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knocking trouble

Discussion in 'Chevy Trucks' started by carl b, Jan 28, 2007.

  1. carl b

    carl b PlowSite.com Addict
    from Ohio
    Messages: 1,330

    My 90 2500 350 motor has a knock when it's in gear ! I'm lost, it's all gears, drive and reverse 2 or 4 wheel-drive It still runs and drives, but You can hear the knock a mile away. I took the front drive shaft off and no help. I have no clue what transmission is in it :dizzy:
     
  2. poncho62

    poncho62 Senior Member
    Messages: 431

    Its probably the engine if its doing it in all gears................Take a broom handle against your ear and put the other end on various parts of the engine.......THat should narrow it down. You could also take the belts off and try it...That would eliminate PS, alternators etc.
     
  3. carl b

    carl b PlowSite.com Addict
    from Ohio
    Messages: 1,330

    It only knocks when in a gear other than park or neutral, does that mean it could still be the motor? Thank you for the quick reply.
     
  4. poncho62

    poncho62 Senior Member
    Messages: 431

    When in gear, its under more load.........Also, check in the torque converter area of the tranny......

    Is it a ticking sound, or a lower knocking sound?

    Really hard to say, not being there...................
     
  5. Sydenstricker Landscaping

    Sydenstricker Landscaping PlowSite Veteran
    Messages: 3,882

    How many miles you got on that thing?? I know they did not start putting the 4L80E in the 2500's till 93 or 94. I am almost positive it is the TH700R4. This may be a dumb question, but is the oil really low?? It could be the flywheel is cracked and could be causing this. Or it could be rod knock or a valve tapping. Poncho could be on to something, it may be the torque converter is gonna take a dump real soon
     
  6. carl b

    carl b PlowSite.com Addict
    from Ohio
    Messages: 1,330

    it sounds like it's coming from the flywheel or torque converter area. one guy said the flywheel, but others say transfer case.
    it's a not like rods but a low knock.
    how would i check the torque converter?
     
  7. carl b

    carl b PlowSite.com Addict
    from Ohio
    Messages: 1,330

    75,000 miles oil is the first thing i checked
     
  8. Sydenstricker Landscaping

    Sydenstricker Landscaping PlowSite Veteran
    Messages: 3,882

    Well, when it is running and warm, check the trans fluid and see if there are any metal shavings in it. Usually that is a sign the converter is taking a crap. Also smell it to see if it has a burnt smell to it
     
  9. carl b

    carl b PlowSite.com Addict
    from Ohio
    Messages: 1,330

    it is burned up and brown. so i'll change it. (i'm letting it warm up now so i can check for chips) do you know how to check the flywheel with out removing the tranny
     
  10. Sydenstricker Landscaping

    Sydenstricker Landscaping PlowSite Veteran
    Messages: 3,882

    No I sure dont. I not exactly a trans specialist. I can help diagnose things and I have taken a transmission out and put in a new one. Never really gotten inside of one. Burned and brown, sounds like a transmission problem to me. Has it ever had a hard time going into gear or shifting gears while you are driving?
     
  11. carl b

    carl b PlowSite.com Addict
    from Ohio
    Messages: 1,330

    No just drove it a couple days ago shifts well, but it sits all summer .So it was put in use 2 weeks ago to plow.
    i'm going to pull the tranny tonight and look at the flywheel if thats not bad time to rebuilt
     
  12. poncho62

    poncho62 Senior Member
    Messages: 431

    All you can really do, is remove the tranny inspection cover, and have a look and see if you see any cracks in the ring gear. Has the starter been making funny noises lately?

    If the fluid is all burnt up, she no sound too good.
     
  13. Sydenstricker Landscaping

    Sydenstricker Landscaping PlowSite Veteran
    Messages: 3,882

    I agree with poncho, it may be time to rebuild. Hey since you are in Akron, I bet you arent too far away from Summit Racing. They have all kinds of stuff for transmissions and other goodies. Keep us posted on what you find
     
  14. Oshkosh

    Oshkosh PlowSite.com Addict
    Messages: 1,655

    Spoiled fluid...

    Brown and burnt would be internal issues,flywheel is external...Doesnt sound good.....
    GM and Engine knocks go back several years....Check out this article.
    My Blazer has a slight engine knock on startup and then I was told by several GM people that is "Normal"...Get that great GM Feeling....

    http://www.mightyautoparts.com/pdf/articles/otl0100.pdf
     
  15. DJ Contracting

    DJ Contracting PlowSite.com Addict
    Messages: 1,392

    The only time my 93" knocked that loud (and I mean it was loud) it ended up being a rear ring gear that tore out some teeth when I was trying to pull a heavy load and got stuck. Not trying to send you in a different direction but before you start replacing things have it checked out by a shop.
     
  16. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    If it's a 6 lug 2500 it will have a 7004R trans but if it's an 8 lug 8600 gvwr It'll have a turbo 400. You can remove the aluminum inspection cover from the bottom of the bell housing and see a good portion of the flywheel and torque converter if you want to look it over although the flywheel's usually break between the crankshaft bolt's and it's a little hard to get a good look that far in.
     
  17. carl b

    carl b PlowSite.com Addict
    from Ohio
    Messages: 1,330

    poncho62
    i don't think i won't to get in the tranny.. i don't have any know how on them so i'm going to a shop.:dizzy: my haynes book says only general repair and it sucks( i got more info here)

    thermos

    i walked to summit yesterday !!!!!!!!!!! they have the best video games there!!! it's my favorite store!!!!! i buy all my parts there and they now have oem parts

    Oshkosh

    that site was helpful but mine is not in the motor.:dizzy: i hope!!!!! (i also have a 94 that has always made the tapping sound wen cold)

    DJ contracting

    that wouldn't make noise wen stopped would it?


    thank you all for the replay at least i wont look like a moron to the tranny guy:dizzy:
     
  18. carl b

    carl b PlowSite.com Addict
    from Ohio
    Messages: 1,330

    It's the 8600 gvw with the factory engine oil cooler.. i paid $200 for the single core radiator
     
  19. B&E snowplowing

    B&E snowplowing Senior Member
    Messages: 159

    Ok here it is, I have a 1990 GMC 2500 4X4 I had the same knocking that you are talking about. IT IS THE FLYWHEEL. Heres what I did to confirm the diagnosis. I pulled off the metal flywheel cover, got a pry bar and pried the flywheel, then I turned the flywheel by hand (very hard to do) and kept prying all the way around,finally I heard a slight tick, so I made a mark on the flywheel, pulled the tranny, and holy crap, where the mark was on the flywheel, there was also a crack. Replaced the flywheel ( $200.00 CDN) and now the knock is gone.

    Hope this helps you out. Sorry I couldn't be of any help sooner.
     
  20. carl b

    carl b PlowSite.com Addict
    from Ohio
    Messages: 1,330

    it's done the flywheel was cracked $325.00 usd