Thoughts on a complicated question

GPster · July 14, 2021, 11:27:59 PM

The Jeepster has been setting in my garage for a while. I fixed the power steering leak problem and I drove it to the Father's day car get together with no problems except when I put it in reverse it took a while for it to start moving. It has happened before and the first comment was to check the transmission fluid level. after that initial hesitation it seemed to be fine so I drove to the get together and didn't check the fluid level til I got back. Checking the fluid with the engine running and the trans in park it took almost two quarts to bring it into the full space on the dipstick. I filled it and parked it in the garage and left it. Went away for the holiday and when I checked it after I got home it was sitting in a pool of ATF. I took a pump and took about two quarts of ATF up the dipstick tube and it quit dripping. It looks like it's leaking out the pan gasket but it hasn't leaked previous to this adding the two quarts of ATF that it took to bring it up to the full mark on the dipstick. I changed the fluid and installed a new filter before it was ready to drive which was a chore because it had been done by a previous owner that had used the wrong pan bolts and stripped some of the holes in the trans case so I had to re-thread the case and install new bolts. It hasn't leaked in over a year so I thought that I had made a good fix. This is a 700 transmission and the drivetrain is '87 GMC 2.5L S15. Is the normal level of fluid in a 700 trans above the gasket line of the pan or is there something else above the pan line that can leak ATF? I can't see anything above the pan laying on my back on a creeper. The local transmission shop had a major fire two months ago and may neighbor that had a repair shop died a year ago so I can't use the lift in his garage to see the situation better. Just talk to me to give me your ideas or make comments about anything that may have slipped my mind. GPster

lofat46 · July 15, 2021, 09:07:29 AM

Not a transmission guy, just throwing stuff out there. Check the o-ring around the dip stick tube and any seals around the speedo gear, where the TV cable comes out of the case. Could also be a bad front seal. Could the case be cracked? Do the bolts on the pan need sealer on the threads?

WZ JUNK · July 15, 2021, 09:21:19 AM

In the past I have had situations where when the vehicle sat idle for long periods, the transmission started leaking. One of the explanations was that there is a check valve situation leaking by in the transmission. That scenario allows fluid back in the pan and the pan is then over full and leaks. I had a car that normally did not leak but when we left it parked for a couple of weeks, there would be a puddle of fluid forming under the transmission. When we started driving it again, it stopped leaking. I seem to remember that it was caused by fluid from the torque convertor leaking back into the transmission pan.

Again, I am not a transmission guy. Hopefully Tony will have some insight.

GPster · July 15, 2021, 09:29:21 AM

I need stuff like that thrown at me because my mind is closed about the fact that I didn't have a problem until I added two quarts of ATF. I need those kind of reminders to know where to look because I can't see it all that well . GPster

GPster · July 16, 2021, 09:26:11 AM

Quote from: "WZ JUNK"In the past I have had situations where when the vehicle sat idle for long periods, the transmission started leaking. One of the explanations was that there is a check valve situation leaking by in the transmission. That scenario allows fluid back in the pan and the pan is then over full and leaks. I had a car that normally did not leak but when we left it parked for a couple of weeks, there would be a puddle of fluid forming under the transmission. When we started driving it again, it stopped leaking. I seem to remember that it was caused by fluid from the torque convertor leaking back into the transmission pan. Again, I am not a transmission guy. Hopefully Tony will have some insight.

This is a good explanation of what I think is happening. Do you remember what type of transmission it was? What did you do to fix it or did you just live with it? I seem to remember Tony saying he used a little bit of brake fluid as an additive in ATF to cure some "Sticky" problems but I wouldn't do this with-out some specific instructions. A local Festival is in two weeks and a car display to be with it. There is some talk that a local group of "Rat Rods" is going to make a showing. It's only a block away and I'd like to make it but would rather not be know for" leaving my mark" on the pavement in front of a neighbor's house. GPster

416Ford · July 16, 2021, 12:31:20 PM

GP, I have used the brake fluid add on old transmission but I was told that it helps with slippage due to seal being old. When the brake fluid (Only about a teaspoon or cap full) is added, it will help to swell up the rubber internal seals.

GPster · July 16, 2021, 04:00:16 PM

As I said: the other day I removed the two quarts of ATF that I had added that had started this whole mess. The dripping had stopped after doing that. Today I checked the level of the ATF (with-out running the engine) and it was at the top of the full level. I started the engine and put the trans in gear. Again it didn't engage at first but after a while (30 sec.) it caught. I then shut off the engine and after 30 minutes I checked the dipstick and was below the full level but not quite down to the low level. It looks like I have that draining back through a check valve problem. I hate running it at low level but I'm adverse to have the car sitting over a pile of Kitty Litter. Our local Vocational School has a class in automatic transmissions but school is off for the summer now. OH WELL ! GPster

Crosley.In.AZ · July 16, 2021, 10:14:14 PM

Do not use brake fluid in an automatic transmission. There is no drain back check valve in a 4L60 series transmission. Drain back from the converter happens with wear and wider clearances in the pump , input shafts, bushings, converter

Check fluid on the 4L60 series trans , with engine running, trans is warm , in park , level ground.

There are 10 to 12 places a transmission can leak from when it sits for extended length of time

GPster · July 17, 2021, 09:33:27 AM

Quote from: "Crosley"There is no drain back check valve in a 4L60 series transmission. Drain back from the converter happens with wear and wider clearances in the pump , input shafts, bushings,

This transmission is a 700. At some point I had to identify it by the mark on the side of the case and the pan gasket, the filter and the new TSC (?) cable are for a 700 transmission. This transmission is not controlled by the computer and the only wires going to it are supposed to be for the converter "Lock". I've been informed that the car display has been moved from the street to the Methodist Church parking lot so the transmission leak has taken on a new concern. GPster

idrivejunk · July 17, 2021, 10:30:05 AM

I've had a pan bolt head or washer a little too big for the flange crease a stamped pan, creating a leak there.

For your show near home, perhaps a makeshift diaper like cardboard bungee'd under the pan could get you by.

Crosley.In.AZ · July 17, 2021, 03:18:21 PM

Quote from: "GPster"
Quote from: "Crosley"There is no drain back check valve in a 4L60 series transmission. Drain back from the converter happens with wear and wider clearances in the pump , input shafts, bushings,

This transmission is a 700. At some point I had to identify it by the mark on the side of the case and the pan gasket, the filter and the new TSC (?) cable are for a 700 transmission. This transmission is not controlled by the computer and the only wires going to it are supposed to be for the converter "Lock". I've been informed that the car display has been moved from the street to the Methodist Church parking lot so the transmission leak has taken on a new concern. GPster

4L60 series transmissions is 700r4 renamed. Same transmission. GM renamed the transmission series decades ago.

No check valves in 4L60E transmission either. This olde wives tail continues on the internet... Now: yes there are transmissions with check valves for various purposes.

I only ask my usual question: Would you run the engine 2 quarts low on oil so it leaks less? Transmission requires lubrication just like an engine does.

GPster · August 17, 2021, 09:52:32 PM

Well as luck would have it, the transmission shop that's building burned down has set-up business in a building 2 1/2 blocks from my house. I decided to "bite the bullet" and have a professional check my problem. The first problem that he saw was with the yoke on the front of the driveshaft. I was concerned that when I had the driveshaft made that I had miss measured and had the driveshaft made too short. I re-mounted the rear end further foreword but then I built the floor in the body and never checked what I ended up with. Just happens that I moved the driveshaft enough foreword that the part of the yoke that had been exposed (and rusted) was now further in the transmission tail shaft housing and the rust had cut the rear seal of the housing. A new seal and yoke and u-joint on the driveshaft appeared to take care of that problem but it was Friday afternoon and quitting time So the Jeepster sat on the lift all weekend. Monday morning I went over to pay the bill and there was a big puddle of ATF under the Jeepster. It appears the converter had drained back and the seal on the fill tube was leaking. Changed that seal and also the seal on the cable and those leaks were fixed. On inspection of the whole situation it became that my construction apparently was flawed in that the tail housing of the transmission was mounted too high and the level of fluid in the pan has to be high on the dipstick so that the rear of the filter is submerged. With the leaks fixed I can run a little more ATF in the trans but I'll need to re-make the transmission mount crossmember and maybe mount the front of the engine a little higher. That solves the transmission problem(?). but the trip un-earthed some other problems. The radiator started to leak. So first I'll try leak stop. When I went to pick it up Monday afternoon it was still on the lift. Seems it wouldn't start. The fuel pump wouldn't run. Happens it was just the relay and luckily it was before the parts stores closed. Got a new relay and that was fixed. So now the Jeepster is home in the driveway. I've got an appointment at Cleveland Clinic Thursday and if they don't keep me more on this subject Friday. GPster

enjenjo · August 17, 2021, 10:57:14 PM

Good luck Joe. I have spent way to much time in Hospitals the last year or so.

Crosley.In.AZ · August 21, 2021, 08:42:48 AM

I dont see a friday post from Joe. Hope things go well for him.

Nice to hear there were a few transmission leaks found and repaired. Leaks on older transmissions can be like a dog chasing its tail when it comes to fixing them.

GPster · August 21, 2021, 09:37:41 AM

Well it set in my driveway for two days over a clean piece of cardboard and not even a drop. While it was on a flat/level place I did some measuring, I must not have figured the thickness of the mount when I built the crossmember. That's how much I have to lower things. Well maybe today I can get the Jeepster up on jack stands and do some figuring while laying on my back. This particular medical problem I'm having has been going on since early May. I had a fall and got an infection in the site of some of my facial re-construction sites so they're going have to cut open the last 25 years of plastic surgery and clean it out. First surgery is going to be 8/31. Enough for now, GPster