs...
There are no torque specs. It is not threaded in. It's cam locked. Less than 1/8 turn is all it takes. Then the impeller "cartridge" comes out.

Chasespeed
07-01-08, 10:24 PM
The leak in that area could be coming from:

1. where the housing cover meets the housing, which is part of the coolant crossover

2. from the pump itself,

3.from where the pump meets the housing,

4. from where the thermostat meets the housing,

5. from where the coolant crossover meets the block or heads.



Well, this is what I do know.

I heard the knocking sound, also started to notice the smell of coolant...

checked, coming from pump side of engine...

Remove tension, knock stops.

I will double check all this stuff in some daylight if it stops raining. Do I have to remove any guards or anything to check these things. I have this car all of 2 weeks, and havent had a chance to find a manual for it...

Chase

Ranger
07-01-08, 11:04 PM
Yes, you'll have to remove the belt shroud. Then spin the pulley's by hand and feel for a rough spot in the bearings.

Chasespeed
07-02-08, 07:15 PM
Well, all done. The old pump had alot of side to side play.... No more leaks.

Job wasnt too bad...

Took photos, I could throw a write up together if anyone wants.... pretty simple... but, with the pics, those without a manual could do it pretty easily.

Thanks for the help gents...

Chase

todderdodder1
06-02-10, 12:13 AM
so did the noise go away with replacing the water pump? i believe i have the same noise on my 01 Aurora with 148,000..

Submariner409
06-02-10, 11:03 AM
This thread is 2 years old, and Chasespeed hasn't logged in for a long time.