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Discussion Starter · #1 ·
So... a few weeks ago I posted a somewhat ridiculous and vague query about a noise coming from the front of my '83 258 I6. Finally, I've made some progress.

I took the pully off the balancer, the noise persisted.
With belts removed, I then pressed my hand against the exposed part of the timing chain cover,(to the upper left of the balancer, below the alternator)THE SOUND WENT AWAY. I release pressure of my hand, the sound comes back.
I tightened a few timing cover bolts, the sound persisted, unchanged.

With this new development, any new thoughts on what the problem is and how I can remedy it?

Thanks very much in advance for reading.

Tim
 
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I remember the post....and Tim....thank you for posting an update....
So many times guys will come in here for help....and then disapear never telling us what ended up being the real problem....best way we can help people is for feedback like yours....

Ok...sounds like you are getting close....how does your harmonic balancer look? Is it wobbly? Any chance it is touching the timing chain cover? If they start to slid on the rubber (pending failure), they will frequently slid back into the cover. When you push on the cover, your pushing it away from the balancer...

You can also look down at it and compare its position with the other pullys....

Thats my best guess....
 

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Link.

That was my guess before. Loose timing chain slapping around. When you put your hand on the cover it muffled the sound.
 

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Discussion Starter · #4 ·
The loose timing chain theory seems more probable...Thanks Taz. Is checking the slack as simple as removing the cap and then turning the crankshaft and noting the movement of the the shaft in relation to movement of the rotor?
How much should the crankshaft turn before the rotor moves?

If a loose chain is the culprit...how do I go about changing it?(my manual disappeared YEARS ago...I don't usually miss it)
Do I need to replace the gears as well?
 

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[ QUOTE ]
The loose timing chain theory seems more probable...Thanks Taz. Is checking the slack as simple as removing the cap and then turning the crankshaft and noting the movement of the the shaft in relation to movement of the rotor?
How much should the crankshaft turn before the rotor moves?

[/ QUOTE ]
Yes, that is what you need to do to check it. LEVE should come along, he had a write-up on it.

[ QUOTE ]
If a loose chain is the culprit...how do I go about changing it?(my manual disappeared YEARS ago...I don't usually miss it)
Do I need to replace the gears as well?

[/ QUOTE ]
Manuals are cheap, buy another one. I keep 2, one clean one for reference before I get into it and one that's become greasy for reference in the middle of the job.

Basically, you remove everything that would prevent the timing chain cover from being removed. Then remove the timing chain cover. Then remove the timing chain, (3 bolts I think in the one on the cam). Get a new chain and a new cam sprocket at a minimum. Now you need to know how the marks like up. I think on the 258 they point at each other on a line drawn from the center of the crank to the center of the cam (On some you have to count links but I don't think so on the 258). If the chain is real loose, I would want to check the marks rather than use the "don't move the cam or crankshaft and you'll be alright" method.

You will also need a new gasket and I wouldn't put it back together without a new crankshaft seal.
 

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The Taz as I remember him (from when I signed on here)! Good advice, follow it, and all will be good. I think the last time I did a 258 chain...It was less than $100 for everything I needed, and 4 or so hours...
 

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I forgot to mention that since you haven’t done this before, you might want to line up the sprocket marks BEFORE you remove the old timing chain.

I don’t have any problem aligning the marks in the chain and then rolling the sprockets around in the chain to get them into position to fit the crank and sprocket no matter what position they were left in.

Put some grease or oil on the new chain at assembly to keep it lubed until the engine oiling takes over.
 

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Discussion Starter · #8 ·
Fantastic. Seems easy enough. I'm gonna seach for LEVE's write-up. I recall reading it a little while back. Hopefully, I'll be able to check the slack tomorrow.I'll be able to do the job next weekend if need be. I'm very excited to almost be rid of this noise, it has been present for at least 2-3years. I've replaced a lot of stuff trying to figure it out...I'll update soon.

Thanks again very much Taz, really nice of you to be so informative and helpful.
 

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[ QUOTE ]
I'm very excited to almost be rid of this noise, it has been present for at least 2-3years. I've replaced a lot of stuff trying to figure it out...I'll update soon.

[/ QUOTE ]

Don't get excited yet. With that 2-3 years, I'm beginning to doubt my diagnosis unless it isn't driven much.

And you are welcome if my diagnosis is correct. Otherwise, I've sent you on a wild goose chase but it's one more thing to eliminate.
 

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Checking slop of the chain -

By hand, rotate the engine in one direction - either way - till the marks line up on 0.
Watch the rotor while you turn it in the OPPOSITE DIRECTION till the rotor barely starts to move.
STOP!
Read the marks as to how much it moved without the rotor moving.

It's important to do the first step - rotating the engine first - transfers all the slop to one side.
Turning it back transfers it to the other side.

That's the total slop.

A new chain is 4-6 degrees.
at about 12 it's worn.
At about 18 it'll jump soon.
Above 18 -- quick, go to Vegas - you are very lucky!
 

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do yourself a favor because working over the top of the grill bites the bowango. cut and put in either a weather pak connector or some guarded blade connectors on the wire bundle heading to the grill. i did my connectors just in front of the horn. take out the grill and radiator and do everything right in front of ya. sure ya gotta drain the radiator, but its a whole helluva lot easier this way.

that wonderful bruise line across your chest just isnt all that fun getting or having.
 

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FYI, this might not work on the 2.5L since it has tensioners. If the tensioners are bad, it might show.
 

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Discussion Starter · #14 ·
I'm gonna have to check the chain slop this afternoon. I was planning on removing the radiator anyway for the chain install, as my puller for the balancer needs the etxra room for removal. All in all, I think I'd be able to replace the chain in 3-4hours(as soom as I can find the time) I just moved to Charleston, SC, so I ride my bike everywhere. I haven't even driven the rig in a a few days, so this matter can wait for a few days. You can be certain that I'll update as soon as I can get under the hood.
 

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Discussion Starter · #15 ·
I checked the timing chain today, I got a reading of about 12* before the rotor moved...6 notches or so...I'm going to go ahead and replace the chain this weekend. I'll update when I screw something up...
 
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Ya gotta love a guy who is honest about their confidence.........

Just remember....We all learn by our mistakes....that's why we are all so bloody smart.....
 

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Discussion Starter · #17 ·
To follow up on my issue:

I replaced my timing chain and both gears a few days ago.
The mystery idle noise went away. However, I still hear a similar hollow noise between 1500-3000RPM. It sounds like the same noise, just a faster rhythm.

The rig runs fine I suppose, not really much different with the new chain, maybe a bit smoother accelaration, smoother idle...nothing really special though.

Why would the new chain still make noise?
I adjusted the timing a bit...I've got it set a 8*, but it seems like it ran better when it was advanced to 12*-14*

I think I'm leaking some oil where the timing cover meets the oil pan, so I'm may remove the timing cover again in an attempt to re-seal it, this time properly. (i'm incredibly free this weekend...) I replaced the front crankshaft seal, but I have a one piece rubber oil pan gasket, so i didn't use the replacement front oil pan gasket supplied.



Tim
 

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[ QUOTE ]
I replaced the front crankshaft seal, but I have a one piece rubber oil pan gasket, so i didn't use the replacement front oil pan gasket supplied.

[/ QUOTE ]
USUALLY, you cut the old oil pan gasket even with the front edge of the bottom of the block. Strip off the old gasket forward of that cut and install the new "patch" piece.

Were there marks inside the timing chain cover where the old chain had scraped against it?

A new chain could make some noise while it "wears in". How loud is it?
 

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Discussion Starter · #19 ·
I was gonna patch the new peice on there...put the one that was in place was looked so nice...(and it had just started raining...) I've a got whole weekend to learn a lesson.

I inspected the cover, much to my chagrin, I couldn't find any distinct marks from the chain....veird.

When accelerating, the noise is about as loud as a rattling catalytic converter heat shield. I thought it was maybe my alternator, so I removed the belt....noise still there.

I'll remove the water pump/ps belt next, to eliminate that.

Can we assume that I put the chain on correctly, as the rig is running perfectly(relatively) fine?
 

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be carefull running it w/ no water pump...

id suggest getting a mechanics stethoscope and listen around for the sound
 
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