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89 Astro van tranny problems, rebuild help questions

3K views 14 replies 6 participants last post by  searay 
#1 ·
Hi to all,

I'm new here and need some expert help. I HAVE tried finding the info I need here and on the internet. I have an `89 Astro with 228,000 miles on it. The tranny was replaced in '92 under warranty at 43,000 miles. In '98 with about 100,000 miles on it, it was rebuilt at a tranny shop.

Several months ago, it started late-shifting. This got progressively worse to the point where I cannot drive it. It shifts hard into 1st from neutral when starting out. It shifts from 1st to 2nd HARD at about 24mph. It shifts HARD from 2nd to 3rd at about 45mph, and shifts hard into 3rd at 55 - 60. Never gets into overdrive (maybe I'm just not going fast enough).

I changed the fluid and filter with no difference in shifting. I also made sure the TV cable was attached and not binding, so I'm guessing the tranny needs to be rebuilt. I'm not afraid to tackle this as I have been doing my own repairs (except warranty) and maintenance since I was 16. I am now 65. I have my dream garage (finally) 48x50 ft., with a 4-post lift and more tools than I should have, but I wouldn't give up any of them.

I need to know what tranny I have, what tools I need to buy, and what kit I should buy. The best source of the tools and kit would be helpful. I plan to get the Paul Zank 700R4 Video.

About the tranny ID, my tag says: HYDRA-MATIC, Code No 1MJM4, SERIAL NO 2134, DIV 250012. I can't find code 1MJM4 anywhere I have looked.

Guys, your help would really be appreciated here. This is the first automatic tranny I have attempted.

searay,

Jim Yanacek
Deal Island, MD
 
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#2 ·
You have a 700r4 most likely and it sounds like a throttle pressure valve problem, such as broken cable, bracket broken, out of adjustment. Do a search on 700r4 tv cable adjustment on here it will point you in the right direction.It sounds as if it is in default mode this protects the trans from burning up if there is a cable problem.
 
#3 ·
as mentioned you can have a TV problem. The inner valve may be stuck in the valve body and will cause the late shifts.

You may also have a worn out valve bore for the TV valve. This can cause a false fail safe situation in the trans. The trans would shift late full time as if the throttle is wide open.

AS the engine idles in park , you can pull the TV cable. There should be some mild resistance and the engine rpm may drop slightly as you reach full pull of the TV cable. Pull the cable a few times (10 +) , this sometimes will help free up a stuck TV.
 
#4 ·
Thanks for the replies.

Thanks to barnym17 and Crosley for the replies. I downloaded the TV cable adjustment procedure and followed it to the letter. Unfortunately, it did not change anything, so I guess a rebuild is in order.

On Ebay I bought a Turbine Shaft Seal Tool, an Inner Overrun Seal Protector Tool, an Inner Clutch Seal Protector Tool and Kent Moore J398551, J398552, J387553 Stator Shaft Seal Resizer/Installer Tool. What other tools do I need to buy to rebuild the 700R4 with the fewest problems?

Also, and most importantly, what kits and/or parts do I need to buy to properly rebuild this tranny?

Your time, help and expertise is MOST appreciated!

searay
 
#5 ·
700r4

Seeray was there much "stuff" in the pan when you had it off?

If not and the TV valve is sticking, you could pull the valve body off and install a kit made by Transgo [jr kit] which will keep the TV valve from sticking.

With a 0-300 lb gauge on the mainline pressure tap it should read[warmed up and engine running] about 70 psi in park.

If it reads over 100psi, your TV valve is sticking.

Did you try pulling the cable as Crosley suggested? This has worked for me.

But, if there was trash in the pan, then it's time for a rebuild.
 
#6 ·
Stuff in pan

briscoe,

The only stuff in the pan was a very, very fine black material. The magnet was coated with about 1/16" of it, and it also coated the bottom of the pan, but not as thick as what was on the magnet.

Yes, I did the cable pulling thing and the entire reset procedure. Ill try the pressure test sometime today.

Thanks for the reply...

searay
 
#7 ·
No pressure test ports

Briscoe suggested testing the pressure at the mainline pressure tap. I can't find any pressure taps on the tranny case.

I got the numbers off the tranny casting itself and they are: 1BBM110A. Supposedly this means when the tranny was replaced by the dealer in '92 they put in a 700r4 made on the 110th day of 1991.

Can someone steer me to the "mainline pressure tap"?

Thanks,

searay
 
#9 ·
High Pressure

OK, the pressure is 135 psi so I guess the valve is sticking.

Is next move a rebuild, or fix the valve, or what?

I'm kinda worried about the fine black schmootz that was in the pan. It is obviously magnetic since so much of it was stuck on the magnet.

I really, really, appreciate this feedback and help. You guys are awesome!

searay
 
#10 ·
Advice still needed

Hi guys,

I still need advice on how to proceed from here. I need to order whatever parts or kits or additional tools to get this properly done.

Also, should I consider adding a lockup kit at the same time. I think there's a couple of kinds and I think I only need the 4th gear one.

Are there any other mods I should consider doing? This vehicle is not used for any heavy towing or unusual use.

Thanks,

searay
 
#12 ·
700r4

Searay, If it were me, based on what you have seen in the pan, I would pull the valve body off and install the transgo [jr] shift kit.

Years ago I decided we would never perform a rebuild on a 700R4 without installing the transgo kit.

I have had vehicles come back to the shop with torque converters that have blown up and dropped gobs of metal into the pan, but the updated TV valve, from the transgo kit, would still move freely.

If the TV valve is free you will not have sky high TV pressure, which causes late upshifts.

Worst come to worst and the transgo kit is not enough to cure a more systemic problem, and you find that you must rebuild the trans anyway, well the transgo kit shoul be in the trans anyway.
 
#13 ·
Thanks to all.

I think I have enough information to proceed with the work on my tranny. I want to thank everyone who took the time to share their expertise with me.

Although it sounds like installing the Transgo shift kit will solve my immediate problem, I will most likely rebuild it since I have already purchased most of the necessary tools.

I will post results when I (hopefully) get it finished.

searay
 
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