noise from piston rods (video) & advice on what to do... - JeepForum.com
 
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post #1 of 7 Old 04-04-2009, 03:08 PM Thread Starter
Matt Graham
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noise from piston rods (video) & advice on what to do...



So I finally dropped the oil pan to replace the gasket & see if I could find the knocking noise from the bottom end and I found the source of the noise...It is the end of the piston rod that attaches to the crankshaft. I can grab the rod cap and wiggle it side to side. I believe all but one of them will wiggle like that. Here is a video of what it looks like:

[YT]x1p2RYwtgLU[/YT]

The quality of the video isn't that good, but what is happening is the rod is sliding left and right on the crankshaft journal maybe 1/16" but there doesn't appear to be any up and down movement or play from the rod on the crankshaft.

So how do I determine if I just put it back together or replace the rod bearings...or go ahead & start the dreaded rebuild? I've never used plastiguage since high school shop class & can't remember how to use it to check...Advice???


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post #2 of 7 Old 04-04-2009, 03:16 PM
df19087
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If you have that much play side to side I would imagine it has some play up and down too. Sot sure if you have to rebuild or jusr replace rod bearings though
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post #3 of 7 Old 04-04-2009, 04:26 PM Thread Starter
Matt Graham
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alright yall here is another video.

[YT]eXYj5aPBe-8[/YT]

All of them do this and I also can see that if I grab the rod cap & try to twist it, I can see the piston head move about 1/16" to 1/32", just barely moving. I've tried to move it up & down to see if there is any play that way and I can't identify any up & down play, just the side to side movement.

Is this amount of play normal for a motor w/ 145,000 mi? I don't really have money to spend on it right now, but I do already have the transmission out & everything.

Put it back together & drive it?
Replace the rod bearings?
Pull the motor & rebuilt it?

I need someone who knows what they're looking at to look at it & advise me on what to do...any help?

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post #4 of 7 Old 04-04-2009, 05:06 PM
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I can tell you that the manual wil have the specs on side to side clearance. Yours sounds HIGH.
Connecting Rods
Total Weight (Less Bearing) . . . . . .657 to 665 grams
(23.17 to 23 .45 oz.)
Length (Center-to-Center) . . . . . 155.52 to 155 .62 mm
(6.123 to 6 .127 in.)
Piston Pin Bore Diameter . . . . . . .23.59 to 23 .62 mm
(0.9288 to 0.9298 in.)
Bore (Less Bearings) . . . . . . . . . . .56.08 to 56.09 mm
(2.2080 to 2.2085 in.)
Bearing Clearance. . . . . . . . . . . . .0.025 to 0.076 mm
(0.001 to 0.003 in.)
Bearing Clearance (Preferred) . . . .0.044 to 0.050 mm
(0.0015 to 0.0020 in.)
Side Clearance . .0.25 to 0.48 mm (0.010 to 0.019 in.)
Twist (Max.) . .0.001 mm per mm (0.001 in. per inch)
Bend Max.) . .0.001 mm per mm (0 .001 in. per inch.)

I will try my best to only answer what you ask.
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post #5 of 7 Old 04-04-2009, 05:19 PM Thread Starter
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here is what I'm thinking...I don't want to spend $150 on rod bearings and put a band-aid on the problem. If I'm going to spend some $ I want to do it all, and right, which pretty much means $1000+ rebuild. Since I don't really need to spend that kind of money right now and my oil pressure has been normal, I'm thinking I should just put it all back together and wait for it to have to be rebuilt. Maybe I'll get lucky and I can get another year or two out of it and then spend the money and rebuilt it all... and do it right...

Anybody else want to chime in???

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post #6 of 7 Old 04-04-2009, 07:28 PM
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I would install a new set of rod bearings and a new oil pump along with a rms while it is open.
New bearings are cheap.
http://cgi.ebay.com/ebaymotors/AMC-J...Q5fAccessories

You will have to determine what size you needstandard, 10 under etc.
Could be a cheap fix or you may find that it is worse than you thought but at least you will know.

Dwayne
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post #7 of 7 Old 04-04-2009, 07:57 PM
laybackman
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Quote:
Originally Posted by 4.7stroker View Post
I would install a new set of rod bearings and a new oil pump along with a rms while it is open.
New bearings are cheap.
http://cgi.ebay.com/ebaymotors/AMC-Jeep-Rod-Bearing-Set-3-8-4-0-4-2L-1964-90-BB612J030_W0QQcmdZViewItemQQ_trksidZp3286Q2em20Q2e l1116QQhashZitem290298556735QQitemZ290298556735QQp tZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

You will have to determine what size you needstandard, 10 under etc.
Could be a cheap fix or you may find that it is worse than you thought but at least you will know.

Dwayne
I agree. A rod or even a main bearing swap out is quite doable as long as you see no deep scarring on the rod journals or the crank. I would go with std size bearings UNLESS this crank has already been turned down before. They have #'s on them. Keep in mind that the bearings are a sacrificial item in the lower end of an engine.
Do the RMS, and think about doing a new oil pump also along with the bearings.

Before you do the tear down, warm up the engine, shut it down add one qt kerosene to your oil, fire her up and let it run for 5 minutes AT IDLE. Shut her down let it drain well.Then dump the base and do your lower end work.

You can clean up the crank if it has minor scarring with crocus cloth. Do it wet not dry.

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Last edited by laybackman; 04-04-2009 at 07:59 PM. Reason: more information in red
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