Griding sound from 97 Deville

[saustin74]

Hi.  I just registered on this forum and searched for a similar issue to mine, but did not find it.  I have a 97 Deville with only 38k miles on it that I bought about a year ago from the original owner.  The car has been very well maintained and is in very good working order.  But I have been noticing a sort of grinding noise when it shifts into (I believe) 3rd gear.  It is a short, quick sound for maybe a second and the car still shifts smoothly.  Sounds similar, though less loud to when someone tries to start a car that is already running.  My fear is that it has something to do with the transmission, but have not found anyone with a similar issue.  I tend to hear it more when going up a hill than down.  Other than transmission, I thought it could have something to do with bearings that run from the belts.  I do hear it with A/C on or off, so that's not it.  But it feels like something that is getting slack from the change in engine torque from the shift, so that's why I thought some kind of bearing (maybe the radiator fan?).  Should I just take it to the dealer?  Wait to see if it gets worse/impacts performance?  I love this car and want to keep it in tip top shape. 

[BodybyFisher]

That way you describe it it sounds like a transmission problem but I have never hear of this type of noise coming from the 4T80E tranny. 

If you insist that it ONLY occurs on the shift into 3rd, it seems to be tranny, but if it occurs at other times, it could be the serp belt tensioner or idler wheel, alternator bearing, even engine mount related.   Its hard to diagnose here, have someone you trust drive it and listen to it and see if they can narrow it down.

[OldCadTech]

My question is are you counting the shift? 

If it is the 3rd shift it is 4th gear or TCC lock-up. May be a noisy TCC solenoid - just a guess - as BFF stated very hard to diagnose a noise without actually hearing it. Try an audio recording with your cell phone...

[saustin74]

Thanks guys.  I drove it a little further than my usual 10 mile commute today, around 50 miles one way.  I had the AC on at highway speed and noticed the temp was elevated, which is rare.  It hit 226 and I turned the AC off, which dropped it to 210-215, though that is still high for highway speed typically.  When I got to my destination, I idled for 2 minutes and saw smoke coming from under the hood.  I killed the engine and looked under the hood.  The smoke was either coming from the AC compressor or the crankshaft.  Hard for me to remember now, but looking at the diagram, it was one of the two.  Is this possibly the clutch on the compressor going out?  I doubt the crankshaft would have smoke coming out in this instance since I am assuming there is no clutch bearing on that.  Sounds like I need to have someone look at it.  My concern on that 50 miles home was that it would seize.  I didn't run the AC on the way home and it ran 197-203 degrees which is more typical.  My thought was maybe the AC is working harder if something is wrong and that drove the higher highway temp on the way there.  Really appreciate the help, and I will try to record the sound tomorrow, though the road/wind noise defn drowns it out quite a bit (it's that quiet).    

[rockfangd]

Welcome to Caddyinfo.

Sounds like your clutch is shot. Explains the noise too.

Does the AC work good?

[saustin74]

Thanks fockfangd.  I am leaning toward the clutch as well.  The AC does work pretty well outside of the blower fan being pretty noisy/vibration on the interior.  But there have been times when it took some time to blow cool air that have made me wonder.

I have it set to have the compressor looked at.  Preparing myself for a 4 digit potential hit, but I look at it from the perspective of I'm not making payments and got a decent deal on the car, paid cash.  With only 38k miles, my repair costs should be less than car payments.  Plus I love the car.

[BodybyFisher]

39 minutes ago, saustin74 said:

Thanks fockfangd.  I am leaning toward the clutch as well.  The AC does work pretty well outside of the blower fan being pretty noisy/vibration on the interior.  But there have been times when it took some time to blow cool air that have made me wonder.

I have it set to have the compressor looked at.  Preparing myself for a 4 digit potential hit, but I look at it from the perspective of I'm not making payments and got a decent deal on the car, paid cash.  With only 38k miles, my repair costs should be less than car payments.  Plus I love the car.

That is a good way to look at the repair.  No payments, I love the car. I had a friend who used to track his repairs after his warranty was expired, when the repairs became more than the payment for a new car, he bought a new car. 

I had a 96 Deville that had a clutch go bad, it squealed on engagement when it cycled.  

Keep in mind that you can always buy the parts and have the mechanic install them.  I would stick with an ac delco or delphi compressor.  

Check rockauto.com for good prices on parts, you may find a 5% discount on this board for parts for rockauto.

[saustin74]

39 minutes ago, BodybyFisher said:

That is a good way to look at the repair.  No payments, I love the car. I had a friend who used to track his repairs after his warranty was expired, when the repairs became more than the payment for a new car, he bought a new car. 

I had a 96 Deville that had a clutch go bad, it squealed on engagement when it cycled.  

Keep in mind that you can always buy the parts and have the mechanic install them.  I would stick with an ac delco or delphi compressor.  

Check rockauto.com for good prices on parts, you may find a 5% discount on this board for parts for rockauto.

Thanks for the reference.  I was going to bring it to the dealer which is by my office, but also trying the yourmechanic.com route.  Anyone have any experience with that service?  They guarantee their work for 12month/12k miles.  Has to be cheaper by a long shot than the dealership.

[saustin74]

So I took it to a local mechanic (not the dealer) and it was the compressor.  $900 repair bill :-(.  At least it wasn't the transmission.  Hoping I don't have anything this big to deal with again for a while.  Thanks to everyone for your help. 

[KHE]

I just noticed this thread.  It was most likely the clutch bearing.  That could have been replaced for far less than the cost of the compressor.

[BodybyFisher]

Glad you got it fixed and now have air.   Kevin (KHE) is right, but finding a mechanic that would do that job and having him warranty it would be the problem.  Most mechanics want to parts replace these days.  Kevin and I would fix the problem, mechanics want to drive up their profit by selling you a new compressor.  Its safer and easier for them to replace the unit rather than fix the hub bearing.  Repairing it takes more experience then replacing it.  Kevin is correct. 

I see the need for mechanics that specialize on Cadillac and Northstar every day.

[saustin74]

You guys are probably right.  That said, the compressor is 20 years old, so if I just had the bearing fixed, could end up being the compressor next year.  I plan to keep the car for a while, so I do feel good knowing that component should give me no more problems.  I live in the DC area, so if you know of anyone good on Cadillacs, I would definitely go there.  Thanks again.

[Cadillac Jim]

The Goodwrench warranty on a new A/C compressor is lifetime, or as long as you own the car, or was when I replaced mine on a 1997 ETC in 2005 or thereabouts.  I know because the next year, the clutch started slipping, and the dealer replaced the whole compressor free, including labor.  That said, the price of that warranty is included in the price of the compressor and installation.  And, rebuilding or adjusting the clutch is done at the dealer level by replacing the compressor/clutch assembly.

In general, it's hard to find someone who will rebuild an A/C clutch and warranty the job, and a compressor that old will intimidate a mechanic because leaks are common in A/C compressors in old cars that aren't driven much.  The failure mode seen in most GM A/C compressors of the types used in the 1990's is reed valve failure, with fragments passing into the accumulator/dryer, and possibly on to the condenser and, eventually, the expansion valve.  When mine went, I got codes and fixed it promptly, with only the compressor and accumulator/dryer needed replacing.

[KHE]

7 hours ago, Cadillac Jim said:

The Goodwrench warranty on a new A/C compressor is lifetime, or as long as you own the car, or was when I replaced mine on a 1997 ETC in 2005 or thereabouts.  I know because the next year, the clutch started slipping, and the dealer replaced the whole compressor free, including labor.  That said, the price of that warranty is included in the price of the compressor and installation.  And, rebuilding or adjusting the clutch is done at the dealer level by replacing the compressor/clutch assembly.

In general, it's hard to find someone who will rebuild an A/C clutch and warranty the job, and a compressor that old will intimidate a mechanic because leaks are common in A/C compressors in old cars that aren't driven much.  The failure mode seen in most GM A/C compressors of the types used in the 1990's is reed valve failure, with fragments passing into the accumulator/dryer, and possibly on to the condenser and, eventually, the expansion valve.  When mine went, I got codes and fixed it promptly, with only the compressor and accumulator/dryer needed replacing.

Actually, the most common failure in the 1990's era compressors (HR-6/HD-6) are case seal leaks.  The compressor ends are not painted (a cost savings measure) and the aluminum corrodes under the case O-rings and creates a leak.  Most shops will still replace the compressor when about $65.00 in seals will fix those compressors.  The GM shaft seal is $45.00 and an o-ring kit is $20.00.

Reed valve failures are not that common in those compressors.

[Cadillac Jim]

I was told at the time that the failure mode for compressors was usually the reed valves.  We didn't have a conversation about that, so your information, based on a number of cars, is better than my one-car experience and a comment by the service manager.

The service manager may have been talking about failure other than leak.  I was getting contradictory Freon pressure codes, and interpreting these it was apparent that the compressor wasn't compressing very much.  No leak, though.  The car had its first four years in the L.A. area and the next in the Philly area, it was driven every day, and the A/C was never off.