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engine howl


mike5514

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My 97 sls has a noise That i cant locate I have changed the idle pully,tensioner pulley and alternator pulley, disconnected water pump belt sound remains. It gets louder when engine revs up. Im now thinking it might be the camshaft chain its hard to tell but it sounds like its coming from the front bank. I thought that i had read on this forum a timing chain adjustment. I searched but could not find the article can you gentlemen help. Mike

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It could be an alternator bearing. However, I suggest that you find the problem for sure before you spend any more money on it.

I suggest an inexpensive baby monitor or similar wireless microphone. If it doesn't work over the FM band and has a receiver, make sure it's battery powered or can be powered from your car. If the receiver is a karaoke unit with a microphone jack, use a Walkman or MP3 player to listen to it. Tape the baby unit (microphone) to different parts of the engine compartment, avoiding the exhaust manifold of course, and listen to the monitor while you drive the car. By moving the microphone around, you can determine where the noise is coming from and tape it right to the offending unit to nail the problem cold.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Thanks jim I have changed the alt bearing I meant to type alternator bearing and not pulley. I have used the stick/ear method on the engine while it was running and placed it at suspected locations while reving the engine. All the items i replaced seemed noisy and because the car has 136000 mi on it I thought it was

time to replace them also I installed new brushes while I had the alt apart. The power steering pump appears to sound as noisy as a normal pump? I then removed the water pump belt and that eliminated the water pump and its tensioner assy. I replaced that bearing for preventive maintenance. Listening to the rocker covers It sounds very noisy on the water pump side. I ck the transmission fluid it was good. And you are correct no more replacing parts. The noise is hard to pick up at idle but does increase at engine speed. Its a whine/howl Now im thinking camshaft chains or transmission It might be time to take it to a shop for troubleshooting. Mike

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The cam chains are on the front of the Northstar, which is the passenger side -- opposite the water pump side. I've never heard of a cam chain being noisy on a Northstar. If you're sure the sound is coming from the front bank, driver's side, the only thing there is the water pump.

You say that you ran the engine without the water pump??? If you did do that, and the noise was still there, I would start looking at the transmission. You can locate sounds there with a long extension and a practiced ear, too.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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How about the A/C clutch bearing. Release just enough tension on the tensioner while idling to let the serpentine belt slip. If the noise goes away, then you know it is on one of the accessories or pulleys on that belt. Then use a stethoscope to determine which one.

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There are two alternator bearings I had a bad front bearing near the pulley that was making a howl, changed it went away, which bearing did you replace?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Thanks all. Ranger I will try the tensioner test. Mike the bearing I changed was the same as yours. Jim that eliminates the cam chains, i will focus on the transmission. This noise is with the trans in park and in drive. I wont be able to get to it for a few days but I will get back to you. Merry Christmas Mike.

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I don't know enough about automatic transmissions in general or the 4T80E in particular to tell you from experience where the howl might be. From what I do know, there is a large chain between the torque converter shaft and the transmission mainshaft but that is not likely it. The torque converter has a sprag clutch and several other bearings that could cause it, but the most common whine problem in the torque converter is bubbles in the torque converter from having been run with low fluid, a bad pump or pickup, or a leak in a case gasket.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Thanks all. Ranger I will try the tensioner test. Mike the bearing I changed was the same as yours. Jim that eliminates the cam chains, i will focus on the transmission. This noise is with the trans in park and in drive. I wont be able to get to it for a few days but I will get back to you. Merry Christmas Mike.

Have you tried starting the engine with the serp belt off, to see if you still have the noise?

There are two thrust bearings, one on each of the chain sprocket gears, when I replaced my ISS sensor, I should have replaced mine, they make a high pitched whine.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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