: Solved by A Field Engineer!



cadillac04
07-12-04, 02:44 PM
I had originally answered as a follow-up to another post on another forum about an odd noise like a oooooooh singing sound at 2200 - 2800 rpms in any gear that could be heard coming through the instrument cluster. The sound made driving the car in any traffic horrible. No one else on this forum seemed to have the same problem as I was having or ever bothered to mention it. It could be heard over music on the radio. I thougnt that I would also post it here just in case someone also had the problem and now could go to their dealer with some info.I was very persistent to get this solved.:lildevil: I bought the car on March 31 and was at the dealership for the problem the first time April 7. It was resolved on June 11.
If anyone is wondering why I never heard the sound when I test drove the car, the sound occurs only when the engine is warm and only at 2200-2800 rpms in any gear. I drove the car on a highway and only for about 1.5 miles.
The problem has been fixed by a GM Field Engineer named :worship: Brett.
Although another post on that thread indicated that the sound was a harmonic from water flowing through the engine and there was NO fix possible, the FE worked to solve it.He worked with a tech from my dealership. The FE was in contact with other engineers at GM and after the sound transferer was found to be the heater core , many steps were taken to eliminate the response. The first suggestion was to remove the tubing that goes to the heater core from the front of the engine back to the firewall connection. Apparently the GM engineers felt that the aluminum tube was restrictive and the place where another pipe was welded on was attached , the attached piece extended too far into the space and water flowing passed it set up a noise. So the aluminum piece was reamed out to open it more and the slight extension of the affixed pipe was ground away to make it a smooth pipe. After which the rubber hoses were re-attached to the firewall , the pipe reclamped in place, and the last set of hoses were attached to the water pump.(Long and tedious process of almost 3 hours start to finish.......drain coolant, remove shroud, clamps, remove battery , etc.:bonkers: ) The fix didn't work!
Finally the FE tried just to lengthen the hose that comes from the water pump and connects to the aluminum pipe. I think he figured that the loop in the hose might change the harmonic.He had the tech, Matt replace the test hose with regular black heater hose the following week. Although there is a slight crimp in the hose, the fix works. I am still testing the fix and will wait til fall to see if the crimp in the hose will affect getting heat inside the car in cold weather. I waited to post this because I really wanted to be sure that the sound was gone. I really is!:) The harmonic sound from the engine is probably still there but is not being transfered to anything else that sends a noise that can be heard.Possibly there will be a bulletin on this problem so that other dealers can solve the problem if it ever comes up.
I have finally been able to 'bond' with this car. I have had no other problems, like wheel hop, or the "clunking" as others have mentioned so I guess that this was mine to be solved and fixed. I am very grateful to my Dealer in Fleetwood, their Service Manager Ron and Service Director Steven, Gm District Area Service Manager, Denise, GM and their Field Engineer,:worship: Brett, to help make me a very happy Cadillac CTS-V owner!!!!!!:)

CadV
07-12-04, 04:05 PM
Finally the FE tried just to lengthen the hose that comes from the water pump and connects to the aluminum pipe. I think he figured that the loop in the hose might change the harmonic.He had the tech, Matt replace the test hose with regular black heater hose the following week. Although there is a slight crimp in the hose, the fix works. I am still testing the fix and will wait til fall to see if the crimp in the hose will affect getting heat inside the car in cold weather.
Is this something we can do ourselves? Can you take pictures of the hose you are talking about? Would this be something we could just remove the hose and switch it out or is there fluid always in it? This happens to my car as well.

Cliff

cadillac04
07-12-04, 07:26 PM
Is this something we can do ourselves? Can you take pictures of the hose you are talking about? Would this be something we could just remove the hose and switch it out or is there fluid always in it? This happens to my car as well.

CliffIt isn't easy to get a picture of this hose because of all of the other hoses, etc, in the way.Yes, you have to drain the coolant before attempting and I am not sure of the length of the new hose that was used. I do remember that the tech was told how to route the hose to avoid it touching the exhaust manifold and that he had to route it downward then up.Have your service manager either call your Area Service Manager to get the info from the FE who did my fix. My Cadillac dealer is in Fleetwood, PA so they should be able to contact them directly and ask for Service Director, Steven. He should be able to get them to the FE. Make sure that your dealer does this and then the fix will be covered by warranty. I do remember that this was an 'unauthorized' fix because it was not approved by Michigan. But it works! I was also told that there are many Vs with this problem and not just mine. So I guess that maybe a more permanent fix will be on the way. More complaints are needed though.

Rich H
07-12-04, 11:40 PM
I have had the noise most of the time since ~200 miles. The noise seems to come from the instrument cluster although I thought it was more on the driver's side.

There are two rubber hoses routed from the water pump housing to separate aluminum tubes that run from this connection back to the firewall. The longest hose loops underneath and connects to the bottom tube. The shortest hose connects to the top tube. The aluminum tubes are held closely togethor at at least 2 support points. Two questions:

1) Which rubber hose was replaced?
2) Since you had the aluminum tubes removed and repositioned, are you sure that the original harmonics wasn't set up in the aluminum tubes? Seems possible the noise was transmitted through two sets of rubber hoses to the heater core but I would think a hard piped connection like the tubes could be the sounding board.

If this isn't clear I can take some photos. Although the hose to tube connection points are obscured, its easy to track the rubber hoses from the pump housing to the tubes.

cadillac04
07-13-04, 10:29 PM
[QUOTE=Rich H]I have had the noise most of the time since ~200 miles. The noise seems to come from the instrument cluster although I thought it was more on the driver's side.
Two questions:

1) Which rubber hose was replaced?
2) Since you had the aluminum tubes removed and repositioned, are you sure that the original harmonics wasn't set up in the aluminum tubes? Seems possible the noise was transmitted through two sets of rubber hoses to the heater core but I would think a hard piped connection like the tubes could be the sounding board.

[QUOTE]
#1 The hose from the water pump to the heater core.(not the return hose)
#2 The aluminum tubes are not involved in the harmonics as determined by trial and error. The harmonics are created in the water passages of the engine. Once the thermostat opens the harmonics travel through the coolant to the heater core which amplifies the sound. The tubes themselves are NOT the sounding board. The sound is transmitted by the coolant. The audible range is in the 2000-3000rpm range of the engine.
1. Source: engine Cannot alter:bouncy:
2. Path: hoses filled with coolant Length can be altered. As determined by field engineer:worship: Brett.
3. Responder: heater core Cannot alter:banghead:

Have your dealer make the change, because then it will be warrantied.

Rich H
07-13-04, 10:54 PM
Thanks, your analysis seems plausible. Sounds like your field engineer spent a lot of time on trial and error solutions. However, if Cadillac is not admitting that this is a problem yet, they may not try to correct it under warranty There is no affect on performance or durability - just nerves occasionally.

There could be two variables at work in the above alteration. Hose length and/or coolant flow rate to the heater core. Let us know if the crimp in the hose reduces your heater efficiency this winter.