I don't know the answer to your question but I would continue to drive it. As it stretches supposedly the engine will lose bottom end torque. If it were my car I'd consider looking at the electric solenoid valves that control the cam position actuators. Make sure they are clean.

 

How often did you change your oil and what type did you use? For the sake of accuracy and the fact that it kind of aggravates me to read it, the chain doesn't stretch, it wears at the pivot points and the sum of wear at all of those points equates to a sizable increase in the distance between links that eventually results in cam angles going out of bounds. Given your mileage is at the point where many Cadi techs recommend chain replacement (120k), chances are the code is legitimate. If you're doing 6k mile oil changes, I'd switch to 3K intervals now and if you have that on the oil now, go ahead and change it before clearing the code, the engine light might stay out for a while following this approach because fresh oil should produce slightly higher oil pressures that might have a positive effect on the chain tensioners.

The wear rate is a slow, and a potentially unpredictable process when you consider some have encountered the codes at as little as 30k miles. That is the nature of excessive wear, the wear rate increases with time especially after the "too much" point. I haven't heard of any sudden failures following continuing to drive after the appearance of the code which some have driven on for quite a bit of miles. Do a general google search referencing the motor instead of the car for a broader reach to get some idea of how long you can "walk the line".

Programming also plays a part on this subject because some cars received updates that increased the tolerance limit, pushing the engine a little closer to the failure point before the code would set. Failure meaning literally and symbolically by jumping timing.

 

Joseph - I had the re-program recall performed about 1 year after I bought it (say 25k miles). I have used the accelerated change interval that was programmed in, which results in changes about every 5k for my driving conditions (fairly mixed Hwy/City). I have always used quality name brand synthetics for full changes - Mobil 1, Penzoil, Valvoline, or Castrol. Mine has always been an oil user so I am putting in 2 extra quarts at least between changes - for these I usually use a cheaper Dexos qualified full synthetic oil - Oriley house brand, STP (autozone), etc. I keep a very close eye on it so pretty sure I have not run it too low at any point.

I also have not heard of anyone having a full catastrophic failure of the chain(s) - after following countless threads over the past decade about this issue. So you feel it is a chain wear (not "stretch") issue that at some point would result in a broken pin? If the chain rollers were wearing, I would think it would take a LONG time to actually wear all the way through the roller and then the pin to cause a failure. Seems it would be friction causing the wear rather than tension in this setup - makes sense that low oil causes this all to happen prematurely due to increased friction. So the acceleration of wear might occur if the friction were occurring on a less hardened area (after wearing through the designed contact metal)?

IF/When I change it will be interesting to see if the wear can be seen on the chain. Of course if it is worn guides or tensioner causing the issue, all of this is moot about the chain stretch/wear!

 

Your oil consumption quantity between intervals is interesting and something to take note of. I had my chains replaced at 175k miles with no codes so perhaps city vs. hwy useage plays a big part in the wear rate as I have read where a 3.6L DI SUV owner was approaching 300k miles on the original timing components with no codes according to the owner. I don't note any oil loss between change intervals and the one time I did it was because I made the holes in the PCV valve modification a little too large which resulted in an immediate drop in oil level in just 80 miles so you may want to replace that part.

You have the silent timing chains, there are no rollers, just link stacks attached by a pin and the holes in the links that pivot on the pin are the ones that elongate and the wear can be significant. I held one of my old chains side by side with the new and noticed the old chain was longer at the bottom loop by at least 1/4 inch which suggests the chain was longer by a 1/2". That's a lot and I suspect either programming, or uniformity in wear on both banks is why a code had not set.

An engine and transmission oil cooler is on my list of things to do. I just can't say it enough, these motors are hard on oil and because of what it looks like in 3k miles when I change it, there's no way I'd let it get near the ~6k miles my oil life monitor would alert at. I can see where a vehicle with a balanced use distribution, or greater city useage will likely have faster chain wear due to higher average engine, oil and coolant temps and lower average oil pressures from idling in traffic during that same period, relative to a motor that sees mostly hwy use which will have the opposite. Heat degrades, cold preserves.

 

Joseph, you articulate knowledge across a broad base of topics. Do you have specific automotive background or perhaps just the broad knowledge and judgement of a seasoned engineer? Or maybe your just a very good BS artist!! (KIDDING OF COURSE!) Anyway, I enjoy reading your posts so hopefully you will keep adding to the knowledge base here!

 

No BS, I developed a strong interest in science and mechanics at a very young age and spent a lot of time dismantling things to see how they worked and experimenting and modifying sometimes bordering into dangerous territory due to ignorance. My education took me through a lot of science/physics courses that many complained about, failing to realize how much those courses provide you with good sense, and judgement as well as arm you with unscripted problem solving skills.

Let's just say I know when to move when someone is doing something they don't realize is dangerous and when to get someone else to execute the moves on something that is dangerous and necessary. My voltage risk limit is 110, although I did tackle a 220 dryer hookup once with fear and trembling. I know 110 can be deadly also. That along with personal experience and some great mentors has taught me an awful lot. There's a lot of reading involved to.

Well I will never have another car with a timing belt. They can have catastrophic failure. Cars with phenolic timing gears (70 SBC) can also self destruct. That said a good chain drive should begin rattling and clanking before it destroys itself (the timing cover now...)

Not sure what the hubbub is about, replacing a timing chain is no big, just should replace any tensioners at the same time. However as long as you follow the service manual it is not difficult.

Unless you have a 2004-2007 Mercedes V6 with the bolt on the back of the balance shaft and the bad balancer gear.

I agree, replacing the timing chain on my CTS is no biggie, replacing the timing chain on any CTS and it not running properly afterwards is a biggie. There's no pressure in working on your own car because you can quit and start up at any time. Like you, I am the only mechanic I trust and I hate working on cars unless there's more horsepower and torque to be had when I'm finished. I'm thankful I have the skills to do it as it has saved me several thousands over the years and it started with a simple rational 25 yrs ago, "If it's already broken, all I can do is risk fixing it".

My crowning achievement is rebuilding an automatic transmission all the way down to disassembly of the valve body with no training whatsoever, reassembling it and it working properly afterwards.

 

Well I will never have another car with a timing belt. They can have catastrophic failure. Cars with phenolic timing gears (70 SBC) can also self destruct. That said a good chain drive should begin rattling and clanking before it destroys itself (the timing cover now...)

Not sure what the hubbub is about, replacing a timing chain is no big, just should replace any tensioners at the same time. However as long as you follow the service manual it is not difficult.

Unless you have a 2004-2007 Mercedes V6 with the bolt on the back of the balance shaft and the bad balancer gear.

 

If you're doing 6k mile oil changes, I'd switch to 3K intervals now

No need to shorten the drain intervals IF you check the level frequently.

 

That suggestion was for the current status of the motor and his interest in delaying repair, given that the oil appears to shear down pretty quickly in these motors. If he's needing to add 2 qts between intervals you can bet he's checking it. Loose tolerances benefit from higher viscosity, which breaks down with use from heat and combustion contaminants and since those tolerances wear faster the further they are away from spec, it helps to keep the oil in good shape. It's just a precaution.

 

My CTS started throwing the code in October last year. I had the chain replaced in August - so, 10 months and almost 20,000 kms (~12,000 miles). By then, I was starting to feel a slight decrease in power but there was no noise or any other symptom. But boy was I wrong about the "slight" - the power dropped off so gradually over that time that I really didn't notice the loss - the CTS was still plenty fast. But after the chain swap!! The car drives like new again. Best $2700 (Canadian $) I've spent on a car in a very long time.

 

That is one of the things that the degrade is so slow that it is not noticed until replaced and then oh my. Northern, at what milage did the code start please ? My experience is usually around 100k miles.

"the oil appears to shear down pretty quickly in these motors. " my experience is that heat is a factor in breakdown and synthetics last longer than pure dino.

I run my computer cars between 180F and 190F - a bit cooler than stock but enough for the computer to be "all in". Have a 180 thermostat on order.

 

I haven't seen anything available other than a 180 deg thermostat during an effort to obtain a lower opening temp, so we all run pretty much the same as you. Heat is always a major factor with oil and many are not aware that it generally runs at higher temps than the coolant, as it comes off of the bearings.

Being a 24 valve motor with three timing chains, three dynamic tensioners, two idler gears and four actuators with individual solenoids, there is probably not another GM motor that has as many friction points to contribute to the heat stress in the oil. Then there's the oil squirters absorbing heat from the pistons.
Let me rephrase my statement to read, because of the added heat stress on the engine oil, it tends to shear down faster. I don't know about the rest of you, but at 3k miles the oil pours out of my motor cold, much thinner than it was when it went in.

One more thing, direct injected engines are subject to higher levels of fuel dilution of the oil, to add to the friction load effects.

It would be nice to see the oil change interval trends between those who perform 3k mile oil changes and those who follow the oil life monitor regarding timing chain replacement mileage. There was a time when I thought 3k mile oil changes were a complete and total waste of time until I heard about the 3.6L timing chain.

 

Are more comments about oil back in the Oil Brand thread but being a Floridian and trending to push things a bit (many Autocrosses in my yout). For many years it was Quaker State and Valvoline 30 wt racing oil. Then for a while in the 70s I used Amsoil. Lately it has been Mobil 1 High Milage 0W-40 (Mercs) and 5W-30 (other cars).

I have learned that everything under the hood lasts longer if you keep computer cars in the 180F-190F range (and keep cars I like for decades). Some cars have had to reprogram the ECU to bring the fans in sooner.

A Stant 180F is on order since I do not like the 200F+ it runs currently. Am otherwise mostly happy with the 3.6 other than the poor MPG - less than my '12 Jeep Grand Cherokee 3.6 (same miles but 1-2 MPG better). Will start with extensive instrumentation.

 

To my knowledge you will be replacing your stock 180 deg thermostat with a newer 180 deg thermostat and ending up with little to no change in engine temps, as there is no variation from the stock 180 deg rated part available that I've seen. I actually deleted part of my previous post which mentioned that engine temps are going to run approximately 10 deg higher than the thermostat rating or more. In order to defeat the stat limited minimum, you'll need to drill a small hole in the perimeter of the base to allow more coolant flow, probably about 1/8" in diameter. I linked to a heavy duty radiator for the CTS offered by RockAuto, which is a CTS-V radiator core with CTS tanks on it for a near 1/2" thicker radiator over stock. SPECTRA PREMIUM CU13108

0W40 would be better suited for cold climates, 5W40 would be better here in FL as the 40 protects the engine better near high temp extremes, the 0 protects the motor better at low temp extremes. I tried 0W40 here in the Orlando area and I got lots of cold start rattle, I haven't heard it since switching to 10W40 and since I have high mileage and rarely spin the motor to the moon, I might switch to 15W50 M1 in the Summer for the added viscosity protection.

You may actually get worse mileage with the 180 in there.

Just the opposite, I used to think the same thing until someone took me back to physics, specifically thermodynamics. It's no secret that cars generally get the worst fuel economy when the motor is cold. Back in the 80s, when manufacturers had a good handle on how to make a cylinder head that wouldn't crack above 200 deg, the normal engine operating temp leaped to 240 deg which was the approximate coolant temp the cooling fan was programmed to turn on. That was because of the fuel efficiency benefit. The more heat in the engine block and cylinder walls, the less heat taken out of the combustion process. The end result is more pressure inside the cylinder on the combustion stroke and therefore more force pushing down on the piston with the same quantity of air and fuel. The same result can be had by increasing the compression ratio, both of which increase the efficiency of the same combustion mixture, with limitations of course. Now temps are coming back down some because of the switch to aluminum blocks and cylinder heads which can't take that much heat.

To demonstrate expansion and contraction of gasses to my kid, I put cold water in a small container, added a drop of dish detergent, put the plastic top on it and shook it. She noted how the container contracted, mainly the top which appeared to be sucked inward. If you do the same with warm water it may pop the top off and make a mess. The kid can clean that up.

 

You may actually get worse mileage with the 180 in there.

 

Oddly the oem t-stat appears to be 187f.

Specifications:
Temperature (F)187 Degrees
Gaskets IncludedNo
Start to Open Temperature (C)86
Start to Open Temperature (F)187

EDIT: The above info is wrong. 187/190 is OE for the 6.2L not the 3.6L which is 180 OE.

 

Oddly the oem t-stat appears to be 187f.

Specifications:
Temperature (F)187 Degrees
Gaskets IncludedNo
Start to Open Temperature (C)86
Start to Open Temperature (F)187

What year? My 08 service manual only shows 203F full open temperature. I can't find a thermostat anywhere that's rated for anything other than 180 deg. Summit racing listed a 190 but it turned out to be for the 6.2L.

 

Yup, the higher operating temperature of modern engines increases efficiency and lowers emissions. The old hot rodder's trick of lowering the operating temperature for higher power works by allowing an increase in both compression ratio and ignition timing without detonation. Aluminum cylinder heads have a similar effect - increasing the limit at which detonation occurs.

 

Maybeso, guess I'll find out. First I'm going to put a new set of iridium plugs in there, then will monitor the pulse width at a steady 70 at 180 and 200. Do know in the current condition it is getting worse MPG than the 3.6 in my '12 Grand Cherokee blimpmobile.

Am surprised the recommended plug gap is only .043", the 3800 in my Reatta with Delco ignition calls for .060". Maybe its the 7k redline.

ps my specs say for the LLT "Thermostat Full Open Temperature 95°C 203°F" (Document ID: 1998042)

 

UPDATE: I have still not taken any action on my P0008 code (best intentions to replace the chain during holidays went unfulfilled!).. I have driven the car normally since it cropped up and I have taken it on 2 - 1200 mile plus trips for my son's hockey tournaments. The car still seems to run perfectly normal, with no change in the sound, performance, or gas mileage of the engine. For the 1st 30 days, the CEL light seemed to come and go, but since then it has not gone out at all. I realize that is a sign that it has likely continued to stretch (it definitely isn't getting any shorter!).

I am certainly NOT recommending people ignore their P0008 light - just sharing my experience. My "redline" so to speak is when I hear a rattling, or experience a deterioration in performance. At that point I would take the time to fix it regardless of convenience. Short of that, I am content to ride it out until spring/summer weather when it is pleasant to tackle the job, rather than fight cold wet dirty garage floors now in the Winter. All the year's on this forum I have not heard of a chain break - HOPE I'm NOT THE 1st! I am in a position where a catastrophic failure of the chain would not be a huge financial hit to me. The car otherwise is in "Fair" condition. The paint has not held up great and she's always been an oil guzzler.

OK let the bashing begin!

 

No bashing here--I'd be doing the same thing if I was in your situation.
Definitely keep a close eye on your oil level (you know this) and keep your ears peeled for any strange or new noises.

I don't want to be a downer, but wagoneer had a bad experience where his CTS experienced catastrophic failure, possibly related to chain stretch and incidents of low oil level.
https://www.cadillacforums.com/foru...13-cadillac-cts-general-discussion/1079362-farewell-dear-wagon-community-2.html

Fingers crossed that you're able to make the repairs on your schedule.

 

:thepan::hammer::hitstick::kick::gun2::brutal:

As long as the delay in changing your timing chain doesn't affect my CTS, I'm okay with it. Thanks for the update and I hope that it holds up until you have the time to change it.

 

Thanks for the link. I missed that thread somehow but definitely makes me think twice! Will be looking to tackle the repair as soon as I get some nice spring weather!

 

NP, JCB.
Not saying it will happen to you and wagoneer was candid about running low on oil a few times, but figured it was worth sharing.

 

Can you park it till the weather breaks?

 

I was under the impression that at some point beyond the "informational" P0008 there was another code indicating a worse condition that triggered a reduced power / limp home mode?

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