sporadic knocking noise
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sporadic knocking noise
Posted: October 09 2007 05:50 AM
 
Justin Hearn (aka Swb360) [ View ] [ Email ] [ Car Ads ] [ Blogs ]
San Antonio, Texas
 
I have an '86 Dodge p/u with a 318/904. recently (gradually getting worse) ive been hearing a sparatic knocking sound coming from what sounded like to be in the oil pan. almost like a broken rod or a chunk of metal getting tossed around. i dropped the pan, checked all the upper/lower rod bearings, main bearings, rods, piston pins, journals, and cut the oil filter open and checked the gears in the oil pump. to find nothing wrong. so i went aft to the transmission flexplate to find that the four bolts holding it to the TC were about hand tight, and one one bolt hole, it was cracked in two areas, which elongated the bolt hole itself. it knocks worse when i have it in drive than in park. tends to go away when i rev it, shakes the truck when i put it in R, and has a tendency to kill the engine, which is weird. does anyone know what could be causing this??? im really hoping its just that lose flexplate situation/crack....... i appreciate ANY help
 
 
 
Comments
 
Posted by BigAlBre  -  10/09/2007 06:00 AM
The flexplate is where I would start you know it's not right... I had a loose flexplate in a 57 ford years ago and it sound awful.... cost me the price of another flexplate and a case of beer to fix it... course I was 19 then and could do anything.... hehehe
Big Al sittin back in paradise. [ View ] [ Email ] [ Blogs ] [ Car Ads ] St Pete Beach, Florida Charter Member since June 1999
 
Posted by Swb360  -  10/09/2007 06:05 AM
haha. yeah i bought a new one for $8.99... figured i might as well change it out 'while we're there'... and the fact that it has these little cracks. im actually only 22 myself... still going through the "learning phase" of all this. its a lot of fun though, gotta start somewhere thanks for your quick response btw
Swb360 [ View ] [ Email ] [ Blogs ] [ Car Ads ] San Antonio, Texas
 
Posted by tlp1968  -  10/09/2007 03:17 PM
I have heard the weirdest noises coming out of bad flexplates. Replace it - bolts and all and make sure you get that impact on them this time. Should be able to do it by swinging the engine back away from the tranny but you know I am a Chevy gal so better let a Mopar person chime in on how best to get this done with the least amount of trouble.
StreetRodding.com Marketing Director [ View ] [ Email ] [ Blogs ] [ Car Ads ] Springfield,, Illinois
 
Posted by brian41chevy  -  10/09/2007 03:49 PM
Pull the trans, replace the flex plate, torque the bolts back in, reinstall.
There is a fine line between hobby and mental illness [ View ] [ Email ] [ Blogs ] [ Car Ads ] New Lenox, Illinois Charter Member since November 2004
 
Posted by hotrodgene  -  10/09/2007 05:43 PM
I agree with the flex plate fix but if noise is still there remove the front damper and inspect for a crack in key way.These engines were known for this problem.Having been a service rep. for Chrysler in 70's I saw a few of these.
Thanks,Gene [ View ] [ Email ] [ Blogs ] [ Car Ads ] Saint Petersburg, Florida
 
Posted by tlp1968  -  10/09/2007 06:03 PM
See I knew we would have a Mopar guy for the answer
StreetRodding.com Marketing Director [ View ] [ Email ] [ Blogs ] [ Car Ads ] Springfield,, Illinois
 
Posted by robymarks  -  10/09/2007 10:23 PM
What Brian said. It sure sounds like the flex plate.
robymarks [ View ] [ Email ] [ Blogs ] [ Car Ads ] Houston, Texas Charter Member since October 2005
 
Posted by Swb360  -  10/09/2007 11:30 PM
i appreciate the quick responses. would this flex plate moving around put strain on the crank and cause it to load the engine.. stalling it out? thats what was getting me, was the fact that the engine would die .. almost like it was under a hard load, which is why i though.. hmm bearnings? bad rod... but even oil psi is good. (considering the gauge/sending unit works haha) .. but its showing right in the middle, right at the normal range for the 318s
Swb360 [ View ] [ Email ] [ Blogs ] [ Car Ads ] San Antonio, Texas
 
Posted by JAWS  -  10/10/2007 04:05 AM
I meant to add this earlier, the knock sensor is "hearing" the noise also and is instructing the PCM. In turn the PCM is compenstating for the believed predetonation and is therefore retarding the timing as well as richening the fuel. The knocking is still there despite the efforts of the PCM and it continues to compensate till it stalls out.


Sounds like the rest of the team is correct on the flexplate/loose converter. That would be my guess, without "hearing" it myself as with them too, I'm sure.


-Brant
An electrical headache can make a great car a pain [ View ] [ Email ] [ Blogs ] [ Car Ads ] Boise, Idaho Charter Member since August 2004
 
Posted by JAWS  -  10/10/2007 04:07 AM
Of course if your '86 is still carburated.....................but, I don't think so, maybe.......????
An electrical headache can make a great car a pain [ View ] [ Email ] [ Blogs ] [ Car Ads ] Boise, Idaho Charter Member since August 2004
 
Posted by robymarks  -  10/10/2007 12:40 PM
I believe all 86's were carbs . I am not even sure that year had the knock sensor yet.
robymarks [ View ] [ Email ] [ Blogs ] [ Car Ads ] Houston, Texas Charter Member since October 2005
 
Posted by ol bear  -  10/10/2007 05:09 PM
sparatic u say ?? just a thought ,may be the fly wieghts in the distributor r hanging up .maycause to much adance to soon ,ol bear
OL BEAR [ View ] [ Email ] [ Blogs ] [ Car Ads ] crown point, Indiana
 
Posted by brian41chevy  -  10/10/2007 06:10 PM
Justin don't get ahead of yourself. Fix what you know is broken first and then go after your other problem
There is a fine line between hobby and mental illness [ View ] [ Email ] [ Blogs ] [ Car Ads ] New Lenox, Illinois Charter Member since November 2004
 
Posted by Swb360  -  10/11/2007 05:38 PM
this truck came stock with a 318/2bbl carburetor but i put on a dual plane intake, and a holley 600cfm 4 bbl. fuel injection came stock on these trucks in 1990 i think? anyway... the distributor is stock with the electric ignition. i'm putting the transmission back together with a new flexplate today and bolting the oil pan back up today. i'll post later in the evening to update on that knocking sound after i fire it up. thanks again for all of the help =)
Swb360 [ View ] [ Email ] [ Blogs ] [ Car Ads ] San Antonio, Texas
 
Posted by Swb360  -  10/15/2007 05:00 AM
well come to find out.. it WAS the flexplate knocking around!! that was an easy fix. time to set timing and tune it all up thanks again for yalls help, i really appreciate the responses and feedback. =)
Swb360 [ View ] [ Email ] [ Blogs ] [ Car Ads ] San Antonio, Texas
 
Posted by young mopar  -  04/25/2008 06:49 PM
prolly whats wrong with my 77
young mopar [ View ] [ Email ] [ Blogs ] [ Car Ads ] waco, Texas
 
Posted by Red's Place Custom & Restoration  -  04/25/2008 07:31 PM
if the flex plate is loose then the torque converter will move around and cause what is caused torque converter lock up not like an overdrive unit but more like a bind and yes it could stall the engine it could also and probably has damaged the trans. I would take the trans out inspect to torque converter for scares or nicks and then replace the flexplate good luck
Red's Place Custom & Restoration [ View ] [ Email ] [ Blogs ] [ Car Ads ] Charlotte, North Carolina
 
Posted by Red's Place Custom & Restoration  -  04/25/2008 07:32 PM
sorry just noticed the date on this my bad followed someone else
Red's Place Custom & Restoration [ View ] [ Email ] [ Blogs ] [ Car Ads ] Charlotte, North Carolina
 
Posted by bigdude  -  04/25/2008 07:56 PM
Its probably -not prolly---- jeesh!
resident know it all [ View ] [ Email ] [ Blogs ] [ Car Ads ] Three Rivers, Michigan Charter Member since January 2004
 
Posted by 37tin  -  04/25/2008 08:43 PM
And I thought it was jheesh--he he!!! your turn.......
37tin [ View ] [ Email ] [ Blogs ] [ Car Ads ] langley, Canada
 
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