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Crap.. Need Trans help.

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by talison79, Oct 15, 2001.

  1. talison79

    talison79 1/2 ton status

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    I need some input. Good guesses are appreciated also. The other day I noticed the engine losing power just before shifting into third. Today I realized that the transmission was slipping when shifting to third. Its not the engine. It shifts fine from first to second and reverse. Tonight I cant get it to shift into third for nothing. I have checked out all the vacuum lines and fluid looks good. Before yesterday I have not had any problems. I wouldn't think a modulator would go bad just all of a sudden. Its a 79, th 350 behind a stock 350 with 203. Anybody got any ideas, I'm sure someone has had the same problem before. I couldn't find anything with a post search. Is it time for a rebuild?
    I bet I have upset the Chevy gods by doing the F*&d shock tower install last weekend.
    Thanks for any help,
    Talison79
     
  2. BrianK5

    BrianK5 Registered Member

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    I'm not an expert, but I'd say it's due for a rebuild. I had a Cutlass with the TH350 and it would only drive in first! I checked into a rebuild and found a place that would do it for around $400 if I brought the tranny in myself. I ended up selling the car before I got it rebuilt, but I hope that helps you out a little.

    Brian

    1985 K5 Blazer
     
  3. newyorkin

    newyorkin 1 ton status

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    Yeh, modulators can go like that... How'd the fluid look? Brown and toasty at all?

    Might just be that time...

    Ratch
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  4. EDdaTREE

    EDdaTREE 1/2 ton status

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    First I would run a new piece of vacuum line to the modulator..you might have a pinhole in the old one. If no change in shifts..next change the modulator, fairly cheap and easy. Did ya try shifting it manually with the shifter? I think Muddin4Fun did that and it finally fixed after a day. Musta been some debris in a valve or something. Good Luck and keep us informed.

    9/11/01..Never forget...Never forgive
     
  5. talison79

    talison79 1/2 ton status

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    Yea I thought it might be a vacuum line also, that's the first thing I did was replace them, but still no luck. I tried shifting manually but it just wont go into third gear. Does an auto trans go bad like that with no warning? The fluid looks good. I just bought a shift kit to put in it last week and its still sitting on the shelf. Always something.
    Talison79
     
  6. Tatman

    Tatman Registered Member

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    I had the same thing happen to me a couple years ago....as mentioned before, changed vac line, mod, fluid filter.... tried all the inexpensive fixes.... ended up buying a rebuilt tranny. Was told the same thing... sometimes Modulator or clogged filter can cause this problem. So I'd suggest going thru the paces and find out if one of these is the cause before dishing out the bucks for the rebuild. You may get luckier than I did.

    Brian
    <a target="_blank" href=http://www.saddletramps.com/BlazerK5.htm>www.saddletramps.com/BlazerK5.htm</a>
     
  7. talison79

    talison79 1/2 ton status

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    Well the problems found so far. Pan was full of all kinds of crap . both the valve body and separator plate gaskets are cracked with pieces missing . Thus the crap in pan . Both filters were blown out.
    I changed the filter and fluid about 4 thousand miles ago and all looked well. I hadn't pulled the valve body before, but let me tell you, there are all kinds of areas that gunk accumulates. Every one should take a day to open up the bottom end and check everything out, because you can't tell what's going on by the fluid alone. Trust me. I'm putting it back together now so everyone cross your fingers.
    Talison79
     
  8. Blue85

    Blue85 Troll Premium Member

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    That's what I was going to suggest. Pull out the valve body and clean it thoroughly. Pull out one valve at a time and write down or draw a picture of how it came out so that you can put it back the same way. Check to make sure that every thing glides like butter. If a valve isn't smooth, polish the parts with some 400 grit sandpaper. Clean everything off good with brake parts cleaner. Then you can do your shift kit at the same time and just use the gaskets that came with it. But if you have some new symptoms, you won't know if it's because of the shift kit or the old problem.

    I say this because a clutch in the tranny usually won't just give out all at once, but any kind of debris in the valves will make it start working strangely immediately. A full rebuild is only needed when a clutch needs replacement or a part has fragged and sent junk through everything. The debris you describe may just be friction material. That isn't too bad to get in the planetaries or the clutches, but it will clog up the valves pretty bad. The only other thing that could be screwed up is the oil pump, but to get to it you have to remove the tranny or at least move it back, which is nearly the same work.

    <font color=green>Does a Dyslexic Insomniac Athiest lay awake at night wondering if there's really a Dog?</font color=green>
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Just for the heck of it, pull the governor and clean it off thoroughly. (and inspect it) Stuck governor can prevent upshifts...I've had it happen in 2-3 shift only as well.



    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</a>
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  10. talison79

    talison79 1/2 ton status

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    Man do I have some bad mojo going on. I got the valve body and everything cleaned up real good, blew out the trans cooler lines. Replaced vacuum lines, modulator, all filters, and installed shift kit.
    Well I got it all back together and test drove it. I went to get some gas. As I pull in, the blazer smells like it's on fire so I shut it down and jump out to look under the hood , nothing. I get back in the cab and the dash is smoking like mad. The cigaret lighter is melting down so I use some pliers to pull it out. Now, one would think it was a short, but it wasn't , the wires are fine. Then after that was over the truck was completely dead, still thinking short, but the positive lead was corroded inside the jacket. I finally got power back and my alarm starts going nuts and won't shut off. To beat all that, the trans now shifts into third but is slipping from first to second now, and the shifts that are supposed to be firmer are so light you can hardly tell its shifting. I must have missed something.
    Hey Blue85, I don't think it was friction material. This was pretty good sized chunks, but they would break up. I though it could be gasket material.
    A word of advice don't work on the trans when you have not had any sleep since Sunday. It goes really slow.
    What is up? I have hardly had any problems with this thing before. I must have gotten solowookies luck! Just kidding my lucks not that bad... LOL I can't drive it anyway, the smell of burnt plastic is so bad it makes me sick! Sorry for the long rant.
    Thanks for the help guys.
    Talison79
     
  11. BorregoK5

    BorregoK5 1/2 ton status

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    I can relate completely! I drove out a 130 miles to meet up with Andykhimanic this last Saturday and noticed for the first time that I was running a little hot going up hills. I've had a slushy second to third shift since I purchased the truck a few months ago ('79 k5 350ci / th350 / np203) but blew it off as having big tires with tall gears. My reverse always seemed fine but thinking back it tended to rev a little higher in reverse than it would engaging first gear. Anyhow, I noticed what seamed to be a small decrease in power a few weeks before but had blown it off as my imagination, big mistake. I was pulling out another truck with a tow strap when my fluid got hot enough to spit out the dipstick into the engine bay... by this time what was a wearing trans was now in the post toasty category. I still had reverse but lost first and second. After a tow, a few hours sleep and pulling out / apart the trans, I can make a safe wager based upon what you've said on your tranny as to what’s going on. First of, all that crud in your engine, while settled in the pan and before the filter, had to first travel through your system before getting there. That’s most likely clutch disk material, which sheds off the disks over time. If your tranny gets hot or exhibits slushy shifts you can get a glazing effect on the disks which contribute to heat and more slippage. This gets pumped out to the pan but does run through the disks on the way causing more wear. The smaller particles can get in between the bearing surfaces on the main shaft and cause damage as well. Heat is the number one enemy of your automatic trans, if your rig is/was like mine, then you were using the stock trans cooler built into the radiator. If your in cold climate then I would add an external B&amp;M trans cooler in series with it, or in hot weather just eliminate the radiator cooler and just use the external cooler. This can dramatically improve its lifespan. I'd also suggest getting an inline filter to help catch some of the contaminates as its easy to get at and replace on a regular basis, we all know how hard we are on our 4x4's. As for mine, the damage was beyond a rebuild (I tried to rebuild it anyhow to get it home but to no avail - it was still bad) and I've purchased a rebuilt tranny along with an rv/towing style shift improver kit to increase the plate pressures and improve the shift response. I also bought a new stall converter for half precaution and also to get a better one to help reduce heat and improve crawling from the stock converter. I'm looking into a trans temp / pressure gauge set so I can spot this type of trouble in advance should I run into this again. Your problems sound like a dirty valve body coupled with worn plates and perhaps some leaking internal seals. Kragen has a rebuilt for $450 but I'd throw at least a shift kit in it and some external cooling if you go that route. Good luck.

    "I'm looking for a Dana60 Front Axle.." I asked, "You wish! HAHA" the wrecker replied! - <a target="_blank" href=http://www.echobit.com:81/k5/> Pictures</a>
     

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