Transmission Leak

2287 Views 22 Replies 4 Participants Last post by  Moparian1997
After dropping the transmission and doing a seal kit, (OEM) from the dealer it's still leaking at the engine. Any ideas why? It only leaks when I drive and the faster I go the more it seems to leak, to the point of smoking at about 70 mph if I keep it at 60 mph no smoke.
Was reading many threads and seen something mentioned about a pressure sensor and solenoid? Could this cause more pressure at the TQ seal and make it leak?
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After dropping the transmission and doing a seal kit, (OEM) from the dealer it's still leaking at the engine. Any ideas why? It only leaks when I drive and the faster I go the more it seems to leak, to the point of smoking at about 70 mph if I keep it at 60 mph no smoke.
Was reading many threads and seen something mentioned about a pressure sensor and solenoid? Could this cause more pressure at the TQ seal and make it leak?
You could have gotten a transtech seal kit, only 69 bucks. They work just as good if not better than the manufacture. Anyways, now that I ranted on that.

Pull off the transmission and see why it might be leaking. Could be that you didn't properly seat the seal. Could be the seal lip from installing the torque converter. Could even be the pump cover, it has two seals; one rubber and one paper. Likely that the rubber seal lip folded over a little. Why does it leak at higher speed, might be temperature related. Fluid expands (gets thinner) as it is heated
Thank's ramvan,
That's the seal kit I installed. I removed the pump cover and replaced some seals on the shaft (5, O-rings) both pump cover gaskets and the TQ gasket, and I used caution when re-installing everything being sure to lube things lightly that required it along the way. This leak was the reason for dropping it and the end result was as if I did nothing at all. Still the same leak.

Someone told me to make sure it wasn't pushing fluid out the vent because it is located behind the TQ at the top of the bell housing, it looked dry from the shaft to the top. I was wondering if the pressure solenoid and sensor could have gotten dirty enough to malfunction causing excessive pressure at high speeds. At this point all I can do is rebuild the valve body and see if I fix the pressure problem. I had a trans guy check the TQ and the pump for wear, he pressed a new bushing in the pump just because I was there and it did show some wear but not excessive.He told me there are so many things that can go bad inside he would only do a complete rebuild for about 1,800.00 but I cant afford to go that extreme, I just replaced the trans in my car back in the spring. So I started looking on here to see if someone had a similar problem with a solution because as long as I don't get in it and drive it doesn't appear to leak hardly at all sitting in neutral or drive, so something is causing fluid to leak out the new seal as much as it did the old one. Me and a friend can only see it being an issue of too much pressure and even the new seal can't handle it. When I first started it to top off the fluid level it left no drops on the floor then I took it down the road at about 30-40 mph a half mile pulled off on the shoulder and only seen a few drips. I've described everything unless I have a specific question to answer.
If the fluid level is at normal level and that is with the engine at normal operating temperature, then it won't come from the vent. Solenoids wouldn't cause it to leak externally. Where was it leaking from exactly originally? Was there oil residue on the top near the vent? In the middle where the input shaft is? Or was the fluid on the bottom. Oh, also.. If the fluid isn't red/brown, then you probably have a rear main seal leak from the engine.

1800 for a rebuild is not bad, from a shop. i charge about 1000 less, but i'm not a shop and i do not do rebuilds often anymore. i've been busy restoring a car and school.
It looked like it was leaking around the TQ seal, but I cant be sure.

It was wet in the center to bottom fanning out from the input shaft.

I'm sure it's transmission fluid. I have worked on my own cars for 30+ yrs. Transmission's are the only thing I never touched because of the fear factor, getting in over my head. Chevy was my car of choice in my youth. Did engine rebuild's rear end rebuild's and a total restore of the classic 69. Always had the transmissions done by a pro. I live in an area far from the city now.

That's a bench top quote. I'm sure I also need to add the cost of a new TQ, not sure about that he does rebuild them also.

Other concern's I have is the input shaft being worn to the point of allowing excessive fluid to get to the TQ seal location or the TQ being worn to the point of being out of tolerance or being cracked. Was even asked if the bell was cracked by the guy at the transmission shop. This all started out of the clear on my way home from work. Stopped to get appt. for the windshield to be replaced after an inspection the day before. Pulled into the driveway at home and noticed it leaking. Wasn't seeing the smoke cloud on the way home like I do now and the drive is 45-50 min. from home. Now it has the cloud at 70 mph. within 10 min. I'm puzzled and tempted to do the rebuild my self because I don't have $1,800.00 to pay someone to do it and would need to wait till next year. I would need the truck in the winter when the weather get's bad. I was watching a video about valve body's and seen a piston valve that releases excess pressure at the higher RPM's, it releases this fluid to the pan. The thought is this might be stuck in the closed position. I need to mention that I neglected the fluid for a period but found no metal particles in the pan that would alarm me. I did however find a piece of a snap ring on the magnet, that concerns me. It was only one piece about 1" long and flat so I only assume it's the defect mentioned by many others who have rebuilt these things. This has been rebuilt but I can't say when, I'm the 3rd owner of the truck it has 220,000 miles on it now. The guy I bought it from left it sitting in the driveway because he couldn't afford the gas to drive it anymore and it had 188,000 when I bought it from him.
If you found snap ring then you are going to need to rebuild the overdrive assembly.

Like I said 1800 is not bad, I see allot of clowns charging 2500. Quite honestly most transmissions only need new seals, some of the planet gears need to be replaced, and valve body upgrades. Other than that the clutches plates and discs do not really wear. Sometimes they do and yes you need a replacement, but that is generally from abuse and tolerance issues... Not actual wear from standard use (includes towing).

I rebuild these in my sleep, the automatic transmission is the simplest thing in the world. Right next to circuit boards, engines, digital cameras, and everything... Nothing is hard to do just do it yourself. These transmissions only go together one way (except a valve in the valve body).

Anyways, to solve your problem... I was thinking that it could be your torque converter that is leaking. Check the welds on the hub for any cracks, sometimes they develop a crack and will leak. If you want a service manual just private message me your email address and I can get you the factory service manual right away. It has pictures which is nice. I use it for checking tolerances and bolt torque specs... The actual rebuilding is common sense stuff. Hect even the tolerances are, but that is just from rebuilding them and what not.

If you do rebuild it yourself I can offer some assistance when you get stuck. I used to tell people what to buy to do a rebuild, but I couldn't be bothered. One cannot learn by being spoon fed everything, I can tell you where to buy and what you need at the very least, but when you open up the transmission and find all those little surprises things will change.

I wouldn't worry about cracking the bell housing. I have done that once. If you tighten the cooler fittings too much it will crack the bell housing because those threads are tapered threads, not straight threads.

As far as the rebuilders, listen to them but grain of salt. Half of them do not know what they are doing. Many people are going to disagree and that is fine... I rebuild them and started rebuilding them when I was 17 or 18 and they are just so simple to put together my god... Fun to rebuild! Especially the OD unit because you get to use a press and make your own tools for the press! (2x4 will be your best friend).

The only special tools to rebuild this transmission can be found at sears, lock ring pliers, snap ring pliers, wrench set, torque wrench, extension bar, hammer, seal remover, screw driver set,large c-clamp, and a press.

If the input shaft is worn it will not leak. The input shaft spins inside of the stator support. The torque converter hub slips over the stator support and goes into the seal. The hub engages into the pump gear's teeth. The stator support engages into the stator, and the input shaft engages into the pump blade inside of the torque converter. You could technically have no input shaft and it would not matter.

I would start to suspect a broken weld on the torque converter, and that is if the seal is not the issue.
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I can't send a private message yet. I'm a newbie so if you can send one to me that would be great. I would really like to see a manual on this unit. It would be handy come time to do a rebuild because I plan to keep this truck as long as I can. It's in excellent condition. Your the second person to suggest the TQ. I didn't know they cracked, I never experienced that before and I had a really cool hot rod in the younger days. Tore up a few rear ends and blew a rod or two but never cracked a TQ. I really want to thank you for all the help you've been to this point. I wonder if I can get the TQ out without dropping the trans all the way out again? It's a 4x4 and looked to have a good amount of room after taking out the transfer case.
Yup Torque Converters crack, the HAZ usually develops a crack. Luckily converters are cheap. Yes you have to drop the transmission to remove the converter. You are going to want to be sure that the hub engages the pump, otherwise you will be in big trouble!

I'll see if I can PM you. If not just post your email address on my page and I'll get that manual out to you right away.
I sent you an e-mail and I left my e-address on your page. Sorry about the PM my pop-up block was turned on and I clicked OK and lost the request. It's been a while. Still learning to navigate this site and feel how it works. Sure you can relate.:doh:

Thanks for the headsup, I'll give it a try. But it was fogging I think because it's leaking out and hitting the crossover pipe on the exhaust. Burnt fluid leaves a mark. I can relate to the scene, people were backing off when it started smoking the highway. LMAO when I think about it. BTW, the only leak is at the engine block to trans. Wouldn't the trans to transfer case also be leaking if it was the OD?
Yea, I found your email on my page and sent you the service manual. Oh, what's going on with the OD unit now? Another leak?
Leak fixed. The TQ had a crack around the nose 1/3 of the way around. Wouldn't have found it except the transmission shop was able to pressure test it, they rebuild TQ's. I also took the OD unit off and replaced a defective o-ring that I found a piece of stuck to the magnet in the pan. Feel better knowing everything else passed inspection while doing all this repair work. Should get many more miles out of it. Decided to do the intake and dug a hole, broke two intake bolts on the passenger side, first and last. Got one out after soaking it with penetrating oil but the other is going to be a pain in the ass. Hope after letting it sit over night it comes out like the other one did.
I just love it when I'm right :D :p LOL Anyways, just me being a _____. Glad to hear the truck is all fixed up now. Keep the service manual handy for the future.
You nailed it perfectly. Thank's a bunch for the help and the manual, it will come in handy in the future I'm sure. The snap ring piece I found from the OD unit was the only part floating, the rest was in tact so while I had it out a second time I replaced it just so I could sleep at night knowing I did it right, also inspected the rest of the unit and looked good for wear. Ready for the next road trip.

I also was able to remove the second broken intake bolt, but only after heating it up a bit. Now I have power like never before. I got the truck 2 yrs ago and the intake must have been leaking then, just didn't know. :LOL:
Yea these intakes are a pain. I rebuilt my engine during X-Mas break and it pulled a little oil. But it's normal with these engines. I didn't bother changing out the belly plate to aluminum, but I did have it on "the list" at one time. Runs fine though, gets 18MPG and has better pickup. I cannot complain, especially for an 18 year old vehicle. Anyways, enjoy the truck. Keep you eye on fluid levels for a while, you're going to want to after any seal replacements. Do not be alarmed if you find a little fluid for the first month. It just takes a while for any residual to clear out and for the seal to conform to the eccentricity of the shaft.
I'll do that for sure. While your on line have you heard about the phantom vent problem. While driving with A/C on the vent closes when climbing a hill and opens back up after easing off the gas pedal. I know it vacuum related and I tried to create a dedicated line for the dash control, worked for a bit but now it's back. I'll go through and look for leaks but thought I would shoot that question at you? Do you have any Idea on how to solve?
It is certainly vacuum related. I would start off by checking vacuum lines for any leaks, including rubber connectors. If all that checks out I would look into the vacuum reservoir, as it might be filled with water from moisture which present in the air. This waster build up in the reservoir would reduce the capacity of the reservoir during times vacuum are low (such as hard acceleration or climbing up hill). In addition I would check the reservoir for leaks and cracks.
That's the canister located on the passenger side frame correct? I hear it pulsing while the engine is running, one round and one square around the back corner of the cab of the truck. I'll check that out. I also think there is an electronic solenoid hooked to the box/canister on the passenger side tire well under the hood because I've been tracking down vacuum lines since I got the truck, inspecting lines also. I've got a few around the transfer case that will need attention eventually, oil/fluid leaks play hell on them. Was wondering if the control on the dash could be worn out, it gets used all seasons and I believe it has multiple vacuum going to it, just a thought.
The canister with the solenoid is the EVAP canister. This EVAP canister contains active charcoal which absorbs evaporate fuel out of the gas tank, when the vehicle is driving it periodically sends signal to the solenoid which in turn allows the engine to pull the vapor from the canister.

It could be an issue under the dash, it could be a check valve under the hood (highly likely), and it could just be a vacuum reservoir. I would just grab a hand vacuum pump (handy pump) and just test every little check valve and the vacuum control valves. I would however drain the reservoir when you find it, I can promise you that water will come out. Mine had about 8oz of water in it.
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