Cam sprocket wearing groove on back tbelt cover

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 283

I've found that the cam sprockets on my 06 have worn/dug a groove into the rear tBelt cover. So I am posting here in the hopes of getting some ideas on what was causing this problem, and what to test for.

I got here from my investigation of repeated P0340 (cam position sensor) errors, the "P0340 Revisted" thread. It seemed that the exhaust cam timing might have been a bit off, so I found an indoor spot I could use for a few days and pulled the timing belt cover. What I found was the entire inside covered in fine metallic powder, as though someone had sprayed it with clear metallic paint. Looking around there is a groove at the edge of each cam sprocket worn in the rear tBelt cover. There were also some other issues, like the tBelt tensioner being set way short of its proper place (moveable arm at 9 0'clock), and several loose screws on the rear tBelt cover.

No doubt the right way to get to the bottom of this would be to pull in intake/valve cover, measure the end play in the cam shafts, and check the spacer and c-clip that hold them in. But unfortunately I don't have this indoor space for long enough to do that and order and wait for whatever parts would be required. So I am hoping to find some alternative "quick checks" that I can do without more disassembly, so that I can move the jeep back outside in a few days with the engine sealed up, and order whatever parts this repair will require.

History on this engine is it broke a tBelt around 89K miles. PO at the time had the tBelt and lifters/rockers (along with associated things) replaced by a mechanic, and then sold the vehicle a short time later to me. I need to look thru the paper work again, but I don't believe the cam shafts were replaced back then. If they were, it leaves open the possibility they forgot the cam spacers or c-clip when reassembling it.

So, back to the questions at hand, anyone have any experience with this sort of thing, a cam sprocket digging into the rear cam housing? If so, what was the cause?

The loose screws on the back tBelt cover don't seem to be a possible cause of the wear, I think. There was no play I could see when trying to force the rear cover forward. So unless more screws on the cover were loose and somehow vibrated tight again (not very likely) I don't think it was cover movement that caused the wear.

I suspect it is cam shaft movement back into the engine that is causing this wear. Could also move the nub on the cam out of location and be generating the P0340 errors. Anyone have any quick tests to see if the end play of the cam shaft is normal with an assembled engine? I had thought of running the engine with the front cover off and trying to see if the cams are moving forward and back. I also thought that I could try moving the cam shaft in by tapping with a dead blow hammer on the bolthead. It should only go 0.5mm or less. But I am not sure if this would be a valid test with the cam in the head and the valve train in place. What do folks think, any other tests I can do with the intake on the engine?

Last question (although a bit far off at this point) is what items around the tBelt would have been compromised by the metal particles flying around in there? tBelt likely. Tensioner and rollers seem OK, but hard to say if they were compromised. Any thoughts on this?

I'd appreciate any thoughts or others' experience with this sort of problem.

Dez · **Posted:** Sat Feb 23, 2019 12:45 am

Is it possible your cams are missing the spacer for the cam pulley used on early crds?

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 283

Thanks Dez.

There is no spacer behind the cam sprocket in front of the cam oil seal, if that's what you meant. I don't recall seeing one there on the other 06 CRD I took apart. Also didn;t see one in the 06 FSM. There is a "spacer" or washer under the oil seal, behind the c-clip (at least there is supposed to be), and that spacer and the c-clip are what limits the backward (into the block) motion of the cam. At least that is what I make of it. Which spacer are you thinking of?

Could be that that spacer and/or c-clip are missing under the oil seal. For now, I am trying to see if the cam has too much motion without pulling the seal out. Only because I don't have the special tools for seal replacement nor a spare seal on hand, and I need to move the jeep out of the indoor space its in now in a couple of days. If I had more time, pulling that oil seal and seeing what is behind it would be the way to go, I think.

Mountainman · **Posted:** Sat Feb 23, 2019 1:28 am

Your cam sprocket is on backwards unless your engine is an anomaly. Your timing belt will also be in danger as it will be protruding over the back of the sprocket. I've made that mistake, but caught it before I put the cover on

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 283

Thanks Mtnman.

Good thought, I double checked and I don't think this is the problem on this engine. If I am following you right, that would have the sprockets flipped front-back, and the bolt and washer would end up in the recess that is the press fit for the end of the shaft. That's not the case on this engine. Cam bolts are on the flat, and gears are not far forward, as I think your way would put them. And the belt is sitting on the sprockets normally.

What I am seeing is wear on the back/rear cover, the alum casting that bolts to the engine block and head. It's caused by the sprockets/cam shafts moving back into the engine and rubbing on that rear cam cover. Could also be the rear cover getting loose and moving forward causing it, but that seems highly unlikely.

I have not yet tried the tapping test to see if there is excessive motion/play in the cams, because I have a bit of concern that the rockers could be pushed sideways from such a test. Anyone have any first hand experience of how much pressure is between the rockers and cam lobes when the engine is off and the lifters have drained down? Think it is safe to try tapping the cam shaft in to see if it has excessive play there?

Mountainman · **Posted:** Sat Feb 23, 2019 4:06 pm

Steve777 wrote:

Thanks Mtnman.

Good thought, I double checked and I don't think this is the problem on this engine. If I am following you right, that would have the sprockets flipped front-back, and the bolt and washer would end up in the recess that is the press fit for the end of the shaft. That's not the case on this engine. Cam bolts are on the flat, and gears are not far forward, as I think your way would put them. And the belt is sitting on the sprockets normally.

What I am seeing is wear on the back/rear cover, the alum casting that bolts to the engine block and head. It's caused by the sprockets/cam shafts moving back into the engine and rubbing on that rear cam cover. Could also be the rear cover getting loose and moving forward causing it, but that seems highly unlikely.

I have not yet tried the tapping test to see if there is excessive motion/play in the cams, because I have a bit of concern that the rockers could be pushed sideways from such a test. Anyone have any first hand experience of how much pressure is between the rockers and cam lobes when the engine is off and the lifters have drained down? Think it is safe to try tapping the cam shaft in to see if it has excessive play there?

You're right, backwards sprocket would be more inclined to hit the front cover, I misread which cover you mentioned. Hmm, 1/8" of movement on the cams would be a lot. I think your cover is loose or something is behind it, or perhaps a PO bent it?
Unless the front seal is leaking, I wouldnt mess with the cams, as you may start a leak.

geordi · **Posted:** Sat Feb 23, 2019 7:34 pm

Lifters don't "drain down" the pressure on them will be constant. You would have to move the cam backwards more than 3/4 of an inch to have any rockers clear the cam lobes.

Unless you can put the cam bolts back in (without the pulley) and pull the cam forward / push it backward, I don't think this is your issue. I've seen where those top M6 bolts are too long and you THINK you have them tight, but are actually bottomed in the hole and the cover is loose. When cast aluminum heats up, especially with an eccentric shape like this has, it will bend in odd ways. I think that is what is happening here. It isn't as much of an issue, the cams have no place to go, and the hall sensor on the exhaust cam is a 1/4" thick block of steel - it would have to move a LOT to be out of position. You likely have a buggy sensor or a wiring issue for that.

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 283

Thanks Geordi.

I will remove the sprockets and see how much play I've got. First I thought I would fire the engine up with the front cover off and see if there is any visible movement front-back on the cams. If that doesn't yield an answer, then on to removing the belt and sprockets and trying a push-pull.

There may well still be an electrical issue with the P0340. But I have tried two new sensors and looked for broken wires without luck. Doesn't mean that I didn't miss something. But these metal filings around the tbelt need to be fixed first I think, even if it doesn't fix the P0340 issue.

Could well be as you say, weird expansion of the rear case forcing it into the gears due to those loose bolts; even though I can't see any motion in the case when its cold. That would really be the easiest explanation here. The depth of the groove the exhaust sprocket has cut into the rear case is roughly 0.9mm (from measurement with my caliper, which is a bit hard to do with the radiator still in there so this is approximate). Depth of the intake groove is much less, maybe half. So this isn't just a little bit of contact now and then. But not knowing the full history and what this looked like at the time of the last tBelt job, some of it may have happened a while ago; from the amount of metal filings in there, it does not seem to be enough to account for all the missing metal.

Since my time inside working on this limited for now, I will just probably try running it, doing a push pull test, then cleaning everything up and putting it back together. I could then drive it for a bit and then open it up again to see if more metal shavings have reappeared or not say after 100 miles or so.

geordi · **Posted:** Sun Feb 24, 2019 2:25 am

Since you haven't pulled the pulleys yet... Is it possible that what you are seeing happening is a result of the cover not having an intentional recess? I have seen quite a few CRDs with a milled "frown" in the back cover - it is about 1 inch tall with obvious tool-shaped edges and runs from about the 10 o'clock to the 2 o'clock positions with rounded ends. That indentation is about 2mm or 1/16" deep... So that if your cover doesn't have that, it could be that yours is an earlier version and they discovered this as a potential fix.

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 283

Well, have the answer (or at least a good part of it).

Took the Tbelt off the cam sprockets, and one at a time pulled the timing pin out and did some checking for front/back play in each of the camshafts. There was ~3-4mm (maybe 1/8") play on the exhaust side. Maybe 2mm of play on the intake side. All of this movement seems to be in towards the rear of the car (into the engine) direction. With this much play, the edge of the sprockets easily could contact the rear case to dig those channels (they fit into the channels when pushed in).

From looking at the FSM, the proper end play on these camshafts is 0.1-0.5mm. And the only thing which limits the movement in is a 2.8mm spacer and a circle clip, both sit under the oil seal on the camshafts. I can't pull the oilseal today to check, but my guess is the previous mechanic who rebuilt the top end forgot to put in the spacers and maybe the circle clips too, or didn't seat the c-clip properly. I suppose it could be that a c-clip broke and is letting the shaft move freely, but it seems unlikely that it would have happened on both cams.

Actually thinking about it, this was pretty much what I expected to find. The original "issue" when I was checking the timing pins was that the exhaust pin would not go in all the way. At the time, I was thinking that the timing was off rotationally a few degrees and that was the cause of it (I was just expecting to reset the timing on this go around and be done). But if the shaft moved back into the engine, it could also cause the pin non-alignment, which now appears to be what was happening.

My plan is (but not right now) to pull the oil seals on both shafts. Look for missing parts, then replace the spacer, c-clip and oil seal. Probably order two seals, c-clips and spacers, just to be sure I have whatever I need on hand when I do this. Thoughts anyone, anything I've missed? Anyone know who would carry these parts (my local dealer is useless for CRD parts)?

Anyone replaced the cam oil seals before? Any tricks or cautions I should know? And does anyone know if these are an old-fashion oil seal (lips held tight by a spring) or the newer flat teflon type that need to be stretched some and placed on a dry shaft? And I suppose I should ask, should I rent the special tools, or will a standard seal puller and installer do?

Geordi: The rear cam cover does have that recessed "frown" in it on the intake side. The groove that the sprocket cut is just a bit deeper than that recess and goes all around. (the exhaust side groove is like 2x as deep). So FWIW its there, but did not really help with the cam end play problem.

I also checked the cover attachment points. The small bolts go thru a rubber like grommet which has a steel sleeve in it to hold the spacing. Some of those rubber gommets are missing some rubber in spots but the steel sleeve is there, so the back cover should be held in place at the correct spot (at least if/when I put back all the bolts and torque them down. Cover having some movement may be a concern but the shaft movement is more than enough to explain all the groove depth in the case.

If anyone can think of anything else I should look at or have forgotten, please let me know...

Mountainman · **Posted:** Mon Feb 25, 2019 12:58 am

Wow, that is a crazy amount of play. Sounds like you have it figured out. The seals just press in, it's been a couple of years since I removed some, but I think I did use a Miller tool. I think you can do it with a socket and hammer. I think the biggest worry was pulling the old one without gouging the aluminum...
I'll try to remember to look at a new seal in my shop tomorrow and that will jaunt my memory on the install. At least you caught it before it blew up and caused a dropped valve or something terrible. I wouldn't run it like that since I've seen broken rockers get pinched and manage to release the valve keepers :dead:

geordi · **Posted:** Mon Feb 25, 2019 3:26 am

To answer your question on where to get parts - there is only one answer needed:

IDparts.com

They will have everything.

GordnadoCRD · **Posted:** Mon Feb 25, 2019 8:05 am

I have both old-style camshafts, complete with the spacers. The cams themselves have less than 0.001" lobe wear. I just pre-emptively bought new cams from IDParts when I bought everything for the non-roadable rig.

Mountainman · **Posted:** Mon Feb 25, 2019 1:03 pm

GordnadoCRD wrote:

I have both old-style camshafts, complete with the spacers. The cams themselves have less than 0.001" lobe wear. I just pre-emptively bought new cams from IDParts when I bought everything for the non-roadable rig.

If Steve doesn't want your cams, with or without spacers, I might be interested.

DieselJeepLuvr · **Posted:** Mon Feb 25, 2019 2:03 pm

Steve,

Welcome to the forum. Sorry to hear your woes. Let this be a warning to all out there looking at these rigs for purchase that "fixed by a mechanic" don't mean crap. I had two Dodge dealerships' mechanics screw up on these rigs. As with anything done right, paying attention to detail is key. Unfortunately it also seems to be a dying art in the automotive industry. Lots of great info here and people willing to help but your best resource for a job well done is yourself and the FSM. Download it. Read it. Learn it.

As for where you are at right now, use the search function for specifics. Removing the cam seals is easily done by using a paint can lid remover (the kind with a flat hooked end). There's videos on Youtube for pretty much everything but beware, some of those mechanics are shadetree as he11.

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 283

Thanks Gordon, I will contact you via PM on those.

So I take it that there is a newer style of camshafts which don't require the spacers (maybe that is why IDParts doesn't have the spacer). Interesting. I need to pull the old seals out and see what is or isn't in there. Spacers may be hard to come by if they are no longer used.

Mountainman · **Posted:** Mon Feb 25, 2019 2:34 pm

On the bright side, I think this thread illustrates that we don't need to worry about cam end-play unless there are missing parts :lol:

I'm impressed that your engine survived, although with my experience I would be worried about your oilpump if there has been "shaving" also going on internally (I'd watch oil pressure light on start up for a month or so).

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 283

Hi JeepDieselLuvr.

Thanks. Yeah it seems I never learn

. Whenever I think I'm saving time and $$ getting a vehicle that someone else has done the work on, more often than not I end up doing that work over again. I may be slow when doing mechanical stuff, but I usually get it right, unlike many of the so called mechanics out there.

Thanks for the paint lid opener tip for the seal removal. I'll try to find a vid or post here on that, but it sounds pretty straight forward. I had been trying to find a tool rental that had a seal puller that is essentially two paint can lid removers that attach to a bar with a screw to leverage the seal out. I would guess that if one is careful and moves the lid remover around you can get the same results.

Mountainman,

Yes that was a concern. But the metals were low normal on my last oil analysis a couple of months ago, so hopefully none of that metal was getting into the inside of the engine (don't see how it would unless the cam/crank seals were letting it pass, and I would be seeing oil coming out by them if that were the case, I think). But yes, I will keep an eye on the oil light. And when warmer weather hits putting a real oil pressure gauge on to see what's up is probably a good idea.

Mountainman · **Posted:** Mon Feb 25, 2019 3:00 pm

Steve777 wrote:

Hi JeepDieselLuvr.

Thanks. Yeah it seems I never learn

. Whenever I think I'm saving time and $$ getting a vehicle that someone else has done the work on, more often than not I end up doing that work over again. I may be slow when doing mechanical stuff, but I usually get it right, unlike many of the so called mechanics out there.

Thanks for the paint lid opener tip for the seal removal. I'll try to find a vid or post here on that, but it sounds pretty straight forward. I had been trying to find a tool rental that had a seal puller that is essentially two paint can lid removers that attach to a bar with a screw to leverage the seal out. I would guess that if one is careful and moves the lid remover around you can get the same results.

Mountainman,

Yes that was a concern. But the metals were low normal on my last oil analysis a couple of months ago, so hopefully none of that metal was getting into the inside of the engine (don't see how it would unless the cam/crank seals were letting it pass, and I would be seeing oil coming out by them if that were the case, I think). But yes, I will keep an eye on the oil light. And when warmer weather hits putting a real oil pressure gauge on to see what's up is probably a good idea.

Yeah, my worry was the cam lobes chewing at the edges inside, but if aluminum levels were low, that's comforting.

geordi · **Posted:** Mon Feb 25, 2019 9:03 pm

I seriously doubt there will be any wear inside in the oil system - Unless rockers have already collapsed from the EGR soot, the rollers have tons of "road" to roll on with the cams so wide.

The front pulleys and the metal shavings there - aren't going to get into the oil system at all. Flush the cover with degreaser to get all the bits out, finish with a hose to wash it out and drive on.

Cam sprocket wearing groove on back tbelt cover

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