Join Date: May 2009
Location: San Francisco Bay Area; Belmont
Re: Atlas Transfer Case Losing Oil
I just went through this entire Transfer-Case fluid-loss ordeal, so perhaps I can add some insight (apologies for the length, but it has been a process that needs to be adequately explained):
I checked the sight-tube level on my Atlas II prior to going on trail near Pierce OHV Area / Yuba River in California (just NW of Tahoe). The fluid was about ½” below the zip-tie. Although I didn’t check the level after getting back off the trail, I did check it once I got home about 200 miles later; it had dropped another approx. 1” (which I later figured-out corresponds to about ¾ - 1 quart).
The entire area was clean…….almost no oily fluid on the Transfer Case, heat shields, underbody, drive shafts, driveway, etc.
After speaking to both Eber (Sp?)at SMB, (Jim and Peter?) at Atlas, my Amsoil dealer, and others, these were the potential places the fluid could have gone:
1) There is a double-seal in the connection between the Transfer case and Transmission and it could be damaged; the fluid could either be trapped between the two seals, or have bypassed the second seal and actually crept into the transmission. Eber had seen one instance of the fluid going the other way; the transmission fluid creeping into the transfer case (TC), however he had not seen the reverse. The Transmission holds I think 14 Quarts of fluid total, so it would be difficult to gauge if just a quart of TC oil was making its way in. This would be the worst-case scenario, because the only way to definitively diagnose this would be to pull the transfer case and examine the seals, etc.
2) The U-joints can fling-off a certain amount of oil….check the area above the rotation; however probably not a quart in just 200 miles.
3) I noticed that there was some oil below the end-plate, aka Bearing Cover (the cast aluminum plate situated behind the sight-tube), held on by 4 hex-head cap-screws. I pulled mine and discovered that there was no seal behind this plate, only aluminum-to-aluminum mating surfaces. I used Red (High-temp) RTV Silicone gasket sealer and replaced the plate. You could tell that there had been Loctite Threadlocker Red used on these bolts, so I re-applied that to the bolts as well. I was kind of disappointed that this was never sealed originally. There remains still a slight bit of oil seepage around the bolt heads, but its very slight, and I doubt this was the reason for my larger loss. If you do this, remember to replace the shims properly prior to replacing the plate, and to keep the layer of sealant thin so as to not introduce too much end-play. Update: Advance-Adapters (Atlas) suggests using Loctite 518 Anaerobic Gasket Maker, and RTV on the bolts as your sealer to prevent fluid seeping-out, something I will do next time I open it up.
4) After replacing the end-plate and replacing the fluid, I drove around for a while. After getting back, I noticed that there was a large drop of oil seeping out between the TC body and the driver’s-side rear-corner of the bottom pan (the lowest point on the TC). I suppose that if the oil was seeping out of this corner, its possible that it went directly onto the roadway surface while driving; thus leaving no trace. There are 14 button-head cap-screws holding the pan on. I checked them and all required only minimal force to loosen. The bolt pattern is poorly-designed; as there are only 2 bolts per end-edge, and they are not situated near the corners…they could definitely use another bolt per end in order to keep the gasket tight in these corners. After removing a few of the bolts, I was again disappointed to discover that these bolts were never Loctited. I replaced all the bolts and torqued them to the recommended 10 Ft-Lbs, using Loctite Red. If you’re going to do this, a couple of Notes: A) The 2 bolts on either end of the pan are through to the gear-box, not blind, meaning that if you remove them while the TC is installed and full of oil, the oil pours out of the hole once you remove the bolt. Besides the mess, in order for the Loctite to work best, the bolt/threads have to be clean and dry. (Update: Advance Adapters recommends sealing these 4 bolts with RTV to prevent the seeping from these 4 bolts – they claim it’s the responsibility of the installer (SMB) to properly Loctite/seal these bolts.) Thus, plan on doing this the next time you change the fluid and drain thoroughly and clean before applying RTV/Loctite. By the way, IMHO, this through-hole design is insane; if even one of those 4 bolts worked their way loose on the trail, you would lose 100% of your lubricant within 1 minute, and probably wouldn’t realize it until it was way too late. B) The bolts installed were button-head cap-screws with T40 Torx-Plus drive….not Torx but ‘Torx Plus’….. ‘Torx Plus’ is a new improvement over regular Torx, the star tips are more rounded, and it allows for greater torque. However, the regular Torx drivers (which I own) are just a bit small, and start slipping at around 8-10 Ft-Lbs. After stopping at NAPA, Home Depot, three different Auto stores, 2 specialty tool sores and Sears, I gave up looking for a Torx-Plus T40 driver-bit. I know they can be pre-ordered at NAPA, or ordered online at Sears, but I wanted it that day. You can also buy them from your Snap-on dealer for about $269/set. So, if you’re going to do this, plan ahead and pre-order a Torx plus T40 driver from Sears for $7. C) I found conflicting information in the documentation and SMBForum on what type of lubricant to use: However both Atlas and SMB agree that 2 Qts. (for the 2-speed TC) of Amsoil MTG GL-4 75W-90 is preferred. D) Nowhere in the Atlas documentation is the oil-filling method detailed…The best way is to loosen the upper sight-tube fitting, and use a hand-pump ($11 at Amsoil; I am fortunate to be living just down the road from an Amsoil dealer) with a narrow conical fitting to pump the fluid into the male-fitting end.
After doing all this, I have driven for about 50 miles and have noticed the sight-tube lubricant level has not dropped, although there is still a drop of oil seeping-out from the lowest corner of the pan. I called Advanced-Adapters and they are going to send me a gasket so that I can replace it next time I have it open. I’m crossing my fingers that the above measures fixed the problem and it is not the transmission seal. Since I still have a bit of seepage at the corner, I will monitor it closely for the next several hundred miles. After that, once I have the gasket and Torx Plus T40 bit in hand, I suppose I will go back and re-seal everything properly, including using RTV sealant on those 4 end-bolts.
This whole process took me several hours of effort and caused me to cancel a weekend of camping, (not including hours looking for ‘Torx Plus’), so you might be better off to preemptively work these fixes into you otherwise regular maintenance schedules if you can.