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I've been trying to trace down a slight leak in my transmission. If I drive it around the corner to the grocery store I don't get any transmission fluid dripping after it's cleaned up to monitor. It also doesn't seem to leak if it just sits in the driveway. If I drive it a couple miles to the hardware store I will get some fluid on the drivers side back of the pan, but I think that may be due to the truck leaning that way. The fluid has almost 30k on it but still looks good as seen in the picture. Today I cleaned that area up again to try and find it again and noticed there may be some transmission fluid on top that is puddling on the reinforcement webbing so I wiped that down. So to me this sounds like it could be coming from the vent on top of the transmission just aft of the bell housing. I couldn't find/feel the vent hose and had to run and pick up our daughter from school, but when I got back there was no fluid in the area I've been noticing. I did check the pan bolts just to be sure and they seem good and snug. It's just a slight leak and is probably related to getting the fluid warmed up before it starts. I've done a search on this forum and couldn't come up with anything, but most don't come back to explain what the issue was...which I fully intend to do...
Hey BW did you check to make sure the pan bolts were not over torqued? That gasket can be pretty sensitive if it is over torqued and those pan bolts have a really low torque spec if I remember correctly.I had a heck of a Time trying to figure out my transmission leak but what did help is using something like brake cleaner to get everything good, clean and dry . Then just closely monitor it every chance you get.
Hey BW did you check to make sure the pan bolts were not over torqued? That gasket can be pretty sensitive if it is over torqued and those pan bolts have a really low torque spec if I remember correctly.I had a heck of a Time trying to figure out my transmission leak but what did help is using something like brake cleaner to get everything good, clean and dry . Then just closely monitor it every chance you get.
I wouldn't suspect pan bolts being over torqued given it's been fine since the last time the pan was dropped is about 25k miles and 3 years ago. I've been using brake cleaner to get everything clean and dry too...
It might not be the pan leaking. Mine leaks where the dipstick tube enters the transmission case and not all the time either. It tracks down the top of the pan flange and leaks across the back of the pan, just like yours. Clean the area around the dipstick tube and look for leaking. It's a huge PITA to fix if it's leaking there.
I got up under the truck and looked again and found a problem...not sure if it's the problem. There is no top 90* vent screwed into the transmission and/or hose. I did look at the filler tube area and it's all good and dry. So after 2 trips to pick up little one from school after cleaning wet areas, there's no transmission fluid to be found. So my suspicion is that because there's basically an open hole up there it's splashing out onto the top of the transmission and puddling in the webbed reinforcing. When they get filled the fluid weeps down and drips.
In looking at the attached picture with said vent circled in red, does anyone know what threads would be in the hole of the transmission so I can pick up something at the hardware store? I'm going to also check the vent on the transfer case and see if there's one there because I can't feel any hoses up there and the one on the transfer case looks like it should run up there also.
I've also heard the transfer case is attached to the transmission internally, therefore the fluid is interchanged. If that is true, is there any reason the fluid level in it should be checked separately?
The transmission and transfer case are not supposed to be "swapping spit". The transfer case adapter will have transmission fluid in it....that's fine as there is no seal keeping it out of there. There IS a seal on the input shaft of the transfer case designed to keep its fluid there and the transmission's fluid out.
The chance of the transfer case causing an overfull condition in the transmission is about 0.01% since under nearly all conditions the transfer case fluid is lower than the transmission fluid, there is no pressure lube in the transfer case ahead of the planetary gearset, and the transfer case itself only holds 2 quarts of fluid; enough to cause elevated fluid levels on a dipstick were it able to fill the transmission but nowhere near enough to cause fluid to come out of the vent.
If the seal between the transfer case and the transmission were to fail, the fluid would go the other direction. Into the transfer case.
Easy to find out if you have any need to. Just remove the fill plug from the transfer case and the excess fluid will pour out the fill hole. The transfer case also has a vent on top. If any ATF comes out of the vent in the transfer case vent you are overfilled by many quarts above the 2 quart capacity. Then you will know the seal is bad. This would also cause the transmission ATF level to be low.
The transmission and transfer case are not supposed to be "swapping spit". The transfer case adapter will have transmission fluid in it....that's fine as there is no seal keeping it out of there. There IS a seal on the input shaft of the transfer case designed to keep its fluid there and the transmission's fluid out.
The chance of the transfer case causing an overfull condition in the transmission is about 0.01% since under nearly all conditions the transfer case fluid is lower than the transmission fluid, there is no pressure lube in the transfer case ahead of the planetary gearset, and the transfer case itself only holds 2 quarts of fluid; enough to cause elevated fluid levels on a dipstick were it able to fill the transmission but nowhere near enough to cause fluid to come out of the vent.
I seemed to recall them being somewhat separate...so I should check the fluid level in the transfer case to ensure correct level. Do you know what size hole and thread count that vent is there on top of the transmission?
If the seal between the transfer case and the transmission were to fail, the fluid would go the other direction. Into the transfer case.
Easy to find out if you have any need to. Just remove the fill plug from the transfer case and the excess fluid will pour out the fill hole. The transfer case also has a vent on top. If any ATF comes out of the vent in the transfer case vent you are overfilled by many quarts above the 2 quart capacity. Then you will know the seal is bad. This would also cause the transmission ATF level to be low.
This was just a question of curiosity and I will check fluid level of the transfer case when all said and done. However, right now I need to get the 90* top vent situation fixed to keep the transmission fluid from leaking out of the hole up there. Do you know what size hole and thread count that vent is there on top of the transmission? I'm hoping the vent on the transfer case is there, but if also missing hopefully they are the same...
I found another issue which will need attention. There's also no vent tube for the transfer case as seen in the attached picture with the red cap. Mine is just a hole with some grime in it. Thought was to remove the fluid level cap and blow some compressed air in there to hopefully free up the grime filled hole. It looks like though that the transfer case vent may be a press in style 90* vent. I've also had someone on another site tell me they thought the transmission vent cap hole took 3/8" NPT, which when I put my finger in up in there it could be the 3/8"...but could also be 1/4".
From what I can see on my spare 4r the vent is press fit and not threaded. I am not sure what size though. The t case vent is definitely a press fitting as well
I've made some progress today and hope to get it fixed in the next day or two. The oem Ford part number is 1C3Z-7034-AA which supersedes an earlier part number. There is a Dorman 47103 which is for the 5R110W that the representative said wouldn't work, though it cross references the Ford part number and includes fitting the 4R100 for the Navigator. I asked what the o.d. is and was told 3/8" so worst case I'll start with that at the hardware or parts store given the local parts store doesn't seem to have the Dorman 47103 in stock. It does appear they are both press in and not screw in. I have also called a transmission shop to see if they have a core that has them I can pull and use...we'll see in the morning...
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