2007 Tahoe Timing Chain Replacement

[Plimbob]

Going to replace the timing chain on my 07 Tahoe 5.3. I was order the melling kit but wasn't sure if I have the one or three bolt cam?
The engine code is '0'. I haven't torn it down yet.

Any feedback is appreciated.

Thanks,
Tim

 

[Gilla]

My 07 suburban has a single bolt. Think they all do from the factory.

 

[swathdiver]

Right, Gen IVs are single bolt camshafts unless AFM was deleted and a 3-bolt cam was used. Many prefer to use the Gen III style timing chain tensioner.

 

[iamdub]

Going to replace the timing chain on my 07 Tahoe 5.3. I was order the melling kit but wasn't sure if I have the one or three bolt cam?
The engine code is '0'. I haven't torn it down yet.

Any feedback is appreciated.

Thanks,
Tim

Single bolt cam is stock for the Gen4 LMG. As far as the chain is concerned, Gen3 and 4 are the same.

If you're that far in (water pump removed/coolant drained, crank pulley removed, oil pump out, etc.), why not do a full AFM delete? At the point of the timing chain, popping off the heads to swap the lifters and replacing the cam is only a couple hours more work, taking your time.

 

[Gilla]

Love the comment " pop the heads off" DANG you are funny!!!! maybe for the ones that have done a few but its been years since i tore one down this much. That WAS easy, tore it all down and went to work out. Now.....not so much

 

[iamdub]

Love the comment " pop the heads off" DANG you are funny!!!! maybe for the ones that have done a few but its been years since i tore one down this much. That WAS easy, tore it all down and went to work out. Now.....not so much

It's still a pushrod engine, and very much like the previous generations. It's actually easier and cleaner to work on since there's no valvetrain lash adjustments and has fewer parts due to roller fulcrums instead of pivot balls and nuts. The coolant is the messiest part of the job and that would already be drained. There's no coolant in the intake manifold. The steps to access and replace the timing chain are more tedious than R/I the heads and cam due to the R/I of the crank pulley and positioning of the front cover so the seal lasts and proper R/R of the crank bolt. The heads, lifters and cam and all related components are a bolt-on with the only "tedious" step being the factory TTY head bolts which can easily be circumvented with ARP bolts. The fact that it is so easy to work on is why I'd do a full mechanical delete if I were that far in rather than have to repeat all that and then some when the inevitable happens.

But, it is a 300K+ engine and maybe @Plimbob is just looking to do the minimum for now and if "the inevitable" happens, he won't be sour about it and would just sell the car or swap in a fresh(er) engine.

 

[Gilla]

Going to replace the timing chain on my 07 Tahoe 5.3. I was order the melling kit but wasn't sure if I have the one or three bolt cam?
The engine code is '0'. I haven't torn it down yet.

Any feedback is appreciated.

Thanks,
Tim

I do agree with IAMDUB. if you can swing it do the delete. I finished up yesterday with taking the heads to the machine shop. Ive got time to finish up the smaller things. My 07 5.3l is engine code 0 too. I am glad that i can do this. Guess it would cost me 3ish times as much for someone else . Rather do things myself. Lord knows its SO much easier now. I didnt have YOU-TUBE. I would go to a shop and ask questions. Most guys didnt mind giving me advice. This is awesome!!!

 

[Taheezy_88]

Going to replace the timing chain on my 07 Tahoe 5.3. I was order the melling kit but wasn't sure if I have the one or three bolt cam?
The engine code is '0'. I haven't torn it down yet.

Any feedback is appreciated.

Thanks,
Tim

If you haven't done the AFM delete then its a single bolt cam.

If you are going that deep into the engine I do the AFM delete. I have a thread where I did my afm delete last year and there is plenty of good info because I'd had asked alot of questions and there I all the right answers in there from the other members

 

[Plimbob]

Hi Guys,

Thanks for the clarification on the cam sprocket. I did contemplate doing the delete as several have suggested. But as IAMDUB commented, this old girl has 306,589 on her and I am trying to do the minimum so it runs Ok and I'll can try and find a new home for her with some young kid that can still crawl around under it ,etc. God knows, it ain't as easy as it once was...

It would be a lot easier if it didn't have to drop the front diff to get the pan off - not thrilled with that idea. None of the bolts come off easy underneath with all the salt miles on her!

As always, thanks for all your feedback and advice- greatly appreciated.
Tim

 

[iamdub]

Hi Guys,

Thanks for the clarification on the cam sprocket. I did contemplate doing the delete as several have suggested. But as IAMDUB commented, this old girl has 306,589 on her and I am trying to do the minimum so it runs Ok and I'll can try and find a new home for her with some young kid that can still crawl around under it ,etc. God knows, it ain't as easy as it once was...

It would be a lot easier if it didn't have to drop the front diff to get the pan off - not thrilled with that idea. None of the bolts come off easy underneath with all the salt miles on her!

As always, thanks for all your feedback and advice- greatly appreciated.
Tim

Is there a problem with the timing or are you doing this as a PM? Generally, the chain isn't much of a wear item compared to many other parts involved/somewhat involved in its replacement that are more of a wear item that should be attacked first. It's not like the older generations of engines where the timing sets show wear at 100K.

At 300K+, I'd let sleeping dogs lie if I were already in the mindset that the Tahoe would be going away unless it had timing issues due to slack in the chain. Replacing a timing chain in one of these is something you do if you plan to keep it for a long time and is a reason to refresh other items along the way.

 

[Plimbob]

@imadub - the oil pressure is funky, it used to always be around 48-52 at 2,500 rpm and 25-30 at idle but this winter it had a heck of a time holding oil pressure. Now that it has warmed up it hold 15-18 at idle and 30-32 at 2,500 rpm. I am thinking the oil pick-up seal is cooked, also weak oil pump all due to miles. I did try and fill it with another coupel quarts of oil and tried to find an incline to see if the oil pressure increased. It did slightly, however, I am not sure I was on enough of an incline either.

The reason for replacement of the timing gear/chain, I am getting the code P0016. I don't have any analysis tools but its pretty hard to start and once it does it runs kind of rough. I guess I was thinking the tensioner probably crapped out but I am not hearing any extraordinary noise though? I did take a breaker bar and socket to tried to move things to see if there was much play and there seem to be some, maybe 1/2 inch - I know not very scientific but...

I thought about it being a crank sensor also and entertained the idea of replacing it to see, heck of a lot less work than the timing chain project.

Anyway, long winded response to your question.

Thanks,
Tim

 

[Fless]

Has a cam/crank correlation been done? And if you do change the crank position sensor, be sure to do the correlation with a capable scan tool.

 

[iamdub]

@imadub - the oil pressure is funky, it used to always be around 48-52 at 2,500 rpm and 25-30 at idle but this winter it had a heck of a time holding oil pressure. Now that it has warmed up it hold 15-18 at idle and 30-32 at 2,500 rpm. I am thinking the oil pick-up seal is cooked, also weak oil pump all due to miles. I did try and fill it with another coupel quarts of oil and tried to find an incline to see if the oil pressure increased. It did slightly, however, I am not sure I was on enough of an incline either.

The reason for replacement of the timing gear/chain, I am getting the code P0016. I don't have any analysis tools but its pretty hard to start and once it does it runs kind of rough. I guess I was thinking the tensioner probably crapped out but I am not hearing any extraordinary noise though? I did take a breaker bar and socket to tried to move things to see if there was much play and there seem to be some, maybe 1/2 inch - I know not very scientific but...

I thought about it being a crank sensor also and entertained the idea of replacing it to see, heck of a lot less work than the timing chain project.

Anyway, long winded response to your question.

Thanks,
Tim

If a chain had enough wear in it to allow that much slack, it'd likely be broken. Hard starts and rough operation are classic symptoms of a faulty camshaft position sensor. I'd definitely swap that before diving into the engine for the timing chain. As @Fless mentioned, a CASE relearn will be necessary. Ideally, this is initiated with a bi-directional scan tool. Supposedly, it can be done without by doing the following:

1. Turn off all of the accessories. With the Air temperature sensor and Coolant temperature within 5 degrees (Centigrade) of each other, start the engine and let it idle in Park or Neutral for two minutes.
2. Accelerate the vehicle to 55 mph at part throttle. Cruise at 55 mph for 8- 10 minutes until the engine reaches operating temperature.
3. Cruise at 55 mph for another 5-6 minutes.
4. Decelerate to 45 mph without using the brakes, and maintain 45 mph for 1 minute.
5. Perform 4 deceleration cycles, without using the brakes, of 25 seconds each where no specific speed is necessary. Returning to 45 mph for 15 seconds in between deceleration cycles.
6. Accelerate to 55 mph and cruise for 2 minutes.
7. Stop the vehicle and idle for 2 minutes with the brake applied and the transmission in Drive (automatic trans.) or Neutral (manual trans.) with the clutch depressed.

The tensioner on the timing chain won't allow any appreciable slack if it were broken. The Gen3 engines had the same timing chain and just had a dampener for the chain to slap against during deceleration, but not have constant tension. The oil pump doesn't really have any parts to wear out and it's always lubricated. Lower pressures at higher mileage is usually due to worn bearings. If the average oil pressures dropped seemingly overnight or during a weather change, I'd be betting on a failed O-ring. I'd repeat the "overfill and incline" O-ring test but on a steeper slope to ensure. Another possibility if the pressure issue was a quick change is a stuck pressure valve in the oil pump. Not saying the oil pump isn't faulty. But, there are other more easily, quickly and cheaply diagnosed and repaired items ahead of it. Just think how you'd react if you replaced the timing chain and still had a hard start, rough operation and P0016 DTC.

 

[Plimbob]

IAMDUB,

You have an excellent point on the cam sensor. I got to thinking about that a few days a go as we have a 2002 Jeep Cherokee the kids drove and it would do the hard start and cranking problem, turned out it was the cam sensor.

I am going to change it out this weekend, as you state - a heck of a lot less work. Thank you very much for the manual re-learn steps. I don't have a scanner to recalibrate with. Once replaced I'll give the manual re-leard a try if it doesn't apply then I'll take it to a shop we use and have them do it.

One question on the o-ring, to replace, you have to drop the pan (+timing cover) correct?

Thanks a lot for the feedback. I'll update on this thread the outcome of the cam sensor replacement.

 

[donjetman]

Just the pan

 

[iamdub]

IAMDUB,

You have an excellent point on the cam sensor. I got to thinking about that a few days a go as we have a 2002 Jeep Cherokee the kids drove and it would do the hard start and cranking problem, turned out it was the cam sensor.

I am going to change it out this weekend, as you state - a heck of a lot less work. Thank you very much for the manual re-learn steps. I don't have a scanner to recalibrate with. Once replaced I'll give the manual re-leard a try if it doesn't apply then I'll take it to a shop we use and have them do it.

One question on the o-ring, to replace, you have to drop the pan (+timing cover) correct?

Thanks a lot for the feedback. I'll update on this thread the outcome of the cam sensor replacement.

Just the pan. Use a new gasket and don't forget the RTV at the four seams.

 

[Plimbob]

Update - as I expected the sensor won't come out. I got it to turn by spraying Kroil on it. I left it over night and still no go.
I see there are various hacks for removal which mostly involving drilling it and using a lag bolt with a pry tool to remove.
I haven't broken the head off it yet but the tab where the bolt goes thru broke.

I knew it was going to be a PIA process.

 

[Plimbob]

Update - well saying the removal of the cam sensor was a PIA is putting it mildly! I drilled a larger hole, screwed a masonry lag bolt into and filled with JB epoxy let set up for 48 hours. Then tried to extract it, used a large pry bar and block of 2x4 as a base for the pry bar. The pressure I was able to put on it with that process did not make any difference, that son of gun will not come out.

I am not down to removing the timing cover to get it out. With the that in mind, what is the best way to hold the HB to remove the bolt? I was going to use a large pair of vise-grips slipped through the opening in the back and up against the AC bracket and use my air impact driver to remove the bolt.

 

[Foggy]

If you are removing the timing cover, just buy a new cover and new cam sensor...
Neither are super expensive and it'll save you a lot of frustration

 

[donjetman]

what is the best way to hold the HB to remove the bolt?

large strap filter wrench
or Ls flexplate flywheel holder