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Cam sprockets discolored. Need to replace?
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Author:  GeoJD [ Tue Mar 16, 2021 11:19 am ]
Post subject:  Cam sprockets discolored. Need to replace?
HI all,

I'm currently in the middle of a timing belt and rocker replacement on my 2006 Liberty CRD. A cascade of failures made my belt fail a bit earlier than I expected. :(

Anyway, when I got down to the cam sprockets, I found that both are slightly discolored (as though by heat) around the bolt - one of them markedly so. Inspecting the "dirty spot" on the the cam side of the sprocket, the more discolored one also looks like it has slipped a little. Someone has changed the belt once before, so I don't know whether it slipped in operation or not. I'm at about 175.000 miles, and this is (at least) the second belt change. Should I replace the sprockets? (I am doing most of the rest of the components already, with the super service kit from idparts that includes the head studs.)

Also, everything I've taken off is pretty rusty, including the crank pulley/harmonic balancer. Are those solid? Can I just clean up the old one and put it back, or are there things I should watch out for?

Thanks,
JD
Author:  WWDiesel [ Tue Mar 16, 2021 1:29 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
Never heard of this before! Don't know how the center area of the Cam Sprocket could overheat as there is nothing rubbing it. :shock:
The closest friction point is the first cam bearing that supports the cam in the head; what does it look like?
Can you post some pictures?

Maybe someone heated the area with a torch thinking it would help release the cam sprocket bolt? Very weird!!!
If it is just a surface discoloration and you don't think the metal integrity has been compromised, I would reuse them.
Otherwise, replace both of them if you think they are compromised.

As to rusted parts, if they are not to bad, clean them up real good with a wire wheel and repaint them with Rust-oleum paint.
https://www.rustoleum.com/.
Author:  GeoJD [ Tue Mar 16, 2021 9:26 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
Here are a couple pics of the sprockets. The "heated it up to get it loose" explanation sounded plausible, until I looked more closely at the seal. Now I don’t know what to think. I suppose I’ll know more when I get the cover off.

Image

Image

Image

And the ends of the cams:

Image

Image
Author:  Jay ne Ohio [ Wed Mar 17, 2021 7:59 am ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
Based on the pictures, it looks like you have a bearing failure on the intake cam. Maybe it is just a bad seal, but is sure looks like some bearing scraps at the lower side of the shaft.
Author:  mrhemi [ Wed Mar 17, 2021 9:10 am ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
If that is a cam bearing failure, I have a set of cams available, but you would also need the cam carrier / cover as well. There are no replaceable cam bearings.
Author:  TURBO-DIESEL-FREAK [ Wed Mar 17, 2021 8:42 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
mrhemi wrote:
If that is a cam bearing failure, I have a set of cams available, but you would also need the cam carrier / cover as well. There are no replaceable cam bearings.



mrhemi:

Wow! NO replaceable cam bearings? The old bearings can not be pressed out and exact size replacements pressed in?

I am posing honest questions here; no sarcasm intended... trying to up my learning curve here.
Author:  mrhemi [ Thu Mar 18, 2021 12:14 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
TURBO-DIESEL-FREAK wrote:
mrhemi wrote:
If that is a cam bearing failure, I have a set of cams available, but you would also need the cam carrier / cover as well. There are no replaceable cam bearings.



mrhemi:

Wow! NO replaceable cam bearings? The old bearings can not be pressed out and exact size replacements pressed in?

I am posing honest questions here; no sarcasm intended... trying to up my learning curve here.


Bearing surface is machined into the carrier / cover. Same as most motorcycles.
Author:  TURBO-DIESEL-FREAK [ Thu Mar 18, 2021 10:53 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
mrhemi wrote:
TURBO-DIESEL-FREAK wrote:
mrhemi wrote:
If that is a cam bearing failure, I have a set of cams available, but you would also need the cam carrier / cover as well. There are no replaceable cam bearings.



mrhemi:

Wow! NO replaceable cam bearings? The old bearings can not be pressed out and exact size replacements pressed in?

I am posing honest questions here; no sarcasm intended... trying to up my learning curve here.


Bearing surface is machined into the carrier / cover. Same as most motorcycles.



Are the cam bearings plain or roller bearings?

If they are plain bearings, can the carrier/cover be machined over-size to accommodate bearing inserts?
Author:  flash7210 [ Fri Mar 19, 2021 7:04 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
That sprocket got "blued" because it was spinning against a frozen camshaft.
You'll find out for sure what happened when you get the cover off the engine.

This is what the cover looks like.
It actually holds the camshafts.
The bearing surfaces are machined into the cover and are not replaceable.

Image
Author:  TURBO-DIESEL-FREAK [ Sat Mar 20, 2021 10:10 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
flash7210 wrote:
That sprocket got "blued" because it was spinning against a frozen camshaft.
You'll find out for sure what happened when you get the cover off the engine.

This is what the cover looks like.
It actually holds the camshafts.
The bearing surfaces are machined into the cover and are not replaceable.

Image



Again, WOW!

If this is not an example of a consumer grade diesel engine, I do not know what is. This is definitely not the way I would design it.

My cylinder head would be iron to match the material of the block, and it would have a separate valve cover with cams running in well supported replaceable roller bearings. Ideally it would be gear driven cams as well.
Author:  GeoJD [ Mon Mar 22, 2021 12:16 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
Well, I finally got my valve cover off this weekend. I had at least 2 rockers with broken clips on the intake side, and 3 on the exhaust side where the lifters pulled apart when I took them out. Not terribly surprising. The head is cleaning up pretty well:

Image
Image

The cams, on the other hand, are another story. I'm going to go out on a limb and guess that they should turn freely. They don't - at all. Coupled with a suspicious lack of oil on the front portion of the intake side, and a gunked-up oil hole there, I'm pretty sure this piece is toast.

Image
Image

As I'm sure many of you know, new intake covers are a little hard to find, and definitely not cheap. I found a couple of used ones from a disassembler in the UK, with cams and sprockets, in "good working condition" for around $250, shipped. That's a pretty attractive option. Anything I should look out for?
Author:  WWDiesel [ Mon Mar 22, 2021 1:25 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
Your bearing issue really drives home the factual importance of performing timely maintenance, a.k.a. oil/filter changes, on an engine using good high quality (preferably synthetic) oil, to keep solids in full suspension so the filter can remove them and not allow them to build up in oil ports and plug them.

Also proves as to the detrimental effects of allowing the EGR system to remain in operation dumping soot into the engine and loading down the the oil with soot particles making sludge. Many have removed or disabled their EGR system from their engine when they bought their Jeep CRD new or used, but must wonder what and how much damage was done prior to EGR removal??? :banghead:

Another thought:
In this engine, If one oil port was found plugged in the cam cover that caused this failure, is it an anomaly or are there possibly others looming in the future?
The very small oil jet squirters that squirt oil on the bottom side of the pistons to keep them cool comes to mind. :5SHOTS:
Author:  GeoJD [ Mon Mar 22, 2021 2:43 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
Indeed, I'm pretty worried now. I didn't post a picture, but when I removed the intake elbow, I found that the EGR pipe at the elbow is at least 70% obstructed. I'm seriously considering handling the EGR problem permanently. My state is an inspection-every-two-years state, and I'm due, so I'd hate to have to put it all back a month from now. If there are any New Englanders (or more specifically, Little Rhody) with experience in this area, I'd love to hear from you.

I'd also be interested to hear suggestions on cleaning out the other places sludge might be lurking.
Author:  WWDiesel [ Mon Mar 22, 2021 3:48 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
If your state does not do a tailpipe sniffer test, you can add a simple EGR block off plate between the EGR valve and the exhaust feed tube and no one but you will know it is there. Everything from a visual standpoint will look fully in place. Only a tailpipe sniffer test on a dyno would expose the EGR being blanked off. See picture below.
Blanking it off will also let you remove the butterfly plate out of the FCV as well. Only takes a few minutes to remove two small torx screws and it slides out.
If you are not worried about visual inspection, you can remove the complete EGR system and all its components with a kit you can purchase on eBay.
Removing everything will require a reflash of the ECM (engine control computer) to get rid of DTC's (check engine light) that will be set when you unplug the EGR valve and FCV valve. Also a plus, complete EGR removal allows removal and elimination of all the EGR coolant hose connections, a source for coolant leaks.

As to flushing the engine, with the head off I have no idea how this could be accomplished. Normally a complete disassembly of the engine would be required to soak the block and clean out all passageways.
Mountainman or one of the others who have extensive knowledge of the bottom end of this engine may could help guide you in this area?
See Item 9 in picture 2 below.

You could just wait until you get it all back together and use an engine flush additive in the oil running it up to normal temperature and draining the oil doing this several times. But doing it this way you always run the risk of breaking something loose and stopping up something else. It would be a gamble!!! :grim:

Image

Piston Cooling Jets no. 9
Image
Author:  thesameguy [ Mon Mar 22, 2021 4:37 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
On my sample of one, I found that while my post-throttle-body intake was pretty goopy with sludge, the actual lubrication system including the pan was spotless. This on a 180,000 mile motor. The air path should not mix with the oil path, so the whole EGR/soot/goop issue should not impact the ability of oil to do its job.

Not CRD related, but in my experience a sludgy oil system is either going to be the result of too-long OCIs, PCV issues, or severe contamination issues that PCV can't handle (fuel, coolant, whathaveyou).

I would not get hung up on the intake tract goop, personally. I would be checking the bottom end for whatever wrecked oil pressure... whether you have sludge in sump, a bad oil pump, etc.
Author:  GeoJD [ Mon Mar 22, 2021 8:47 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
I started thinking “maybe I’ll just pop the oil pan off, and maybe I can clean or replace those oil jets...”. Then I checked the service manual about removing the oil pan. Good lord...
Author:  WWDiesel [ Mon Mar 22, 2021 9:44 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
I certainly am no expert, but based on many reports posted on this forum by other owners, after EGR delete or blockoff, many owners have reported their oil remains much cleaner between changes. I don't know how the EGR carbon manages to get into the oil, but it absolutely does get in the oil and contaminate it. After I removed all my EGR crap years ago, my oil does not blacken near as fast after oil changes as it did prior to the EGR delete.
Maybe it gets by the rings somehow and into the oil? There are not many paths available that soot can migrate from the intake & combustion chamber and into the oil.

And yes, pulling the oil pan on this vehicle is a major undertaking. Some say it is easier to just pull the engine out to gain access.
Author:  GeoJD [ Tue Mar 23, 2021 8:34 am ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
I'm slowly getting over the sticker shock of this job, and I'm entering the "well, as long as I'm in here..." phase. I've been doing a little reading, and it seems like since I'm over 170,000 miles, I should think about valves. Are there other things I should be replacing or checking?
Author:  WWDiesel [ Tue Mar 23, 2021 5:46 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
GeoJD wrote:
I'm slowly getting over the sticker shock of this job, and I'm entering the "well, as long as I'm in here..." phase. I've been doing a little reading, and it seems like since I'm over 170,000 miles, I should think about valves. Are there other things I should be replacing or checking?

On the engine, valves, rockers w/dampers, new head gasket, and remove all the EGR parts while you got it apart. Check harmonic balancer pulley closely as some have been known to start coming apart with old age.
Update torque converter with a better than factory and replace the front pump assembly in the transmission if you can. It's a good time to do while you got the engine out. Service the transmission, fluid & filters, use Mopar filters and ATF+4 only.
Clean out the CAC (intercooler) as oil can accumulate in the bottom of if you don't have a ProVent filter installed.
Install a ProVent filter if you don't already have one, it keeps the oil out of the CAC.
There are some others, but that's a good start. :wink:
Author:  thesameguy [ Tue Mar 23, 2021 6:04 pm ]
Post subject:  Re: Cam sprockets discolored. Need to replace?
Given the nature of the damage, I would strongly consider pulling the motor. If you seized a cam, you may also have oil-related issues in the bottom end. Personally, I would not even consider putting that motor back on the road without eyes on the crank first.

From recent experience, I will say that even though pulling the engine isn't exactly fun, it's much nicer to work on the motor while it's on a stand versus hunched over the engine bay. I mean, that's true of all cars, but especially the Jeep. Once you've got the camifold off, you've already done most of the annoying work in pulling the motor anyway. The front cooling core comes out easy, the only real annoying bit left is the bell housing.
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