El Camino Central Forum banner

Need some help with my th200

3K views 6 replies 3 participants last post by  mnunn 
#1 ·
I've got an 85 El Camino with the th200 from a 79 El Camino in it. I put that trans in when I did my engine swap, and I've had problems with it ever since.

Whenever I drive, the transmission has a hard time selecting a gear and staying in it. If I floor it from a stop, it'll shift from first, to second, back down to first, and keep doing that until it hits a speed where it can be comfortable in second. It also doesnt' downshift correctly to pass on the highway.

I checked the TV cable, and it was correctly adjusted.

I'm not sure what else to check. When I looked at the TH250 that was in the 85 originally, there's a little vacuum canister near the tailshaft that isn't on the TH200..but I'm not sure if it's supposed to be that way or not.

The th200 that I'm having problems with has been to a transmission shop and rebuilt to stock. New seals have be used as well. Throughout all these problems, the trans fluid was always at the proper level.

Sorry for the long question, I just wanted to provide as much info as possible. I'm completely stumped, and I went ahead and dropped the transmission to try and figure out what's wrong with it.


Thanks in advance for any help. :)
 
See less See more
#2 ·
Anyone?
I'm going to start getting it ready to reinstally tommorrow, and I'd just like to know if there's anything I should look at while I've got the trans out of the car.

Thanks in advance. :)
 
#3 ·
Sounds to me like the fluid level could be low or the filter could be clogged, the converter could be bad, or the transmission's hydraulic pump may be so worn that it isn't producing enough pressure to clamp the planetary clutch bands in place. Any of these 3 could make it "feel" like it's changing gears.


If it's truly shifting back and forth between gears (and not just feeling like it), I'd suspect something's wrong inside the valve body.

'Wouldn't hurt to check out the governor as well to make sure it's not misbehaving.

All of this is a guess on my part. Were I you, after I checked for an obstructed filter, low oil level and maybe for low hydraulic pressure, I'd visit a reputable transmission shop that can be trusted and pay them to give me an accurate diagnosis.

Before going there though, I'd have in my hip pocket an estimate for (a) a complete trans replacement from a salvage yard (why spend $1000 to have your rebuilt when decent used one might be had for $200-$300?) and (b) the cost of a rebuilt one purchased over the counter/internet (why rebuild yours for $1000 if a beefier one can be bought O.T.C. for 1500?)

Hope it helps
 
#4 ·
See that's just the thing. This transmission has been completely rebuilt. All new internals, new seals, new filter, all of that.

It truely is shifting incorrectly too, because like I said if I manually put it through the gears then it works fine.

I think I've reached the point now where I'm going to reinstall it and make sure everything is set just right..and if still is acting up, then I'm just going to take it somewhere. The only thing I could think of at that point is if they messed up somewhere when the trans was rebuilt.

I've looked it over with the transmission out of the car, and I can't really see anything obviously wrong with it. Of course I really don't know much at all about automatic transmissions.

I'm pretty much out of ideas. :mad:
 
#5 ·
Sounds like something is wrong with the kickdown. I have no idea about your transmission, but an old two speed auto I had had similar problems once when the kickdown linkage failed (a fastener broke loose) and once when I changed to a v-8 from a straight six. I couldn't keep the same kickdown linkage so I had to shift manually, otherwise it would shift out of first at really odd times and fail to downshift properly. I think the same problems can be caused if the vacuum on the tranny isn't hooked up properly. Of course you said the new tranny doesn't have that so I don't know... Just my experiences.
 
#6 ·
Thanks, that gives me a few more things the look at. The only thing I noticed about the kickdown is it seems to be a bit stiffer on this trans vs. the original, but I chalked that up to the trans being rebuilt.

I think at this point I'm gonna stick by reinstalling the trans, and if I still have problems I'll just take it somewhere to have it looked at. I'm trying not to spend too much money on it because I plan on swapping it out for a nice built up 700r4 at some point later on.
 
#7 ·
couladin127 said:
See that's just the thing. This transmission has been completely rebuilt. All new internals, new seals, new filter, all of that.
Did you rebuild it, or did you pay a professional? If a professional, I'd take it back to them.

If you did it, then I'd guess there's a spring, a ball or something minor out of place in the valve body assembly, but I'm only giving you my best guess. I'm certainly no expert on the matter. An expert might be able to tell for sure.

Let me tell you of a little dilemma I caused mysely about 10 years ago. I had ripped the polution control stuff off of my 82 bonneville wagon. When I put it all back together it wouldn't shift out of 1st gear. Thinking the trans was controlled by the computer I'd just ripped out, I feared now having to go buy a non-computer controlled transmission. I stopped in a trans shop and explained my problem. He wanted me to bring it in and charge me $100 to fix it. Explaining that I was 50 miles away and the car would only drive in 1st gear. He conceded the point and explained that I'd probably left the vacuum hose off of the transmission's modulator when I was cutting out all those vacuum control hoses. Reattached the hose to the modulator and VIOLA! she shifted perfectly from then on. I was so tickled that I didn't have to buy a transmission, that I went back and gave him $50 just for his advice.

Moral of the story. If you did the work yourself, it's probably something simple. Go back and check all the details. You may find the problem's right under your nose.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top