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Rear Main Oil Seal

Discussion in 'Engine & Drivetrain' started by Larryjb, Mar 15, 2020.

  1. Larryjb

    Larryjb Full Access Member

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    Lowering the transfer case with a transmission jack is very doable, but I will consider putting something grippy like a mouse pad on the deck of the jack to keep the TC from sliding around. That was the biggest problem I had.

    Now, onto the transmission. It took a good 1/2 hour to remove two electrical connectors. I think they use some sort of glue to keep moisture out. They certainly didn't come out like in any one else's video.

    Edit: Wish I'd seen this first:


    at 31:30 he uses a heat gun to melt the glue. The plugs come right out.
     
    Last edited: May 28, 2020
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  2. Galante

    Galante Supporting Member

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    this....i did it on my 01..... much easier than unbolting the bracket and the drain bolt was seized to the pan...
     
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  3. Larryjb

    Larryjb Full Access Member

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    In principle, I like to keep things in as original shape as possible. My thinking is probably flawed on this one, but I don't like the idea to bend the bracket. Because many seem to have done it, I assume it has no effect on shifting, although I presume the shifter cable has to be adjusted after.

    I did notice a small amount of rust on that second torx bolt that was stuck. I got it out alright once the front drive shaft was out of the way. I may add a dab of antiseize on them to prevent them from seizing up again in the future.

    The gasket that goes between the transmission adapter and the transfer case is paper. Does that gasket go on dry? Interestingly, the GM service manual says very little about that gasket. In the installation of the transfer case section there is no mention of a gasket, but in the installation of the transmission adapter, they do mention installing the gasket before installing the transfer case. I guess the writers of GM's service manual aren't perfect either!
     
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  4. Larryjb

    Larryjb Full Access Member

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    Got to the rear main seal.

    For those of you who are considering removing the transmission for the first time, here's a tip. With the transmission supported, remove the front crossmember that goes underneath the engine oil pan. Then you can tip the transmission just a little lower. This allows you to actually reach inside to start bolts, attach brackets and such onto the hard-to-reach bell housing bolts.

    It was definitely leaking, so this was a good call. I don't regret just doing the pan gasket first. That is easy compared to the removing the transmission. Don't get me wrong, it wasn't bad, but definitely involved, and kind of like playing Tetris backwards:

    How do you remove part A?
    Oh, you have to remove part B first.
    But part C is in the way, so take it out.
    Oops, part A is in the way of part C....

    And on it goes. If this were on a hoist it wouldn't be so bad. No scooting around to the other side, then back, then around to the other end, then back out to get a different tool.....

    Also, the transmission jack I got I felt was the best for this job. Everything else was designed to adapt a regular trolley jack, and I really didn't like that idea. I could see losing a transmission real easy. Can you say "timber?" The others were designed for use under a hoist.l This was the only one I could find locally that would fit under a car on floor jacks:

    https://www.princessauto.com/en/detail/1-100-lb-low-lift-transmission-jack/A-p8667875e

    When I first got it, it barely had any hydraulic fluid in it. Then, it seemed to work nicely with the transfer case. But when I got it under the transmission, I leveled the deck under the pan of the transmission, and that worked fine. Then, when I got the transmission off the dowels, it started to tip forwards. I tried to adjust the deck of the jack, but turning the fore/aft knob undid a lock nut underneath which wasn't supposed to come undone. I got the nut back on, put another strap on the transmission going fore/aft to keep it from sliding right off. I did use 2 pieces of 1x6 underneath which probably prevented it from slipping right off.

    The weight of the transmission put pressure on the lock nut which caused it to unscrews from the bolt as the adjustment bolt turned. I was NOT happy. I have since removed the nut and reinstalled it with some locktite blue. I may have to go with red, but I hope not.

    I've seen people use a motorcycle lift, but that seemed tippy too, for a transmission.
     
    Last edited: May 29, 2020
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  5. Larryjb

    Larryjb Full Access Member

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    Here's a picture of my rear cover. There's quite a bit of fresh oil on the cover itself, some around the bolts, some around the seal itself. Interestingly, I see some oil on the threads of the two long pan bolts. I'll pay attention to whether the oil is coming from the bolt hole, or if the oil is making its way over the side and onto the threads. I may want to extend my bead of RTV beyond just the corner and past the bolt hold. (but just a thin bead). Tahoe rear main.jpg
     
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  6. Larryjb

    Larryjb Full Access Member

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    After removal of the rear cover, I could tell that the gasket material on the metal frame was completely flat and flush with the metal. There was oil in ALL the bolt holes for the rear cover.

    Given how badly this was leaking, I don't see how I could make the leak worse by almost any mistake other than taking my drill and drilling holes into the oil pan.

    Onto cleanup then reinstall.
     
  7. jonnytahoe

    jonnytahoe Full Access Member

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    I had the same problem with the trans Drain Plug. Talked to a GM tech that told me most have a factory sealer on them so they don't leak which over time makes them hard to remove. Mine did the exact same thing I rounded off the plug even with a six point socket so I just left it in. I decided to bend my cable bracket after having the exact same problem your having.
     
  8. Larryjb

    Larryjb Full Access Member

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    Rear main and cover, and flexplate is installed. Now onto reinstalling the transmission.

    Here are a few things to took up an unnecessary amount of my time. If this is your first time doing this, this may help you:
    1. Draining transmission: If you are unwilling to bend the bracket, wait until the front driveshaft is removed so that you can get in there better with your wrench. Use a bit of penetrating oil if necessary. This probably wasted a couple of hours easy.
    2. Remove transmission attachments before removing the transmission mount: heat shield, park/neutral position switch connector (use heat to melt glue inside), main electrical connector, fuel line bracket bolt, torque convert bolts). It's way easier to do so without a transmission floor jack in the way.
    3. Don't try to remove exhaust Y pipe without removing the transmission support cross member. That wasted a 1/2 hour of my life.
    4. Removing all the electrical stuff from the transfer case was time consuming. I believe there are 5 connectors and a couple of wire loom clips. There was only one connector that was a pain, and it was on top. I wasted a little time in removing the loom clips though. I forgot that they can be slid off the pin mount if you unlatch the clip from the pin mount. That made it fast and easy.
    5. If you are unsure about the weight of the transfer case (some remove it without a jack), a transmission floor jack is well worth the money. (see my note later about the transmission jack). But, make a wood base to put on the metal deck. This provides a little friction so the transfer case doesn't slide right off as you lower it.
    6. Some have wasted a lot of time with the transmission cooler lines. There are 2 caps that pop off and slide away exposing two spring clips. They are hard to see, so get a good light and get a good pick set. I got a Milwaukee set because it had finer points on it, plus a better selection of hooks. You will appreciate the finer hooks when trying to get these clips out.
    7. Some have wasted a lot of time trying to remove the transmission oil pan dipstick. Simply pop it out of the transmission and leave it. Make sure it doesn't bind or get pinched as you lower the transmission. After, if you want to remove it, it comes out super easy from below.
    8. Leave the vent tube connected. This is much easier to remove once the transmission is on the ground, IF you want to remove it.
    9. Remove the front crossmember to allow you to tilt the transmission a little more. This gives you easier access to the bolts (use a long 3/8 extension). With it lowered slightly, you can actually reach in and grab any upper bolts and brackets by hand from the rear of the transmission instead of from the side.
    10. Invest in a cordless impact. This was great for removing the flexplate bolts. These bolts have threadlocker on them. This would be no fun without an impact.
    11. Invest in a set of thread chasers, for bolts and for the bolt holes. I still don't have one, and I wasted 2-3 hours picking out theadlocker from the flexplate bolts. (This needs to be done, or you will NEVER get the correct torque.)
    Transmission hydraulic jacks:

    This jack was absolutely necessary for me, but there are three things that wasted the equivalent of a day:
    • It was almost devoid of hydraulic fluid.
    • The deck has a lot of fore/aft slop.
    • The retaining bolt at the bottom of the fore/aft adjustment bolt comes off easily

    Once filled with fluid, it worked fine.

    Be aware of the fore/aft slop. Don't just line up the transmission jack to the transmission, strap it, then lower it. Because of the slop and the forwards center of gravity of the transmission, it tipped a good 20° down to the front. You'd think this would be easy to fix, except that turning the fore/aft tile knob caused the retaining nut on the bolt shaft to turn off giving me NO fore/aft control! So, check the slop. Remember that the transmission will be heavy to the front, so make sure the slop doesn't tip forwards. Instead, adjust the tilt first so it is level when pulling the deck of the transmission jack down to the front. Also, if you place the transmission pan square on the transmission jack, it could have a tendency to tip forwards. Place the transmission so the front edge of the transmission oil pan is behind the front edge of the transmission jack deck. Also, make a plywood base to fix to the deck of the transmission jack. This gives a little more friction and keeps the transmission more stable on the jack. Finally, I used ratchet straps instead of the supplied chains.

    The only one I could find locally was from Princess Auto in Coquitlam BC. Perhaps there are others out there, but I couldn't source them. I chose this because it has a wide base and is low profile. Most other transmission jacks were either the adapters you get for a regular floor jack (I consider this highly dangerous!), or the style that you use under a hoist.

    I've seen many use one of those scissor type jacks. I'd be scared of those too because of the small base. If the transmission had tipped 20° on one of those scissor jacks, I'd probably have lost the transmission. The transmission jack is not the tool to skimp on.

    --------------------------------------

    Overall impression: This job has not been so intimidating as I figured it would be. Most of the difficulties were a result of the transmission jack. I'm still glad it got it, but I wish I knew about its limitations beforehand. Would I do this again? Well, yes, if you paid me a 12 pack/hour (to be consumed after of course). The others on this forum are right, it's not bad, just a lot of work. And when I saw guys removing transmissions on gravel driveways, I realized this was entirely possible in my nice comfortable garage. I don't know what I'd do if I had a newer Tahoe that wouldn't fit in the garage.

    Note correction in the edit: Place the transmission so the front edge of the transmission oil pan is behind the front edge of the transmission jack deck.
     
    Last edited: May 30, 2020
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  9. Larryjb

    Larryjb Full Access Member

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    Oh, I need to ask this. At the time I was installing the rear main seal itself, I couldn't find my volume 2 of my FSM, so I relied on the seal instructions from FelPro. The FelPro instructions said to lubricate the OUTSIDE diameter of the seal, but said nothing about the INSIDE diameter. Because I've seen others lubricating the INSIDE diameter, I did apply a very thin film of oil on the crankshaft to aide the installation. I found my Volume 2 today and it said in block letters DO NOT apply any lubricant of any sort on the inner diameter of the seal or the crankshaft.

    So, is this the type of error that I should stop and take everything apart again and redo? Or should I be fine?




    Indicates it is a Teflon seal, but does not give any lubrication indications:
    https://drivcat.com/livedocs/2067(4-1).pdf

    And:


    Oh #[email protected]#% Even GM states to not lubricate the seal. Why didn't Felpro state that?

    I know I shouldn't, but I'm going to get things slapped back together and see. If I have to do this again, it's not going to take me nearly this long. I'd probably be able to have the transmission out in an afternoon now. Besides, I will still have to deal with the transfer case. If it does leak, I don't see it leaking nearly so badly as it was before. Hopefully I'll be okay. I did wipe most of it off before installing the seal.

    ---------------------

    If you read the comments below from the referenced video, they don't leak because of the oil, they leak because they were damaged during installation. The PTFE gives an added advantage, that's all. I guess I'll find out.
     
    Last edited: May 31, 2020
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  10. Larryjb

    Larryjb Full Access Member

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    Lifting the transfer case into place was the worst part of this job so far. I actually don't mind doing the transmission. It has fewer connections and its weight is predicable (as long as you consider the jack you are using). If I were used to heavy weights, this would have been fine, but on my back in the garage, and not toned for lifting weights, I had to rely on the transmission jack. Now that I have it figured out, I think I'd be okay with it.

    I left the transmission mount in place (cross member removed), and couldn't get the transfer case close enough on the jack. I could have tried to lift it, and I did, but I tired before I could get it on the splines. I had to ask the good Lord to calm my nerves a few time, then finally removed the mount and was able to get the jack right beside the transmission adapter and it slid right on.

    At least with a transmission, you can take a break knowing it's secured on a jack. That transfer case has a really weird center of gravity. Also, I'm certain that this transfer case has been opened before. The service manual very definitely states to NOT use ANY silicone or liquid gasket material on the gasket or seal. (There's a seal between the adapter and transmission, gasket between the adapter and transfer case). There was black silicone on the transfer case side. Also, the fluid was right up, and not the colour of transmission fluid. Yes, eventually I should pull the case apart and look at the pump, but not this year. If I get a leak and need a new case, so be it.

    Left to install: transfer case wiring/vent hose, exhaust/O2 sensors, cross members, starter motor, drive shafts. I've got a new filter for the transmission, then fluids.
     

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