Timing Chain...

[Wayne Sihler]

From 96 FSM
Camshaft sprocket=80 Ft lbs
Oil Pan 1/4x20=129 inch lbs
5/16x18=156 inch lbs
Oil pump
short=10 ftlb, long=17 ftlbs
Rocker arm to head=21 ft lbs
Timing cover=1/4x20=60 inch lbs
5/16x18=192 inch lbs
Valve cover=115 inch lbs

Wayne

 

[Alex E]

Thanks for the Specs! I have bad news though...I was getting the engine ready to be put back together and cleaning everything one last time...but the fact that I didn't know what caused the chain to fail was still bothering me. Chains don't just fail and I had looked the engine over very thoroughly and couldn't find anything. I was thinking EVEN if the crank or something was messed up that wouldn't matter because the crank drives the cam so the chain would only be stressed by whats driven NOT whats driving it. I decided for piece of mind I'll slide the cam forward and look at all the bearings just to make sure I covered everything I can. Well, needless to say my hunch was right. The second bearing from the front was wasted. Why? I'm not sure at the moment, hopefully my machinist will have a answer for me on Monday. Being a mechanic and working at a shop means oil and filter changes were no problem. Like I said the engine has around 25,000 miles on it or so. You'd think that if it was installation error it would have happened with in 2.5 minutes of the break in, 250 or 2,500 miles but not 25k later. Trips to Moon Rocks, Washington State, Sierra Nevadas and every where else and then all the sudden this. I suppose it wears over time, I think its just one of those things that happen now and then and I happen to be that unlucky person. I'm kind of bummed but I'm happy I found the problem so at least when its fixed I can be sure its fixed correctly...or thats what I thought when I had the engine rebuilt??? lol

Its hard to see (dang cell phone pic) but the bearing is wasted. Its not really pitted on the one side but it had deep voids, looks like the metal got hot and is all sunk in.

 

[Talyn]

Crap. That sux. I'd be interested in hearing what the machinist says as I have had issues with cam bearing failures as well. Any other ones like that? I would be interested in seeing the wear pattern on all of them. On the bright side at least it looks clean.

 

[Alex E]

Crap. That sux. I'd be interested in hearing what the machinist says as I have had issues with cam bearing failures as well. Any other ones like that? I would be interested in seeing the wear pattern on all of them. On the bright side at least it looks clean.

How many times have you had issues with cam bearings and at what mileage intervals where they? From what I could tell the rest looked pretty good. Yeah it is clean as a matter of fact, except for the carnage floating around in the oil and sitting on the bottom of the pan! The cylinder head and underside of the valve cover was all nice and pretty, as is the oil pan and bottoms of all the pistons and parts of the crank. It just sucks be EVEN if I could pull the radiator and what not to pull the cam completely then install bearings and do the whole 9 yards...I fear the oil passages are contaminated and who knows what else could fail next. I'm going to talk to my machinist and see what he says but in my opinion I think my best bet is to pull the engine, have all the bearings and rings replaced and have the damn thing hot tanked. You know I'm happy this happened 3 minutes from my house and not on the Rubicon or Moab. Gotta stay positive!atriot:

 

[Talyn]

You would need to pull the engine to replace the last cam bearing anyhow. Look at your main and rod bearings. If they show dirt then you need to replace them, have the crank examined and have everything cleaned. Also, look at the piston shirts and walls to see if they show evidence of scuffing. Most likely the oil filter and screen caught the worse parts and all you will need to do is install new cam bearings.

Also, when you pull the lifters keep them in order so they go back on the same lobe as before. If you pull the crank and pistons, keep track of those bearings as well if you intend to reuse them.

 

[Alex E]

Yeah, I've been keeping track. Hopefully everything is reusable for the most part. It has new pistons from the rebuild, among other parts so I hope those aren't scuffed up. The cam looks in pretty good condition. Nothing looks messed up on it and it has the same color on the steel at the bearing spots so hopefully it didn't get to hot from what ever went on where that bearing failed. There are some irregular lines on that one part of the cam where the failed bearing is but they don't go in the direction of rotation. I can't feel them with my finger nail either. I wonder because of the two different types of metal, the cam being hard and the bearing being soft, the cam just got kind of stained or tarnished from the heat of the bearing resting on it after the failure. Its hard to explain but thats my only conclusion. Its not a rotational mark or scuff it just looks like a irregular circle type stain in the metal of the cam.

 

[Talyn]

The cam bearing material will take up on to the cam itself. If you see black on the bearing and cam journal the bearing was cut through the babbit into the steel backing.

When you say there are some irregular lines that don't go with the cam rotation, what do you mean? Have any pics of that?

 

[Alex E]

I'll try and get some pics later, the lines dont divide any spots or discoloring so Im not sure why they are there. Once this is all fixed Im going camping damn it!

 

[Alex E]

Ok, no pics yet but I talked to the machinist and I'm going to pull the engine. Im going to have the bearings replaced and everything else checked out and tanked to make sure its all clean. I figured a few extra bucks for the piece of mind and making sure its completely clean is the right way to go. I don't want to cut corners to save a few hundred bucks and then end up with another broken timing chain or spun bearing while on the Con or in the middle of the Moab, then I'd be really F*$@ed. Haha

 

[Alex E]

Ok, so I got the engine pulled. Its at the machine shop getting cleaned and redone BUT now I noticed the ring gear on the flywheel is getting wasted in my opinion. Has anyone seen this before on their XJ? Does anyone know of a way to shim or correct this problem? At least the engine is out and I can fix this too. The flywheel, clutch, pilot bearing, TOB and all that were replaced at about 5,000 miles before the engine was replaced, or about 30,000ish miles ago. FYI everything was bran new including the flywheel. Keep in mind its a 95 engine BUT...the tranny, all clutch components including flywheel and backing plate on the engine are all off my old 87 engine so a 87 starter should be fine.

Any thoughts?

 

[Talyn]

Odd. I wonder if it wasn't hardener is it gets hardened. I would replace both that and the gear on the starter

 

[Alex E]

Does any one happen to know if different year flywheels and starters have different tooth counts. It looks like the engaugement on the teeth might not be enough, obviously you dont want too much either. I wonder if the starter gear is too small or something...my poor Jeepous.

 

[Alex E]

So I stopped by the machine shop today. They tore down the engine and inspected it all. Looks like my number one piston is ruined from oil starvation, the connecting rod bearings are bad and all my rings are getting replaced. He said all the damage is caused by oil starvation. I've been on some pretty gnarly hills and rocks that are super steep and I'm guessing driving on steep angles for extended periods isn't good. Does anyone know of oil starvation issues with the oil level and pick up? Is there a way to correct this?

 

[Talyn]

Do you have an HV oil pump?

I have ran into two issues with oil pumps. 1) some blocks interfere with the mounting of the oil pump. Put it on with out a gasket and rotate it about 30*. If it feels notchy it may be interfering with the block. Grind the block if it still needs a wash or the pump if the block is clean. 2) The pickup may not be secure to the pump to suck air in.

Another thought it too little clearance between the pickup and bottom of the pan. Check it using silly putty.

 

[Alex E]

Yeah, I thought about the clearance between the pan and pick up, I should check that. Your 100% right about the fitment though on the pick up to the oil pump. I recall it not being as tight to fit in there as most other ones I've done. I wonder if it was sucking air. What do you do to correct the pick up if it doesn't fit tightly into the oil pump body? Also I noticed the gasket looked compressed and even when I pulled the pump off the block so I think the fitment is ok. Were you referring to sucking air at the block and pump body?

 

[Talyn]

Both. If the pump isn't flat on the block it will suck air there too. The fitment issue is on the inner side of the block. It was on 3 2000 blocks I have, so yours may be different. Part o fthe casting hit sthe pump and puts it at an angle.

If the pickup isn't tight get a new one. You have to make sure it goes in straight. Some places you can rent the correct tool. I made one out of plexi (just because it was quick and easy on the laser) to hold the pickup in a vise the knocked the pump in. If you can easily rotate the pickup with your hand then that is part of the problem.

 

[dobbs571]

A nother way to install the tube is get a can of duster for cleaning computers its CO2 let the pump set to where its warm spray the end of the pick up tube for a fu seconds and it will allmost fall in place just make sure you have it where you want it because once they both reach the same temp you wont move it . I install a lot on bearing this way. This works on any thing that is a press fit bearings bushings tubes. Just rember what one you will need a fu thou smaller to fit and spray it

 

[Alex E]

So I finally had time to wrench on the Jeep. Got the engine all put back together, most of it installed and ready to go. Just have to install my radiator, ps pump, distributor and a few other things. I got all my old parts and I'm trying to make sense of it all. Like I said, I know driving on steep inclines can cause oil starvation problems but how is it that I'm the only person who's ruined a engine by wheeling it...I find it kind of hard to believe but I suppose anything can happen. I checked out the oil pump and tube and it was pretty tight. I started to think, hey maybe it was loose but I guess it wasn't after I checked. The fitment to the block looked pretty nice too, the old gasket looked evenly compressed also. Well if all goes well I should be able to fire it up tomorrow. Can't wait to have my Jeep back on the road! Here are some pics of the carnage...maybe you've seen this?

What I say is typical wear in a engine, ok maybe not ideal but nothing I haven't seen thats caused any issues...what was a bran new piston with 25,000 miles on it.

Now the OTHER SIDE of the same piston...

These are 3 different parts of the connecting rod bearings...

This is what only 2 of the 4 camshaft bearings looked like, I believe the center 2 are the wasted ones and the 2 outers were ok.

I noticed 3 bearings had 1 hole from the oil galley but 1 bearing had 2 holes, also some had a manufactured groove and some (or just 1) were compleatly smooth. Any one know why they are different? I'm sure if those were in the wrong order when they were installed I'm sure that could have caused a problem but since I didn't remove or install them I wouldn't know for sure if they were in there correctly. :doh:

 

[stroked88]

i know what happend. who installed the motor? when we put my stroker in that we just built we had a similar problem with the cam bearings, and we discovered that they had been disformed from the original shape into an oblong from having to pry the motor mount over to get the motor in. the 4.0 blocks are pretty thin and the 2 middle cam bearings pretty much line up the the passenger side mount. we caught it quickly when a lifter started ticking, and got it fixed before it did as much damage as yours but it had scoring on the pistons similar to that but not nearly as bad. i only had like 200 miles on it but suspect that it could go a while like that. the scoring is from the metal in the oil as the cylinders arent pressure fed. the rods stopped getting oil from all the slop in the cam bearings. if you pried the motor (excessively) to line up the mounts it will likely happen again.

 

[Alex E]

I didn't have to pry it much at all. What I ended up doing was just installing the short block because the cylinder head was already off so I figured a block with some pistons a oil pan would be easier to manhandle. It worked out pretty nice and I just installed the lifters, head and all that after the bottom end was in. Worked out easier because I did it in my driveway this time where last time I did it at my shop. The weirdest thing of it all is for 25k miles it NEVER made any noise, it never burned oil and working at a shop changing the oil every 2,500-3,000 miles wasn't a problem at all. I'm only human and we make mistakes but I'm pretty frick'n meticulous and I've been working on cars for close to 10 years. I duno, I'm just annoyed because I'm pretty careful about things and the only conclusion I can come up with is either the engine builder who did the machine work and installed the rotating assembly messed up or I guess wheeling it did something. I find it hard to believe wheeling it hard did anything though. But it always go back to why 25k miles is a pretty long time. Usually something will happen at 200 miles like for you or at 200k if the engine was taken care of. Not some random 25k miles all the sudden...