2007 cadillac dts 4.6 y

[MAC]

I went out to grab some lunch the other day and was approached by a woman who wanted to know how I like my STS. I said I liked the it and enjoy driving it. She said she owned a 2007 STS-V8 but parted with it after the timing chain broke. I told here that it would be very rare for a Northstar timing chain to break since it's steel. She claimed it's a common problem. I told her that I have never heard of any such problem.

My question is has anyone heard anything about Northstar timing chains breaking on 2005 and newer models? I don't recall any such problem on earlier models either.

[JimD]

This is the first time in more than seven years lurking here and cadillacforums.com that anyone has even suggested that a chain "might" break. Even the folks who propagate second and third hand "wisdom" regarding Northstar head gaskets don't speak ill of the timing chains.

Common problem indeed!

[Texas Jim]

I have "NEVER" heard of a N* timing chain breaking.

Of course I have only had N*'s for 5 years...so there may be something I am not aware of.

But in my 4 years on this forum, I don't recall ever hearing of one breaking.

[BodybyFisher]

The guru said the timing chains were bullet proof and good for the life of the engine, I have not heard of any timing chain issues on the NS only the CTS

[adallak]

The guru said the timing chains were bullet proof and good for the life of the engine, I have not heard of any timing chain issues on the NS only the CTS

I remember the guru saying that too. He also mentioned that unlike Northstar, the engines in Benzes and BMWs needed replacement of timing chains at 100.000 km.

[Ranger]

Ditto on all of the above.

[Cadillac Jim]

I have never heard of an internal steel timing chain breaking on anything in normal use and reasonable mileage. Admittedly I don't have a lot of experience in European exotics and short-lived non-imported cars, but this includes American V8's (all of them that use timing chains, e.g. GM since 1949, Chrysler since 1951, Ford since 1954), the Quad 4 and Quad OHC series, The Northstars, etc.

Either this woman or her informers confused one of the V6's with the Northstar or there is something serious going on, down in the noise, like more FUD about American cars.

[winterset]

Dealership owner was probably behind on a few boat payments & screwed her over.

[Kris Poland]

Hi I got cadillac SRX with LH2 4,6 engine, and chain is not broken but, screws from timing idler sprocket fall of and chain fsll out too. As i see I'm te first :(((((.

Next post I send pictures.

I wonder what now, what shud I fix more than timming??

Kris form Poland

Sorry form my English mistakes.

 

[Bruce Nunnally]

Welcome Kris.  I understand your question as for your LH2 4.6L V8, the timing idler sprocket screw loosened, the timing idler sprocket fell off, and the timing chain fell off.

Now you need to replace the idler sprocket and the timing chain.   What other items should Kris replace at the same time?

[Kris Poland]

Thanks for fast answer, 

Im afraid that valves could hit the pistons. IS IT passible in this engine?

 

[KHE]

It is very likely that some of the valves are bent if the chain fell off.  Very unusual failure.

[Cadillac Jim]

All modern engines are interference engines, and if a valve is standing fully open and the engine is turned, the piston will hit that valve.  If the engine has not been turned, it is probably OK.  The starter is strong enough to damage the engine if a valve is standing open.

If the engine was apart and not running when the problem occurred, you may be OK.  If it was running when the timing failure occurred, then, as KHE says, you will have damage.

As KHE says, this is a "very unusual failure."

[BodybyFisher]

In photos show us what sprocket you are talking about.  

Are you talking about the intermediate chain sprocket, shown here?

If you remove a head you will need to repair/restore the head bolt threads in the block.  Do not reassemble the engine without repairing the bolt threads by timeserting the bolt threads and replacing the bolts, head gaskets, etc

[Kris Poland]

Yes, behind that Sprocket are 3 bolts, correct was. For few howers I sed Pictures. I havent photos on mobile. 

[Kris Poland]

Under is pictures I got before I take this to pieces.

[Kris Poland]

[Kris Poland]

[Kris Poland]

Unfortunately, the failure happend during ride when engine running. 

[Cadillac Jim]

Perhaps a used engine from a recycling yard is available?

[Logan]

I don't know on Northstars...but on some engines...only the intake valves get damaged since they are the larger valve.

A full set of new Northstar valves can (intake and exhaust) be found for under $100US. 

I did see a picture on Google of what the gear is suppose to look like.

 

 

 

[Logan]

What to expect inside. Bent valves. Saturn V6 head shown...all intake valves bent.

[BodybyFisher]

Anyone have any ideas about what happened here?  Did the three bolts pull out of the block?, those bolt holes will need to be repaired if they did.

Has work been done to this engine before?  Does the sprocket spin freely?  We have never seen a failure like this before.   What are you seeing as the cause for this?

[Cadillac Jim]

The fact that the idler sprocket mounting bracket seems to have been forced to the right to pull its mounting bolts - see thread damage in photo in post above - it seems possible that the first failure was one of the cams locking, which would happen when a few teeth were skipped on that cam.  When all the parts are out and examined, we may be able to tell what the first failure was, and why it happened.

[Kris Poland]

Hi! Today I make a lot of detailed photos.