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Cadillac DTS 2001
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Discussion Starter #1
Hi, hopefully someone can send some advise my way.
what happend: knock at acceleration.
In parking lot, leaving a spot and heard loud knocking noise. thought the car needed oil, (even though the dash didn't call for it) put in oil, same noise.

2001 DTS, 97,000 miles, regular gas (always), Mobile 1 (always), no codes, no engine light. Had coil and plugs changed past summer. FIRST time hearing this noise today. does not loose power while driving. Carbon buildup???? do open throttle once in a while.

any suggestions??

thanks,
Kim
 

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White Diamond '03 DHS (with DTS floor shift)
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One loud knock or constant knocking? Does it get quieter? Does it ever go away? Do you hear it at idle?
 

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Cadillac DTS 2001
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Discussion Starter #3
HI,
WHEN IT IS FIRST STARTED UP AT CRANK (2 TO THREE SECONDS) YOU HEAR IT, THEN IT GOES AWAY, BUT AS YOU GIVE IT GAS ITS THERE AGAIN. IT SOUND LIKE WHEN YOU PUT CARDS IN THE SPOKE OF A WHEEL AND GIVE IT A GOOD WHIRL. lOUD AND CONSISTANT TILL YOU LET OFF THE GAS. WE DID AN OIL/FILTER CHANGE THINKING IT MAY BE A CLOGGED FILTER..... NOT THE CASE.
IT IS NOT CONSTANT THROUGH THE WHOLE RIDE. JUST WHEN GAS IS GIVEN. NOT AT IDLE. ???

KIM
 

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White Diamond '03 DHS (with DTS floor shift)
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Turn off the CAPS LOCK.

Sounds a little lick cold carbon rap. That generally goes away after the cylinders get warmed up. When was the last time you gave it any WOT?
 

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Cadillac DTS 2001
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Discussion Starter #5
Hi,
WOT yesterday after problem started.
the sound gave no indication or warning. Just happend all of a sudden. It has us baffled
& majorly discouraged at this point.
By the way, it's 92,000, not 97,000 miles.


thanks!
Kim
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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Is the sound speed or RPM related?

Get a stethoscope or a piece of rubber hose and listen around. Does it sound like it's coming from the cam cover? That would be more of a tick tick. A hard loud knock sounds more like lower end (rod knock), but that is almost unheard of. Also CAREFULLY listen around the pulleys. Could be a bad pulley bearing.
 

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Cadillac DTS 2001
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Discussion Starter #7
thanks,
I'll relay your info to my husband and we'll let you know what happends.


kim
 

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Cadillac DTS 2001
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Discussion Starter #8
4.9L Northstar rod knock. Need help!

Hello,
We posted over the weekend with a problem with the engine. a VERY loud noise coming from the engine when we accelerate. Not a tapping, a loud knock. almost like when kids put playing cards in their spokes. Continuous noise until the gas is released.
Just wondering how hard is it to determine what cylender has the problem. To get at this problem would the oil pan need to just be removed OR the whole engine???
Sound/problem gave us no indication there was a problem even begining, it just happend. Started the car up from a parking space and there it was.
ANY advice would be most helpful. trying to figure out if it something that we can do; husband is machanically inclinded.

Thanks!!
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Re: 4.9L Northstar rod knock. Need help!

There's a chance that this is actually a stuck EGR (Exhaust Gas Recirculation) valve. That piece of emissions equipment routes some exhaust gas back into the intake manifold in order to slow down the flame travel in the cylinders by diluting the fuel/air charge. If the EGR valve sticks open or partially so it causes a nasty spark knock under acceleration only which can sound as you describe. The valve itself is bolted to the intake manifold, has a pipe which comes from an exhaust manifold, and an operating mechanism which is either electric or vacuum controlled. Check, or have someone check, that system before you assume a rod knock, which is engine overhaul time.......

Update your User Profile with your car, model, engine, and year. It makes diagnosis easier.........
 

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1997 Seville STS, 2000 Seville STS
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Re: 4.9L Northstar rod knock. Need help!

If its really a rod knock, you can pull the spark plug wires one at a time. When you pull the wire on the cylinder with the bad bearing the knocking noise will decrease or disappear.
 

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Cadillac DTS 2001
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Discussion Starter #11
Re: 4.9L Northstar rod knock. Need help!

Hi,
my car is a 2001 DTS, 92,000 miles, regular oil changes with Mobil 1, engine 4.9 32 valve Northstar.
 

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White Diamond '03 DHS (with DTS floor shift)
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Re: 4.9L Northstar rod knock. Need help!

OK, wait a minute. First off, a rod knock does not just appear out of the blue on the next start up. I think we can rule that out. Right guys?

Secondly, you have a 4.6 (Northstar). The 4.9 was its predecessor and was a conventional single cam overhead valve engine.

Thirdly, PLEASE do not start new threads. It makes it very hard to follow. I'll merge this one.
 

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Discussion Starter #13
Sorry about the threads being all over the place, & thanks for grouping me together( kinda new at this).

Anyway! about the 4.9 engine, hmmm, that's what our hood says. did buy the car "almost" new, makes me wonder now! Husband knows we have a twin cam.
Thanks for the glimmer of hope thinking it may be a stuck ERG valve. Much better than a comlpete overhaul. We'll check on that tomorrow.
Like i said, out of the blue, only when gas is given and first at start up for those 2/3 seconds, AND yesterday when he started it up and drove it up and around the driveway it didn't make a sound till he was almost ready to park it.
Does an ERG valve un-stick itself?? and how does it get stuck in the first place?? Easy job? Hard job?

thanks guys!

Kim
 

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White Diamond '03 DHS (with DTS floor shift)
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OK P, if it is an '01, there is no way it is a 4.9. They where not even made after '96 I think. Not sure what you are looking at there.

No, the EGR will not unstick itself. It is a little bit of a PITA as the fuel rail is somewhat in the way and has to be lifted. That said, it's a lot easier than dropping the drivetrain. There is a tutorial in the Tech Tips section. The pintle valve gets carboned up and sticks open or closed, it should set a DTC if it is not operating properly.

I can assure you that it is not a rod knock. A rod knock will not go away after 2-3 seconds. That sounds more and more like cold carbon rap to me. Have you ruled out pulley bearings, tensioners, belts etc.?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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If your car is a 2001, there's no way the engine is a 4.9.

EGR routes plain ol' exhaust gas back to the intake system. The EGR valve is susceptible to all sorts of nasty gunk and contamination from oil sludge and carbon buildup. If the car is well-used (not granny-driven) the EGR may never give a hiccup. Not saying that this is your problem, but it's the vastly easier and cheaper first step in an engine noise diagnosis.

Spend $20 or $45 to subscribe your car to www.alldatadiy.com for 1 or 3 years. In addition to the GM shop manuals you get every sort of diagnostic, recall, part, labor rate, electrical, who-knows-what info you can ever use, all right there in your keyboard.


AND, keying on Ranger's post, read the entire Cadillac Technical Archive up ^^^ in the black bar. Note the article "Occasional full-throttle is good for your engine".
 

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Discussion Starter #16
Your correct. It's a 4.6. (can we attribute it to dyslexia??)

Doing the ERG valve now. let you know what happens!!
 

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Discussion Starter #17
OK!! We have the EGR off. IF you shake it, should it make a noise, clicking/clanking??? As if you would shake a liquor jigger. well, ours makes a clicking noise, VERY similar to what we are hearing when the engine is on and gas is given. would cleaning it only take care of that problem??????

wiat to hear from you. Thanks!!

ps...a couple times when we pressed down on the spring loaded area, it did stick, other times, not.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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The EGR valve should make no noise when shaken: that pintle works against a diaphragm and strong spring. Vacuum/electric signal pulls it open with the tapered pintle metering more or less exhaust gas into the intake manifold. As load comes off the engine, the opening signal decreases and spring pressure closes the pintle (tapered valve seat) Very uncommon, but the spring may be broken. If the pintle sticks, then you have heavy spark knock on acceleration.

www.rockauto.com, Luke in parts at Lindsay Cadillac over there --------->
or www.gmpartsdirect.com
 

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White Diamond '03 DHS (with DTS floor shift)
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I think Sub is right, but I think he will agree that EGRs are pretty reliable and I would not hesitate to get one from a junk yard, clean it up and use it. Probably would be a LOT cheaper.
 

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Discussion Starter #20
Bad news, looks like engine needs to be replaced.

I've posted my dealings already with the knock in the 4.6L. By chance other forum members (which we fully appreciate) thought it may have been the EGR valve. We cleaned that, put back in, and that was not the problem. It appeared to be in working condition, and noisy, but it wasn't stuck anymore. No codes are being given...we are stuck on this problem.
How hard it it to change this motor over??? Don't know what else to do. The sound is coming from the inside middle, lower half of the motor. The sound comes when gas is given. we are pretty much discouraged at this point.
some statistics: DTS, 92,000 miles. DID get low on oil pressure at one point several moths ago, no problem since then. No engine light, no codes.

suggestions??
Thanks.
 
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