Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Curious Metal on Metal Sound.... Any ideas?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by cashew, Sep 8, 2003.

  1. cashew

    cashew Registered Member

    Joined:
    Sep 12, 2002
    Posts:
    11
    Likes Received:
    0
    Location:
    SF Bay Area
    Ok, so my '75 has been running really well for the past year or so. Fouls the plugs every now and then, but normally that only happens if I get lazy and run the cheapo gas. However, this past month, the truck has started to develop a strange scrapeing sound.

    Symptoms:
    Started with a barely audible light scratching noise while at idle in Drive. Put it into park or reverse, and the noise would stop. Drive, L2, L1 and Neutral all had the scrape. Checked the engine, tranny, and Tcase oil, all in good condition.

    The noise has now progressed to being in all gears, so I'm fairly certain it's not the transfer case. I only hear it in the morning, when I fire up the truck for the first time. By the time the truck is warmed up, the sound stops. It definately sounds like it is coming from the transmission/engine area, but that is just by listening in the cab and under the truck.

    No lack of power, no noticeable jumps in the tranny when it shifts, and no shimmy from anything seeming to be out of balance.

    Truck Details:
    1975 K5
    350, 4bbl carb
    TH350 Tranny, NP203
    Dana 44 front, 14 bolt corp. rear, Warn Hubs, 33's, stock open diffs front and rear (yech, got to fix that at some point)

    So, does anyone have any ideas? The motor and tranny and tcase are all stock original, so they have 250K miles on them so far. Getting pretty old, but if I can get an idea of where to look, maybe I can replace some parts, instead of the entire units.
     
  2. seanp

    seanp Registered Member

    Joined:
    Sep 3, 2003
    Posts:
    68
    Likes Received:
    0
    Location:
    S.E. KS
    On my 79 the motor mounts were shot causing the harmonic balancer to rub on the engine crossmember.
     
  3. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

    Joined:
    Feb 17, 2000
    Posts:
    7,385
    Likes Received:
    0
    Location:
    Atlanta
    [ QUOTE ]
    On my 79 the motor mounts were shot causing the harmonic balancer to rub on the engine crossmember.

    [/ QUOTE ]
    Same problem I had on my 75.

    Might want to drop the inspection plate and make sure the torqconverter is not coming loose. Looks for any metal dust in there as well. If the flex plate is cracking it usualy leaves some fine metal dust in the bellhousing.
     
  4. cashew

    cashew Registered Member

    Joined:
    Sep 12, 2002
    Posts:
    11
    Likes Received:
    0
    Location:
    SF Bay Area
    Good tips guys, thanks. I'll dig into it this weekend.
     
  5. Blue85

    Blue85 Troll Premium Member

    Joined:
    Jul 26, 2000
    Posts:
    9,082
    Likes Received:
    486
    Location:
    Grand Rapids area
    It's good to check every couple of weeks for imports stuck under your K5. Maybe that's your problem.
     
  6. cashew

    cashew Registered Member

    Joined:
    Sep 12, 2002
    Posts:
    11
    Likes Received:
    0
    Location:
    SF Bay Area
    Finally got some time to dig into the blazer, and sure enough, the harmonic balancer is barely scraping on the crossmember. SO, got an order in for some new motor mounts.

    Thanks again guys, this forum saves me money every day! /forums/images/graemlins/smile.gif
     
  7. mudjunkie 82

    mudjunkie 82 1 ton status GMOTM Winner

    Joined:
    Dec 27, 2002
    Posts:
    11,449
    Likes Received:
    0
    Location:
    Cleveland Ohio
    I would replace the tranney mount while you are doing the motor mounts
     

Share This Page