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TH350 transmission

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dasanii19, Nov 20, 2006.

  1. dasanii19

    dasanii19 1/2 ton status

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    I dont know if I should go all out and get my transmission rebuilt quit yet, it shift fine, the only thing Ive noticed is that it takes a little time going into reverse, and sometimes, not all the time reves up high in reverse with hardly any movment.

    Im thinking maybe If I change the filter and transmission fluid that might help? Im not a transmission mechanic but would like to hear the somewhat simple things I can do on my own before paying out and getting it totally rebuilt at a shop, maybe I dont need it rebuilt quite yet? The only things I have in mind are, a new torque converter, change the filter and tranny fluid, and of course new gaskets. what else?
     
  2. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Try fluid and filter change first for sure. A bit of maintenence never hurt!
     
  3. imiceman44

    imiceman44 1 ton status

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    Do the filter and fluid change first, don't change the TC it won't help your reverse problem.
    I had this problem and drove it for a few years before I did fix it, reverse is usually a problem because many will rebuild the forward and forget about the reverse, I even did that mistake with my first rebuild.
    When you put it in reverse wait a few seconds then slowly give it some gas, most times it will live a little longer before it goes completely.
    :eek1:
     
  4. BKinzey

    BKinzey 1/2 ton status

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    Of course use the opportunity to check out the sludge at the bottom of the pan and on the screen. It should feel like graphite. The more chunks you can feel the greater cause for concern;) Certainly if you can identify the pieces, like ball bearings, springs, teeth, etc.:eek1:

    There is something to be said about the amount of sludge but I don't know what is too much. More than a shot glass? A Hi-Ball or a Beer Mug?:laugh:
     
  5. dasanii19

    dasanii19 1/2 ton status

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    Thank you!!

    So whats the best way to clean all the sludge from the pan and screen?

    Also what transmission fluid should I put in it after I get it all clean and the filter changed? any special filter I should use?

    Last but not least, what gasket should I buy? is there a pattern I should follow while tightneing the bolts to the pan back up? what should they be torqued at?


    Oh yea, is there a trick to pulling the pan off? I dont have a lift, ill be working under the truck on the ground. Ive never done this before so I dont want to drop tranny fluid all over my face..
     
  6. dasanii19

    dasanii19 1/2 ton status

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    Ok here is another thing. I'm not even sure this is a TH350 transmission. is there a way to find out? I'm new to this truck as I just bought it 3 weeks ago.. I'm just surmising its a TH350

    I have to install a new Torque Converter, the one that's in the truck now the bolt mounts have broke off of it, im talking about the mounts that the fly wheel bolts to.

    So how do I figure out what Torque converter to get? Should I just pull out the old one and go by that? or should I upgrade to something better? how d I figure out what TC to upgrade to if I don't know what kind of tranny is in it?

    I know I have alot of questions but please help me out.
     
  7. imiceman44

    imiceman44 1 ton status

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    Well the th350 is easy to ID: the pan is a square with one corner cut.
    If it's a full square, it's the 700R4
    If it's an odd shape on the back of the tranny and square at the front it's a th400.
    I will try and find a post that shows the pics.
    To clean the sludge of the bottom of the pan, gas will work or Brake parts cleaner.
    Use a GM filter, is what I say, there might be better but they are good enough.
    As for fluid use any DEXTRON MERCON III ATF, I get the Chevron because it's the cheapest here.
    To get the TC once you know which tranny you have just ask for a stock replacement.
    Here you go:
    http://www.technicalvideos.com/identify_my_transmission.phtml
     
    Last edited: Nov 21, 2006
  8. dasanii19

    dasanii19 1/2 ton status

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    Very helpfull, thanks again
     
  9. BKinzey

    BKinzey 1/2 ton status

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    I bought a portable fuel / oil pump from Northern Tool it's 12v and works great! Got clear hose from the local hardware store and ran it down the tranny fill tube. No tranny fluid on me!

    You can get a $15-$20 hand pump from your local auto parts but it's just not as easy and tiring. If you do go that route do it while it's warm. It will be thinner and A LOT less effort to pump:bow:
     
  10. dasanii19

    dasanii19 1/2 ton status

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    well I actually had a little time to look at the truck this weekend, the tranny fluid was low 2 1/2 qts!!! The motor oil was low 2 1/2 qts as well. I topped everything off and tightened the tranny pan bolts, oil pan bolts, valve covers bolts and cleaned the K&N air filter. Im thinking the low fluids might have had something to do the reverse problem I was having. I cant test it because my seats are out of the truck right now. (ive had the truck for 3 weeks, it wasnt me that didnt keep the maintenance up) :D

    What do you guys think, 2 1/2 qts low on transmission fluid could be a problem right? "reverse" "shifting properly" all that stuff right? I hope so, that means im going to save $600+ $$$$$$
     
  11. imiceman44

    imiceman44 1 ton status

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    Being low 2 quarts will definitely not be good, hopefully that is it.
     
  12. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Yeah that's plenty low enough to cause problems.
     
  13. dasanii19

    dasanii19 1/2 ton status

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    Im about to change my tranny fluid and filter, If I dont use the pump method do I still need to warm up the tranny fluid? my truck cant be driver right now and I know this might be a very dumb question but can I even warm up the tranny fluid by letting the truck just idle?


    If I am very carefull pulling the pan off with the tranny fluid in it, it is possible I can get it down without dumping it everywhere? Should I just invest in some sort of pump?

    Any tips please, I am about to go work on this right now.

    Thanks
     
  14. dasanii19

    dasanii19 1/2 ton status

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    Ok got the pan off with a little mess...

    Questions questions questions...

    First off the tranny fluid was pretty black...


    This first picture is of the bigger peices of metal I found in the bottom of the pan, other then this I saw alot of little tiny metal shavings. Is this normal wear or should I be a little more concerned? The picture probably enhances how big the peices really are, so keep that in mind. What are they from?

    [​IMG]


    This second picture is of the whole underside of the tranny showing the filter, my questions are, do I need to check anything or tighten any of the bolts I see in here? Is this a factory filter?

    [​IMG]


    Here is something I noticed that wiggled somewhat freely, what is it and should it be moving?

    [​IMG]

    Anything that you feel I shoiuld check/maintenance/tighten Id really like to hear about it so please add your 2 cents..
     
  15. dasanii19

    dasanii19 1/2 ton status

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    Not to avoid the questions above but, as for a new gasket and filter, I only see two options for my TH350 which look exactly the same on summit racings website, do you know what the differences are between two? and which one should I get?

    FRM-FT1021

    FRM-FT1021-01

    also, do I just put the gasket on by itself or do I add a sealant on as well?
     
    Last edited: Mar 29, 2007
  16. imiceman44

    imiceman44 1 ton status

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    I don't see a difference but they say one is for th350 and the th350 C which is lock TC
    the other says th350 and th375 which is the HD th350 so they should be both the same.
    :rolleyes:
     
  17. slider

    slider 1/2 ton status

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    Never add sealant to a gasket. You can glue it in place with some hi tac or gaskasinch. Never use silicone on a gasket. The two filter sets look the same to me, but they might use the same pictures.
     
  18. dasanii19

    dasanii19 1/2 ton status

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    Should I go ahead and get a new transmission pan while im at it? If so ive been looking at them on summits page and they have a buch of options like, drain plug? no drain plug? capacity increase? aluminum?

    I probably dont want to spend over $50 on one but thought id see what you guys thought first before I bought one..
     
  19. imiceman44

    imiceman44 1 ton status

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    If you have money to throw at it the aluminum pan is better because it helps cooling has bigger capacity and a drain plug.
    But I don't think it is only $50.
    If you want to do something cheap and usefull, add a drain plug to your pan.
    I believe Summit has a kit for that and it's cheap.
     
  20. dasanii19

    dasanii19 1/2 ton status

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    I meant black RTV not silicone. Sorry.. I use that stuff with my gaskets on my thermostat gasket front and back rear end covers etc.. thats why I was asking if people use it on a tranny pan as well..
     

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