TH727 fluid leak via overflow drain

vso737 · May 18, 2017

Hi,

Has anyone experienced the transmission fluid purge itself via the pump housing overfill hole?? My 1977 "TCI" Street Fighter tranny ONLY purges itself upon A COLD start after the car is inoperative for a while. Once the engine warms up, it does not leak at all. Not even after turning it off and starting it up again.

NO, it is NOT an overfill issue. I drained all the fluid, got approx. 4 quarts. I put 3 quarts back in it, drove it and the tranny did not function properly due to fluid being TOO LOW. The dipstick confirmed the fluid was too low. I ended up putting the 4th quart back in the tranny.

Once the motor/trans. are nice and hot, after driving around for a while, and checking the dipstick with the tranny in NEUTRAL reveals the dipstick fluid is at the correct level.

Even though it is NOT an overfill purge. The tranny leaks the fluid via the overflow the next day when I start the car for the first time.

I KNOW very little about transmissions but it sure seems to me like something is preventing the fluid from circulating properly during a cold start.......the end result is that it gets forced out via the overfill drain hole on the pump housing.

The tranny ONLY has approx. 1,200 miles but it was installed approx. 18 months ago. I changed the filter and fluid at the 500 mile mark as recommended ............... it may be a gumming up issue in the valve body. I just purchased some 'Sea Foam Hydra trans tune' and hopefully this will give me a positive result. ONLY TIME WILL TELL..........

Any input would be highly appreciated.

Thank you in advance,
LG,
Mike

inputdrum · May 18, 2017

have you installed a sealed dip stick tube, if yes get rid of it, if not, try removing the dipstick next time for a test, and get back to, I am a trans builder,now retired. we will go step by step utill we get it thanks Harold.

vso737 · May 18, 2017

inputdrum said:
have you installed a sealed dip stick tube, if yes get rid of it, if not, try removing the dipstick next time for a test, and get back to, I am a trans builder,now retired. we will go step by step utill we get it thanks Harold.

Hi Harold,

Thanks for the quick response.

YES and NO, I purchased the steel dipstick tube that bolts to the bell housing and the dipstick has the FLIP LOCK handle at the top. I assume this is the STOCK steel neck and dipstick. I purchased the "TCI" tranny; 2400 stall T/C; fluid; dipstick and steel neck all as a package from Summit Racing.

I was thinking last night that I have been starting it in NEUTRAL. I read somewhere a while back that the T/C fills up faster by having the car in NEUTRAL. I suspect the T/C drains back into the transmission but it should NOT be causing my problem.
A couple of days ago I purchased a one way check valve and installed it on the HOT fluid line to keep the trans. cooler fluid from draining back into the tranny. DID NOT SOLVE MY ISSUE- Still over spilled during the cold start.

A few days ago I read that the fluid pressure is different in PARK vs. NEUTRAL. This is why it is better to put the car in NEUTRAL to fill the T/C before taking off. Now I'm thinking, maybe I should be starting it first in PARK and then shifting to NEUTRAL before taking off.

The guy who did the transmission swap placed the HOT line (front line) on the TOP of the trans. cooler. I placed the line on the bottom of the trans. cooler the way it is suppose to be. The fluid travels UP the cooler and NOT down. Maybe the guy did it because he was having the same issue. Especially when he put 2 quarts too many in my tranny. I assume he was checking the dipstick with the car in PARK. He made some other screw ups as well.

Can't wait to incorporate your suggestion and starting it in PARK. I will be doing this later on today. I have to get it ready for the "Santa Barbara State Street Nationals" this Sunday.
The ONLY thing I know for sure is that the fluid level is at the proper mark. The car runs great and I love the way it shifts......both in manual mode and in the "D" automatic mode. SUNDAY will be strictly "D" mode with mama and the two furry babies in the car...........LOL

A few years ago I restored a 1957 Corvette. It was my retirement project.......took me 8 1/2 years. It earned "NCRS" TOP FLIGHT on its first judging. It was the basic 4 barrel two speed power glide transmission. Surprised to learn that the transmission DID NOT take a transmission fluid cooler. More surprised to learn that the transmission would spill out fluid via the dip stick tube after left parked for any length of time. The T/C would drain back and literally flow out the dipstick tube. The FIX was either to start the car more often or RUN it a quart low. (picture of the car in my gallery)

I noticed that the RR FLUID reads pretty high on the dipstick when the car is parked for any long period of time. I assumed this is the reason for the DIPSTICK having the rubber seal and lock handle. Without it, the fluid would spill over just like the '57 Corvette.

Thanks a bunch,
LG,
Mike

inputdrum · May 18, 2017

now if under stand right, the fluid leak is only cold right? now we cant see the vent or converter hub (front pump at the seal), we will start at the easiest,things first, that unit need some air even if it not a vent problem, loose that sealed tube. and that's about all there is to vent issues. now your right about converter drain back, we will talk about that if the dipstick trick don't work, park or neutral makes no difference on start up, but check it hot in neutral, we do that because the valve body is exhausting fluid in park.

dmartin · May 18, 2017

Hey big guy did you put on O ring seal around the tube and make sure it goes down in the hole properly it may help

Sent from my iPhone using Tapatalk

vso737 · May 18, 2017

Hi,

I just finished my tests. First, before I did anything, I wanted to check the fluid level on the dipstick. It is high and over the TOP loop of the stick. I expected it to be really high.........

I started the car in PARK and with the DIPSTICK removed. Exactly 5 oz. of transmission fluid poured out of the PUMP HOUSING overflow drain hole. I can see the fluid pouring out of the bell-housing under the dust shield I made.

I was afraid that the fluid would pour out of the fill/dipstick tube but it did NOT. Leaving the dipstick out made NO difference................

I put the car in NEUTRAL after starting it in PARK and shifted through all the gears. I let it idle quite a while to get everything nice and HOT. The leak stopped right away once the car started getting hot. I turned it off and started it 3 different times. NO leaks in any of the starts when the car was hot.

I do NOT have a leak from the DIPSTICK TUBE. YES, I put the rubber washer and gasket maker sealer around the gasket to make sure I did NOT get a leak from the filler tube. I have NO leaks anywhere in the tranny with the exception of the fluid pouring out via the pump housing overflow hole during COLD start up. The spilled out fluid measured exactly 5 oz. ...............

I checked the fluid level in NEUTRAL while everything was nice and hot and the fluid is right at the bottom LINE where the checker section starts- at the add a pint line.

I can probably go back and start it again now after an hour of running the motor and it most likely will NOT spill over. I know for sure that tomorrow morning when I start it again, it will over-spill another 5 oz. of fluid until the car warms up.

One thing for sure, I can NOT be the only person this has happened to. Usually, my problems end up being something very trivial...........for the life of me, I can NOT figure this one out but then again, I KNOW zilch about transmissions.................LOL

My plan is to pour the "Sea Foam Hydra trans tune" when start the car and drive the 35 miles to Santa Barbara for Sundays show. I figure that by the time I get there the solution will have had plenty of circulation inside the tranny. This way I will NOT be wasting any of the 'magic solution" by purging any of it during a cold start. It will be interesting to see if I leave 5 oz. of fluid on State Street once the show is over...................That will be the true test.

vso737 · May 18, 2017

inputdrum said:
now if under stand right, the fluid leak is only cold right? now we cant see the vent or converter hub (front pump at the seal), we will start at the easiest,things first, that unit need some air even if it not a vent problem, loose that sealed tube. and that's about all there is to vent issues. now your right about converter drain back, we will talk about that if the dipstick trick don't work, park or neutral makes no difference on start up, but check it hot in neutral, we do that because the valve body is exhausting fluid in park.

Before I forget again, this transmission is shifted via cable and has a floor "Quick Silver" "B & M" shifter. The 'neutral safety switch' is not used. The guy who did the transmission swap tied into the wire harness to get the dash reverse light to come on and I assume the car will NOT start in anything other gear other than PARK or NEUTRAL.

I don't know if this has anything to do with my fluid overflow issue but felt it worth mentioning it. The transmission shifts good....................

inputdrum · May 19, 2017

can you tell me what the diameter of your converter, Im begging you not to pour in anything but fluid, there is no fix in a can!, you have a converter drain back issue, the converter is not draining down like it should.

vso737 · May 19, 2017

inputdrum said:
can you tell me what the diameter of your converter, Im begging you not to pour in anything but fluid, there is no fix in a can!, you have a converter drain back issue, the converter is not draining down like it should.

TCI Breakaway Torque Converters 141200
Torque Converter, Breakaway, 11 in. Diameter, Chrysler, 727, 24-Spline, 2,400 Stall, Each

This is right out of their website. (What I like about Summit Racing.........I can access my account and view every item I purchased from them)
Did I tell you that the FIRST torque converter "Summit Racing" sent me started leaking, at the weld, after 1100 miles on it. This is the SECOND T/C...........They were NICE enough to honor the fact the first one was defective even though it was in my possession for 18 months.

I was thinking maybe having suspended/placed the transmission vertically when I removed the input shaft seal and pump housing seal might have loosened something in the valve body.

I did put 1 quart of fluid in the T/C before installing it and made sure it was all the way in.

Before I wrote this post, I contacted "TCI" and spoke with a tech. The tech. suggested I use "Sea Foam Trans Tune" because the transmission does not get much use during the past 18 months and maybe has gummed up. He did mention a possible T/C issue and valve body issue as well but quickly realized he was talking to someone who had no clue what he was talking about. I do recall him saying he could not talk me through the valve body solution. I got out of it that there may be something wrong with the valve body. He said that this trans tune has gotten good results and it may take about 15 times before it works. I assume he meant 15 cold starts.

One thing for sure, the transmission will not function properly even with (1) one quart low.

While I had the Hooker headers and transmission out of the car. I wrote down all the MOTOR ID #'s and discovered that the motor is a 1972 400 CID.............

vso737 · May 19, 2017

inputdrum said:
can you tell me what the diameter of your converter, Im begging you not to pour in anything but fluid, there is no fix in a can!, you have a converter drain back issue, the converter is not draining down like it should.

Hi Harold,

Talked to a tranny GURU today and he confirmed your opinion that it is a T/C drain back issue. I just got off the phone with the TCI tech- he also agrees and tells me it is the BLEED BACK VALVE in the pump that is allowing the T/C fluid to drain back into the tranny. It needs to be UNSTUCK. He says the fix is NOT in the valve body.

I will install a DEEP TRANNY PAN if I can NOT get this valve unstuck and run it a quart low to prevent the overflow during startup.

I'm NOT about to take this tranny out again ...........I want to put some miles on this 'monster' before I mess wiht the transmission. This transmission is starting to be the "thre tranny from hell"...........................LOL

droptop · May 19, 2017

vso737 said:
...........While I had the Hooker headers and transmission out of the car. I wrote down all the MOTOR ID #'s and discovered that the motor is a 1972 400 CID.............

A 72 400 is externally balanced. I hope you have the correct TC. If not, your front pump will not last long. And I agree with the other Harold, there is no tranny fix in a can.

vso737 · May 19, 2017

Hi Harold,

The converter is 11" and it holds 3 1/2 quarts of fluid.

Attached is a picture of the trans. dipstick and the various FLUID levels. The overnight level; when it is HOT in driving condition; and what the level is after being parked for ONE hour after running it hot.

LG,
Mike

fluids LEVELS- hot- 1 hour- n overnight.jpg

vso737 · May 19, 2017

droptop said:
A 72 400 is externally balanced. I hope you have the correct TC. If not, your front pump will not last long. And I agree with the other Harold, there is no tranny fix in a can.

TCI Breakaway Torque Converters 141200
Torque Converter, Breakaway, 11 in. Diameter, Chrysler, 727, 24-Spline, 2,400 Stall, Each

This is what I purchased with the package......................

inputdrum · May 20, 2017

Hey do this tonight,, put it low and leave it all night and see what happens in the morning,this will tell us if a manual valve will fix it

vso737 · May 20, 2017

inputdrum said:
Hey do this tonight,, put it low and leave it all night and see what happens in the morning,this will tell us if a manual valve will fix it

I had it running today. Getting it ready for the car show. BOY does it drive nice..............purged about 5 1/2 oz. on the cold start but never leaked again the rest of the day. I topped it off for tomorrow's drive. I expect it to purge when I first start it up but sure would be nice if it did not. Just placed it in 1st gear.......

I ordered a DEEP PAN which will hold 2 more quarts than the shallow stock one. I don't mind waiting for the T/C to fill up, I just don't want the leaking fluid evey time I start it cold.

Thanks again for your help and hopefully, you will solve the mystery and I'm sure someone else will benefit from it as well.

Check this lousy video I made today to capture the AWESOME motor ...........my camera volume is not set correctly again. Will have to play with it tomorrow at the car show.

https://www.youtube.com/edit?o=U&video_id=xIeRSVZV3V0

LG,
Mik

69hemibeep · May 21, 2017

I had one that would drain back after use sometimes. I put a shift kit in it that said it would eliminate drain back and it did

vso737 · May 21, 2017

inputdrum said:
Hey do this tonight,, put it low and leave it all night and see what happens in the morning,this will tell us if a manual valve will fix it

Hi Harold,

I can NOT believe it. I put it in 1st gear as you recommended. Started it up this morning and it DID NOT leak at all. Put at least 60 miles on it today and so far so good.

I now have it parked in FIRST gear and will start it in a couple of days and see what happens. I should get the DEEP PAN this Friday...............

Would be nice to have the problem resolved plus also having the extra 2 quarts of fluid.

I installed a one way check valve on the OUT line just to make sure the fluid did not travel back into the tranny......................it did not fix my issue but I thought it would not hurt it either.

¿ What's next ??

Again, thanks a million and I really appreciate you taking the time and sharing all your expertise..............

LG,
Mike

TODAY'S CAR SHOW...............ONLY 3 1969 RRs IN THE entire SHOW AND AS USUAL..................."NO" TROPHIES BUT I FOR ONE CAN TELL YOU THAT A lot of people REALLY LIKED MY RR...................

vso737 · May 21, 2017

69hemibeep said:
I had one that would drain back after use sometimes. I put a shift kit in it that said it would eliminate drain back and it did

I purchased the tranny from Summit Racing. It is a "TCI" Street Fighter which I believe that part of the modification is a shift kit. I really DO NOT know what all they do to modify it from a stock A727 but it sure is a LOT of fun to MANUAL SHIFT it.

I did NOT have any issues with the DRAIN back when I first had it running. It wasn't until I replaced the leaky T/C that this drain back issue started. The "TCI" techs swear that it is a stuck 'bleed back valve' in the pump and that the "Sea Foam Hydra trans tune" will fix the problem....................

LG,
Mike

vso737 · May 30, 2017

inputdrum said:
Hey do this tonight,, put it low and leave it all night and see what happens in the morning,this will tell us if a manual valve will fix it

STILL waiting for the filter extension adapter.
The transmission BURPED fluid after being left in FIRST gear, but NOT as much as before when left in park or in neutral.

I purchased a DEEP TRANS PAN that the VENDOR claimed NOT to need a filter extension. GUESS what, HE LIED. The pan is ONLY 2" deeper than stock and 3" overall depth. The 1" adapter will place the filter at the bottom of the pan and should take care of my issue.

Once I have it all back together, I do NOT expect to have any more problems with 'T/C drain back'. I will post my results....................

LG,
Mike

vso737 · Jun 6, 2017

vso737 said:
STILL waiting for the filter extension adapter.
The transmission BURPED fluid after being left in FIRST gear, but NOT as much as before when left in park or in neutral.

I purchased a DEEP TRANS PAN that the VENDOR claimed NOT to need a filter extension. GUESS what, HE LIED. The pan is ONLY 2" deeper than stock and 3" overall depth. The 1" adapter will place the filter at the bottom of the pan and should take care of my issue.

Once I have it all back together, I do NOT expect to have any more problems with 'T/C drain back'. I will post my results....................

LG,
Mike

__________________________________________

I started the RR today after the car was inoperative for 3 days. I was surprised to see that it STILL leaks from the vent hole in the pump housing since I installed an extension for the filter and a deeper fluid oil pan.
I think that if my issue is a T/C 'drain back', the 2" deeper pan which holds two extra quarts should solve the problem if I run the car low on fluid. The problem/task is I can not run it too low .............
I test drove it today and it runs good. Now, if it continues to burp the fluid, I intend on just letting it find its own level like we do with an overfilled water radiator.
The amount that came out of the vent tube was not as much as in the past so hopefully a few more cold starts will take care of the problem.
I will continue to monitor and start it often until and see if it stops leaking.
I hate the thought of having to remove this tranny again.................NOT going to happen this year for sure!!!!

LG,
Mike

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