Automatic transmission slippage problem

[Tom Colitt]

Hi

You all (Pat, Joe, Dan) already helped me diagnose my leaking automatic transmission a few months ago and now the problem has suddenly gotten so bad that I will have to pull it all apart. I wanted to ask you what I can do to prepare and what parts I can buy ahead of time to have minimal down time as I may even have to do the job curb side.

I have a few more symtoms that I can add that might help pin point the problem even more. You already narrowed it down to either a bad primary pump seal, a worn bronze pilot bushing (I assume for the torque converter) or the riveted connection of the fluid coupling. If they aren't too pricey I'll get all those except the coupling in advance. Also front and rear main radial seals even though I already did the front. Can there be anything else? The transmission has now started to slip very badly and drips from the bell housing worse now, but different from before, it now slips a lot in all forward gears when accelerating from standstill or slower rpms, even though the fluid level isn't low (and after adding ATF anyway, it may even be high).

The BBB also mentions other possible causes that I know nothing about, like a defective "check valve secondary pump" (15) (primary pump pressure escapes via secondary pump duct); also primary pump defective; also "Main pressure regulating valve (11) binds (pressure builds-up at increasing engine speed).

In my case the power transmission does get to 100% once a higher engine speed is reached. That's why the defective main pressure regulating valve sounds like a good suspect too, yes?

Tom Colitt

[Tom]

Tom,

I had a slipping tranny during acceleration and it was a vacuum connection that was loose.  It would be great if your problem was as simple as a vacuum leak.  Sounds like you are beyond this as a possibility but I mention it nonetheless.

Best,

Tom

[Tom Colitt]

Thanks Tom

Oddly the problem did appear to get worse after I had just fixed a break in the vacuum line from the venturi to the speed switch, but i don't see how it can be related. However, I would like to check where the vacuum enters the transmission, if i knew where that was. The only connection I know is a pipe that goes from the manifold to the transmission, but I don't know what it actuates.

regards, Tom

Tom Colitt

[ja17]

Hello Tom,
That metal vacuume line terminates at the modulator assembly on the passenger side of the transmission. It act on the modulator diaphram. If this diaphram goes bad the engine will suck transmission fluid up into number six cylinder causing a lot of white smoke. If I were pulling that I would be prepared to replace the diaphram, front seal and o-ring, the bushing if needed. The front transmission cover gasket may also have to be replaced if the cover is removed. The valve body bolts should also be checked for tightness. Change the filter, fluid and the cork pan qasket. Have the torque converter pressure checked for a leaky riveted hub. Examination of any debris in the pan should indicate if additional deterioration is occuring in the transmission. This transmission was also used in some 108 series sedans, 250-S, SE (1965- !967) and early versions ,280-S, SE (1967, 1968). Always unbolt the torque converter and remove it with the transmission.


Joe Alexander
Blacklick, Ohio

[Tom Colitt]

Hi Joe

Thanks a lot for your help. I ordered the parts. I was wondering what the best way to check the rivetted torque converter would be? Should I use compressed air or do I have to have some specialized shop do the check?

I don't have any white smoke, but I'm replacing the diaphram anyway. I feel a little guilty for not replacing the clutch disks. Would checking and replacing them be a lot more work or do they hardly wear out at all?

Best Regards, Tom Colitt

quote:Originally posted by ja17

Hello Tom,
That metal vacuume line terminates at the modulator assembly on the passenger side of the transmission. It act on the modulator diaphram. If this diaphram goes bad the engine will suck transmission fluid up into number six cylinder causing a lot of white smoke. If I were pulling that I would be prepared to replace the diaphram, front seal and o-ring, the bushing if needed. The front transmission cover gasket may also have to be replaced if the cover is removed. The valve body bolts should also be checked for tightness. Change the filter, fluid and the cork pan qasket. Have the torque converter pressure checked for a leaky riveted hub. Examination of any debris in the pan should indicate if additional deterioration is occuring in the transmission. This transmission was also used in some 108 series sedans, 250-S, SE (1965- !967) and early versions ,280-S, SE (1967, 1968). Always unbolt the torque converter and remove it with the transmission.


Joe Alexander
Blacklick, Ohio

Tom Colitt

[ja17]

Hello Tom,
I used to drain the converter, fill the outer dished area around the rivets with water, presurize the converter with shop air and look for air bubles at the riveted connection. I used a wet rag around a air nozzle to make the seal at the converter opening.
Of coarse taking the converter to a transmission shop with real equipment is a little more assuring.
These transmissions are designed to operate with little or no clutch wear. That is why their shift is so pronounced. Smooth shifting automatics often have a little slip designed in for a smooth shift, thus more clutch wear. Examine the pan, if it is fairly clean then the clutches will should be fine. Find another  used transmission (exactly the same in some of those $300 sedan parts cars) and experiment with it. These four speed automatics in such compact unit are very complex inside. You can only be guaranteed of 100% success if you have some extremely expensive bench testing equipment. So keep your explorations down to a minimum.

Joe Alexander
Blacklick, Ohio

[Tom Colitt]

Hi Joe

Thanks a lot, especially for that last bit of advice. I do tend to get a little too curious and coming from you I will take the advice and stick to the repair at hand.

I'll keep you posted how it goes. Probably won't happen for another week o so though.

Regards, Tom Colitt

quote:Originally posted by ja17

Hello Tom,
I used to drain the converter, fill the outer dished area around the rivets with water, presurize the converter with shop air and look for air bubles at the riveted connection. I used a wet rag around a air nozzle to make the seal at the converter opening.
Of coarse taking the converter to a transmission shop with real equipment is a little more assuring.
These transmissions are designed to operate with little or no clutch wear. That is why their shift is so pronounced. Smooth shifting automatics often have a little slip designed in for a smooth shift, thus more clutch wear. Examine the pan, if it is fairly clean then the clutches will should be fine. Find another  used transmission (exactly the same in some of those $300 sedan parts cars) and experiment with it. These four speed automatics in such compact unit are very complex inside. You can only be guaranteed of 100% success if you have some extremely expensive bench testing equipment. So keep your explorations down to a minimum.

Joe Alexander
Blacklick, Ohio

Tom Colitt