Rear of Engine Oil Leak-- Rear Main Seal?

[Carimbo]

So much for the orange seals, this is what I got:


Larger one on right is the torque converter seal, smaller one is the extension housing seal.

Set up a session at Al's for 5 Jan, hope I have everything I need for the rear main seal replacement:

RMS
TC Seal
Ext. housing seal
4 ft. 5/16" tranny cooler hose
Tranny mount

Also bringing my red steel ramps and lots of quarters to facilitate washing the undercarriage at the jetspray before starting.

Oh looks like I forgot the exhaust headpipe packing seal...

[asavage]

The headpipe gasket is a gasket:




If you want to do a transmission fluid change, buy a pan gasket (do not buy a filter, they are wire mesh and do not need replacing!) and about a case of ATF -- I like Chevron, but it's not a religion, and name-brand ATF will do. I have the pump and tubing (see my Aerostar post on this). You will need to bring some plastic antifreeze or milk containers to contain the oil fluid. About three one-gallon jugs.

[asavage]

Carimbo and I had a swell time Saturday, R&Ring the LD28 rear main seal. We began at the local car wash at about 9:30am and ended the next day at about 1:00am, with a break for lunch. Yeah, I'm slow.

Carimbo did almost all the work, I just provided the entertainment.

It was all pretty straightforward, with only a handful of, "Hmmmms".

Though the ATF was dark and smelly, the trans' pan was extremely clean. Very odd.


RMS was very loose in the engine. When I inserted the hooked seal removal tool, the seal spun in the block! I popped it out with almost no force. We used a thin film of RTV on the OD when installing the new one.

Old seal:





I banished the aviary under the hood (bird chirping): the alternator belt was very loose and chirping. Carimbo's ride needs to have all four belts replaced. The three visible ones also have visible cracking.

The aftermarket trans mount we installed . . .


. . . did not seem to have the exhaust brace studs in precisely the same location as the old one, and I Dremel'd the mounting holes oval. It's possible that we didn't have the trans centered laterally the same as prior to disassembly, but I don't think that was the cause.

We replaced the torque converter seal and the extension housing seal while we had the trans out. The extension housing seal, though new, leaked a puddle approximately 10" in diameter during the flush procedure, which was quite a while after we started. Neither of use saw it until we'd started/stopped the engine a half-dozen times and were done flushing and ready to clean up. After removing all the oil, and driving it four miles, it does not seem to be leaking any more (?). Well, I saw two drops after the four-mile drive. Carimbo will have to inspect it later, but at 1:30am Sunday we really didn't have a lot of options so he drove it home that way. I assume he'll report here his Monday findings.

Undercoating on the rear of the driveshaft . You'd think that will all the warnings I'd heard over the years about not getting undercoating on the driveshaft (upsets balance) that folks who undercoat for a living would know better, or at least remove it with a solvent rag before it became cement, but apparently not.

Carimbo reported more drivetrain noise with new (aftermarket) trans mount, than old, soft OEM mount.

What else, Caxambu?

[asavage]

I see that NAPA lists the same part Nos. for the L24e and LD28 for 1983, with one of the four seals offered having dimensions:

ID = 80mm
OD = 100mm
Width = 10mm

Actual seal was 13mm wide, not 10.

[Carimbo]

Sending a very heartfelt thanks to Al for making the shop available and his time and efforts. If he works slow as he mentioned, then I am embarrassed to state my rate of (actually complete lack of) working speed.

Also was pleased to make acquaintance of another lister-- Mark Hartz.

Made it home 3:30AM after a long day. Looked under the car after several hours parked; rear main seal was apparently a success, trans extension housing seal apparently not. Car is still leaving great puddles, only further back! Well if there has to be troubles I prefer it this way-- at least this one will be easier to try to fix.

I forgot my camera; Al took some great photos and then some. I will work with him to get them posted here.

Off the top, here are some important points about this R/R engine RMS procedure:

• Basic process is straightforward, mostly good access, fasteners seem stout enough that we didn't break any.
  Torque converter to flexplate bolts were relatively easy to work and reassembly was simple because they lined up easily and without drama.
  Problem areas were:
  Steel lines (vacuum and trans fluid cooler lines) that run under bellhousing front to side of tranny were difficult to work around and reattach.
  Electrical butt connectors on both sides of tranny are tucked up between the tranny side and tranny hump on the unibody without much room to access disconnecting/reconnecting them.
  Trans fill tube fastener bolt also difficult to access.
  Exhaust pipe bracket did not line up w/ new tranny mount. My hunch that this is contributing to the heavy vibration at idle and booming exhaust at 60MPH.

I can report that the major parts of the process went smoothly and quickly-- most of the time was spent on the (frustrating) problem areas listed above.

Note that ALL these problem areas were the areas I was working on, so that right there you can presume part of the difficulties were my lack of skills, talent and experience.

Plus we were starting to slow down from lack of dinner (Al doesn't eat dinner)(but I did manage to sneak a few cookies when he wasn't looking) and huffing plenty of aerosol carb cleaner. This and general fatigue really affected our ability to thimk clearly.

Obviously glad to have stopped that large messy engine oil leak; the rest (trans seal and exhaust mounting) is relatively minor and I will address them as the weather clears up.

Al's help and guidance was priceless. Most valuable to me was that I learned a lot during this session.

Obligatory tip for future readers:
Tranny cooler pressurized line is the one on the passenger side.

[Carimbo]

Even if the tranny pan was ultra clean (surprised everybody), I'm glad we flushed the tranny and TC: Last tranny service was at 192854 mi. Oct 2002, 60,000 mi. ago, and before that at 126240 mi., Oct. 1993.

But here is the clue for the next project:
Last (documented) IP belt change 114747 mi. Oct 1992. Yikes!

[Carimbo]

Decided to to with an OEM seal this time, dealer says it has arrived; I will pick it up tomorrow and schedule some time this weekend to install. If there is enough time I may replace the new tranny mount w/ the old one (thanks for salvaging/sending it Al) because of the annoying extra vibration and noise at idle and at 60 MPH.

Tranny has gone thru 4 qt.+ of fluid in approx. 1400 mi. Lost propulsion on a few occasions when I did not catch it in time.

[asavage]

Lost propulsion on a few occasions when I did not catch it in time.

Ouch! That is very bad for an automatic.

[Carimbo]

Hopefully it didn't damage anything too bad-- happened early AM (cold) backing out of driveway. Was not able to get fluid warmed up enough to get a good level reading before starting out.

Just now finished installing the new OEM tranny extension seal. First tests while still on jackstands show no fluid dripping or seepage. Ran thru the gears, let it run for 5-10 minutes.

Couple things I noticed:

Splined trans output shaft has approx. 1/4" radial play at end. Is this normal? Also the part of the housing that is normally hidden inside the "cup" of the driveshaft had some radial scratches along its circumference.

After removing the old seal, a look inside the rear extension showed the seal spring was in there. No way to tell if my screwdriver seal removal method did this or could that have been the source of the leak?

During the run test the LR wheel bearing was ticking loudly. This coincides w/ some mild thumping around right hand corners I have experienced at times, mostly able to discern better on smooth pavement. Looks like time for bearing replacement, probably easier to find a decent rear suspension A-arm at the JY and replace the whole assy.

[Carimbo]

After 25 Mile trip trans extension housing/driveshaft slip yoke is dry. Good news so far.

Not enough time to swap the trans mount (hard new for soft old) but was able to make adjustments to shift the mount itself relative to the transmission and frame crossmember so that the exhaust pipe was not forced to the side. Vibration at (cold) idle is only slightly better.

Here is a pic of the OEM seal Nissan P/N 31336-x0101:

[asavage]

Splined trans output shaft has approx. 1/4" radial play at end. Is this normal?

1/4" is pretty loose. Actually, very loose. I like to keep it under 1/8". My grey '89 Aero I rebushed and it went back to 1/8" pretty fast, but didn't get worse. It leaked pretty much the entire eight years I owned it, three seals and one rebush since the trans was rebuilt, but just a drop every so often.

After removing the old seal, a look inside the rear extension showed the seal spring was in there.

I probably knocked it out during installation, though it I don't recall having done that since the 70's. Since it was leaking pretty much immediately after install, it makes sense.

During the run test the LR wheel bearing was ticking loudly.

I replaced mine on the Wagon (RR) at ~110k and it had been making noise for at least 20k before then. It is starting to make faint noise again now (at 171k). Same brg. I've been told that the Sedan and Wagon use exactly the same rear wheel brg, even though they are in wildly different suspensions.

Replacing it on the Wagon is not too difficult, though I paid a shop to do the presswork on the axle -- about $10, nine years ago.

[Carimbo]

After a 150 mile trip, no leaks, not from engine, not from tranny, yay!

Immediately lowers my stress level by not having to worry constantly about accidentally running low engine oil or trans fluid levels. And not having to check all the time.

Also now I can park in ritzy driveways w/o feeling guilty.

But: TC is not locking up like it used to (37MPH). Will have to take a look at the vacuum lines as they got a bit abused during the tranny R/R. L3N71B.

[asavage]

TC is not locking up like it used to (37MPH). Will have to take a look at the vacuum lines as they got a bit abused during the tranny R/R. L3N71B.

Referring to 1982 FSM page AT-42, there are a finite number of things that can inhibit TC lockup on the L3N71b. Unfortunately, only one of the them can be checked without pulling the trans out

The easy one to check is the external governor tube, which is the smaller, snaky steel line that runs from the rear to the front on the driver's side. Shown below is the L4N71b (first a gasser, then a diesel version), but the governor line is in the same place, only a bit longer on the OD transmissions:



If that line isn't crimped, I'm afraid your next most likely thing to have changed when we had the trans out is what is somewhat mysteriously called the input shaft o-ring. You'll notice that the input shaft is never really shown in the '82 FSM, though it is shown in the 1984 FSM . We had the input shaft out -- it's the loose splined-on-both-ends shaft about 16" long that is co-axial with the torque converter. It falls out when you top the trans face-down. It's possible a ring got nicked, but I don't think it's an "rubber" o-ring. The FSM likes to use the term "o-ring" and "seal ring" (a steel, square-section ring) somewhat interchangeably in the AT section. Seal rings are pretty hardy creatures, but we did touch it . . . so that makes it the next most-likely.

After that, the FSM's offerings don't seem to have much comfort. Nothing mentioned seems any more likely than anything else, WRT what we did.

I will try to remember to pull an input shaft on one of my core L4N71b trans' up in the attic tomorrow, and get a better idea of what the FSM is referring to. If I'm not snowed-in.

[asavage]

I pulled a TC today off one of my L4N71Bs, and the smaller shaft does have what appears to be a very stiff o-ring. Or maybe not an o-ring, but not steel at any rate.

(click on any image for larger)

[Carimbo]

Now there is a more serious problem to consider:

While changing the oil today I decided to take a look at the new tranny cooler hoses & their connections. While poking around there I noticed the air conditioner sheave on the crankshaft balancer is loose. It can move fore and aft. This might be contributing to the awful vibration (low drone) just off idle, or at fast (cold) idle.

Do I need to stop driving the car until fixed? Will this damage the crankshaft?