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.

Transmission Flushing

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Casey 86K5, Aug 18, 2000.

  1. Casey 86K5

    Casey 86K5 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    119
    Likes Received:
    0
    Location:
    Brownsburg, Indiana
    I am wanting to flush the fluid in my daily driver truck ('79 C-10), but I am confused as to what to do. If you can believe it the transmission has 234,000 miles on it and I was told by a friend that if I flushed it the transmission would fail becuase it was so old and had so many miles on it. Is this true? Although the transmission shifts fine and does not leak, the fluid has an orange color to it and I would like to clean all of that old fluid out. I cant afford to have the tranny rebuilt right now (the K-5 is getting all the $$$). Please help!
    thanks Casey 86K5
     
  2. 90K5

    90K5 1/2 ton status

    Joined:
    Jun 1, 2000
    Posts:
    3,719
    Likes Received:
    0
    Location:
    Lubbock, TX
    That doesn't make much sense but I dont know much about that. If I were you I'd just get the cheapest ATF I could find take the pan off and run a few quarts thru it. You could als ochange the fluid, drive it around and change it again, but if it works ok now just change the fluid and leave it.

    90K5
     
  3. coopertwpk

    coopertwpk 1/2 ton status

    Joined:
    Mar 18, 2000
    Posts:
    478
    Likes Received:
    0
    Location:
    Spring Valley Lake Ca.
    Pay an oil change place to do it ,its a messy job .To do it your self you need about 2 gals of atf and 2 5 gal buckets ok detach your upper trans cooler line that is the suction line add a hose to this into the new atf now add a barb fitting into the cooler and add a hose to this to dump the old atf start the motor it will siphon out the new and pump out the old and most likely blow atf all over the place but at least it will be the dirty atf on the garage floor and inside the engine compartment the pretty red will be inside the trans.
     
  4. 78Blazer

    78Blazer 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    873
    Likes Received:
    0
    Location:
    Michigan
    DO NOT DO IT.. I used to work at a oil change place and we used to do this. If the fluid in your vehicle was not changed regularly all of its life this is not a good move. What happens is it will actually clean all the buildup and varnish up off of the gears that have built up over the years and will actually cuase you transmission to start to slip. We would not perform this on any vehicle that had over 100,00 miles and fluid was not changed regularly withougt the customer signing an agreement that we were not responsible for it. Yer better off to leave the fluid thats in it and run her till she dies..



    Scott
    78blazer
     
  5. MudRebel350

    MudRebel350 1/2 ton status

    Joined:
    May 20, 2000
    Posts:
    324
    Likes Received:
    0
    Location:
    N.J.
    I agree with 78blazer. I know 3 people that had the fluid changed in there trans and they all started to slip. It is not a wise move if it was never changed before. the cars were an 86 delta 88, 86 buick century, and a saab. even though none are a c10 it still applies.

    JD
    88 Gmc Jimmy
     
  6. dumbfounded

    dumbfounded 1/2 ton status

    Joined:
    May 20, 2000
    Posts:
    176
    Likes Received:
    0
    Location:
    Castalia, NC
    What they said is true, but I'd just do a normal pan change. Putting a new gasket and a filter plus the couple of quarts shouldn't hurt. But the guys who worked at the oil change place would be the ones to listen to. I think a new filter would be a good idea though. I've never had good luck with Auto's they don't last for me except my 95 camaro with the 4L60E which has almost 140,000 on it. It needs a rebuild only because one of the internal seals on the pump leaks by internally and causes slow shifts and no lockup when hot other than that it's ok and this has been occuring for about 85,000 miles and still going. And it was a chevy dealer who said it was a pump seal not a worn tranny (believe that), but either way it needs to be rebuilt so I guess it didn't matter what they said. I'm going to rebuild my K5's TH350 by my self and maybe progress to a 4 speed auto, who knows.

    Love, Peace, and Hair Grease...........
     
  7. BlazerGuy

    BlazerGuy 3/4 ton status

    Joined:
    Apr 20, 2000
    Posts:
    9,206
    Likes Received:
    0
    Location:
    abcde
    Would that happen to a trans that has about 70,000 miles on it. I dont think it has ever been changed, just fluid added to it.

    [​IMG] Sept 1
     
  8. 78Blazer

    78Blazer 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    873
    Likes Received:
    0
    Location:
    Michigan
    Blazerguy

    It all depends on how your fluid looks if it is real burnt then its probably not wise to do the flush. Just drop the pan. If it does not look to bad you may be ok. But in my opinion why take the chance????? They ran for years before with out the flush system so why switch now.. I know alot of people who have had problems with slipping trannys after the flush. Dropping the pan and changing filter and gasket very rarely causes this problem..

    Scott
    78blazer
     
  9. Casey 86K5

    Casey 86K5 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    119
    Likes Received:
    0
    Location:
    Brownsburg, Indiana
    Thanks for the help. i guess i wont be flushing it, but i will change the filter. I am pretty sure the fluid has been changed it in at least once or it probably wouldnt have lasted this long. I just hope the tranny will last through the winter.
     

Share This Page