Dexron in 1972 transfer case ??

[CCCC]

I am sort of an old-timer with a few old trucks, most of which only get driven a bit here and there. Consequently, none of them require much work or serious checking, but I am careful with them even though I may not be "up" on all the latest tricks, etc.

Yesterday decided to check all of the underside lubricants on a 72 Blazer that has only been driven about 900 miles in the past 11 years. I remember having filled the transfer case with gear oil way back when after I installed new seals in it. When I opened the top plug on the NP transfer case expecting to poke my finger in to check the gear oil level - surprise - instead got a rush of pretty red liquid that looks and smells for all the world like Dexron. Clearly the case was over-filled with the stuff.

About 1200 miles ago I had a shift kit and new seals installed in the T350 and am supposing that the trans guy not only pulled the transfer case but also drained it and later refilled it - but with Dexron??

Or - I do not know how - but could the Dexron somewhow be leaking into the transfer case from the T350?

Can any of you guys with big 4X4 knowledge fill me in on this? The truck has not been run in 4WD since the trans work, so no problem in that regard. But is Dexron or something like it normal and OK in there?

Any info will be greatly appreciated.

[OrrieG]

np205?

[Stocker]

I heard years ago you can use either gear oil or ATF in NP205 or 208 transfer cases. My Clymer manual calls for Dexron II in both of those. However, I have Mobil 1 75W-90 in my NP205, which I put in before the manual was given to me.

There is a seal between the TH350 and the TC -- if it is leaking (as mine once was), it will force ATF from the trans into the TC, overfilling it.

[CCCC]

Thanks for responses so far.

The transfer case is an NP205. Not good to hear that a poor seal can allow trans fluid to be forced into the transfer case. That may be an issue in this instance. How common is this condition - anyone else experience this, and to what degree/amount of fluid?

[Livrat]

Its a common problem in a T350 equipped 205 with the two seals on the coupler sleeve.. often because of a worn bearing on the coupler shaft or input bearing on the transfer case.. Mine made it 9 years after a rebuild before it started filling up my transfer case with dextron.. I have been to busy/lazy to fix it, (I just keep adding dextron to the trans)

[Stocker]

Originally Posted by Livrat

I have been to busy/lazy to fix it, (I just keep adding dextron to the trans)

Good thing is, you never have to buy fluid... just drain the excess out of the TC and pour it back into the transmission!

[y5mgisi]

whoa whoa whoa... Not to hijack, but

CCCC;
67 Sting Ray Coupe 327 4sp
69 K20 LWB Lifted 383 4sp
69 C80 Fire Truck V6 478 5sp/2sp
69 C20 Longhorn 327 4sp
70 C30 Wrecker 350 4sp
70 C30 Flat Bed 350 4sp
70 GMC 3500 w Alaskan 350 4sp
71 C20 LWB 350 4sp
72 K5 Blazer CST 350/TH350
72 K5 Blazer 350 4sp
72 K5 Blazer Conv 350 4sp
72 3500 Utility w Lincoln Welder 350 4sp
72 C30 MoHome 350/TH400
72 C30 MoHome 402 4sp
72 C20 Longhorn 402 4sp
75 GMC 6000 Boom/Aerial 350 Allison Auto
52 Mack LTL Supercharged Cummins 5sp x 3sp
01 Dodge 5.9 HO Cummins 6spd



And Livrat;

68 GMC 3/4ton 4X4. 468,tach,tilt,AC,vac,spd warning,posi (a driver for 24 years)
71 Burb 4X4, 350,At,tach,tilt,roof AC,posi. (SOLD!!)
67 GMC 3/4 Ton 454,AT (rusty parts truck)
69 C10 Short SWB 350/350 project (FOR SALE)
72 Cheyenne SWB 6 cyl, T400 tach,tilt ps, AC (FOR SALE)
72 Sierra Grande 3/4 ton 4X4,tach,tilt, AC (SOLD!!)
72 Blazer 2WD,Tach, tilt,AC,454,700R4,posi (wifes)
72 Chev/Chinook Motorhome,350 AT,cruise (FOR SALE)
72 Blazer 2WD, 396, T400,posi (FOR SALE)
71 Blazer 2WD, 350/350 (FOR SALE)
70 Blazer 2WD, tach, tilt awaiting a dropmember, bags, a 427 and 700R4,
72 CST Blazer 4x4
72 Blazer 350,T350 4X4
71 Custom 2WD pickup (wifes driver)
68 "Kodiak" crewcab project
34 Stude Dictator.. (FOR SALE)
33 Stude 5W Coupe awaiting a 392 Hemi
54 Stude Champion Lowboy coupe
56 Stude Power Hawk (donor for the 53)
71 Harley Electra Glide bagger
77 Harley Electra Glide Bagger
79 Avanti II, L82, T400
94 S10 extended cab,4.3 loaded.. econo box driver
Livrat is offline Report Post Reply With Quote

Are you kidding me?
Thats awesome! Quite the collection.

[CCCC]

Possibly not a collection - maybe a disease. But, a great way to be sick - lots of fun.

[71blksuper4x4]

Originally Posted by CCCC

Possibly not a collection - maybe a disease. But, a great way to be sick - lots of fun.

This is true, I am on my way but you guys have some years on me. Trevor

[Bluehealercsf]

Yep, I've been having the same problem. Dropped the trans case 3 months ago to reseal for that problem and it lasted 3 months, takes a few weeks and I have to drain trans case and recycle back to transmission. Guess I missed something on tear down that is causing problems like that worn out bearing? Not looking forward to pulling the trans case out again...=(

[Livrat]

Originally Posted by CCCC

Possibly not a collection - maybe a disease. But, a great way to be sick - lots of fun.

YUP... Definately a disease!! and......... no 12 step recovery program... I can think of much worse addictions!! LOL....

[CCCC]

Well, the potential has proven to be reality. After two separate 1 hour test drives that ended with no apparent leaking of fluid from the transmission to the transfer case, I attributed the high level of Dexron in the transfer case to the transmission shop having purposely filled it with trans fluid instead of gear oil - and a little too much fluid at that.

WRONG !!

We kissed the old Blue Blazer goodbye this AM and my son in law and grand daughter set off on the 1800 mile drive up to Washington. After two hours of driving westward the truth came through - transfer case overflowing and transmission low on fluid. By this evening, having now dropped the transfer case, it is clear that the O ring on the shaft had hardened badly, the front transfer case seal seems hard as well, and the rear seal on the transmission should be replaced.

Can not detect any bearing wear or shaft play at all, so am going to assume that the cause is limited to aged and hardened/worn seals - will replace them and see if that does the job. Now, I am a true believer in what guys wrote above - this syndrome seems fairly common, even in the best maintained "K" models mated with T350 autos.

Sadly, this is one more confirmation of my decision of a couple of years ago to get rid of all automatics, even ones that I dearly love. To all who posted, thanks for the expertise and for taking the time to reply.

[Burt4x4]

I run 90w in my NP205

[chevy2racr]

my Th350 leaks into my 205 too, sometime I'll drop the t-case and replace seals