1979 DeVille transmission slipping/vibrating.

[Benzilla]

In a nut shell, the Phaeton is being a pain - again.

Here's what's going on. I left it parked for about a month due to lack of time to drive it, finally got it back out and running about four days ago. First day the trans acted normal, second day it felt like it was hunting for the gears a little too much, especially around 15 mph. Third day it would shudder while shifting under moderate/heave acceleration. Fourth day shifting is a chore. Heavy vibration/slipping while shifting into 2nd, almost undrivable.

It has had a leak for the last two years. It has been to three different shops, all of who claimed to replace seals, and it still leaks just the same. Thinking it's the rear main seal, as it leaks less with the nose down hill. When I started it this time, I had to jump it and let it run in park for a while about 1 qt low on fluid until I could check it and top off.

Never had a shifting issue before, and Ideas? The trans fluid is always fresh, because I have to add a cup every week... isn't it lovely?

Advice would be great, I'm moving this week and having a little trouble dealing.

Thanks,

Ben

[Benzilla]

Update:

I just went out and tried it again. On start up, it had a noticeable whine, then I tried to shift into gear... nothing, no kick down, just like every gear was neutral... this doesn't sound good at all does it.

Ben

[csbuckn]

I dont see your tranny going out that fast without any other warning signs unless it is REALLY low on fluid. But if it isnt going into gear than its something inside, I bet its a clogged filter. That sounds about right. I'd probably drop the pan and take a quick look, change fluid/filter, say a quick prayer and go for a ride. Maybe the rear seal is so gone that you cant build pressure.

[Benzilla]

Checked the fluid while I was out there and it's full. If the rear seal was *gone* wouldn't it be pouring fluid out by the second?

Thanks for the advice.

Ben

[csbuckn]

yea i suppose a seal would be easy to diagnose. I just have a hard time thinking any hard parts would go out that fast without any other signs. Maybe its the filter. So you went from good to nothing in 4 days?

[Benzilla]

Yup, that's what I'm saying. When I parked it, everything was fine, first day back out everything seemed fine. Then all hell broke loose. Tomorrow I'm goiong to call a very well known local trans shop and have them take a look at it. I really don't have the area to do much with it. And trans are a little out of my league anyway. My friend/roommate Armen knows a great towing place, so I'll see what kind of deal we can get

I'll keep you guys updated.

Ben

[dirt_cheap_fleetwood]

Check your throttle valve cable. The cable that goes from the trans to the throttle is what controls fluid pressure in the clutch packs and valve body. Its a common problem on Lincolns (it happened to mine) for a little bushing to rot away and then the cable comes disconnected. It causes the trans to slip horribly because there is no fluid pressure to put friction on the clutches. If not dealt with quickly it can burn up the trans in less than 10 miles.

[greencadillacmatt]

Originally Posted by dirt_cheap_fleetwood

Check your throttle valve cable. The cable that goes from the trans to the throttle is what controls fluid pressure in the clutch packs and valve body. Its a common problem on Lincolns (it happened to mine) for a little bushing to rot away and then the cable comes disconnected. It causes the trans to slip horribly because there is no fluid pressure to put friction on the clutches. If not dealt with quickly it can burn up the trans in less than 10 miles.

Aren't the Throttle Valve cables only on the 2004-r and 700r-4 transmissions? I think that Ben's trans is a TH-400, which is controlled by vacuum from the engine. (I could be totally wrong, though.) GOOD LUCK BEN!

[dirt_cheap_fleetwood]

I have no idea, I just threw out all I know about auto transmissions.

[Benzilla]

Got it into the shop today. Don't know anything yet. Although when the tow truck driver moved it, he revved it up a lot and got it to go into reverse, so it's not totally dead. Not that I know much about this, but doesn't that kind of sound like a vacuum problem?

[jayoldschool]

It sounds like low fluid. I know, the level is right. So, next guess is that the clutch pack material is worn out, and it is rebuild time.

[csbuckn]

Originally Posted by jayoldschool

It sounds like low fluid. I know, the level is right. So, next guess is that the clutch pack material is worn out, and it is rebuild time.

I'm still leaning towards low fluid also, thats why I was thinking to drop the pan to make sure. I can be hard to read dipsticks sometimes, especially if its not warming up and doesnt get into all the gears first. Hopefully no rebuild is needed.

[77CDV]

First off, good to see you back, Ben!

As to your question, the 1979 FSM is not particularly helpful, although everything seems to point to a problem with fluid flow and pressure within the transmission. If the fluid level reads full when hot on a level surface, the manual seems to suspect the internal pump or a blocked filter as most likely, with the modulator also making a strong showing.

From all the symptoms you've described, my money's on the pump. Here's hoping everything is squared away quickly and the old girl is herself again soon.

Craig

[Benzilla]

Just got a call from the trans shop......

They said the transmission is toast. I'm going in later to get details on how exactly this could be. It's supposed to be the best shop in the area, so I'm not doubting them, I just don't know how this could happen so quickly. They quoted me $1100 out the door for a rebuild.

[jayoldschool]

I believe you can get TH400s rebuilt for less than that. They were just talking about that on "Extreme 4x4" on Spike last weekend. Check online sources. Try Bowler Transmissions and see what they say...