One of those weeks... 1965 Chrysler

MONC440

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Monday & Tuesday I checked the pressure at the Line Pressure & Rear Servo ports.

LINE PRESSURE PORT

Cold start, high idle cam engaged, idling for less than 2 min. No kickdown

D/2/1 pressure 68-73 psi Slight whine

N/R/P pressure 0 psi Louder whine in R, quiet in N & P

Regular Idle, engine has been running about 6 min. No Kickdown

D/2/1 pressure 45-65 (mostly 55-65) Very slight whine

N/R/P pressure 0 Maybe some whine in R, quiet in N & P

Regular Idle, engine has been running about 11 min. Full Kickdown

D/2/1 pressure 8-9 psi

N/R/P pressure 0

Regular Idle, engine has been running about 15 min. No Kickdown

D/2/1 pressure 6-7 psi

N/R/P pressure 0

REAR SERVO PORT

Cold start, high idle cam engaged, idling for less than 2 min. No kickdown

Basically 0 psi – slight twitch in R & 1 (maybe 1-2 psi)

High Idle, engine has been running about 6 min. Full Kickdown

Basically 0 psi – slight twitch in R & 1 (maybe 1-2 psi)

Regular Idle, engine has been running about 13 min. No Kickdown

0 psi in any gear


So it seems like maybe there are 2 separate things going on.

From a cold start, the forward gears are pretty normal, but after 10 min of idling it loses pressure and stops working.

Reverse isn't getting any significant pressure at all.
I would say the low pressure when warm and whine noise you probably have a pump problem. Probably a pump seal is going bad and when the fluid gets hot it leaks past the seal worse or the pump has worn into the case and made to much clearance. I don't think it is that but I have seen it in trans brake transmissions because the pressure is running at 180+ all the time. Looks like a rebuild to me but you could pull the valve body and check to make sure it isn't gummed up. It isn't a plugged filter because that would do the opposite it would have low pressure until the fluid warmed up then it would be better.

It could also be a bad seal in the rear servo.

Pulling the pan will also let you see if you have any clutch debris from the low pressure. I would assume you do and if you do it is time for a rebuild.

You are close so I could help you with the rebuild if you need it.
 

D Cluley

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Looks like it will dry out this weekend, so hopefully I'll get the pan pulled then.

Could a problem with the rear servo cause the overall pressure problem? I don't really know, but have kind of assumed that was going bad based on the problem getting reverse sometimes that has been a thing for years.
 

cbarge

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Dan you milked the trans for years and a rebuild is inevitable.
You owned the car seems like forever so it owes you nothing and deserves a rebuilt trans.
Cars are like houses...20 year projects!!! Lol!
See you in Detroit!
 

MONC440

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Looks like it will dry out this weekend, so hopefully I'll get the pan pulled then.

Could a problem with the rear servo cause the overall pressure problem? I don't really know, but have kind of assumed that was going bad based on the problem getting reverse sometimes that has been a thing for years.
The rear servo could be the reverse problem but the line pressure is main issue. It could also be a valve body or a leaking governor. I suspect it needs a rebuild but pull the pan and let us know what you find.

I think even if the line pressure can be fixed you have probably already damaged the clutches. When you have soft engagement and you rev up the engine you are doing clutch damage.
 

D Cluley

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Forever is right. It will be 20 years in a couple of months, and looks like I've gone about 85,000 miles.

I am mostly assuming it needs a rebuild. Questions are mostly just trying to understand things. If it could be put off and turned into a planned project rather than a need to deal with today project that would be great, but if not, will just keep working at it now.
 

MONC440

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Forever is right. It will be 20 years in a couple of months, and looks like I've gone about 85,000 miles.

I am mostly assuming it needs a rebuild. Questions are mostly just trying to understand things. If it could be put off and turned into a planned project rather than a need to deal with today project that would be great, but if not, will just keep working at it now.
Depending on what you find after dropping the pan a band aid may be possible. The down side is it could leave you stranded someplace when the band aid falls off.

727's are one of the easiest trans to rebuild IMO.

Like I said if you need help let me know. I know the tricks to making it last and have the few specialty tools to make the job easy.
 

D Cluley

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I'm definitely not looking to half ass this. At this point I just want to make sure we look at all the on car options before I start trying to pull the transmission.

I seriously appreciate your offer of help, and will PM you to talk details once I get closer to having it out. Based on previous projects, I'm guessing that is somewhere between a week & a month, but wouldn't want to really try to predict.

And a possibly dumb question. I check the fluid level once it has warmed up. If the pump isn't making pressure at that point, will that affect the fluid level in the pan? If I check it cold (when there is pressure) is there a typical adjustment to the level? I assume it the fluid expands, so will read a little low when cold?
 
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MONC440

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I'm definitely not looking to half ass this. At this point I just want to make sure we look at all the on car options before I start trying to pull the transmission.

I seriously appreciate your offer of help, and will PM you to talk details once I get closer to having it out. Based on previous projects, I'm guessing that is somewhere between a week & a month, but wouldn't want to really try to predict.

And a possibly dumb question. I check the fluid level once it has warmed up. If the pump isn't making pressure at that point, will that affect the fluid level in the pan? If I check it cold (when there is pressure) is there a typical adjustment to the level? I assume it the fluid expands, so will read a little low when cold?
OK sounds good.

That's not a dumb question at all. That's why the service manual says to check the level when the fluid is warm.
 

HWYCRZR

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My ‘68 had this similar issue (40 years ago). It was the reason it was parked in the late ‘70’s early ‘80’s. We used it daily for the 2 miles to the bus stop but couldn’t quite make it the 7 more miles to town. (We weren’t old enough for drivers licenses any way).
Would work fine when cold for about 2-3 miles, then would start slipping when warmed up. In high school when I was getting close to getting my drivers license I put in new rebuild kit (disks, bands, seals) and had the torque converter flushed.
As mentioned above it is a pretty easy re-build, just keep rag particles out of your valve body and respect the torques called out in the manual when re-assembling.
 

MONC440

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My ‘68 had this similar issue (40 years ago). It was the reason it was parked in the late ‘70’s early ‘80’s. We used it daily for the 2 miles to the bus stop but couldn’t quite make it the 7 more miles to town. (We weren’t old enough for drivers licenses any way).
Would work fine when cold for about 2-3 miles, then would start slipping when warmed up. In high school when I was getting close to getting my drivers license I put in new rebuild kit (disks, bands, seals) and had the torque converter flushed.
As mentioned above it is a pretty easy re-build, just keep rag particles out of your valve body and respect the torques called out in the manual when re-assembling.
That's funny you were driving it before having a license. I used to drive the Dodge farm truck around the farm before I had mine also I was about 12. I got a restricted Farm license when I was 14 that allowed you to drive a farm vehicle on the road as long as you were doing "Farm Business", I always had a bag of grain in the back in case I got stopped. LOL

Yes 727's are an easy rebuild but you need to know how to check for problem areas, how to properly install the lip seals without rolling them and check the clearance on assembly to make sure it is going to last.

I have re-rebuilt 727's for my friends that did the job themselves then wondered why it didn't work. Not trying to discourage anyone from doing there own rebuild just do the research and don't think you just need to replace the clutches and go.
 

D Cluley

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Pulled the pan tonight. The fluid looked good, but as I said before, most of it was new this year and has less than 100 miles on it. The filter & the bottom of the pan tell a different story.

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cbarge

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If it has not been mentioned already, installing the 3-2 part throttle kickdown while she is getting rebuilt is a great upgrade.
I did it in the Boab and love it compared to the 66 300 and 69 Fury's which dont have it...yet.
It optimizes the torque curve of the engine and does save wear and tear on the trans itself. Makes passing on the freeways effortless since you dont have to downshift into second manually.

FB_IMG_1641479814740.jpg
 

D Cluley

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Transmission is out of the car. I didn't drop anything on my head, and I don't think I broke anything!
 

D Cluley

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Just want to give a shout out to MONC440, who spent all day today going through my transmission. It will be a few days before I can get everything back in the car, but if it works as good as it looks I will be very happy.
 
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