Motor Noise After New Parts Installed ?

[MACH90XJ]

New to jeeps,but not to mechanics.I got a 90' ,4.0 ,aw4 ,4wd bone stock.159,000 and still strong lotsa torque for a 6 banger.

Picked it up for 500.00,bad blow by,oil leaks,all fluids needed changed,tps was bad owner thought tranny was gone,about 400.00 later I'm ready to drive this thing almost.

My problem is a metallic noise like a bearing on an alternator or something.The last work was rear main seal,oil pump and pick up tube(coated with sludge) cleaned pan out,and while down there timing chain had lots of slack changed that too.Noise was not there before I changed these parts so I suspect one of these,did all 3 before reassembling and running.I have run motor w/belt off noise still there.noise seems to be in front of motor.I went back in and checked rear main torque,not much to screw up here.Rechecked oil pump,primed w/tube in oil pan straight bolt up.Timing chain oil slinger flared lip facing out ?,cam sprocket torqued w/spring and pin installed(not sure what the purpose of this is for).
Any ideas ? what am I missing here,It runs good but something sound like it is rubbing or a metallic bearing noise.

 

[RTicUL8]

It might be something on the outside of the engine. The crankshaft pulley has an inner and outer circle separated by a piece of rubber. If stock, the rubber is probably cracking pretty bad at 159K. The outer circle will slip either forwards or backwards. If it slips backwards, it might be rubbing against the timing case cover which can sound metalic. It did this on my '88 XJ until it wore a hole - and I was left wondering why I was spilling oil....not fun.
Good Luck...

 

[Eagle]

I hate to say it, but my first guess was the camshaft spring and pin. Your post says you torqued the sprocket and set the pin, but could it have slipped while installing the cover?

I don't remember which way the slinger is supposed to face. That's the other likely culprit.

 

[MACH90XJ]

Thanks RTicUL8 but I forgot to mention I also replaced balancer at same time,it was separated about 1/4 inch towards cover.

Eagle I'm still not sure about that spring and pin either,it just sits in there right.The end of the pin definately has been wearing on the timing cover,which would seem ok but my latest trip to u-pull-it/hands on classroom revealed 2 motors without the spring just the pin installed ?What does that spring and pin do for the cam sprocket,just spin around and wear down.Oil slinger goes on past the keyway,nothing to keep it from rattling around right?I dont know just throwing it out there.

Sorry about slow replies but got metal in my eye the other day and cant focus on computer screen for very long.

 

[5-90]

The spring and pin are supposed to help prevent cam "walk" by providing a bit of push against the cover - but I'm not sure how much it's supposed to help, since it's a pretty mild spring.

If you're running without the belt, the only things making noise near the front of the engine will be involved with timing, and the damper. The damper's easy to check - get a look at it. If there's a lot of cracking or the rubber is starting to squirt out, replace it. At 150K, you're due for a new one anyhow (I really wish Fluidampr would make one for the 4.0, but they don't plan to yet. Check in and make your voice heard...)

When you had the front cover off, was there any significant wear on the inside near the top? That would indicate cam walk, and the resulting metal-on-metal wear would sound like a light scraping and would leave fragments in the sump (mostly Aluminum from the cast cover.)

The damper hub rides on a rubber ring, and if you had the engine that far apart, you probably replaced it already.

You didn't really define the character of the noise - rubbing, scraping, tapping, knocking, what? That helps as well.

Bearing noise with the engine running I have usually found in the alternator or the water pump, but you said still getting it with the belt off (the idlers take longer, as there is no load after they turn.)

Got any more info for us?

5-90

 

[MACH90XJ]

I would describe it as a rubbing or scraping metallic noise that is consistant with the motor speed,rev it up it gets faster and louder.The 2nd time it was apart I inspected for rubbing on cover inside and the only wear was the spring pin set up,it was indented and pin tip was visibly worn.I am not familar with cam walk though, does that mean side to side play of some sort that the spring is suppose to hold in place,but that spring doesnt have very much tension to hold anything in place.You must have missed my recent post I replaced harmonic balancer/vibration damper.

 

[Casper]

It might be your harmonic balancer. I did read where you replaced it. Myself, I replaced mine about a week ago, and after I installed it, I was hearing metalic noise as well. It took a couple of days to find because the balancer was just barely touching the timing cover. The solution to my problem was I was sold the wrong balancer. I bought it from AutoZone. They sold me a balancer for a 4 cylinder. I needed the 6 cylinder balancer. The coller on the balancer for the 6 cylinder is a little longer than the 4 cylinder balancer. So when you install the new balancer, you will eventually bottom out on the crankshaft lip. If you have the balancer for the 4 cylinder, it will touch the timing cover by the time it bottoms out on the crankshaft. Take a look at your new balancer when you get it off, and compare it to the old one if you still have it, or go to the parts dealer where you bought it and place it on the counter side by side and check the coller. That's what I did and it was very apparent that the 4 cylinder balancer coller is shorter than the 6 cylinder. Hope this helps,

Casper

 

[5-90]

"Cam Walk" is end-to-end displacement of the camshaft, usually caused by the slight endwise force from the helical cut on the distributor drive gear and the resistance from turning the oil pump (I hope that doesn't sound too nuts - best way I can think of to explain it.) It is generally non-existant in my experience when going to a dry sump system, because you are no longer driving the oil pumps (!) with the helical gear cut into the cam. This is the same gear that drives the distributor, but the distributor itself offers (effectively) no resistance to turning.

If it were a "crown" or "spur" gear instead of a helical cut, this would be a non-issue. However, the helical cut is the most efficient means of angular motion transfer - that's why it's used in axles (R&P setups are a more aggressive version of helical gearing, and you can find the same thing happening in the D300 and Atlas transfer cases.

You are correct - there is little resistance to cam walk from the button on the cam nose (it's usually called a "Thrust button") and you may want to check you damper. I missed your replacing it, and I didn't know there were differences (when I replaced mine, I got OEMR - price was reasonable.) That also makes sense, especially if the noise is at all intermittent...

5-90

 

[MACH90XJ]

Thanks Casper and 5-90 I got the old balancer but not the old timing set,I'll check those things out when I dig in for the third time this weekend.That was the reason why I changed balancer because it torqued down onto timing cover before it bottomed out the first time around.

You got me thinking on that one,your saying the balancer should bottom out on the crankshaft itself and not the oil slinger and gear set up?I might try installing with cover off to see where balancer is bottoming out,cant hurt I got air tools to make quick work of it.
Any more checks to perfom that I am missing anybody ?

 

[5-90]

I don't recall, but it sounds right. It might not hurt to do a "test install" of the damper with the cover off and turn the engine by hand to see if there is any interference between the crank sprocket and the block face. If everything is fine without the cover, it should be okeh with. Also make sure the front main seal is fully bottomed in its bore - I've seen a protruding seal cause funny noises once or twice in the last 20 years or so, now that I think about it...

5-90

 

[MACH90XJ]

Thanks I totally forgot about the damn seal I also replaced.It seats flush with cover or all the way down bottomed out in cover?

I appreciate the fresh insight on this problem,I've done my share of these kinds of things on my SB chevys without a hitch.I just figured it was a jeep thing that I was missing.

 

[5-90]

I believe "bottomed out" = "flush" - but I'll go more for bottomed out over simply flush. I always like to use some RTV around the rim to make sure the damn thing stays put until I pull it out the next time...

5-90