: timing chains



Jerry Grass
06-18-12, 10:02 AM
I found this forum Friday after my wife picked up her car, a 2005 SRX, from the Dealership after having the timing chains replaced. I am sure this will be the last Cadillac I will purchase (I have owned several). I will certainly let my friends know about the built-in defect that Cadillacís have that I discovered here.
The car has 84,000 miles, is garage kept, has been maintained according to the manual. If the car had 125,000 miles or more this would not have been a surprise.
I see that Cadillac has recognized they have a problem by giving an additional warranty on the 2007 SRX. Why have they not extended the warranty on all model since this is their fault.

curtc
06-18-12, 11:24 AM
Because 06s and older are out of warranty...I will never buy another GM 3.6 again...hence why I got the N*. A timing chain going out should always be a surprise as they are supposed to be good for the life of the vehicle...timing belt, now that's expected to need replacement around 100k.

jimmbo
06-18-12, 12:15 PM
Anything with a 3.6 DI should be covered up 192,000 km(120,000 miles) or 10yrs, I don't know about nonDI engines. The real problem is how GM skimped out on the chains. They look flimsier than the ones on a bicycle. Ba$tards

Loren
06-18-12, 12:22 PM
I got a letter from Cadillac last week telling me my warranty on the timing chain is 120,000 miles or 10 years from the date it was originally put in service. I had previously had the ECM reprogrammed to prevent premature wear as a result of another letter they sent me last year.

curtc
06-18-12, 12:53 PM
The issue is not the chain, it's the crap shoot of a PCV system, or lack there of...the vent orifice clogs, then oil gets sucked into the intake, causing the crankcase to be low on oil...all 3.6 owners should check their oil religiously...

jimmbo
06-18-12, 01:03 PM
Yeah the reprograming drops the oil change interval to about 5500 miles using Mobil 1.

curtc
06-18-12, 01:38 PM
I did 5k intervals with my CTS, didn't care what the OLM said.

kschwed
06-20-12, 01:58 AM
So what exactly is the issue with the timing chains? I check my oil because I notice that I burn through it. Is there a way to fix that?

jimmbo
06-20-12, 04:00 AM
The skimpy little chains that Gm used as timing shains are stretching. This is causing the valve timing to alter enough that the engine will not be able to meet emission targets. It triggers a code.

kschwed
06-20-12, 09:18 PM
What is the relationship between these chains and burning through oil? And can the timing chain issue be avoided by keeping oil levels at an optimum level?

EChas3
06-20-12, 10:55 PM
Most are fine. The 3.6 was new. The DI, tensioner changes and supplier changes didn't help.

Look at all the issues that crop up a few years into production of most new designs. Even the best have some failures. As designs become obsolete, they are often finally perfected.

I love the STS Northstar.

curtc
06-21-12, 01:17 AM
I love the STS Northstar.

I 2nd that! I loved my FWD N* in my 2001 STS, but the RWD revision is even better!

prospyder
07-01-12, 10:12 PM
I just had my 07 STS V6 in for the 30k mile service. Two days before the appt at the Cadillac dealer, the engine light came on steady. When I called the service advisor, he said it was OK to drive in for service as long as the light was steady, which it was. After checking the car, the service advisor told me the timing chain had stretched and would be replaced under warranty. (I had previously had a problem with the car not starting in January due to carbon build up -- I was told by the service advisor it was common in low-mileage cars -- which cost me $213 since it was considered a maintenance item! -- see another thread I posted on that. It was not covered under the GMPP I purchased in Dec of last year!)
After a day and a half in the shop, the car was "ready." I noticed a knocking or rattling sound right after starting the car a day after I picked it up, so took it back to the dealership. I suspected a problem with the newly installed timing chains. After another day in the shop, I got ahold of the service advisor who told me one of the chain tensioners was not working properly and it would take another day to repair, I finally have the STS back but I'm now conerned that another stretched timing chain may occur in anther 30,000 miles.
I will not use the Cadillac dealer that did this work for service again, but aside from that, I'm not sure if it's wise to keep the STS. (I had planned to keep until 60,000 miles.) Are the timing chains used to replace the OEM chains of better quality or can I expect another premature chain stretch/failure?
JEP
Kirkwood, MO

1BadCadSTS
07-02-12, 09:47 AM
If your worried about it shoulda bought the bulletproof n* v8

curtc
07-02-12, 04:00 PM
:yeah: that's why I didn't get another
3.6, heard too many horror stories when I had the CTS...

EChas3
07-03-12, 08:59 PM
You need a new dealer. 'Carbon build-up' is BS.

SC2150
07-05-12, 04:03 PM
2 ways to avoid this issue. 1. ALWAYS use a good full synthetic oil....the dexos approved syn blend is not enough protection to keep the chains from stretching. Ignore the idiots in marketing that reccomend a blend.

2. keep oil level full. The tensioners are 100% dependant on oil pressure and have no back up spring so if you suck air at all with low oil the tensioners collapse and jumping timing is sometimes the result.

The replacement chain kit is an improvement, but these motors need a good full synthetic oil due to the design of the cahins and gears. Should be a double chain and not single, and the gears teeth are app 1/2 the height they should be. Just like the "87 octaine" that the scamming greedy marketing brass have decided on. All a decision to lure the target demographics to purchase.

:thumbsup:

dkozloski
07-05-12, 05:40 PM
FWIW, roller chains don't stretch like pulling taffy but they do wear at the pin joints. The links stay the same length but the assembly gets longer. At this point the sprocket and the chain do not match. The chain engages the sprocket farther and farther out on the teeth until the whole thing goes to hell. It's pretty clear at this point that the cam chain drive system design was botched and the designer is probably unemployed.

SC2150
07-06-12, 10:47 AM
FWIW, roller chains don't stretch like pulling taffy but they do wear at the pin joints. The links stay the same length but the assembly gets longer. At this point the sprocket and the chain do not match. The chain engages the sprocket farther and farther out on the teeth until the whole thing goes to hell. It's pretty clear at this point that the cam chain drive system design was botched and the designer is probably unemployed.

Correct. This is the biggest design flaw and they did NOT improve it for the LFX either.

We see them in every state of wear to outright failure in the shop here, and the ones that we have serived since new and have had nothing but 100% full syn oil in are showing little to no wear (yes, the stretch I refer to is the entire chain assy). THis is not the solution though, only a way to avoid premature failure. Until GM redesigns the timing chain/gears this will continue to be an issue.

:thumbsup:

dkozloski
07-06-12, 01:03 PM
When the last high pressure sliding contact in engines was eliminated by the use of roller cam followers the level of ZDDP(extreme pressure anti-wear additive) in motor oil was lowered significantly. Unfortunately this is just what is needed to preserve chain life. To further compound the problem the 3.6L motor was produced without an oil cooler which puts more stress on the oil.

You shoulda had a V8.

Loadtoad101
07-06-12, 01:31 PM
My 08 timing chain was replaced at 34k. It now has 85K with no problems, for what it's worth.

SC2150
07-07-12, 12:27 PM
And the zinc phosphate needed to control wear on the tensioner bores harms the catalytic converters over time so almost no brand name oils have it anymore. Thanks EPA.

MoistCabbage
07-07-12, 12:51 PM
Fleet and marine oils have higher levels of zinc.

Submariner409
07-07-12, 12:59 PM
And the zinc phosphate needed to control wear on the tensioner bores harms the catalytic converters over time so almost no brand name oils have it anymore. Thanks EPA.

Not so. Get into the oil manufacturers sites and find their various product sheets - ZDDP levels have been reduced, not eliminated. One very large reason is the number of engines that have gone to roller lifters or cam followers - these don't need the same levels of anti-scuff protection as a flat tappet engine.

Compare the spec sheets for popular EPA-approved 'starburst' oils with those HD oils like Shell Rotella, Pennzoil LongLife, Chevron DELO and its variants, some of the Quaker State high mileage blends ("Defy"). (Shell, Pennzoil, Quaker State - all the same company, SOPUS (Shell Oil Products U.S.))

Starburst circle = Greenie oil
Plain old spec circle - nasty good ol' engine oil

SC2150
07-09-12, 12:35 PM
I should have split hairs and been clearer, you are techincally correct as there are still trace amounts of zinc in todays oils, but only a fraction. Run any of todays oild in a old flat tappet cam engine and in short order you will begin to see lobes go away. The zinc is to protect against the sliding friction and not roller/rotatinging friction thus the reason even todays best full syn oils will not protect a flat tappet cam.

:thumbsup:

ktr-sb
07-09-12, 05:25 PM
After a day and a half in the shop, the car was "ready." I noticed a knocking or rattling sound right after starting the car a day after I picked it up, so took it back to the dealership.

I had a similar noise right after I changed my timing chains. I replaced the oil filter cap (which contains the bypass valve). The noise went away. It has stayed away. My experience has led me to believe that on many engines, the bypass valve is sticking open, allowing chronic dry starts which allow loose chains to wear at an accelerated rate.

The caps are about $30, or you can replace the valve alone for less than $10. I think way too many chains are being changed because of noise - it's gravy work once you've done one, and no one disputes the diagnosis anymore.

YMMV

ktr-sb
07-09-12, 05:31 PM
My 08 timing chain was replaced at 34k. It now has 85K with no problems, for what it's worth.''

Any chance you still have the receipts? Did they replace either part no 12583470 or part no 25014612?

ktr-sb
07-09-12, 05:34 PM
The issue is not the chain, it's the crap shoot of a PCV system, or lack there of...the vent orifice clogs, then oil gets sucked into the intake, causing the crankcase to be low on oil...all 3.6 owners should check their oil religiously...

As noted above, another likelihood is chronic dry starts due to a worn out oil bypass valve. I never ran mine out of oil, and my PCV orifice was not clogged.

Greg00coupe
07-11-12, 06:08 PM
Everyone bragging up the Northstars............ how many years did it take Cadillac to fix all the inherent problems with that engine? Compared to the N the V6 is a great engine for the time it has been out and I had 2 Ns.

1BadCadSTS
07-11-12, 06:32 PM
Because the n* is better plain and simple.

curtc
07-11-12, 06:51 PM
I'll take something that has essentially been in use since 93, and prefected over the years, over the 3.6 that came out in 04, to then be changed over to DI 4 years later, still with timing chain problems..also, I'll take a blown HG or half case leak over a busted timing chain any day.

KRSTS
07-11-12, 07:32 PM
NOT when GM stepped up to the plate and now warranties the timing chains for 10 years or 120K miles. HG and half case leaks not beyond original factory warranty.:thumbsup:

curtc
07-11-12, 07:36 PM
NOT when GM stepped up to the plate and now warranties the timing chains for 10 years or 120K miles. HG and half case leaks not beyond original factory warranty.:thumbsup:

Not for all of them, anyone with an 04-06 got screwed by the same problem, no warranty or reimbursement for those owners...and by extending the warranty that shows that GM knows they screwed up, but aren't willing to correct the flawed design...

Timing chain breaks at freeway speed and kiss your engine goodbye...the N* will survive its flaws, the 3.6 won't be so fortunate.

1BadCadSTS
07-12-12, 07:41 AM
^game set match WINNER!

SC2150
07-12-12, 05:58 PM
I detest the Northstar...the LLT/LFX are ages ahead. But yes on the bypass valve, and the v8's have the issue as well. When we dissasemble the oil pumps it appears it is not the valve so much as the casting/maching flash/burr's. All they need to do is take a little more time in finishing after rogh machining and the bypass valves should not be that bif od an issue.

:thumbsup:

EChas3
07-14-12, 07:11 PM
Unfortunately, all too often 'perfected' and 'obsolete' amount to the same thing.

SC2150
07-16-12, 10:44 AM
So true.

jimmbo
07-22-12, 03:02 AM
FWIW, roller chains don't stretch like pulling taffy but they do wear at the pin joints. The links stay the same length but the assembly gets longer. At this point the sprocket and the chain do not match. The chain engages the sprocket farther and farther out on the teeth until the whole thing goes to hell. It's pretty clear at this point that the cam chain drive system design was botched and the designer is probably unemployed.

He probably was, like almost all incompetent management, promoted and given a HUGE bonus for designing something on the CHEAP.

8323matt
07-22-12, 04:08 PM
ktr-sb,

Did you order this from your Dealer or off the web? If you did I would like to know what site. I changed my timing chains, tensioners, and guides before I was deployed and still made a whinning-groaning type of noise for about 30 seconds. Its kind of hard to explain the noise. But your answer to this makes perfect sense! Thanks man