: Umm, Knocking motor at 125,000miles?



NorthernHillbilly
04-23-11, 02:51 PM
Anyone have any engine issues?
Here's my situation.
When the engine is cold, it sounds like it had rod knock under load... Which tells me it ISN'T rod knock, as it would knock only when the engine is UNloaded.

Once warmed up, the knock goes away...Sounds possibly like piston knock?

Is there carbon-ing issues with this motor? Or perhaps something with the Variable cam timing?
Oil filter examination reveals no particulate, or debris...

TexFinn
04-23-11, 09:15 PM
Piston slap. Quite rare for it to start after so many miles, but still.

evois
04-24-11, 09:19 AM
can you take a video?

hcvone
04-25-11, 01:15 PM
Anyone have any engine issues?
Here's my situation.
When the engine is cold, it sounds like it had rod knock under load... Which tells me it ISN'T rod knock, as it would knock only when the engine is UNloaded.

Once warmed up, the knock goes away...Sounds possibly like piston knock?

Is there carbon-ing issues with this motor? Or perhaps something with the Variable cam timing?
Oil filter examination reveals no particulate, or debris...

Ever have the fuel system pressure cleaned? Have seen it done of some high mileage engines and it really cleaned the carbon out. Have a friend and a customer with over 200k on their trucks, I believe they like me drop a bottle of Techron in their tank every 5k miles

RippyPartsDept
04-25-11, 01:29 PM
a bottle of techron in the gas every oil change is actually a good idea (especially if you're not using top tier gas)

hannity
04-26-11, 05:42 PM
Piston slap. Quite rare for it to start after so many miles, but still.

Cosign, maybe it was there before and he never noticed. But to make it that far w/o that noise is a miracle. Mine started doing it around 3500 miles. :( It would not be a problem for me, but I was told by 2 different service departments that it is normal for GM trucks.

Cadillac Cust Svc
04-27-11, 11:57 AM
NorthernHillbilly, this may not be something you want to hear but you may want to look into speaking with your dealership. They would be able to diagnose the vehicle for you and if you feel it is something that can be done by you or a friend then by all means but atleast you will have a starting point on what is wrong with the vehicle. Of course if it proves to be something that you aren't familiar with or are unable to do yourself they would also be able to fix the vehicle for you. Also if parts do get replaced you would have a 12 month 12,000 mile parts warranty on the replaced parts as well. I hope this and all the other suggestions help you.

Jeff Morris, Cadillac Customer Service

NorthernHillbilly
04-28-11, 07:31 PM
Well, I'd like to keep this rusted out, knocking turd on the road a bit longer...It does sound like piston though...


HCVONE - What is this pressure cleaning?
RippyPartsdept - What the heck is Techron?

I'm hesitant to take it in to the dealer (at $115/h), as I'm afraid they'll do the 'dis-assembly" method of diagnostics...And pull the heads and tell me what I already suspect...Then what?! I'm stuck with a lawn ornament...AND a $5,000 bill to get it back...(And honestly this has happened to me with a pick-up that had a bad miss, and a code...I didn't have time or ambition to look into it...I assumed they'd do a compression test and tell me what I suspected, but instead they pulled the intake, both heads, pan and one piston...to tell me I had a dead #3...)

larry3760
05-02-11, 12:33 AM
just bought a 07 ext 89k. when I start it up in the morning it knocks, actually it sounds pretty close to a diesel. changed oil to amsoil. nothing changed, after motor warms it does not knock anymore. No idea whats up.

TexFinn
05-02-11, 01:25 AM
just bought a 07 ext 89k. when I start it up in the morning it knocks, actually it sounds pretty close to a diesel. changed oil to amsoil. nothing changed, after motor warms it does not knock anymore. No idea whats up.

Just like OP: piston slap. Unfortunately.

It's here ans there's not much you can do about it... Other than buying a new engine, that is.

Punmax
05-02-11, 06:56 PM
Here's a video of my truck:


http://www.youtube.com/watch?v=o88urey-UDU

Piston slap. Dealer says it's normal.

NorthernHillbilly
05-02-11, 10:40 PM
Mine only does it under load...:( I can rev it like that freely and it's silent...pop her in gear and attempt to accelerate...Knock Knock Knock...

Cadillac Cust Svc
05-10-11, 01:02 PM
just bought a 07 ext 89k. when I start it up in the morning it knocks, actually it sounds pretty close to a diesel. changed oil to amsoil. nothing changed, after motor warms it does not knock anymore. No idea whats up.

Hello larry3760, have you spoken with our Customer Assistance team to see what we can do to assist you with this issue? Thank you fro your time.

Jeff Morris, Cadillac Customer Service

NorthernHillbilly
03-07-12, 07:59 PM
I've heard from a friend with the LS3 Camaro, 60000 on her, and she's banging cold, and a friend of the g/f has a Trailblazer SS, doing it too...Guess it's an LS thing...

Tec80
03-08-12, 03:12 AM
Still making the noise with the same intensity, or worse now after 1 year?

emseedee
03-15-12, 05:09 PM
I just took mine in for state inspection today. Inspector very nice and helpful. They weren't too busy so he took his time. He rolled it in the garge and his first comment was "sounds a little noisey under the hood." So, he pops the hood (not needed for state inspection) and we look at the belts. His first thought was a water pump or pulley. We looked down and saw the tensioner pulley (all the way at the bottom) jumping a little bit. I am going to see if I can tighten it up or possibly replace. Then I may have to look at pulley allignments.

Just another idea to check real fast.

Mr Monte
03-15-12, 05:44 PM
I've heard from a friend with the LS3 Camaro, 60000 on her, and she's banging cold, and a friend of the g/f has a Trailblazer SS, doing it too...Guess it's an LS thing...

My Son's LS1 is his Camaro SS is bad when cold with 88K of very hard miles. My 07 Escalade with 86K only does it when cold. My 99 Suburban with it's fully forged 6" rod 383 stroker is really bad when cold. If it still knocks when warm then I'ld be concerned.

Playdrv4me
03-15-12, 08:41 PM
The general rule with piston slap/cold carbon knock is that it should be most audible during the first 30 seconds to few minutes after startup. If the knock continues after the engine is at full operating temperature, there is a more severe problem. Even still, most of these Escalades have a little bit of tap tap when warm. If you hear it clearly from several feet away *when at operating temp* it's more serious.

quattrotman
03-16-12, 12:11 AM
Check your exhaust manifold for leaks/broken bolts. It will make a diesel-like sound on start up and go away when warm just like piston slap. I know because I had this issue. Truck sounded horrible and I brought it in...sure enough on stud had broken off and there was a small leak. After it was fixed it sounded like a new truck again.

Afox70
03-17-14, 11:19 AM
just bought a 07 ext 89k. when I start it up in the morning it knocks, actually it sounds pretty close to a diesel. changed oil to amsoil. nothing changed, after motor warms it does not knock anymore. No idea whats up.



My 07 Ext does the same thing. It did it at 40k miles and the dealership had to do a complete valve job. The noise went away but is now back at 116k. So frustrating and can't put 4k into this truck now because of a divorce. Just going to keep driving it until it strands me. If I have the radio loud enough I don't hear it.