700r4 help please!! Won't shift out of park

[flash550]

Sorry guys, I'm new and I'll post a proper intro ASAP, but I'm in a bind and need some help.

I bought a '92 Blazer about a month ago and it has a few issues but has been running fine, no major problems. Yesterday, for no apparent reason, it wouldn't shift out of park. I opened the door and rocked the truck back and forth while I tried to get it in reverse, and after a few attempts it worked. Since then, every time I park the truck I have to do that to get it out of park, and sometimes it makes a grinding sound while backing up. Once it's out of park the tranny works fine, no slipping or shifting issues.

Any advice would be much appreciated, this is my DD and I'm trying to get this sorted out this weekend. Thanks in advance!

 

[flash550]

Well, just disconnected the linkage and tried to shift it at the trans, and it does the same thing so it's not the linkage. One it breaks loose it shifts fine, but if I rock the truck forward there's a clunk and it locks up in park again. Unless someone has a better/cheaper idea I guess I'm going to start looking for a new trans. Bummer.

 

[diesel4me]

It could be the parking pawl pin in the transmission..dont despair,I think that can be fixed or replaced without doing much more than dropping the pan,so dont condem it just yet..

It could also be the linkage inside that connects the valve body to the shifter shaft or the valve body dewhickey itself sticking..

I once bought a 4x4 Suburban (1971) that had a "blown tranny" and when I got it home,all I found wrong with the tranny was several valve body bolts had fallen out and landed in the pan!..the ones holding the shift "link" were very loose and the bracket had jammed against the case..replacing all the bolts and tightening them "fixed" it like new..I suspect a backyard mechanic tried putting a shift kit in it,and they failed to tighten the bolts properly...it did sift nice and firm !.

If you dont feel confident taking the pan off,a good tranny shop will probably be able to fix "park" without pulling it apart maybe..

 

[flash550]

Yeah, I think I'm going to take it by a transmission shop and see what they think. The last time I tried to "fix" a trans myself it didn't turn out very well. I just backed it out of the garage and it made a loud grinding sound the entire time it was in reverse, so I think there's something more serious going on. Thanks for the advice!

 

[Carcinogen]

I would still suspect the parking pin

 

[flash550]

I would still suspect the parking pin

Any idea how big of a fix that is? Can they do it without dropping the trans? The internals of the trans is the only thing that I'm not skilled enough to fix myself, so naturally that's what would break....go figure.

 

[Carcinogen]

Like diesel4me said, I think you just drop the pan and pull the valve body but I am really not the person to ask about automatic transmissions

 

[diesel4me]

Unfortunately my only book on 700R4's (Harpers) has only rebuilding procedures and photos showing step by step info on how to do it,they dont have a chart telling you what can be serviced "in car" like some of the Motor's or Chiltons books do...I know on a TH350 you can replace the park pawl without removing the tranny,the tail housing might have to come off though,and on a 4x4 that means pulling the transfer case out..but thats not as bad as pulling both..

Greg Ducato is the man here who'll know exactly what needs to be done..

I prefer to replace automatics that try "fixing" one..dont think I'd be very successfull at rebuilding one myself ,even with all the info and photos..
I've tried taking a few apart to strip out all the steel parts when scrapping them to get more money,and found that difficult!..never mind putting one all back together..engines dont scare me...

I could probably rebuild a manual trans--but automatics do scare me though..I dont really see how all the thousands of peices,springs and gizmos in one work together so perfectly for so many millions of cycles myself..or handle the towing loads they do,when the clutches are tiny compared to a manual..

 

[flash550]

I'm in the same boat. If the engine blew I wouldn't be worried at all, I know how to fix that. The last time I got in to a trans I ended up with a pile of springs and parts that I had no idea how to put back together. I am going to get a quote from a shop to see how much it will cost to fix, but I suspect that it will be cheaper to get a used one and change the whole thing. Just wasn't planning on the time, labor, and cost right now.

 

[Blue85]

Just drop the pan and look at the parking pawl and linkage. I bet the problem will be visible and there is little risk of messing up your transmission. There is no need to touch the valve body. Don't you need to change the fluid and filter anyway? This diagnosis will be no more involved than that.

When you drop the pan you'll see the shift linkage coming in from one side. The park link is the long rod with a spring on it (at the bottom of the photo below. Ignore the green arrow, it's pointing to the manual valve linkage). Make sure all of that is attached probably and not bent up or rubbing on on something. The end of the rod is like a conical pin that pushes on the parking pawl. Look at the teeth on there and make sure nothing is messed up. Can you take pictures for us?

Here's a picture of the actual pawl - the screwdriver is prying on it:

 

[flash550]

Dude, that's awesome! Thank you! I had no clue what a parking pawl was or where it was located. Like I've said, the internals of a trans are all PFM to me. This weekend is a 4 day (being a govt employee has its perks) and I will def drop the pan and see what is going on with the linkage, and fresh fluid/filter couldn't hurt. I will post pics if I can remember to take some.

Another question: if the pawl is jacked up, would it hurt anything to just remove it and use the parking brake? I'm driving the truck now and just not putting it in park and minimizing the use of reverse and it works fine.

 

[Greg Ducato]

The rod that goes from the rooster comb to the parking pawl has a swedged end where it goes into the pawl which holds the bullet shaped part against the spring above it. The swedge can deteriorate over time allowing the bullet end to slide too far down and contantly contact the pawl. You can remove the rod, push the bullet back into place and put a small bead of weld at the end or just replace the rod all together. If that part is ok, there is a spring in the case that holds the pawl back off the ring gear, if that spring has broken it will require pawl and pin removal, not too easy to do even on the bench. I hope it is the former and not the latter.